i

Best Practices in Sustainable Management of Membrane

Based Water Treatment Effluent Streams

Jon Colin Leonard: USF-ID U93852055

20 July 2012

Patel School of Global Sustainability

Best Practices in Sustainable Management of Membrane Based Water Treatment Effluent Streams

Master of Arts Project

by

Jon Colin Leonard

Supervisors Dr. Kalanithy Vairavamoorthy (USF) Dr. Kebreab Ghebremichael (USF)

University of South Florida Patel School of Global Sustainability

20 July 2012

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Abstract

Fresh water scarcity is a growing problem as the human population climbed through

seven billion in 2012. Water scarcity is also worse and worsening in areas of the greatest

population density and growth. Simply stated, the fresh water on Earth is not where we need it

and not in the quantities currently required. With fresh water withdrawals currently accounting

for around 50% of what is available; growing fresh water demand forces us to desalinate

seawater to maintain population growth and to support the increasing industrialization of

developing countries and other human activity. Membrane technology, such as reverse osmosis

(RO) and nanofiltration (NF) have displaced thermal distillation as associated energy costs have

declined due to energy efficiency of membranes. Unlike thermal distillation however, membrane

systems produce an environmentally toxic liquid concentrate stream. In coastal areas, RO

concentrate from seawater desalination plants may be simply and economically treated and

returned to the sea. Unfortunately, water desalination is moving inland as inland water supplies

are compromised, presenting difficulties for the sustainable disposal of concentrate streams from

reverse osmosis and other membrane-based water treatment systems and their attendant pre and

post treatment systems. Further complicating the growing use of inland desalination is the

addition of wastewater streams in an effort to wring every drop of fresh water from the water use

cycle. Wastewater from waste water treatment plants (WWTP) and from oil and gas production

operations contains toxins from pharmaceuticals to industrial solvents which must be removed

from the concentrate stream in addition to high levels of chlorides which membrane systems

efficiently concentrate. Finally, water use is directly tied to energy production which represents a

rapidly growing demand for freshwater.

The management of waste streams from membrane based systems, while more difficult in

inland systems, nevertheless present a challenge to the development of sustainable management

of both water and energy resources globally. The technologies of desalination, whether for the

desalting of seawater, brackish water, or even for water sources with relatively low chloride

levels, are situated directly between the environment and the economies of every region in which

they are deployed. Desalination mediates the supply and demand of water and energy and the

sustainability of this remediation requires mastery of the technologies and their impacts on the

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environment, but also the development and mastery of processes and policies that lead to

sustainable application and use of desalination technologies. This paper examines the technical,

economical, and socio-political forces that must be aligned to achieve sustainability with regard

to desalination, and provides a set of strategies and guidelines that may be used by engineers,

policy-makers, water users, and other stakeholders in the effort to achieve triple bottom line

sustainability whereby society, the economy, and the environment are preserved for generations.

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Table of Contents

Abstract ................................................................................................................................... ii

Table of Contents ................................................................................................................... iv

List of Figures ......................................................................................................................... v

List of Tables ......................................................................................................................... vi

List of Notations .................................................................................................................... vi

1 Introduction ............................................................................................................................. 1

1.1 Background ...................................................................................................................... 2

1.2 Problem Statement ........................................................................................................... 9

1.3 Objectives ....................................................................................................................... 10

1.4 Research Questions ........................................................................................................ 11

1.5 Significance/Justification ............................................................................................... 12

1.6 Scope of this Report ....................................................................................................... 13

2 Methodology ......................................................................................................................... 13

3 Work Plan ............................................................................................................................. 15

4 Expected Results and Recommendations ............................................................................. 16

5 Environmental Impacts of Concentrate Streams................................................................... 17

6 Models for Assessing Sustainability ..................................................................................... 27

7 Models for Designing Sustainable Water Resource Management Systems ......................... 31

8 Current Proven Technologies and Processes for Managing Concentrate. ............................ 36

9 Emerging Technologies and Processes for Managing Concentrate Streams. ....................... 43

10 Conclusions ........................................................................................................................... 61

11 Acknowledgements ............................................................................................................... 62

12 References ............................................................................................................................. 63

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List of Figures

Figure 1: Rendering of Polyamide Membrane .................................................................... 2

Figure 2: Water Stress ......................................................................................................... 4

Figure 3: Estimated Chemical Discharges ........................................................................ 22

Figure 4: Typical Steam and Cooling Loops in Power ..................................................... 25

Figure 5: General Model for Policy, Experts, and Public Interaction .............................. 28

Figure 6: Different Perspectives in Choice of Narratives ................................................. 29

Figure 7: Biodiversity Early Warnings ............................................................................. 30

Figure 8: MCA for MBDS ................................................................................................ 34

Figure 9: MCA for MBDS – IWRM/TBL ........................................................................ 35

Figure 10: Dual Pass Brackish/Seawater High Recovery RO System ............................. 41

Figure 11: Dual Pass Brackish/Seawater High Recovery RO P&ID ................................ 42

Figure 12: Emerging Concentrate Management Technology Funnel ............................... 44

Figure 13: Navigating the Universe of Concentrate Management Technologies ............. 45

Figure 14: Technology and Process Funnel for Emerging Technologies ......................... 47

Figure 15: Transport Processes in AGMD........................................................................ 49

Figure 16: Non-Dispersive Solvent Extraction ................................................................. 50

Figure 17: Eutectic Freeze Crystallization ........................................................................ 52

Figure 18: WAIV/MCr System ......................................................................................... 53

Figure 19: MDC Laboratory Unit ..................................................................................... 54

Figure 20: FO/RO ............................................................................................................. 55

Figure 21: RO/EDM ......................................................................................................... 56

Figure 22: EDM Module ................................................................................................... 57

Figure 23: ED in a Concentrate Management Water Train .............................................. 58

Figure 24: 3-D Model of EDR with Crystallizer and Settler ............................................ 58

Figure 25: Cutaway Illustration of Pellet Reactor ............................................................ 59

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List of Tables

Table 1: Common Contaminants ........................................................................................ 5

Table 2: Pharmaceutical Contaminants .............................................................................. 6

Table 3: Overview of Adverse Environmental Effects ....................................................... 8

Table 4: Characteristics of Concentrate and Backwash Streams ...................................... 18

Table 5: Comparison of Constituents in Seawater and Brackish Water Sources ............. 19

Table 6: Comparison of Raw Water and Concentrate Water Quality .............................. 21

Table 7: Water Quality in Artificial Wetland ................................................................... 26

Table 8: Common Current Concentrate Discharge Methods ............................................ 38

Table 9: Emerging MBDS Concentrate Management Technologies ............................... 46

List of Notations

AGMD Air Gap Membrane Distillation

BRWO Brackish Water RO

CDCC Cooled Disk Column Crystallizer

CWA Clean Water Act

DCMD Direct Contact Membrane Distillation

ED Electrodialysis

EDI Electrodeionization

EDR Electrodialysis Reversal

EFC Eutectic Freeze Crystallization

EIA Environmental Impact Assessment

EPC Engineering Procurement Contracting Firm

FO Forward Osmosis

GFD Gallons per Square Foot per Day

GPD Gallons per Day

GPM Gallons per Minute

HLIX Higgins Loop Ion Exchange

IWRM Integrated Water Resource Management

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IX Ion Exchange

LPD Liters per Day

LPM Liters per Minute

m3/d Cubic Meters per Day

MBDS Membrane Based Desalination Systems

MCA Multi-Criteria Analysis

MCr Membrane Crystallizer

MD Membrane Distillation

MDC Membrane Distillation Crystallization

MED Multi Effect Distillation

MEDC Multi Effect Drying and Condensation

MM Multimedia Filtration

NF Nanofiltration

NTBC Non-Thermal Brine Concentrator

OEM Original Equipment Manufacturer

PBEMS Product Based Environmental Management System

PPB Parts per Billion

PPM Parts per Million

RO Reverse Osmosis

SDI Sustainable Development Indicators

SWRO Seawater RO

TDS Total Dissolved Solids

TFC Thin Film Composite

TSS Total Suspended Solids

UF Ultrafiltration

VEMD Vacuum Effect Membrane Distillation

V-MEMD Vacuum Multi Effect Membrane Distillation

WAIV Wind Aided Intensified eVaporation

WWTP Waste Water Treatment Plant

ZDD Zero Discharge Desalination

ZLD Zero Liquid Discharge

1

1 Introduction

From outer space, the Earth appears as a blue sphere – a water planet. In fact,

water covers over seventy percent of the planetary surface. This makes Earth a special

place in the documented universe where liquid water is a rare commodity. Appearances,

however, may be deceiving as the surface water on earth represents only 0.02% of the

Earth’s mass (Murakami, Hirose, Yurimoto, Nakashima, & Takafuji, 2002). Even more

deceiving is the fact that over ninety-seven percent of this water is seawater with an

average chloride level of thirty-six thousand parts per million which renders it unusable

in its natural state for land-dwelling inhabitants (Postel, Daily, & Ehrlich, 1996). Simple

arithmetic reveals that roughly 2.5% of the remaining water on the planet is freshwater

available for all of the land-based life, and that of the freshwater ecosystems in rivers,

lakes, ponds, and underground biomes. Unfortunately, much of the freshwater is

contained in the polar ice caps and in glaciers leaving only 0.77% of all water on earth for

use by biomes that are driven by freshwater consumption (Postel, Daily, & Ehrlich,

1996). The seven billion people on Earth are currently using approximately forty percent

of the available freshwater and are increasing their demand every day in spite of the fact

that the supply is extremely limited ( (Postel, Daily, & Ehrlich, 1996). It is increasingly

easy to empathize with the sailor in Samuel Taylor Coleridge’s epic poem, “The Rime of

the Ancient Mariner”:

“Water, water, everywhere,

And all the boards did shrink;

Water, water, everywhere,

Nor any drop to drink.”

This rather bleak picture is mitigated by the ingenuity of human beings who have

developed numerous techniques for removing the salt from brackish and seawater.

Together, these technologies are referred to as desalination. The oldest of these

techniques is to boil the water and capture and condense the resulting steam in a process

known as thermal distillation. This is an effective means for producing water with very

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low total dissolved solids (TDS) but thermal distillation requires a great deal of energy

per unit of purified water. Beginning with research in the 1940’s, an alternative to

thermal distillation began to emerge as a lower energy alternative which relies on the

principle of osmotic transport of ions across a semipermeable membrane. The newer

technology, known as membrane-based reverse osmosis (RO), has rapidly overtaken all

other technologies to hold an eighty percent share of desalination systems globally

(Greenlee, Lawler, Freeman, Marrot, & Moulin, 2009). The rapid adoption rate is due, in

large part, to the relative and increasing efficiency of reverse osmosis compared to

thermal distillation. Thermal distillation equipment cost on average three times more than

RO and requires ten times the electricity which has resulted in the dominance of RO as

the primary desalination technology, representing more than eighty percent of

desalination globally (Greenlee, Lawler, Freeman, Marrot, & Moulin, 2009).

1.1 Background

RO technology splits an incoming raw water stream into two paths; the product

water (permeate), or the de-salted water and the concentrate stream. The concentrate, or

brine stream contains all of the dissolved solids that were rejected by the RO membrane

and TDS levels that are twice that of the incoming feed water resulting in a waste stream,

in the case of sea water with

a TDS of over seventy-

thousand parts per million

(ppm). In the case of coastal

RO desalination, the

concentrate stream is usually

discharged into the open

ocean or bays where the

environmental impact has

been minimal (LaPointe &

Barile, 2004). With inland

desalination, however, there

are no oceans in which to discharge the concentrate, or brine waste stream (Brady,

[ Source: (Pankratz, 2011 )]

Figure 1: Rendering of Polyamide Membrane

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Kottenstette, Mayer, & Hightower, 2005). In the United States alone, over five hundred

desalination plants were running in 2002 and it is projected that “over $20 billion will be

spent worldwide over the next 20 years” (Brady, Kottenstette, Mayer, & Hightower,

2005). Additionally, high chloride levels are only one component of the waste discharge

stream of an RO. The concentrate from an RO may also include a host of chemicals from

antiscalants to antibiologicals. Figure 1 depicts the polyamide membrane surface

interacting with chlorides and water molecules.

