Phosphorus Reduction Strategies and Technologies to Minimize Phosphorus Release in Receiving Waters to Minimize Potential for

Harmful Algal Blooms

Key Environmental Topics: SWOWEA IWC MeetingMason, OH

January 26, 2017

Disclaimer

• The views expressed in this document are those of the individual authors and do not necessarily, reflect the views and policies of the U.S. Environmental Protection Agency (EPA). Mention of trade names or commercial products does not constitute endorsement or recommendation for use. This document has been reviewed in accordance with EPA’s peer and administrative review policies and approved for publication

Acknowledgements (USEPA/ORD/CIN.)

• Nick Dugan: ORD Project Lead for Reducing the Impacts of HABs research

• Joel Allen: Task ORD Lead for HAB risk management research

• Christopher Nietch: ORD STREAMS facility watershed management research

• Don Brown: ORD STREAMS facility watershed management research

• Jorge Santo Domingo: ORD microorganism identification research

• Mallikarjuna Nadagouda: ORD phosphate sorption research

• Daniel Murray: ORD wastewater treatment, CSO research

• William Adams: ORD analytical methods for HAB toxins research

• Lesley DAnglada: OST, Office of Water

• Joh Kang, TTEMI, Ann Arbor, MI

Harmful Algal Blooms (Ohio)

• Lake Erie Western Basin 2014• Bloom of Microcystis (Cyanobacteria species)• Water advisory

• Ohio River 2015• Late September 2015 a Microcystis bloom occurred• Started in West Virginia, flowed past Cincinnati

into Indiana (> 600 miles)• Impeded recreation along the river• Caused by high nutrient loads Grand Lake Saint Mary’s• High microcystin concentrations; warnings issued

• Lake Harsha (East Fork State Park)• Large microcystis bloom summer 2014-2016

The Enquirer/ Patrick Reddy

Environmental Conditions Favorable to HAB

• There are a wide range of favorable parameters for HAB occurrence:• pH: 6-9 (pH changes as inorganic C (CO2) is removed from system)

• Light availability (solar radiation)

• Temperature• Ranges from 5-30oC (> 23oC favors Cyanobacteria)

• Eutrophic or hypereutrophic environments• High nutrients and dissolved oxygen

• Nutrient Levels• Redfield Ratio: C:N:P of 160:16:1

• P in water column > 0.03 mg/l

• Eutrophication

• High nutrient levels, warm water, slow moving water, and other factors promote high photosynthesis rates

• Algae experiences growth

• Decaying algal matter is consumed by aquatic organisms

• Respiration depletes dissolved oxygen in the water column

• Eutrophication contributes to issues with water quality and hypoxic environments

Environmental Impacts of HAB

(Pearl et al, 2011)

Health Impacts of Toxins

• Cyanobacteria and dinoflagellates (“red tide”) can produce several types of toxins:

• Hepatotoxins (ie. Microcystins)

• Neurotoxins (ie. Anatoxins)

• Cytotoxic Alkaloids (ie.Cylindrospermopsin)

• Carbamate alkaloid neurotoxins

(e.g. Saxitoxins - paralytic shellfish poisoning)

• Dermatotoxins (ie, skin Irritants)

• Saxotoxins

• Other toxins

Photo: (Thomas Archer 2009)

Routes of exposure (Human Health)

• Oral: consumption of organisms or toxin-contaminated water

• Dermal/Adsorption: skin contact with contaminated water

• Inhalation: wave action may produce aerosols?

• Decaying blue-green algae produces smell that may be considered an irritant

• St. Lucie River HAB in Florida had been report to influence the release of H2S

• Residents near Grand Lake, St. Marys report noxious odor linked to algal decay

Acute Health Effects of HAB exposure

Ohio Department of Health, 2016

US EPA Cyanobacteria/Cyanotoxins, 2016

EPA Health Advisories

• Non-regulatory: Developed as guidance to help health officials

• Microcystins (10 Day health advisory)• 1.6 µg/L for school age children through adults

• 0.3 µg/L for bottle-fed infants and pre-school children

• Cylindrospermopsin (10 Day health advisory)• 3.0 µg/L for school age children through adults

• 0.7 µg/L for bottle-fed infants and pre-school children

Health Advisories obtained from: 2015 Drinking Water Health Advisories for Two Cyanobacteria Toxins. US EPA, 2016

Regulatory Framework Addressing HAB

• HAB and Hypoxia Research and Control Act (HABHRCA) 2014

• Drinking Water Protection Act (HR212) 2015

• States (http://www.epa.ohio.gov/ddagw/rules.aspx)

Risk Management Strategies

• Risk Management Strategies: Minimize Phosphorus Entering Water Bodies:• Use of BMPs for reducing nutrient loading

• Reducing urban and agricultural runoff• Reduce impervious surfaces (roadways, parking lots, buildings)

• More sustainable fertilizer practices• Development of nutrient reuse techniques

• Reduce P concentration in wastewater treatment plant effluent by chemical or biological nutrient removal (BNR) methods

• Pre-capture phosphate before entry into receiving stream, lake, or river with phosphate sorbents or constructed stormwater wetlands

Nutrient Runoff Prevention Techniques

• A major contributor to eutrophication (and HABs) is the runoff of nutrients from agricultural fields and cultivated areas

• Nitrogen and phosphate based fertilizers runoff from agricultural fields and into streams and transported to other areas such as rivers, lakes, and oceans

• Methods to reduce runoff to waterways include:

