ASSESSMENT OF POTENTIAL TO DEVELOP WATER REUSE SYSTEMS IN RAND WATER

Framework for a water reuse system business case

Sameer Morar

17 July 2019

Structure of the presentation

• Background & Study Objectives

• Water balance Assessment

• Wastewater availability & quality of wastewater

• Identification of potential consumers for reuse systems

• Business Case Development Example

• Financial Viability

• Institutional arrangements and risk

Background

• Vaal River Supply Area – considered the main economic hub of the country & continent

• All economic sectors – agriculture & mining to industries are located in the VRSA

• Water – one of the major economic factors of production

• Rand Water is major bulk water supplier of potable water supply in the VRSA

• Upper & Middle Vaal WMA

• Transfers to the Crocodile (West) catchment

• Transfers to the Olifants catchment

Background (cont.)

• VRSA faces the problems• fast growing populations,

• rapid urbanization,

• rising costs of water provision, (year on year tariff increases)

• pollution of fresh water resources.

• Available water supply in the VRSA is likely to be exceeded by the demand in the supply area

• HSDWS continue to emphasize reduction of water losses & improvement of water use efficiency in the VRSA

• Envisaged drivers of demand continue to grow

• Impact of WC/WDM initiative do not appear to be gaining sufficient traction

Objectives of the study

• Main objective of the study was to• determine whether there is a business case to utilise treated

effluent

• Whether source substitution can improve water use efficiency in RW area of service

• Scope of work to achieve above objectives• Quantify the nature and extent of the growing demand for

freshwater supplies in the RW area of service

• the quantity and quality of the wastewater treated from the municipal wastewater treatment works available for potential reuse

• Potential consumers for substitution of potable water with non-potable water

• Risk assessment

• Business case of developing water reuse systems

Available effluent in RW’s Area of Service

Extent of existing reuse

Types of water reuse

• Six broad categories of wastewater reuse and the potential constraints

• Agric. & landscape irrigation; industrial & mining reuse; recreational; non-potable urban reuse; potable reuse; groundwater recharge

• used to identify potential existing and future customers

• Approach taken to identify potential customers• Review & analysis of RW customer billing database

• Consumer database of municipalities

• Constraints in the format and information presented

• No categories of consumers could be identified (except for CoJ)

• Spatially linked the customer database to the RW area of service

• Determine potential water reuse management areas

Identification of potential customers

• Drivers of water reuse demands• Quality of the available treated effluent

• Potential constraints • Scaling, corrosion, biological growth and fouling

• Public health concerns

• Potential toxic chemicals

• Public acceptance

• Additional treatment requirements for water reuse options

• Key issue is quality of treated effluent

Treatment requirements for water reuse options

Water Reuse

ApplicationsTreatment Requirements for Various Parameters

General Category Specific UsesPathogen

Removal

Disin-

fection

Suspd.

Sol.

Removal

DO*

Presenc

e

BOD** &

COD***

removal

Nutrient

Removal

Taste,

Odor,

Color

Remova

l

Trace

Organic

s &

Metals

Rem.

Excess

Salinity

Remova

l

Agricultural irrigation Crop irrigation xx xxx xxx xx xxx -- x xx x

Landscape irrigation

Parks, golf courses, residential,

school yard, freeway medians,

cemeteries, greenbelts

x -- x x x -- x x --

Industrial reuseCooling, boiler feed, processing

water, heavy constructionxx xx xxx xxx xxx xxx xxx xx xx

Groundwater

recharge

Groundwater replenishment, salt

water intrusion, subsidence

control

xxx xx xxx xx xxx xxx xxx xxxx --

Recreational and

environmental reuse

Lakes and ponds, marsh

enhancement, stream flow

augmentation, fisheries,

snowmaking

xxxx xxxx xxx xxxx xxxx xxxx xxxx xxxx xx

Other non-potable

urban reuse

Fire protecting, air conditioning,

toilet flushingxxxx xxxx xxxx xxxx xxxx xxx xxxx xxxx xx

Potable reuseBlending in water supply, pipe to

pipe water supplyxxxxx xxxxx xxxxx xxxx xxxxx xxxx xxxxx xxxxx xxx

Identification of potential consumers

• Prioritised Industrial & mining reuse category • Cooling

• Boiler feed

• Process water

• Heavy construction

• Dust control and concrete production

• 2nd priority non-potable reuse & landscape irrigation• Municipal Parks

• Freeway medians

• Golf courses

• landscaped areas surrounding commercial, office and industrial development

Potential for substitution in RW

• Significant mining and industrial use supplied with potable water

• Rustenburg area – potable water used for process water

• Mining activities in Westonaria & Merafong areas• Process water in gold recovery on existing tailings