Due to increasing demand and water scarcity there is great interest in recovering

water from RO concentrate but the number of alternatives is nearly equal to the number

of research papers and pilot studies of the problem. This presents a conundrum for

engineers who are tasked with designing desalination systems. Increasingly, the job must

include a plan for the recovery of water from concentrate and also a means of managing

the disposal of salts and other constituents in the waste stream in a sustainable way but

there are no clear best practices for achieving these goals. This paper examines the

problem of brine disposal and characterizes the current state of available technologies and

their application.

Several factors conspire to move RO desalination inland where brine disposal is

more problematic. The predominant factor is a result of the water/energy nexus. Water is

a key tool in the production of oil and gas with “roughly ten times more water is

produced than oil in many fields” (Brady, Kottenstette, Mayer, & Hightower, 2005).

Water is often used to get the last drop of oil out of oil fields as they play out but water is

increasingly used in a process called hydrofracking where enormous amounts of water

and a slurry of other chemicals is pumped into shale formations to liberate natural gas

and oil. This process produces equally vast quantities of contaminated water that must be

cleaned up before discharge using RO and a host of other technologies. On the electricity

production side of the equation, freshwater withdrawals in the U.S. for thermoelectric

cooling account for thirty-eight percent of total withdrawals (Shandling, 2012).

Additionally, base load power plants employ large high-flow/high-pressure boilers which

require high purity water to operate at all, while smaller plants require purer-than-

municipally-treated water to operate efficiently.

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Another factor driving the need to better manage brine streams is the increased

use of municipal wastewater as a water resource. This is accomplished by RO-based

water treatment trains because of RO’s high rejection of dissolved solids, cysts, viruses,

bacteria and some pharmaceuticals. Unfortunately, not all pharmaceuticals are rejected

and concentrations in RO brine are high enough to complicate disposal into water

supplies (Radjenovic,

Petrovic, Ventura, &

Barcelo, 2008).

The treatment of

formerly freshwater

resources that have been

contaminated to the point

of exceeding the U.S.

Clean Water Act (CWA)

maximum allowable

concentrations of salt is

another driver of the need

to use RO in inland parts

of the U.S (Brady, Kottenstette, Mayer, & Hightower, 2005). The situation is the same in

other parts of the world, such as rapidly developing and industrializing nations such as

China where most of the country is experiencing water stress. While the U.S. uses far

more water per capita than any other country, the increase in water demand is in the areas

of the world that are also experiencing the most water stress like China, India, Northeast

Brazil, the Middle East and Pakistan (Kabat & Schaik, 2002).

The migration of the demand for desalination inland may be the harbinger for the

end of substantial quantities of available freshwater. As fresh water supplies are

compromised as a function of water stress and increased withdrawals, and as demands

water reuse increase, desalination plants are becoming ubiquitous parts of the water

infrastructure regardless of their proximity to the sea. In addition, the number of harmful

chemical constituents in the concentrate stream of reverse osmosis systems begins to cast

doubt on the current practice of dumping RO concentrate into the oceans. Figure 1 is a

[Source: (Kabat & Schaik, 2002)]

Figure 2: Water Stress

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projection of water stress geographically in 2020 (Kabat & Schaik, 2002). As water stress

increases and migrates inland, the demand for efficient means of managing waste streams

from RO plants, whether municipal, industrial or commercial takes on greater and greater

significance in regard to the sustainability of water resources.

The problem of managing concentrate streams from RO plants begins with a

characterization of the chemical constituents that make up the waste stream. Obviously,

high chlorides are to be expected as they are concentrated out of the feed water stream.

The precise composition of RO concentrate is a function of the raw water fed to the RO,

chemical additives used to protect the membranes and other system components during

operation and maintenance such as antiscalants, flocculants, cleaning chemicals and

corrosion inhibitors. There is also wide variation in the feed water based on location

lending credence to the assertion that water is always a local problem. As noted by

Brady, et al, “most inland waters are enriched in calcium and depleted in sodium relative

to seawater” (Brady, Kottenstette, Mayer, & Hightower, 2005). Table 1, also from Brady,

et al, demonstrates the variation seen between a seawater reference value and several

cities in the Southwestern U.S. where water stress is already at extreme levels and where

surface waters must be treated to meet potable water standards.

Table 1: Common Contaminants (mg/L)

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[Source (Brady, Kottenstette, Mayer, & Hightower, 2005)]

As previously stated, more and more municipal wastewater is being reused in

municipal and even potable applications. RO is ideal for this purpose based on high

rejection rates for pathogens and for most pharmaceuticals (Radjenovic, Petrovic,

Ventura, & Barcelo, 2008). While this is good news for users of the RO permeate, the

high rejection rate of pharmaceuticals means that they find their way into the concentrate

stream in levels that are unacceptable for discharge into the environment.

Table 2: Pharmaceutical Contaminants

[Source: (Radjenovic, Petrovic, Ventura, & Barcelo, 2008) ]

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Table 2 from Radjenovic, et al, shows the concentration of twelve common

pharmaceutical compounds as they move through a typical water purification train

beginning with the raw water, then the permeates of nanofiltration (NF)membranes, the

permeate of RO membranes and finally the brine of RO membranes. Table 2 shows that

membrane-based water treatment systems are quite effective at concentrating common

pharmaceuticals (Radjenovic, Petrovic, Ventura, & Barcelo, 2008).

Another class of chemical contaminants that populate RO concentrate streams is

made up of additives that are almost always required to effectively operate an RO-based

water treatment train. These include “biofouling inhibitors such as chlorine and

halogenated organics, coagulants such as iron-III-chloride and polyacrylamide,

antiscalants such as H2SO4, antifoaming agents such as polyglycol, and high/low pH

cleaning chemicals such as detergents (dodecylsufate), EDTA, oxidants (sodium

perborate) and biocides (formaldehyde)” and sodium metabisulfite for dechlorination

(Lattemann & Höpner, Environmental impact and impact assessment of seawater

desalination, 2008). Heavy metals may also find their way into the concentrate stream

due to corrosion of water treatment system components. Of particular concern are

biofouling inhibitors which if left in the reject stream and discharged can wipe out

unintended species (Lattemann & Höpner, Environmental impact and impact assessment

of seawater desalination, 2008). Of all the chemical constituents in the RO waste water

stream, disinfectants pose the greatest risk to the health of the environment (Fritzmann,

Löwenberg, Wintgens, & Melin, 2007). The wide range of raw water, or feed water

conditions, and the variation in operational chemicals suggest the cause for the myriad

approaches to post-treatment of RO reject streams. Assuming that “dumping to drain” is

not a sustainable activity for inland desalination systems, nor for shallow coastal systems,

owing to the presence of contaminants that are not fit for discharge even into the open

ocean and that many coastal RO plants will be treating other sources than seawater, there

are several leading strategies for sustainably managing RO concentrate waste streams.

Table 3, from C. Fritzmann, et al, details the generally harmful impacts of RO

concentrate, and mitigation techniques for seawater desalination plants.

A key strategy in the treatment of RO concentrate for coastal seawater

desalination systems is the reduction or elimination of chemical pretreatment so that the

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chemicals and the compounds they create in the reject stream are not concentrated

requiring further water purification before disposal. This is a common emerging theme in

the design and operation of water trains for both seawater desalination and industrial and

municipal desalination of freshwater sources. Costs of chemicals has created a desire to

lean more heavily upon mechanical solutions for water treatment and this has had the

desirable outcome of creating a mindset among water system engineers that minimizes

dependence on chemicals. The easiest and least expensive way to remove a contaminant

from a water stream is to prevent it from entering. This strategy includes using ultraviolet

disinfection or ozonation instead of chlorine or chloramines. Likewise, heavy metals

entrained in the water stream from corroding plant equipment may be avoided with

proper material selection in the design and specification process (Fritzmann, Löwenberg,

Wintgens, & Melin, 2007). System design also plays a role in determining the amount of

antiscalants that will be required for a give flux rate, that is the gallons of water that pass

through a square foot of RO membrane per day stated as GFD. Higher GFD rates are

possible with the use of additives like antiscalants in order to achieve the highest

production of permeate possible. This decreases the cost of water per cubic meter but it

also places a burden on the post treatment of concentrate prior to discharge. Again, the

best solution is the one that avoids contamination altogether. The second best approach is

to minimize the contamination.

Table 3: Overview of Adverse Environmental Effects Associated with Desalination

Processes:

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[Source: (Fritzmann, Löwenberg, Wintgens, & Melin, 2007)]

1.2 Problem Statement

The management of waste streams from membrane based systems, while more

difficult in inland systems, nevertheless present a challenge to the development of

sustainable management of both water and energy resources globally. The technologies

of desalination, whether for the desalting of seawater, brackish water, or even for water

sources with relatively low chloride levels, are situated directly between the environment

and the economies of every region in which they are deployed. Desalination mediates the

supply and demand of water and energy and the sustainability of this remediation

requires mastery of the technologies and their impacts on the environment, but also the

development and mastery of processes and policies that lead to sustainable application

and use of desalination technologies.

Currently, the process of research, engineering and building desalination systems is

a highly regional process that often relies on policies that have not evolved to address the

hazards of concentrate streams from membrane based desalination systems leading to

environmental degradation and expensive remediation once policies and regulations catch

up. This “catch me if you can” process is counter to the notion of sustainability.

Additionally, there is no widely-accepted method for analyzing all available technologies

10

for a given water problem for technical fit, economic fit, environmental fit and societal

fit.

At the macro level, water treatment plants, wastewater treatment plants, power

plants and oil and gas operations often operate in a single environment from silos without

regard to how each are effecting, and are affected by each other, nor how the

environment and society are affected by their operations.

1.3 Objectives

This paper examines the technical, economical, and socio-political forces that must

be aligned to achieve sustainability with regard to desalination, and provides a set of

strategies and guidelines that may be used by engineers, policy-makers, water users, and

other stakeholders in the effort to achieve triple bottom line sustainability whereby

society, the economy, and the environment are preserved for generations.

Firstly, planners and engineers need a set of tools for assessing the environmental

impact of their proposed plant, especially with regard to water resource management.

This paper will present current best practices in environmental impact assessment (EIA)

and suggest a consolidated model tailored for water resources to form a baseline set of

project objectives in terms of sustainability; water resource/environment, economic, and

social. This tool will also advocate the cross-functional and cross-utility review of power

and water management for the region in question to eliminate the risk of one element

working at cross purposes with another. The output of this tool is a defined current state

of sustainability, a set of sustainability indicators, and a defined future state of

sustainability in the area including future sustainability metrics and non-metric indicators.

This process should take into account the capability of current policies and regulations in

relation to the desired future state, and anticipate required changes to stay ahead of the

sustainability policy curve, if not to drive the definition and direction of that curve.

Naturally, this process will require a stakeholder engagement approach that may be quite

different from the current process of EIA and permitting in a given region. Regardless of

the current state of policy, it will be recommended that the current stakeholders develop

solutions that are sustainable, even if policy and regulations are inadequate to define

sustainability in light of the emerging environmental, economic and social realities.

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Secondly, once the current state of the environment is known, and a desired future

state defined, plant designers need a tool to evaluate available technologies and

techniques with regard to their capability of delivering the desired transition between

current and future states of sustainability. There are no current resources that define

current and existing technologies in one place where engineers and managers can avail

themselves of technical and cost data. This paper will present a list of current

technologies and practices that are proven for their capability and reliability to manage

contaminants in waste streams from MBDS, along with a suggested model for selection

of those technologies across technical, economic, environmental and social dimensions.

Thirdly, engineers and managers need a live funnel of emerging technologies as

they move from theory, to the lab bench, into pilot testing and finally full scale testing.

This paper will present a list of emerging technologies, techniques, and concepts in all

phases of development, along with a suggested process for keeping the technology funnel

full and up-to-date.

1.4 Research Questions

• What are the environmental impacts of concentrate streams and other effluent streams

from MBDS?

• How do those streams differ from one location to another?

• How do those streams differ from one type of geography/hydrology?

• How do water and energy interact and what are the impacts of that interaction?

• How does wastewater reuse impact MBDS waste streams?

• What are the best models for assessing sustainability?

• What are the best models for designing sustainable systems across resources, especially

water resources?

• What are the current proven technologies/processes for managing wastewater streams

from MBDS?

o What are their costs?

Capital

Operational

o How do they operate and interact with other technologies?

o What are their operational capacities?

o What are their pros and cons?