• Soil phosphorus testing, e.g. knowing how much fertilizer is necessary and not over applying

Utilization of “Engineered” Systems

• Reduce phosphorus load from wastewater effluent by physical, chemical, or biological treatment systems

• Use of Riparian buffers or wetland zones

• Allow water to flow through zones of vegetation that uptake N and P as well as reduce runoff into water bodies

• Sorption of phosphate onto material that is lining stream banks or capture zone before lake

• Sequester the phosphate and possible recycle nutrients back on the agricultural land

• Treat water at drinking water plant to remove cyanotoxins

Phosphorus Speciation depends upon pKa = f(pH)

Phosphorus Cyclingfigure ref: www.Suezwaterhandbook.com

Wetlands Cycling of Phosphorus figure ref: www.wetlandsinitiative.org

• Soluble reactive phosphate (SRP) sorption onto Fe/Mn-oxides particulates

• SRP can be re-mobilized during storm events or in anaerobic environments (sediment)

Engineered Systems to Harvest Algae from Water

Algal Scrubbers Aquaculture

Wastewater Unit Process Options for Reducing Phosphorus in WWTP Effluent

SOLUBLE P

- chemical precipitation and settling

- sorptive media

- biological nutrient removal (BNR)

NON-SOLUBLE, PARTICULATE P

-settling

-filtration

Precipitation (lime, Fe and Al salts) followed by some form of filtration

• Used for many compounds including heavy metals

• Typical effluent values between 0.5 – 1.0 mg/l depending upon filtration process modifications

• Sludge production and disposal

USEPA 2016

Sorptive Media for Reducing Phosphate from Wastewater

• MetaSorb/DOW titanium dioxide media

• Bayer BayOxide 33 iron oxide media (used for arsenic)

• PHOSLOCK (lanthanum/bentonite)

• others

OSTARA Process for Phosphorus Recovery

• WASSTRIP unit process sequesters magnesium and phosphate pre-digestion to minimize struvite; PEARL unit process forms struvite; Crystal Green fertilizer (struvite)

Biological Nutrient (N and P) Removal

• Manipulation of the environmental conditions of phosphorus accumulating organisms (PAOs) to take advantage of enhanced accumulation as well as nitrogen removal

• Bardenpho

• AZENIT (VEOLIA)

• A/O

• SBR (SBR Technologies Inc.)

• Oxidation Ditches (EIMCO)

• note: Variables such as temperature, or NO3 level impact performance

Phosphorus Cycling in WWTP ref: Forbes et al. 2009

Why is Phosphorus so Difficult to Remove in a Traditional WWTP?

• For traditional biological treatment systems, expected removal of 90% of soluble BOD5, 50% of TKN, and only 33% of TP because of unequal C:N:P ratio:

cell formula: 100 : 2.5 : 0.5

influent of 250 mg/l : 60 mg/l : 15 mg/l

Any additional removal of phosphorus may involve operating biological wastewater plants differently; but more likely require chemical addition and filtration to achieve levels below 0.5 mg/l

note: Biological wastewater treatment processes may not completely degrade/remove emerging contaminants of concern that are recalcitrant

BPR: Favorable Conditions for Phosphate Accumulating organisms (PAOs)

Sequencing Batch Reactor Process Schematic

Eawag and Spuhler

Sequencing Batch Reactor Process

• Anaerobic fill period results in phosphorus release from organisms, and high organic concentration results in denitrification of any nitrate residual from previous aeration period

• Subsequent aeration period results in phosphate being sorbed onto organisms and results in nitrogen being converted to nitrite or nitrate

• Total phosphorus removal < 1.0 mg/l

A/O Process (aka Ludzack)

5-Stage Bardenpho Process

Oxidation Ditch

Eawag and Spuhler

Keys to Biological Removal of Phosphorus

• Volatile fatty acids• Readily biodegradable, available COD• Temperature• SRT• Nitrate control• Dissolved Oxygen control• System flexibility to operate at anaerobic/anoxic/oxic conditions, e.g. jet aeration

systems for some SBR systems have high oxygen concentrations near jet, but low oxygen concentrations away from jet

• Maintaining the organism community capable of removing and accumulating phosphorus (PAO) and other microdiversity organisms

Advanced Technologies for Low Phosphorus Target

• Tertiary clarification with filters (sand bed, cloth, membrane)

• Specialty filters

- CoMag (ballasted flocculation, clarification, magnetic separation

- Blue Pro

- Trident HS

- Infiltration bed

The expected TP effluent level has been developed from plotting WWTP effluent levels vs. time frequency to account for cold temperature interference

Comparison of the Reliability of Various Technologies for Phosphorus Removal ref: Fig. 2-36 EPA 632/R-08/006

Suggested EPA Technical References

EPA 600/R-10/100 EPA 632/R-08/006

Removals of cyanotoxins in drinking water treatment plants

• Physical removal processes remove cyanobacterial cells and cell-bound toxins:• Coagulation/flocculation/sedimentation• Dissolved air flotation• Granular media filtration• Ultrafiltration membranes

• Dissolved toxins removed by:• Powdered activated carbon• Granular activated carbon• Permanganate oxidation• Chlorine oxidation• Ozonation

Summary Points

• Agricultural and urban runoff remain a nutrient source

• Research in sustainable concepts of agricultural nutrient management is ongoing

• Wastewater treatment plants can be operated to minimize phosphorus release into the environment

• Drinking water plants can be operated to control Cyanotoxins