dams• Major industries – e.g. Sasol

• Significant potential exists in substitution of potable water for reuse water

• Subject to meeting quality needs

Demand centers for water reuse system

• Four demand centres identified• Rustenburg area to supply mines and industries

with reclaimed water

• Westonaria – Merafong area – to supply gold mines in the area

• Johannesburg – existing tailings dams being re-mined

• Portions of Ekurhuleni –identified as a potential demand centre late into the study

Rustenburg water reuse system -Business Plan development

• Rustenburg area• Conducted a business case for developing a water

reuse system

• The business plan was completed and forms part of the long term plan to address water supply problems in Rustenburg area

Process followed

• Quantification of reclaimed water available • Identified potential wastewater treatment

• Rustenburg & Boitekong Wastewater Treatment Works

• Quantity of available wastewater in the Rustenburg area

• Average Dry Weather Flow (ADWF)

• Peak dry weather flow (PDWF)

• Focused future inflow into the wastewater treatment works

• Identified the process flow of the existing plants to determine additional requirements

Water Quality Assessment

• Engage with the mines • Determine the quality requirements to meet the service

water use at the shafts

• Determined location of the demand points for each mine

• Process design to meet the quality requirements• To address the Fats, Oils and Grease (FOG) problems

• Treat the iron and manganese problems from the wastewater treatment plants

• Reduce high chlorides

Process design example

Preparation of distribution system layout

• After determination that adequate production capacity exists to meet demands for substitution of potable water with reuse

• Distribution system layout to deliver reuse water develop

• Hydraulic modelling used (WaterGEMS)

• Distribution system designed to connect consumers to the reclamation facility

Proposed water reuse system for Rustenburg west

Technical analysis

• Identified potential pipeline routes• Servitude requirements may pose significant

challenges

• Environmental impact assessment critical for theconstruction of the bulk pipeline

• Capital investment requirements• Significant capital investment

• Pipe jacking required in a number of areas

Financial Viability

• Set up a financial model to determine the viability of the water reuse system

• Critical was the determination of the energy costs• Pump energy efficiency model set up for each pump station

• Pricing of the water reuse• Based on an incentive based system as a % of current potable

water supply

• Approximately 70% of current potable water supply cost

• 2 of the 3 water reuse systems found to be financially viable

• BCR greater that 1 after sensitivity analysis was done

• AIC less than current bulk water tariff at the time

Institutional arrangements• NWRS 2 allows for & encourages development of water

reuse particularly to meet low water quality demands • DWA is supportive of developing a water reuse system in

Rustenburg

• Critical issue is licensing for water reuse system• Requires the municipalities to apply for amendments to the

existing water use license

• Negotiations between RW and the municipality

• Payment of treated effluent• Legislation is not very clear

• Precedents has been established between the mines/industry and municipalities

• LM can sale treated effluent to Rand Water under contract

• Conditions can be established on the quality of effluent to be sold

Risk Assessment• Municipal commitments to sell directly to the end

consumers• Engagement with municipalities

• Risk on uptake of water reuse• Commitment from the mines/industry will be addressed by the off

take agreements

• Risk on current revenue• Significant pressure on potable water resources in most

municipalities

• Resale of substituted water to municipalities

• Unit cost of potable water less than for industries

• Reduce bulk purchase of raw water

• Legislative risk• Major constraint & still needed to be addressed

Business Case• There is a business case to develop a water reuse system

• Rustenburg area to supply process water for cooling and dust suppression in the mine shafts

• Johannesburg area to supply the mining of tailings dams – potential to supply urban use such as landscape irrigation of parks & golf courses

• Develop a reclamation facility to meet the water quality requirements of customers

• Willingness from potential users of reuse water

• Not all areas viable to develop water reuse systems • Westonaria not viable

• Risk• Institutional requirements to give effect to the reuse system • Lack of ownership of the reclaimed water by RW can be a constraint • Need to establish governance arrangements between RW and

Municipalities • Legislative requirements – amendments of license conditions

Questions & Comments

(Don’t be afraid to REUSE some of them posed to the previous presenter)