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Economic

Environmental

Social

o How do they compare with rival technologies?

o How are the technologies trending with regard to acceptance and adoption?

• What are the best methods of evaluating an ideal water train for managing wastewater

streams from MBDS?

• What are the emerging technologies/processes for managing wastewater streams from

MBDS?

o Where are they in their development cycles?

o What are their costs?

Capital

Operational

o How do they operate and interact with other technologies?

o What are their operational capacities?

o What are their pros and cons?

Economic

Environmental

Social

o How do they compare with rival technologies?

o How are the technologies trending with regard to acceptance and adoption?

o How can one create and maintain a living technology/process funnel for use by

stakeholders, engineers, and managers?

1.5 Significance/Justification

This paper seeks to address a growing problem with the management of wastewater

streams from MBDS and to make it easier to view the problem from the standpoint of

sustainability of water resources in particular. Knowledge is often regionalized with

engineers reinventing the wheel for a particular problem that may have been solved, or

solved in a better way in another region or another industry. The variation in this

approach represents wastes in the forms of duplicated efforts, less effective designs, and

most importantly, solutions that are not optimally sustainable across the economic,

environmental, and social dimensions.

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This paper will provide a way forward from this current state that has been

identified by engineers at many EPC firms as inadequate and so far unsolved by the

myriad original equipment manufacturers working individually.

1.6 Scope of this Report

This paper addresses membrane based desalination systems in the context of water

resource sustainability, including seawater, brackish, and fresh water across the

economic, environmental, and social dimensions of sustainability. It examines the state of

the art of technology, practice, environment, economics and society from a minimum of

15 countries across North America, Europe, Asia, The Middle East, India and Australia.

The research of the current literature has determined the geospatial scope. The research is

based on articles from peer reviewed journals, conference proceedings, interviews and

dissertations from that last 12 to 15 years, although care has been taken to select

resources from as recently as possible, particularly with regard to evaluation of

technology.

2 Methodology

The method of this research has been the careful review of the most recent data

available on each of the questions put forth in section 1.4 “Research Questions”. This

process began in the Spring Semester of 2012 whereby the topics surrounding MBDS

waste streams were selected for any research paper or project possible across the four

courses I completed. This research included review of articles from peer reviewed

journals, conference proceedings, interviews and dissertations.

The second phase of research also included review and analysis of articles from peer

reviewed journals, conference proceedings, interviews and dissertations on site at

UNESCO-IHE in South Holland. Being on site granted me access to the IHE library, TU

Delft’s research resources, and difficult to obtain conference proceedings from 2011 back

to 2004. The significance of these proceedings is their timeliness and greater level of

detail in what is to many researchers a niche area. Being at UNESCO-IHE also afforded

me guidance from Dr. Maria Kennedy and Dr. Sergio Salinas who were enthusiastic in

their support and guidance regardless of their busy schedules. It was also fortuitous that I

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was able to make the acquaintance of several PhD candidates who were generous enough

to listen to my research approach and provide feedback. Tessa van den Brand, of KWR

Watercycle Research Institute in Delft in particular provided papers and keen insight on

wastewater treatment plants and emerging practices and alternatives that pulled me into

productive areas of research and provided confidence in an area that has been “over the

fence” for me since my career in water began nearly 15 years ago.

The third phase of my research will begin the week of May 24th with a trip to the

New Orleans, LA area to meet with EPC’s and end users / owners of water systems. I

will engage the “water doctors” at these firms and businesses to obtain feedback on key

concepts of my research so far and seek criticism or confirmation of my analysis and

proposed action.

The fourth phase of the research will be to approach several key water doctors at

major EPC’s (Fluor – Dennis McBride/Rafiq Janjua, Burns and MacDonnell – Cliff

Crosman, KBR – Glen Rider, CH2M Hill, Bechtel, and other members of the

International Water Conference), as well as consultants like Paul Puckorius and David H.

Paul who have offered to challenge my research and provide feedback. These people are

at the top of their professions and I highly value their opinions.

The fifth and final phase, occurring concurrently with phase four, will be a review by

select application engineers at Crane Environmental (Crane Water). I am looking for

feedback from them, but also to encourage the development of the technology funnel in

the form of a product development/adoption roadmap for Crane Water, and the

immediate development of a Crane Water University training module on Management of

Waste Streams from MBDS. This module will be used to educate engineers at EPC’s

across North America as part of our ongoing Lunch and Learn program for providing

continuing education units to engineers and increase our customer intimacy. This putative

sixth phase, while outside scope of this report, will provide a means of further refinement

and a way of influencing the thinking of the engineers who sparked the notion of this

research in the first place.

15

3 Work Plan

Wastewater Stream Management from Membrane Based Desalination Systems

Research Action Plan (Macro) - Strategy Deployment

Action Step Owner Assisting Planned Dates Ja

nFe

bMa

rAp

rMa

yJu

nJu

lAu

gSe

pOc

tNo

vDe

c

Phase 1Opportunistically seek out assignment oppurtunities in Spring 2012 Classes C. Leonard Various 29-Apr-12 C

Phase 2Research at UNESCO-IHE, TU Delft C. Leonard Various 19-May-12 C· What are the environmental impacts of concentrate streams and other effluent streams from MBDS?

C. Leonard Various 20-May-12 C

· How do those streams differ from one location to another? C. Leonard Various 21-May-12 C· How do those streams differ from one type of geography/hydrology? C. Leonard Various 22-May-12 C

· How do water and energy interact and what are the impacts of that interaction?C. Leonard Various 23-May-12 C

· How does wastewater reuse impact MBDS waste streams? C. Leonard Various 24-May-12 C· What are the best models for assessing sustainability? C. Leonard Various 25-May-12 C· What are the best models for designing sustainable systems across resources, especially water resources?

C. Leonard Various 26-May-12 C

· What are the current proven technologies/processes for managing wastewater streams from MBDS?

C. Leonard Various 27-May-12 C

o What are their costs? C. Leonard Various 28-May-12 C§ Capital C. Leonard Various 29-May-12 C§ Operational C. Leonard Various 30-May-12 Co How do they operate and interact with other technologies? C. Leonard Various 31-May-12 Co What are their operational capacities? C. Leonard Various 1-Jun-12 Co What are their pros and cons? C. Leonard Various 2-Jun-12 C§ Economic C. Leonard Various 3-Jun-12 C§ Environmental C. Leonard Various 4-Jun-12 C§ Social C. Leonard Various 5-Jun-12 Co How do they compare with rival technologies? C. Leonard Various 6-Jun-12 Co How are the technologies trending with regard to acceptance and adoption? C. Leonard Various 7-Jun-12 C· What are the best methods of evaluating an ideal water train for managing wastewater streams from MBDS?

C. Leonard Various 8-Jun-12 C

· What are the emerging technologies/processes for managing wastewater streams from MBDS?

C. Leonard Various 9-Jun-12 C

o Where are they in their development cycles? C. Leonard Various 10-Jun-12 Co What are their costs? C. Leonard Various 11-Jun-12 C§ Capital C. Leonard Various 12-Jun-12 C§ Operational C. Leonard Various 13-Jun-12 Co How do they operate and interact with other technologies? C. Leonard Various 14-Jun-12 Co What are their operational capacities? C. Leonard Various 15-Jun-12 Co What are their pros and cons? C. Leonard Various 16-Jun-12 C§ Economic C. Leonard Various 17-Jun-12 C§ Environmental C. Leonard Various 18-Jun-12 C§ Social C. Leonard Various 19-Jun-12 C

Factors to Consider

Target to Improve

Action Plan

Currnent work environment will not allow for a contiguous 6-week absence. Will need to phase project research to include 3 weeks of paid time off (PTO) in Delft, and the remaining 3 weeks in the USA.

Define a process for evaluating current state of sustainability around MBDS and defining and implementing a desired future state. Define a process for technology selection and maitaining a clear view to emerging technologies.

TeamC. Leonard, K. Gebramichael, K. Vairavamoorthy, R. Pape, et al.

Strategic Priority OwnerDefine Best Practices in the Management of Waste Streams from Membrane Based Desalination Systems (MBDS) Colin Leonard

16

o How do they compare with rival technologies? C. Leonard Various 6-Jun-12 Co How are the technologies trending with regard to acceptance and adoption? C. Leonard Various 7-Jun-12 C· What are the best methods of evaluating an ideal water train for managing wastewater streams from MBDS?

C. Leonard Various 8-Jun-12 C

· What are the emerging technologies/processes for managing wastewater streams from MBDS?

C. Leonard Various 9-Jun-12 C

o Where are they in their development cycles? C. Leonard Various 10-Jun-12 Co What are their costs? C. Leonard Various 11-Jun-12 C§ Capital C. Leonard Various 12-Jun-12 C§ Operational C. Leonard Various 13-Jun-12 Co How do they operate and interact with other technologies? C. Leonard Various 14-Jun-12 Co What are their operational capacities? C. Leonard Various 15-Jun-12 Co What are their pros and cons? C. Leonard Various 16-Jun-12 C§ Economic C. Leonard Various 17-Jun-12 C§ Environmental C. Leonard Various 18-Jun-12 C§ Social C. Leonard Various 19-Jun-12 Co How do they compare with rival technologies? C. Leonard Various 20-Jun-12 Co How are the technologies trending with regard to acceptance and adoption? C. Leonard Various 21-Jun-12 Co How can one create and maintain a living technology/process funnel for use by stakeholders, engineers, and managers?

C. Leonard Various 22-Jun-12 C

Phase 3Meet with EPC's in New Orleans Area and Obtain Feedback C. Leonard Various 26-May-12 C

Phase 4Seek feedback in person and via telecommunications from Industry Leaders C. Leonard Various 15-Jun-12 C

Phase 5Seek Feedback in person from Crane Environmental Application Engineers C. Leonard Various 29-Jun-12 C

4 Expected Results and Recommendations

Firstly, planners and engineers need a set of tools for assessing the environmental

impact of their proposed plant, especially with regard to water resource management.

This paper will present current best practices in environmental impact assessment (EIA)

and suggest a consolidated model tailored for water resources to form a baseline set of

project objectives in terms of sustainability; water resource/environment, economic, and

social. This tool will also advocate the cross-functional and cross-utility review of power

and water management for the region in question to eliminate the risk of one element

working at cross purposes with another. The output of this tool is a defined current state

of sustainability, a set of sustainability indicators, and a defined future state of

sustainability in the area including future sustainability metrics and non-metric indicators.

This process should take into account the capability of current policies and regulations in

relation to the desired future state, and anticipate required changes to stay ahead of the

sustainability policy curve, if not to drive the definition and direction of that curve.

Naturally, this process will require a stakeholder engagement approach that may be quite

different from the current process of EIA and permitting in a given region. Regardless of

the current state of policy, it will be recommended that the current stakeholders develop

solutions that are sustainable, even if policy and regulations are inadequate to define

sustainability in light of the emerging environmental, economic and social realities.

17

Secondly, once the current state of the environment is known, and a desired future

state defined, plant designers need a tool to evaluate available technologies and

techniques with regard to their capability of delivering the desired transition between

current and future states of sustainability. There are no current resources that define

current and existing technologies in one place where engineers and managers can avail

themselves of technical and cost data. This paper will present a list of current

technologies and practices that are proven for their capability and reliability to manage

contaminants in waste streams from MBDS, along with a suggested model for selection

of those technologies across technical, economic, environmental and social dimensions.

Thirdly, engineers and managers need a live funnel of emerging technologies as

they move from theory, to the lab bench, into pilot testing and finally full scale testing.

This paper will present a list of emerging technologies, techniques, and concepts in all

phases of development, along with a suggested process for keeping the technology funnel

full and up-to-date.

5 Environmental Impacts of Concentrate Streams and other Effluent Streams

from Membrane Based Desalination Systems

The growth in demand for fresh water, coupled with the relatively scarcity of fresh

water has resulted in the rapid rise of membrane based desalination. In 2006, 39.9 million

m3/d of fresh water was produced (Holthus, 2011). In 2010, this figure grew to 64 million

m3/d and is expected to exceed 97 million m3/d in 2015 (Holthus, 2011). This growth rate

in the production of fresh water, or permeate, via membrane based desalination systems

(MBDS) is naturally accompanied by increased production of a concentrate stream of

highly saline waste water. In conventional seawater desalination systems, recovery of

fresh water is only 35 to 40%, meaning that the projected 97 million m3/d of fresh water

produced from MBDS in 2015 will produce an estimated 149 to 162 m3/d of highly saline

waste water (Gottberg, Pang, & Talavera, 2005). In addition to concentrate streams form

MBDS, there are also backwash streams stemming from attendant technologies such as

ultrafiltration and microfiltration which are often employed in MBDS as prefiltration. In

most cases, the backwash streams are infrequent enough, and of low enough overall

volume to contribute little to the problem of MBDS waste streams in the coastal setting.

18

Table 4: Characteristics of Concentrate and Backwash Streams

Source: (Mickley, 2001)

The environmental impact of this growing waste stream depends on the location of

the waste stream, the concentration of salts and other constituents in the receiving water

body, the waste stream, and the treatment and disposal scheme applied to the waste

stream (Mickley, 2001). There are three primary types of environments for discharge of

concentrate from MBDS; open ocean, shoreline, and inland (Greenlee, Lawler, Freeman,

Marrot, & Moulin, 2009). The simplest and least detrimental case is open ocean, while

the most difficult and potentially damaging case is inland concentrate discharge. In all

three cases, efforts to improve the efficiency of MBDS, driven by sensitivity to costs can

increase the concentration of chemicals, such as antiscalants, which are sequestered in the

concentrate stream (Campbell & Jones, 2005). Antiscalants enable greater system

recoveries by allowing reverse osmosis (RO) systems to run at higher pressures and

greater flux rates, as represented by gallons of permeate per square foot of membrane per

day, or GFD (Campbell & Jones, 2005). Naturally, greater efficiencies in recovery of

fresh water from seawater also increase relative concentration of contaminants in the

19

concentrate stream. The table below illustrates common constituents found in seawater

and brackish water sources.

Table 5: Comparison of Constituents in Seawater and Brackish Water Sources

Source: (Greenlee, Lawler, Freeman, Marrot, & Moulin, 2009)

The impact of MBDS concentrate stems from three basic characteristics: “pH,

density, and toxicity” (Bloetscher, et al., 2006). RO systems produce “concentrate that is

generally lower than most surface waters” and the total dissolves solids (TDS) are

naturally much higher than the source water (Bloetscher, et al., 2006). Both changes “add

toxicity to marine environments” (Bloetscher, et al., 2006). “The imbalance of ions in RO

concentrate was identified to be the cause of acute toxicity in freshwater and marine

organisms” (Bloetscher, et al., 2006) (Mickley, 2001). Mickley has identified “calcium,

fluoride, and potassium as the “ions which appear likely to cause problems” (Bloetscher,

et al., 2006). Current and emerging solutions for mitigating environmental and

sociopolitical impacts of concentrate disposal will be addressed later in this report, but

the scope of the problem, based on the location of MBDS requires clarification.

Open Ocean Desalination

In the open ocean, disposal of concentrate from MBDS presents few challenges to

the environment. The sheer volume of ocean water compared to MBDS concentrate

20

streams coupled with the fluid dynamics of ocean currents quickly mixes and dilutes the

concentrate stream to background levels (Mickley, 2001). The case of open ocean

concentrate discharge is also less environmentally impactful because of the relative low

volume and size of MBDS plants on the high seas (Mickley, 2001). Given sufficient

depth, the issue of slightly negative buoyancy of MBDS effluent is negated by diffusion

and mixing in the water column to the degree that benthic species occupying the ocean

floor are not at risk (Mickley, 2001). In the open sea, pH, ion concentration, and toxicity

are effectively dealt with by the aforementioned natural phenomenon, which is itself a

strategy for dealing with the harmful effects of concentrate disposal (Campbell & Jones,

2005).

Coastal Desalination

Compared to open ocean MBDS, coastal desalination plants pose significant risks to

benthic species and the social and economic processes that depend upon them

(Bloetscher, et al., 2006). Coastal waters, especially estuaries, are sensitive to changes in

pH and ion concentrations (Mickley, 2001). As coastal desalination has continued on a

rapid adoption curve, driven by increased demand for fresh water and the ever-increasing

efficiency of MBDS, the common practice has been to depend on nature to absorb and

respond to the introduction of concentrate streams into coastal surface waters. According

to Mickley, “Nature can only do so much, and the assimilative capacity of the receiving

waters [has been] exceeded and pollution [has] resulted” (Mickley, 2001).

Of key concern in the coastal regions is the key role these biomes play in the life

cycle of countless species of plants and animals that depend upon these fragile

ecosystems. These ecosystems are fragile webs of interdependencies for wildlife but also

for human beings who lean on those systems for fishing, recreation, tourism, industry and

other uses which form the basis of coastal cultures and economies (Mickley, 2001). As

Holthus points out, “Desalination is taking place in an increasingly crowded and

complicated coastal and nearshore seascape of competing ocean users. Offshore oil and

gas, shipping, ports, submarine pipelines, marine tourism, renewable energy, [and]

recreation […] all may potentially affect, or are affected by, desalination operations”

(Holthus, 2011). This crowded environment complicates any mutually beneficial water

quality specification that serves the environment, society, and the economy that is a

21

necessary step in addressing the problem of concentrate discharge. The following table

depicts the ions found in various raw water and concentrate streams.

Table 6: Comparison of Raw Water and Concentrate Water Quality for Different

Water Types in Hollywood, Florida

[Source: (Bloetscher, et al., 2006)]

The Arabian Gulf presents a study in the widespread use of coastal desalination. The

countries surrounding the Arabian Gulf were early adopters of seawater desalination,

using abundant energy resources to build massive thermal distillation plants to supply

rapidly growing urban centers with fresh water (Lattemann, Development of an

Environmental Impact Assessment and Decision Support System for Seawater

Desalination Plants, 2010). As shown by Lattemann, “the combined discharge of

concentrate into the Arabian Gulf is nearly 1.6 million m3/d” which “compares to the

Shatt Al-Arab river, between Iraq and Iran which produces flows of just over 2 million

m3/d” (Lattemann, Development of an Environmental Impact Assessment and Decision

Support System for Seawater Desalination Plants, 2010). The epic combined flow of

concentrate into the Gulf results in the daily discharge of “23.7 metric tons (t) of chlorine,

64.9 t of antiscalants, and 296 kg of copper” (Lattemann, Development of an

Environmental Impact Assessment and Decision Support System for Seawater

Desalination Plants, 2010). Unfortunately, as Lattemann points out, a lack of adequate

data monitoring masks any deleterious effects from this massive influx of chemicals, but

the increased salinity and chemical content, including eight heavy metals, of the near

22

shore Gulf represent a massive experiment without adequate observation (Lattemann,

Development of an Environmental Impact Assessment and Decision Support System for

Seawater Desalination Plants, 2010).

In the graph below, the extent of implementation of desalination in the Gulf region

can be seen which includes thermal distillation, represented by multi-stage flash

distillation (MSF) and multi-effect distillation, as well as RO. The density of seawater

desalination in the Gulf is the highest in the world and provides a glimpse into the future

of coastal desalination across the globe as coastal population density increases and fresh

water scarcity increases.

Figure 3: Estimated Chemical Discharges of Chlorine (top), Copper (middle) and

Antiscalants (bottom) in the Arabian Gulf in kg/d

[Source: (Lattemann, Development of an Environmental Impact Assessment and

Decision Support System for Seawater Desalination Plants, 2010)]

23

It is a relatively simple thought experiment to imagine the density of desalination

plants mapped out against all of the high population density areas across the globe. It is

also equally unimaginable to do so without conclusive evidence of the environmental

safety of such an imagined future. The lack of conclusive evidence of widespread

ecological damage is not evidence that no damage is taking place. Lattemann observes

that “impacts from desalination activities may be overshadowed by other sources of land-

based pollution or anthropogenic activity, such as the permanent oil burden, or land

reclamation” (Lattemann, Development of an Environmental Impact Assessment and

Decision Support System for Seawater Desalination Plants, 2010).

As coastal desalination continues to expand, it would be prudent to project the

expected effluent outflows onto ecosystems around proposed projects and design

experiments to determine the impact to each unique biome. In the United States, for

instance, California, along with several other states, has enacted policy which requires the

pilot testing for any new coastal discharge. Mike Tache, P.E., project engineer with Black

& Veatch in Walnut Creek, California, described the pilot system his team was required

to build as proof that the outflows from a proposed municipal MBDS would not harm the

local ecosystem. “We built a small 1,500 GPD RO system and mixed the concentrate

with an accurately scaled volume representing the changeover rate in the bay. Both flows

were contained in a scaled catchment where native fish and plant species were cultivated.

The system was operated for one month and examined for negative impacts.” (Mike

Tache, 2012). The fact that the fish and plants survived the simulated flows allowed

Black & Veatch to proceed with engineering the full scale desalination plant, but this

method, as practical as it may seem, fails to take into consideration the interaction of the

full scale plant with other flows and uses of water in the area.

Inland Desalination

The relatively forgiving favorable mixing, dilution, buffering, and volume of

water characterizing the environments surrounding coastal desalination systems are all

absent in inland desalination scenarios. While the raw water TDS is generally much

lower in water resources available to inland MBDS, there are also severe limitations on

the disposal of effluent from desalination systems. The use of concentrate blended with

24

irrigation water supplies results in a gradual buildup of chlorides and other concentrate

constituents in the soil, and eventually surface waters.

The increasing salinity of natural inland water resources in South Western United

States foreshadows the global future of fresh water resources. In Southern California, the

Colorado River and other water supplies have grown increasingly saline to the point of

“exceeding the U.S. Public Health Service standard” (Glater & Cohen, 2003). Naturally,

surface water discharge of RO concentrate and pretreatment effluent in areas with

increasing surface water salinity is contraindicated. Complicating matters, in most parts

of the developed world, water treatment and wastewater treatment capabilities are

manage separately. This results in a concentrate stream created by water treatment

authorities being discharged to sewer where wastewater authorities must deal with

constituents in the waste stream with little input into the process.

In the United States, the National Pollutant Discharge Elimination System

(NPDES) and NPDES II were established to protect the environment from industrial and

municipal pollution but testing of MBDS effluent, including RO concentrate streams “is

not part of the NPDES permitting process in states other than Florida” (Mickley, 2001).

This is particularly troublesome when wastewater plants provide treated water to

municipal and industrial water treatment plants whereby dangerous constituents such as

pharmaceuticals find their way into concentrate streams (Radjenovic, Petrovic, Ventura,

& Barcelo, 2008). According to Radjenovic, et al, “many chemical constituents that have

not been considered historically as contaminants are present not only in wastewater, but

also in natural waters at global scale” (Radjenovic, Petrovic, Ventura, & Barcelo, 2008).

The slow build-up of dangerous contaminants such as pharmaceuticals in the water to

wastewater treatment cycles is accelerated by MBDS technology which is very effective

at concentrating most pharmaceuticals in the waste stream where they are deposited into

the environment where they may disrupt plant and animal life cycles (Radjenovic,

Petrovic, Ventura, & Barcelo, 2008).

As the severity of water scarcity increases, so does the pressure on water users to

reuse more of the water flows, which in turn, introduces more contaminants into source

water feed flows introduced to MBDS. This dynamic greatly complicates the concentrate

management for inland desalination plants. This is particularly true of industrial water

25

users including power generation, pulp and paper manufacturing, oil and gas production,

petroleum refining, and chemical processing. In these industries, water is used in large

quantities as steam for myriad processes and for cooling in even greater quantities. Both

the steam loop and the cooling loop collect contaminants which must be removed

continuously or periodically by a process referred to as blow-down. This blow down

water is increasingly being targeted as an additional source of water which, in order to be

fit for reintroduction into the various manufacturing processes, steam loops, and cooling

loops, must be treated and purified, often by membrane based technologies. The

concentrate streams stemming from the reuse of blow-down water contain a long list of

contaminants from heavy metals to antiscalants. In the case of cooling loop blow-down,

heavy chemical use in cooling towers presents a particular challenge, as many of the

chemicals used are of proprietary formulations which form secondary and tertiary

chemicals and compounds which are difficult to manage in the purification process and

even more difficult to manage in concentrate streams. Currently, NPDES focuses

predominantly on TDS which does not begin to deal with the other contaminants in

cooling loop and steam loop blow-down water, or the concentrate streams from water

purification technologies (VandeVenter, et al., 2011).

Figure 4: Typical Steam and Cooling Loops in Power

[Source: the author]

26

The above scenario is further complicated by the desire of many municipalities to

use reclaimed water to supplement industrial feed water streams. The following table

illustrates the range of constituents found in reclaimed water from the 1,400 acre artificial

wetland system created by the city of Lakeland, Florida (VandeVenter, et al., 2011).

Table 7: Water Quality in Artificial Wetland: Lakeland, Florida

Parameter

Units

Effluent (Cell 7) Water Quality Intermed. (Cell 4) Water Quality Average Minimum Maximum Average Minimum Maximum

Conductivity µS/cm 1012.3 802.0 1119.0 1114.3 715.0 1334.0 Total Dissolved Solids m g/L 615.9 520.0 810.0 715.3 490.0 860.0 Turbidity NTU 4.3 0.6 10.6 15.7 1.2 72.6 Total Organic Carbon m g/L 15.5 11.0 18.0 15.3 9.9 23.0 Color CFU 61.2 10.0 100.0 72.1 15.0 120.0 pH Std. Units 7.9 6.7 8.7 7.3 6.9 7.7 Temperature °C 28.2 22.3 31.0 26.9 22.3 29.8 Total Suspended Solids m g/L 9.8 2.8 54.0 18.1 1.2 210.0 Hardness m g/L 247 220 270 256 200 320 Total Alkalinity m g/L 143 120 160 172 140 230 Hydroxide Alkalinity m g/L 0 0 0 0 0 0 Bicarbonate Alkalinity m g/L 143 120 160 172 140 230 Carbonate alkalinity m g/L 0 0 0 0 0 0 Antimony m g/L 0.004 0.004 0.004 0.004 0.004 0.004 Arsenic m g/L 0.004 0.004 0.006 0.004 0.004 0.006 Barium m g/L 0.004 0.002 0.022 0.008 0.004 0.014 Beryllium m g/L 0.001 0.001 0.001 0.001 0.001 0.001 Cadmium m g/L 0.0001 0.0001 0.0001 0.0001 0.0001 0.0001 Chromium m g/L 0.002 0.002 0.003 0.002 0.002 0.002 Copper m g/L 0.003 0.003 0.003 0.003 0.003 0.003 Iron m g/L 0.069 0.050 0.300 0.115 0.018 0.170 Lead m g/L 0.0003 0.0001 0.003 0.0001 0.0001 0.000 Nickel m g/L 0.003 0.002 0.004 0.005 0.003 0.014 Silver m g/L 0.001 0.001 0.002 0.001 0.001 0.001 Selenium m g/L 0.0005 0.0005 0.0005 0.0014 0.0006 0.0050 Thallium m g/L 0.005 0.005 0.005 0.005 0.005 0.007 Zinc m g/L 0.006 0.005 0.021 0.039 0.005 0.450 Sulfate m g/L 98.7 79.0 110.0 112.9 48.0 160.0 Total Phosphorus as P m g/L 2.024 1.600 4.100 3.038 2.500 3.900 Nitrate as N m g/L 0.100 0.100 0.100 0.112 0.100 0.520 Ammonia as N m g/L 0.115 0.010 0.250 0.170 0.010 0.910 Total Nitrogen as N m g/L 1.6 0.9 2.3 2.0 1.0 5.0 HPC m g/L 7,765 270 57,000 39,979 35 880,000 Chlorophyll-a, Dissolved m g/L 44.7 7.7 199.0 73.8 9.3 318.0

[Source: (VandeVenter, et al., 2011)]

As shown in the table, many of the contaminants are present in small amounts, but

these amounts are concentrated in membrane filtration systems, whether those systems

are used prior to or after a given industrial process such as cooling or steam. This

complex interaction of increasingly diverse water streams and inland desalination is the

27

emerging reality for water use and environmental pressure. As with coastal desalination,

monitoring is inadequate in distribution and in scope which obfuscates the extent of

threat posed by concentrate and effluent.

6 Models for Assessing Sustainability

Sustainability, for the purposes of this report, includes the ongoing multigenerational

survival of the global environment, the various societies that populate the global

environment, and the economies of those societies. This approach, referred to as triple

bottom line (TBL), people, planet, profit (PPP), and also environmental, social and

governance (ESG) has grown out of the realization that performance metrics that focus

only on profit, or only on the environment, or only on social concerns are myopic and

unlikely to garner the support and action required to achieve sustainability (Vlahov,

2010). The philosophy behind TBL is that sustainability requires reporting that

adequately measures outcomes across the dimensions of people, the planet, and profits in

order to protect all three and to unify people in making difficult decisions necessary to

effect that protection (Vlahov, 2010).

Along with TBL, another concept critical to sustainability is “Lean Thinking” which

was born of the lean manufacturing world of waste identification and elimination as well

as visual controls (Womack & Jones, 1996). While lean manufacturing evolved out of the

automotive industry, the concepts are rooted in the natural world where waste is nearly

nonexistent. In nature, ecosystems large and small maintain a dynamic balance between

perturbing forces. Energy is spent with amazing economy and any excess or waste in one

process is taken up opportunistically by another process or organism. With the exception

of the six or so mass extinction events throughout the Earth’s six billion year history, life

has adopted a waste not, want not strategy that imbues the planet with a level of precision

that we are only beginning to understand and appreciate (Gould, 2007).

The countless biomes across the Earth are tied together in a global web of

interdependencies of which people are inexorably linked. Up until the industrial

revolution, people generally existed within the limits of these diverse biomes and adapted

to make the most of whatever resources presented themselves. Industrialization afforded

people the opportunity to exploit resources at an unprecedented rate that is decoupled

28

from the local biome’s ability to react and assimilate the changes an industrialized group

of people can induce. TBL seeks to reintegrate people with the environment with the

understanding that human societies are rooted in the need to monetize materials and

efforts (Vlahov, 2010).

Assessing sustainability will of necessity require the establishment of baseline

data which adequately describes the current along with a specification for a desired future

state. As discussed in the previous section, assessing the current state of water quality and

environmental impact is hampered by a lack of sufficient monitoring. Current monitoring

schemes predate the rapid rise of MBDS and water reuse. In a broader sense, however,

the specification of TBL sustainability requires the selection of sustainability indicators

that adequately reflect all of the stakeholders including those, such as the plants and

animals that inhabit the same biomes as we do. While the definition of sustainability

models beyond those required for water resource management are beyond the scope of

this report, it is worth noting the overarching environment in which water resources

resides. The figure below illustrates the framework from which sustainability indicators

are developed (Aslasksen, Ericson, Funtowicz, Garnasjordet, & Giampietro, 2010).

Figure 5: General Model for Policy, Experts, and Public Interaction in the Development

of Sustainability Indicators

[Source: (Aslasksen, Ericson, Funtowicz, Garnasjordet, & Giampietro, 2010)]

29

Rather than forming a monolithic paradigm, sustainability means different things to

different stakeholders. It is critical that the attitudes of all stakeholders are understood at

the assessment stage. These attitudes form the current state from which the desired future

state will evolve. The radar graph below illustrates how various stakeholders occupy the

space identified as the importance of nature across the dimensions of resource harvesting,

ecosystem functioning, conservation values, and cultural values (Aslasksen, Ericson,

Funtowicz, Garnasjordet, & Giampietro, 2010).

Figure 6: Different Perspectives in Choice of Narratives, Biodiversity, and Importance of

Nature.

[Source: (Aslasksen, Ericson, Funtowicz, Garnasjordet, & Giampietro, 2010)]

Other stakeholders, such as the plants and animals inhabiting the environment, must

be represented by proxy. Sustainability indicators related to these stakeholders seek to

preserve biodiversity which is a key dimension of the environments ability to adapt to

change and assimilate perturbation without collapse. The figure below depicts a radar

30

graph populated with proposed sustainability indicators across the dimensions of priority

species, stress factors, governance, and important land areas (Aslasksen, Ericson,

Funtowicz, Garnasjordet, & Giampietro, 2010).

Figure 7: Biodiversity Early Warnings

[Source: (Aslasksen, Ericson, Funtowicz, Garnasjordet, & Giampietro, 2010)]

Finally, economic growth is represented across the dimensions of aspects of

economic growth, national policies, quality of life, and consumption as viewed by

economists and social scientists (Aslasksen, Ericson, Funtowicz, Garnasjordet, &

Giampietro, 2010). Aslasken, et al point out that it is especially important to pay attention

to the youth component among other age groups saying, “The true measure of a nation’s

standing is how well it attends to its children – their health and safety, their material

security, their education and socialization, and their sense of being loved, valued and

included in the families and societies into which they are born” (Aslasksen, Ericson,

Funtowicz, Garnasjordet, & Giampietro, 2010). Indeed, the first hurdle of sustainability is

31

to think far enough ahead to provide our children – the next generation – a world that is at

least as healthy and vibrant as the one we inherited from our parents. Water is central to

the sustainability of all life and the best model for assessing sustainability will give

adequate weight to indicators that protect water resources.

7 Models for Designing Sustainable Water Resource Management Systems

As detailed in the previous section regarding sustainability indicators, it is worth

stating that “what gets measured gets done” (Drucker, 1954). Peter Drucker coined this

phrase to emphasize the importance of the phenomenon of the body following where the

eyes focus. This effect is also powerfully demonstrated by the effectiveness of the visual

control systems perfected by Toyota and other manufacturers, hospitals, municipalities,

and even countries. The power of metrics is such that once defined and implemented,

they are difficult to change, but nature rarely offers static conditions for long. The

successful sustainable water resource management system will exercise the capability to

assimilate new data, and new data streams in response to the unfolding current state as

well as supporting migration from current state to desired future states. Nature

automatically follows a plan/do/check/adjust strategy which has resulted in the state of

dynamic equilibrium in evidence across the planet.

This report asserts that the best models for sustainability will embrace TBL and lean

thinking in order to provide a way forward with the least possible drain on resources, and

that efficiency is the hallmark of a sustainable system. In the context of well-chosen and

dynamic sustainability indicators, the best design for sustainable water resources

management systems is the one that addresses overall sustainability indicators in a least

waste way. Such a system will necessarily address the need for remediation of damaged

environments, societies, and economies, but the primary focus should be on the

prevention of damage. A theory of lean thinking promotes the notion of a steep curve

regard to prevention versus remediation (Womack & Jones, 1996). The least expensive

and most effective means of dealing with a problem is preventing its occurrence. Once a

problem occurs, it begins to become more expensive to mediate and the quality of the

outcome derived from mediation begins to suffer. Over time, a point of no return may be

reached whereby no amount of effort will successfully mediate the problem (Womack &

32

Jones, 1996). Another way of characterizing this effect is the concept familiar to medical

doctors of “first do no harm”. Both concepts promote a preemptive approach, which in

the realm of water resources means that the least expensive, most effective method of

ensuring water quality of a given specification is to avoid contamination in the first place.

In addition to TBL and lean thinking, another key ingredient, alluded to in the

previous section, is the integration of water resources management. The previous section

dealt with ascertaining adequate sustainability indicators across the spectrum of

stakeholders. This brings system planners and designers into contact with stakeholders

whose interests cross many sociopolitical and economic boundaries, yet water resources

are managed in silos. Water and wastewater treatment facilities are not only separate in

most municipalities, but the management and planning of those facilities are also largely

independent while both impact the other, particularly when viewed through the lens of

sustainability. There are examples of the successful integration of water resources

management that demonstrate the immediate benefit of integration among which is

Charlotte, North Carolina (Isbell, 2006). In Charlotte, the integration of water resources

management produced a first year savings of 20% which equated to $3 million in 2006,

which was immediately available for other water infrastructure and quality improvement

projects (Isbell, 2006). Integrated water resource management (IWRM) is more than

another tool in the management tool shed, it “is becoming recognized as the only

sustainable solution” (Durham, Rinck-Pfeiffer, & Guendert, 2002).

IWRM, however effective, does not exist in a vacuum and successful sustainable

management of water requires the recognition of the role water plays in energy resource

management as well (Durham, Rinck-Pfeiffer, & Guendert, 2002). Sustainable IWRM

“must be supported by legislation, agreed quality standards, finance, and ownership by a

single governing body responsible for all water resource issues” (Durham, Rinck-Pfeiffer,

& Guendert, 2002).

Sooner or later, however, the management of water resources requires the design,

engineering, manufacture, implementation, and operation of water purification systems.

Whether these systems are synthetic or remediated natural phenomena such as wetlands,

or complex technological marvels of science, the scarcity of fresh water mandates that

practical water purification takes center stage in order for people and the planet to have

33

the volume and quantity of water required for survival and growth. As previously

discussed, coastal desalination is expanding at a rapid pace, and now it is clear that

desalination is expanding inland where water quality is diminishing. This presents

requirement for a set of guidelines to plan and design MBDS that conform to the

specifications dictated by the broader sustainability planning effort. Since the demand for

water sets the expectations for social and economic performance of MBDS, the

environmental dynamics are the typical starting place for MBDS engineering. This

analysis is typically in the form of and environmental impact assessment (EIA).

“Environmental impact assessment studies are a widely recognized and accepted

approach for evaluating and mitigating potential impacts of large infrastructure projects

on the environment, and are usually also part of the permitting process for major

desalination developments” (Lattermann, Anarna, Schippers, Kennedy, & Amy, 2009). A

thorough EIA will deliver sufficient data, particularly within the framework of a solid set

of sustainability indicators, to feed the MBDS design process. Lattermann, et al have

created a formalized decision tool in the form of a “multi-criteria analysis” (MCA) tool to

“integrate the decision criteria and to highlight preferences (Lattermann, Anarna,

Schippers, Kennedy, & Amy, 2009). This particular multi-criteria approach that hinges

on the optimization of pretreatment systems, in the spirit of “first do no harm”

recognizing that the best way to treat harmful constituents in the MBDS outflow stream is

to eliminate their use on the front end of the process where pretreatment resides. The

MCA tool represents a scale version of the higher-level sustainability indicator

development process and is aided by a strong problem definition at the IWRM level.

The strength of the MCA is the ability to evaluate many alternatives against a set of

weighted criteria. This allows for the optimization of the MBDS across all of the

dimensions of sustainability including disparate stakeholder groups. This process may be

cycled through several rounds of optimization and ideally reviewed in forums to improve

transparency, facilitate communication and understanding, and subsequently achieve buy-

in among stakeholders (Lattermann, Anarna, Schippers, Kennedy, & Amy, 2009). Rules

governing the development of criteria ensure that they “add meaning to the objectives,

are independent, do not duplicate other criteria, and are few as possible in number to aid

in making a well-founded decision” (Lattermann, Anarna, Schippers, Kennedy, & Amy,

34

2009). In this regard, the MCA satisfies requirements of lean thinking which seek to

eliminate complexity and waste by streamlining the creation of value, which begins with

the problem statement and a specification for mediation in a least waste manner. The

figure below represents the MCA tool developed by Lattermann, et al to capture the

critical few criteria surrounding the design of MBDS.

Figure 8: MCA for MBDS: Objective-tree or Value Tree Hierarchy with Main Objective

(Left), Sub-objectives (middle) and Evaluation Criteria for the Sub-objectives (yellow)

[Source: (Lattermann, Anarna, Schippers, Kennedy, & Amy, 2009)]

35

The above application of the MCA tool for coastal MBDS has been amended for

inland MBDS to include the capture the importance of managing concentrate and effluent

streams in this more challenging environment. The resulting diagram depicts the role of

TBL and IWRM in the development of MBDS

Figure 9: MCA for MBDS: Objective-tree or Value Tree Hierarchy with Main Objective

Showing the MCA Relationship to TBL and IWRM

[Sources: Adapted from (Lattermann, Anarna, Schippers, Kennedy, & Amy, 2009)]

The above variant of the MCA for MBDS created by Lattermann, et al presents

stakeholders with a comprehensive graphic representation of alternatives and provides a

framework for the development of system specifications based on any number of water

36

and wastewater treatment technologies. Naturally, the MCA, as informed by TBL-based

sustainability indicators and driven by IWRM, depends upon these technologies and

naturally-occurring phenomena to move theory into practice and to safely convert

unusable water and unsustainable methods into fresh water in a sustainable manner.

Water treatment technologies, like many technologies are evolving at a rapid pace and are

the subject of the next two sections. It is also worth noting that these technologies with

their associated costs, capabilities, and side effects inform the IWRM and MCA

processes and influence the direction sustainability may take for given sociopolitical and

natural environments.

8 Current Proven Technologies and Processes for Managing Concentrate and

Effluent Streams from MBDS.

Unlike consumer electronics technology, water and wastewater treatment

technology possesses a very shallow and conservative adoption curve. This is due in large

part to the large capital expense required throughout a long project lifecycle. MBDS

plants can cost hundreds of millions of dollars and are designed to be in operation from

thirty to forty years. This produces a risk-averse atmosphere that permeates every phase

of development. Although reverse osmosis technology was commercialized in the 1970’s,

it was not until the late 1990’s that the technology began to gain a reputation as a reliable

technology. In fact, many senior engineers at well-established engineering, procurement,

contracting (EPC) firms still prefer to specify older technologies such as deionization

because of their long familiarity with the technology. Many of these engineers are only

grudgingly embracing RO while their less seasoned counterparts are hungry for

Electrodeionization (EDI), electrodialysis reversal (EDR), forward osmosis (FO) and

dozens of other specialized technologies that promise higher performance or greater

selectivity for contaminant removal.

When it comes time to spend a billion dollars on a water and wastewater

treatment plant, however, it is the proven technology that prevails. This environment is

characterized by large projects that are dominated by mature technologies while smaller

projects and pilot projects are consumers of emerging technologies. There are cases

where desperation drives planners to adopt leading edge and more risky technologies.

37

Such is the case with sectors of the oil and gas development industry where vast amounts

of wastewater are generated in the recovery of oil from tar sands or natural gas from the

fracturing of shale formations (Oasys Water, April). In these cases, the investment is

outweighed by the returns from the ability to continue to exploit an energy resource. In

other cases, the adoption of unproven technologies results from tightening discharge

regulations at existing facilities, or emerging environmental concerns.

While leading edge technologies do not typically find their way into large

infrastructure projects, their adoption in an experimental fashion informs the water and

wastewater treatment community and paves the way for innovation in dealing with

concentrate and effluent streams that were previously of little concern to plant designers.

Communication surrounding effective technologies for dealing with wastewater streams

suffers from the silos that still surround water and wastewater communities. Therefore,

the slow adoption process is further slowed by a lack of channels for cross-functional and

cross-discipline communication and learning. Furthermore, both communities suffer from

a lack of tools for assessing the suitability of the suite of technologies required to form a

complete water treatment train whether from proven or emerging technologies. The

current paradigm is characterized by a few “water doctors” at EPC and consulting firms

practicing water and wastewater treatment design based on what they have learned

through years of practice rather than drawing upon what is possible, or optimal. This

paradigm impairs the functionality of the aforementioned MCA tool as well as the IWRM

process.

The next section will address emerging technologies, but an examination of

proven technologies will reveal that their application is not optimized for TBL and

IWRM with regard to inland desalination. Momentarily focusing on technologies where

performance is accepted as reliable and effective removes a high degree of complexity

from the discussion so that a clearer path forward may be ascertained. Again, the area of

highest concern from a sustainability standpoint is the disposal of concentrate streams

from inland desalination systems. The remainder of this report will focus exclusively on

the problem of concentrate and effluent flows generated by inland desalination plants.

The issue of MBDS concentrate disposal has been around since the adoption of

reverse osmosis for desalination regardless of the location. The still common practice for

38

inland MBDS is to send concentrate to sanitary sewer for treatment at wastewater

treatment plants, or to discharge into surface waters (Sparrow, Man, Zoshi, & Mortensen,

2011). Tightening rules and regulations have made it more difficult or impossible to

simply dump RO concentrate into these traditional pathways. The chemical makeup of

brackish water also poses a more difficult problem for system designers than seawater,

which is relatively simple to address. Brackish RO recoveries are “often limited to 75%

due to higher concentrations of membrane fouling salts such as calcium carbonate and

silica which results in a concentrate stream with TDS of around 30,000 ppm” (Sparrow,

Man, Zoshi, & Mortensen, 2011). The table below details the most common current

methods of concentrate disposal.

Table 8: Common Current Concentrate Discharge Methods

Option Constraints Benefits Cost ($/m3 disposed)

Well injection

• No water recovery • Requires specific geology • Economic only at scale (>10,000 m3/day)

• Regulatory & environmental acceptance re aquifer pollution

• Low footprint • Lowest cost

option at scale

$1-10 varies with scale

Evaporation ponds

• No water recovery • Large footprint and potential land damage • Only feasible in net evaporation climates • High upfront capital cost in most regions

• Regulatory & environmental acceptance re land usage & dike failures

• Low energy use and operating cost

$3-6

Concentrator - crystallizers

• High capital cost: alloyed steel and titanium • High capital and operating cost • High energy usage: concentrators (15-

30kWh/m3) crystallizers (60-70kWh/m3) • Reliability challenges with mechanical

compressors • High tower profile and noise

• Increased water recovery

• Increased site flexibility

• Reduced permitting risk

$5-12

[Source: (Sparrow, Man, Zoshi, & Mortensen, 2011)]

39

Well Injection

Well injection of concentrate is the most cost-effective means of concentrate

management where hydrogeological conditions are favorable (Maliva, Missimer, &

Fontaine, 2011). Well injection falls into three categories: “shallow, deep high-capacity,

and deep high pressure” (Maliva, Missimer, & Fontaine, 2011). Shallow injection wells

are most common in coastal settings and are not generally suitable for inland

desalination.

Deep high-capacity wells have been successfully utilized for MBDS concentrate

and effluent, as well as the disposal of process waters from oil and gas production.

“These wells are usually drilled into saline water zones and are intended to isolate the

injected water from drinking water sources and the environment” (Maliva, Missimer, &

Fontaine, 2011). Again, hydrogeological features such as saline aquifers separated from

fresh water aquifers by a suitable “confining strata above the injection zone” are most

common in coastal regions such as Florida and are not typically appropriate for

sustainable inland MBDS concentrate management (Maliva, Missimer, & Fontaine,

2011).

“Deep high-pressure injection wells discharge into moderate permeability

formations under high injection pressures (often greater than 7,000 KPa) (Maliva,

Missimer, & Fontaine, 2011). This method is often selected in inland areas where care

must be taken to map out the characteristics of the reservoir especially with regard to

adjacent fresh water aquifers (Maliva, Missimer, & Fontaine, 2011).

From a sustainability standpoint, the largest problem with well injection is the

waste of water and energy involved in the process. Especially in inland desalination

where recoveries are relatively low, an average of 25% of water in MBDS is wasted.

While there is no documentation of environmental harm form the practice, the risk

remains that injecting what amounts to seawater into hydrogeological structures in

perpetuity will eventually threaten fresh water aquifers (Maliva, Missimer, & Fontaine,

2011). The perceived risk to fresh water aquifer contamination is enough to make

obtaining stakeholder buy-in problematic. As the density of inland MBDS increases, it

will become more difficult to locate appropriate well injection sites.

40

Evaporation Ponds

“At this time, [evaporation ponds are] the most widespread method of brine

disposal from inland-based desalination facilities” (Glater & Cohen, 2003). Evaporation

ponds are simply constructed surface water features designed to contain MBDS

concentrate long enough for the water component to evaporate leaving only the solids

behind. These ponds require large areas of land and an environment where evaporation is

efficient. High population density areas and areas with high humidity are poor candidates

for evaporation ponds (Maliva, Missimer, & Fontaine, 2011). Evaporation ponds also

suffer from stakeholder skepticism regarding leaks and the high degree of visibility. As

with well injection, there is no recovery of water that is produced at the same expense as

permeate from MBDS. The loss of roughly 25% of the water in the MBDS process will

become increasing unacceptable in the framework of sustainability.

There are techniques that may improve the efficiency of evaporation ponds in

areas with favorable conditions. One such method is wind aided intensified evaporation

(WAIV) which uses increased air flow to accelerate the evaporation process (Katzir,

Volkmann, Korngold, Mesalem, Oren, & Gilron, 2011). This technique allows for

smaller footprint – as much as ten-fold – and also for the potential collection of valuable

minerals such as magnesium.

Concentrator-Crystallizers

In its simplest form concentrating concentrate is a simple matter of applying

seawater RO (SWRO) systems to the concentrate stream of brackish water RO (BWRO)

systems. Since the concentrate from BWRO systems is essentially seawater, SWRO units

are well suited to recover water from concentrate. This arrangement is essentially a two-

pass RO. Obviously; the expense of the addition of an SWRO increases the cost per m3,

of water produced by the MBDS, but overall recoveries easily reach 90%. (Maliva,

Missimer, & Fontaine, 2011). The reduction in concentrate volume may bring other

technologies and techniques into economic and technical feasibility. While expensive,

41

additional passes of SWRO may be employed to further concentrate salts where other

alternatives are not possible.

Common to the operation of MBDS is the blending of some volume of

concentrate into the feed water stream. Since the TDS of BWRO permeate averages

around 4-5 ppm, some of the concentrate stream may be recycled to the feed water stream

without increasing the permeate TDS beyond acceptable limits. The figure below

illustrates a simple dual pass brackish/seawater RO process flow, with ultrafiltration

pretreatment, which recovers between 88 and 90% of raw water.

Figure 10: Dual Pass Brackish/Seawater High Recovery RO System

[Source: the author, courtesy of Crane Environmental]

The advantage of dual and even triple-pass RO systems is that they are well

understood and relatively simple to operate and maintain. Their high energy use is offset

by the high recoveries possible. The process and instrumentation diagram (P&ID) below

42

illustrates the flows and controls required for a 7 GPM unit, but the system performance

and costs scale up roughly one to one.

Figure 11: Dual Pass Brackish/Seawater High Recovery RO System Process and

Instrumentation Diagram (P&ID)

[Source: the author, courtesy of Crane Environmental]

While concentration of concentrate by multi-pass RO is an effective means of

reducing concentrate outflows, there still remains the remaining 10% of water to manage.

This is where crystallizers take over. Unfortunately, these systems, which are comprised

of many variations and technologies, must all be classified as emerging technologies.

There are only a couple of commercially available systems represented by a few case

studies. The results from crystallization technologies are impressive, even though the

43

costs are currently among the highest for concentrate disposal. Crystallizers will be

discussed in the next section.

Currently, with regard to proven technologies and processes for managing

concentrate disposal, stakeholders are left with a limited set of options. In many cases,

disposal options are pieced together to form a solution. In other cases, concentrate

remaining from multi-pass RO systems is collected and trucked off to specialized

wastewater treatment centers or to other disposal sites. Trucking is a costly and energy

intensive alternative. Pipelines to remote disposal sites have been deemed far too

expensive to consider a viable alternative, although some short-run regional pipelines

have been built to manage wastewater flows from hydrofracking operations.

What is clear from the literature review is that proven technologies for managing

MBDS concentrate flows are inadequate with regard to sustainability and stakeholders

and engineers must look to emerging technologies for optimal solutions. Unfortunately,

there are no established processes for capturing and maintaining a funnel of emerging

technologies, nor a way of systematically evaluating those technologies for applicability

to specific inland MBDS requirements. The following section provides an initial survey

and analysis of emerging technologies and proposes a process for improving access to

and analysis of information that is required by stakeholders and engineers in the context

of designing sustainable freshwater systems.

9 Emerging Technologies and Processes for Managing Concentrate and Effluent

Streams from MBDS.

As detailed in the last section, the sustainable management of MBDS concentrate is

complicated by a lack of optimally sustainable solutions. There are many exciting and

promising developments in this area, but they are difficult to assess and their largely

experimental nature poses a barrier to entry in large municipal and industrial MBDS

projects. Nevertheless, sustainable production of water using inland MBDS is a critical

goal in the larger natural resources management arena and the pressure on designers to

provide solutions is growing daily.

44

Emerging technologies and process populate the universe of water treatment

solutions along a path to wide scale adoption that is roughly defined by four milestones;

lab/bench top, pilot installation, full scale installation, and multiple case studies. The

figure below illustrates this technology and process funnel.

Figure 12: Emerging Concentrate Management Technology Funnel

[Source: the author]

In order to develop sustainable approached to inland MBDS, especially with

regard to management of concentrate flows, planners and engineers must choose from the

universe of possible technologies based on criteria established during sustainability

assessment, environmental impact analysis, and multi-criteria analysis phases within the

framework of integrated water resources management. The figure below illustrates the

45

challenge facing planners and engineers today as they seek to provide stakeholders with

viable alternatives optimized for specific sociopolitical and environmental viewpoints. As

with the technology funnel, IWRM participants would greatly benefit from an all-

inclusive database of technology performance and suitability data. Very few engineers

have the time to thoroughly and regularly review emerging technologies.

Figure 13: Navigating the Universe of Possible Concentrate Management Technologies

[Source: the author]

It is worth nothing that all desalination technologies are technologically suitable

for brine concentration. Lower cost methods applied to either the front end raw water, or

back end brine may allow for more expensive disposal methods to be employed. From a

holistic viewpoint, the same concept applies to IWRM techniques which may achieve

operational and administrative efficiencies that allow a community to use more expensive

technologies and processes to manage concentrate streams. Nearly all concentrate

46

management schemes are comprised of multiple technologies to for a water treatment

train. The more complex the water train, the more likely that constraints for each

technology will cause degradation of performance or system breakdown, therefore,

system complexity is a valid criteria for alternative evaluation during the MCA process,

and one that should carry considerable weight. The table below illustrates a collection of

the most promising emerging technologies and approaches for managing concentrate

streams from inland MBDS.

Table 9: Emerging MBDS Concentrate Management Technologies

[Source: the author and other as noted in text]

Technology Funnel Option Constraints Benefits

Cost ($/m3

disposed

Lab Air Gap Membrane Distillation

Production rate, membrane durability

Low energy requirements (heat and pressure)

$0.75

Lab Nickel & Cadmium Recovery - NDSX

Complex Recovery of valuable metals

NA

Lab Chromium Extraction - NDSX

Complex Recovery of valuable metals

NA

Lab Discharge into Depleted Oil Fields

Location, need for transport Inexpensive $0.03

Lab Eutectic Freeze Crystallization

Scaling, power use (without chilled water)

98+% recovery, clean water and NaCl

NA

Lab Membrane Crystallizer + WAIV

Expensive, fouling, crystallization inhibition

88.9% recovery $2.91

Lab Membrane Distillation Crystallization

Batch processing 90+ % recovery NA

Lab RO+FO Fouling 98+% recovery NALab RO+VEDCMD Scaling propensity 96% recovery NAPilot ZDD - RO+EDM Expensive, scaling constituents 98+% recovery $0.97Pilot ZDD - NF+EDM Expensive, scaling constituents 98+% recovery $0.76Pilot RO+EDR+WAIV Expensive, complex system 98+% recovery $3.00

Pilot Electrodialysis Batch processing, membrane scaling

98+% recovery NA

Full Scale RO+EDR+Evaporator Complex system, high capital costs

98+% recovery $3.22

Multi-Case Pellet Softening + ZLD High chemical dosing, pellet diameter

Enables multi-pass RO with difficult water

NA

Multi-Case Seawater Toilet Flushing Stakeholder buy-in, requires IWRM

100% recovery, no disposal cost

$0.00

Multi-Case Tandem RO ZLD Maximized primary RO recovery 97-99% recovery $3.00

Wide Scale Beta Blocker Oxidation Turbidity Efficient degradation of micropollutants

$0.93

47

The above technologies and techniques populate the technology funnel below.

There are likely many more currently emerging technologies, but the literature review

identified these as the most applicable. A key to the sustainable management of water

resources in general, and MBDS concentrate management in particular will depend on

the institution of a process by which the technology and process funnel is populated and

maintained on a regular basis. Decision makers, planners, and engineers need to have

access to a database of options that is coded for performance, price, and other criteria in

order to develop and communicate viable sustainable alternatives.

Figure 14: Technology and Process Funnel for Emerging Technologies for Managing

MBDS Concentrate Steams and Concentrate Steam Constituents

[Source: the author and other as noted in text]

48

The use of oxidation in the form of ozonation is a widely adopted technology for the

sterilization of water supplies, but it is placed on the emerging technology funnel because

of its novel use in oxidizing micro-pollutants such as beta blockers and other

pharmaceuticals (Benner, Salhi, Ternes, & Gunten, 2008). It should be expected that

other mainstream technologies and techniques used elsewhere will find their way onto the

MBDS concentrate management technology funnel. This pathway provides the benefit of

stakeholder trust through years of accepted application and sufficient real world data in

which to base technology selection decisions.

The following section of this report briefly examines the technologies that populate

the preceding emerging technologies funnel. Again, the position of the technology on the

funnel represents the technologies’ use in the management of MBDS concentrate streams.

Air Gap Membrane Distillation (AGMD)

AGMD is a variant of membrane distillation (MD). “MD is a combination of

evaporation of water from saline solution and diffusion of vapor through a hydrophobic

membrane. The driving force is the vapor pressure difference created by temperature

difference across the membrane” (Bahar, 2012). AGMD is one of several categories of

MD which includes direct contact MD (DCMD), vacuum MD (VMD)(also known as

vacuum effect MD), and sweeping gas MD (SGMD) (Bahar, 2012). “These

classifications are based on the membrane distance from the coolant and the mode of

collection of distillate” (Bahar, 2012).

The primary advantage of MD is the low pressure, energy, and temperature

requirements relative to reverse osmosis. Interest in MD is driven by the promise of

reduced costs associated with desalination. The wide variety of MD configurations and

permutations of design geometries belies the experimental nature of this technology. The

volume of laboratory research is dedicated to working out the optimal mechanical design

and operational processes required for a given feed water stream (Bahar, 2012).

The promise of AGMD and other MD processes is the reclamation of water from

MBDS concentrate streams at lower costs, since high costs are a leading current limiting

factor in the acceptance of concentrate management. AGMD is theoretically capable of

49

producing water from inland MBDS concentrate streams of 30,000 to 36,000 TDS with

energy input as low as 0.18 kWh per cubic meter (Bahar, 2012). This is a small fraction

of the average 3.5 kWh/m3 required for SWRO (Macendonio, Drioli, Gusev, Bardow,

Semiat, & M.Kurihara, 2012). This cost differential may be widened even further if waste

heat is available from power generation activities (Bahar, 2012). The diagram below

depicts the transport processes in AGMD.

Figure 14: Transport Processes in AGMD

[Source: (Bahar, 2012)]

Non-Dispersive Solvent Extraction (NDSX)

NDSX is not designed to recover water from concentrate streams, but rather to

recover heavy metals like nickel and cadmium from highly concentrated solutions

(Galan, Roman, Irabien, & Ortiz, 1998). This is a case of a widely used technology being

adapted to a new use, hence its location on the emerging technology funnel. The concept

50

of recovering economically valuable resources from concentrate streams is not new, but

when coupled to the concept of sustainable resource management, the value of removing

constituents from MBDS concentrate streams increases. As seen in the figure below,

NDSX is a complicated process that requires significant economic or environmental

justification.

Figure 15: Non-Dispersive Solvent Extraction

[Source: (Galan, Roman, Irabien, & Ortiz, 1998)]

NDSX represents an improvement over dispersive techniques “which cause loss

of extractant as well as solutes (Galan, Roman, Irabien, & Ortiz, 1998). The rapid

adoption of Ni-Cd batteries has created the need for safe disposal and recycling of these

metals and a means of economically viable recovery of these metals is critical to the

broader sustainable resources management paradigm (Galan, Roman, Irabien, & Ortiz,

1998). Conceptually, recovery of valuable constituents from MBDS concentrate is an

51

important consideration that should be addressed as part of the IWRM and MCA

processes.

Concentrate Discharge into Depleted Oil Fields

Injection of MBDS concentrate into wells is not new, but the injection of this

water into oil and gas fields represents an attractive twist on an old theme (Nicot &

Chowdhury, 2005). Naturally, the attractiveness of using existing wells is based on the

cost savings related to not having to develop new wells as well as the ability to rely upon

existing data regarding the geology surrounding those wells. This method depends on the

availability of such wells, but large areas of the world that are experiencing water stress,

and as such are experiencing growth in the fleet of MBDS installations, are also areas

where oil and gas exploration have flourished. In addition, the successful injection of

MBDS concentrate into oil and gas wells depends on adequate pretreatment to prevent

scaling, but this process is “done routinely in the oil industry” (Nicot & Chowdhury,

2005).

Eutectic Freeze Crystallization (EFC)

“EFC separates the solution into pure water and pure salt by cooling to the

eutectic temperature at which both ice and salt crystals are formed. By gravitational

forces the salt and ice are separated and after filtration and washing the pure products are

obtained” (Verbeek, 2011). This is a fascinating technology whose utility may be further

enhanced by regions possessing excess cooling capacity. Since the eutectic temperature

for NaCl solutions is -21.1o C, chilling processes used in the cooling loops for power

plants may support EFC technology (Verbeek, 2011). The attractiveness of EFC is that it

is truly a zero liquid discharge (ZLD) process leaving only crystallized NaCl and water as

the end result. Very few concentrate management schemes are truly ZLD. The high

energy use of 395 kWh per cubic meter of feed makes this process expensive, but

improvements in efficiency or the use of existing chilling capacity may ameliorate the

52

energy impact. The EFC process takes place in a cooled disk column crystallizer (CDCC)

as shown in the figure below (Verbeek, 2011).

Figure 16: Eutectic Freeze Crystallization – Cooled Disk Column Crystallizer

[Source: (Verbeek, 2011)]

Integrated Membrane Crystallizer (MCr) and Wind-Aided Intensified Evaporation

(WAIV)

As previously stated, many concentrate management schemes utilize multiple

technologies in configurations that allow for the recovery of water from MBDS

concentrate streams. In this case, MCr and WAIV have been configured to work together

to reduce the energy and capital costs associated with conventional evaporation ponds

and SWRO units (Macedonio, Katzir, Geisma, Simone, Drioli, & Gilron, 2011).

The figure below depicts a hybrid WAIV/MCr system where well water is fed to

an RO system. The concentrate from that system is fed to the WAIV system. Concentrate

from the WAIV system is then fed to the MCr system which produces desalted water,

53

salts, and MCr “purge” water which is similar to back wash effluent from convention

filters. At a cost of $2.91 per m3, the WAIV/MCr system is slightly less than using

conventional multi-pass RO, but requires an operating environment that supports net

evaporation (Macedonio, Katzir, Geisma, Simone, Drioli, & Gilron, 2011).

Figure 17: WAIV/MCr System

[Source: (Macedonio, Katzir, Geisma, Simone, Drioli, & Gilron, 2011)]

Membrane Distillation Crystallization (MDC)

Compared to conventional crystallizers, MDC units are modular which allows for

the scaling up of systems for different flow rates without changing the basic

configuration (Ji, Curcioa, Obaidani, Profioa, Fontananovaa, & Drioli, 2010). MDC is

based on principles of MD, but uses hollow fiber membranes with their high contact area

to “achieve reliable evaporation fluxes already at moderate temperatures (40-500 C) with

energy consumption of about 15-20 kWh/m3” (Ji, Curcioa, Obaidani, Profioa,

Fontananovaa, & Drioli, 2010). This compares favorably to “forced circulation

crystallizers and draft tube-baffled crystallizers that generally operate at temperatures

higher than 700 C with specific energy consumption of ~ 30 kWh/m3 of distillate” (Ji,

Curcioa, Obaidani, Profioa, Fontananovaa, & Drioli, 2010). The figure below shows the

MDC laboratory unit.

54

Figure 18: MDC Laboratory Unit

[Source: (Ji, Curcioa, Obaidani, Profioa, Fontananovaa, & Drioli, 2010)]

Reverse Osmosis (RO), Forward Osmosis (FO), and VEDCMD

The combination of RO with FO and VEDCMD is another attempt to improve

upon energy intensive methods like thermal distillation, thermal evaporators, spay driers

and others. “Although these processes are proven effective for volume minimization, the

capital and operating costs often exceed the cost of the desalting facility and thus, they

are not typically used (Martinetti, Childressa, & Cath, 2009). The significance of FO is

that it is able to handle water chemistry that is high in scaling constituents (Martinetti,

Childressa, & Cath, 2009). This is important due to the propensity of inland water to

contain higher levels of scaling factors as previously discussed (Martinetti, Childressa, &

Cath, 2009).

55

The successful application of FO in place of VEDCMD further demonstrates the

fact that water is always a local issue and that engineers and planners will likely need to

choose from a robust technology suite in order to optimally manage water resources. This

is especially true of managing waste streams from water treatment systems, particularly

MBDS. The figure below depicts the FO/RO configuration.

Figure 19: FO/RO

[Source: (Martinetti, Childressa, & Cath, 2009)]

Zero Discharge Desalination (ZDD) and Electrodialysis Metathesis (EDM)

ZDD, which is a patented term by Veolia, is another term for ZLD. Veolia has

bundled several technologies to achieve near ZLD performance from a series of pilot

systems they have built to deal with challenging environments. According to Veolia,

“EDM is simply electrodialysis (ED, or EDI) with an innovative arrangement of ion

exchange membranes” (Biagini, et al., 2012). Veolia has combined both RO and

nanofiltration (NF) with their EDM system to achieve relatively low cost concentrate

treatment of $0.97 and $0.76 per m3 disposed for RO and NF respectively. While the

56

capital cost of the equipment is still high, the combination of RO and electrodialysis is

well accepted in the industrial water community. The EDM variant produced by Veolia is

very similar to EDI but the special arrangement of the ED membranes is less susceptible

to scaling (Biagini, et al., 2012). Nevertheless, increased silica necessitates the use of a

ceramic membrane filtration system to prevent EDM fouling. The figure below depicts

the RO/EDM system.

Figure 20: RO/EDM

[Source: (Biagini, et al., 2012)]

There are several other variants using non-proprietary EDI that are making their

way into the pilot testing phase of development. A configuration employing EDI in

concert with WAIV takes advantage the low fouling potential of evaporation-based

systems but at $3.00 per m3 of concentrate disposed, it is on par with multi-pass RO and

57

can only be used in regions where net evaporation is supported (Oren, et al., 2010) The

figure below shows Veolia’s EDM system with its special arrangement of electrodialysis

membranes.

Figure 21: EDM Module

[Source: (Biagini, et al., 2012)]

EDI Variants

Electrodialysis, whereby electrical current differential is used to coax molecules

across a membrane surface, uses a similar process to reverse osmosis, but rather than

osmotic pressure, the driving force is electron potential. Whether EDI, EDM or

electrodialysis reversal (EDR), the benefit of ED is the ability to “operate with minimal

fouling or scaling, or chemical addition (U.S. Bureau of Reclamation, 2010).

Additionally, EDI is tolerant of silica which bedevils RO performance, and these systems

are also able to handle higher turbidity and up to 0.5 ppm of chlorine at relatively low

58

pressures (U.S. Bureau of Reclamation, 2010). The following figure depicts the

application of ED in a water train including multi-pass RO, WAIV, ED,

Crystallizer/Settler, and Submerged ultrafiltration (UF). Following this figure is a figure

depicting the installation as a rendering of a 3-D model.

Figure 22: ED in a Concentrate Management Water Train

[Source: (Oren, et al., 2010)]

Figure 23: 3-D Model of EDR with Crystallizer and Settler

[Source: (Oren, et al., 2010)]

59

Pellet Softening

Several promising technologies allow MBDS to operate with more difficult water

chemistry that often exists in inland desalination scenarios, especially when raw water

streams are supplemented by recovered waste water. Pellet softening is one such enabling

technology. Pellet softening “not only reduces the concentrations of calcium and

hydrogen carbonate, but can achieve significant removal of silica as well” (Houwelingen,

2010). Pellet softening uses a seed material, usually silica sand, to facilitate the

precipitation of calcium or hydrogen carbonate out of the water stream (Houwelingen,

2010). The figure below shows a pellet reactor with its pellet discharge which selectively

eliminates the largest pellets in a continuous stream.

Figure 24: Cutaway Illustration of Pellet Reactor

[Source: (Houwelingen, 2010)]

60

Seawater Toilet Flushing

Using seawater to flush toilets is not a new concept, and the technique enjoys

widespread use in Japan (Ekama, Wilsenach, & Chen, 2012). This approach assumes that

seawater can take the place of freshwater for the purposes of waste transport from toilets,

thus relieving pressure on fresh water production systems. What is novel is the concept of

using concentrate from inland MBDS for this purpose. The concentrate stream would still

require treatment for any hazardous or otherwise undesirable constituents, but in many

cases, this pretreatment would be minimal. Naturally, infrastructure would require

modification, but this reworking of infrastructure may be part of IWRM for a given

population. The attractiveness of this approach is the low cost and the ability to gain

utility from a waste product. In Hong Kong, the community saves 1/3 of fresh water by

using filtered and chlorinated seawater to flush toilets (Ekama, Wilsenach, & Chen,

2012).

Tandem RO

Multi-pass RO is also not a new concept, but the common application has focused

on the production of ultra-pure water for industry. When applied to the management of

inland MBDS concentrate streams, dual or even triple-pass RO can provide “maximum

water recovery [using a] universally applicable process (Ning & Troyer, 2009). From the

previous examples of ZLD, it is obvious that double-pass RO is a common theme in

MBDS concentrate stream management, with additional technology applied to deal with

specific constituents or water conditions.

Oxidation via Ozonation

Another technology that enjoys widespread use in other application is ozonation.

Ozonation is usually applied as a disinfection process in a water train for the elimination

of pathogens. In the context of concentrate management, ozonation may be applied to

degrade certain pharmaceuticals such as beta blockers which may be present in

61

supplementary feed water streams from wastewater recover operations (Benner, Salhi,

Ternes, & Gunten, 2008).

As previously stated, emerging technologies for the management of MBDS

concentrate streams offer a glimpse into the future of IWRM and sustainable

management of water resources. It should also be noted that improvements in efficiencies

through IWRM, as well as technology performance improvement, may allow for the

economical use of energy-intensive, but proven technologies like thermal distillation and

crystallization on the last 2-10% of remaining water in the effluent streams of the above

technologies. It also bears repeating that removing constituents early in any water

treatment process greatly simplifies downstream treatment and improves outcomes. This

is clear when confronted by the myriad technologies and processes required for dealing

with various difficult constituents in MBDS concentrate streams. If would obviously be

cheaper and simpler not to have to deal with a contaminant in the first place. This brings

the focus back to overall water shed management and legislation line the Clean Water

Act and various European directives regarding the protection of natural water resources

from pollutants.

10 Conclusions

It is clear that technology alone cannot solve the problem of managing waste streams

from inland membrane-based desalination systems. As with most efforts toward

sustainability, the problem of sustainable water resource management involves a wide

array of stakeholders, including the environment, whose interests must be considered.

Even though the challenges are daunting, there have been many advances in

management, technology, and awareness that may be brought to bear against the current

state of wasteful water use and unsustainable water treatment practices. In addition, the

management of water resources itself presents a rich environment for improvements in

efficiency which may fund needed capital and operational expenses for new technologies.

Viewed in this way, technologies and approaches currently viewed as too expensive, may

62

find favor with stakeholders. In the short term, using proven technologies may provide

the best route while emerging technologies continue to mature.

With regard to emerging technologies, stakeholders, decision-makers, and engineers

require a resource that keeps them abreast of the most promising technologies and

approaches to difficult water management challenges. The current state at EPC firms

results in the perpetuation of tried and true technologies and approaches that are

unsustainable. To break this cycle, EPC firms require more and better information

regarding their options in order to communicate those options to end users and the

stakeholders they represent. In a world of Google, Facebook, and IBM’s Watson, it is a

simple matter to envision a properly-coded data base that can accomplish the task of

establishing and maintaining an emerging technology and process funnel.

Finally, once armed with adequate knowledge of technology and process options,

stakeholders, decision-makers, and engineers need a rational and repeatable process for

evaluating options from the various perspectives of stakeholder groups. Tools such as the

multi-criteria analysis process presented earlier present a framework for accomplishing

this difficult task and for quickly communicating alternatives in order to facilitate buy-in

and action.

11 Acknowledgements

The author thanks the professors in the USF Patel School of Global Sustainability and its

leadership. In particular, Dr. Vairavamoorthy provided initial guidance and latitude to

address the problems addressed in this report. Also, Dr. Ghebremichael provided

oversight and paved the way for the author’s work at UNESCO-IHE in Delft, NL. The

author also thanks Dr. Maria Kennedy at UNESCO-IHE and Dr. Mario Salinas who

opened their doors, their databases, and their minds to the research process required in

completing this report. In addition, the author thanks the management team at Crane

Environmental, and dozens of engineers and dozens of EPC firms for their assistance.

The author also gratefully acknowledges the support of L. Aden Russell Leonard without

whom the work done here would have been impossible.

63

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