Research

 

Click here to go to a website on nitrate in drinking water

Summary of current and recent research

Organic Matter & DBP Related Projects:

  • Controlling the Formation of Nitrosamines During Water Treatment, Project 4370, Krasner (PI), Mitch, Westerhoff (ASU share $100,000; 2012-2014)
  • Constructed Wetlands for Treatment of Organic and Nanomaterial Pollutants, Westerhoff, Herckes, Halden (Water Research Foundation, $250,000, 2010-2013)
  • Paul L. Busch Research Award from Water Environment Research Foundation Endowment for Innovation in Applied Water Quality Research, Tools to Characterize and Understand the Risk of Biogenic and Commercial Nanomaterials in Wastewater Effluents ($100,000)
  • Pathway Generation and Byproduct Estimation for Chemical Oxidation Processes in Water Treatment, Crittenden, Li, Westerhoff (NSF $280,000; 2006-2009)
  • Sources for Municipal Disinfection By-Product Control, Westerhoff (SRP, $39,000, 7/1/09-6/31/-10)
  • Development of a quartz tuning fork sensor for chloroform, Westerhoff, Tao (Arizona Water Institute, $25,000, 2007)
  • Monitoring of Trace-Level Pharmaceuticals and Personal Care Products in Salt River Project Waters, Westerhoff, Herckes (Salt River Project, $40,000, 2007-2008)
  • AwwaRF: Organic Chloramine Formation in Water Distribution Systems and Influence on Nitrification and Disinfection Efficacy, Westerhoff, Abbaszadegan (AwwaRF $150,000; 2006-2009)
  • AwwaRF: Occurrence and formation of nitrogenous DBPs (Project#3014), Mitch, Westerhoff, Pastor, Krasner, Leenheer (AwwaRF total project $400,000; Westerhoff share $100,000, 2006-2009)
  • Predicting Organic Carbon and Disinfection ByProduct Precursors in Metro-Phoenix Surface Water Reservoirs, Westerhoff (Salt River Project, $40,000; 2006-2007)
  • AwwaRF #2948:Contribution of Wastewater to DBP Formation. MWD, Univ. of Colorado, Malcolm Pirnie Inc, ASU (2003-2005)
  • AwwaRF#2900: Dissolved organic nitrogen (DON) in drinking water and reclaimed wastewater Click Here to link
  • AWWARF#2758: Evaluation of Conventional and Advanced Treatment Processes to Remove Endocrine Disruptors and Pharmaceutically Active Compounds (ASU Subcontractor to Southern Nevada Water District – Shane Snyder; other co-PIs include Louisville Water Company, Black and Veatch, and United Water) Click Here to link
  • Mechanistic-based Disinfectant and Disinfectant By-Product Models (USEPA) Click here to link
  • Kinetic-Based Models for Bromate Formation in Natural Waters (USEPA) Click Here to link

Taste and Odor Related Projects:

  • AWWARF: Tailored Collaboration with City of Phoenix: Developing a Customer-Driven Response Strategy for Dealing with Public Perception (taste and odors at the tap) and Potential Health Concerns (algal biotoxins)
  • Development of gene probes for monitoring occurrence and distribution of MIB/Geosmin producing cyanobacteria in SRP water systems-I, Salt River Project, Westerhoff (PI), Hu, Sommerfeld ($35,000) (2002-2003)
  • Using DNA Fingerprints to track MIB/Geosmin-producing cyanobacteria in the SRP water distribution system-II, Salt River Project, Hu, Q., Sommerfeld, M., Westerhoff, P. ($35,000; 2003-2004)
  • Reducing 2-Methylisoborneol (MIB) and Geosmin in the Metropolitan-Phoenix Area Water Supply, City of Phoenix through NSF WQC, Westerhoff (PI) and Sommerfeld ($225,000; 2003-2004)
  • Regional Water Quality Monitoring and Evaluation for the Metropolitan-Phoenix Area Water Supply, Westerhoff (City of Tempe, $15,000, 1/1/08 – 12/31/11)
  • Regional Water Quality Monitoring and Evaluation for the Metropolitan-Phoenix Area Water Supply, Westerhoff (City of Phoenix, $155,000, 2007-2010)
  • Reducing Taste and Odor and Other Algae-Related Problems for Surface Water Supplies in Arid Environments (A Cooperative Research and Implementation Program among ASU, SRP, CAP, and the City of Phoenix)Funding: City of Phoenix ($1.2 Million over 1999-2006), Cities of Phoenix, Tempe, Peoria + Central Arizona Project (~ $300,000 during 2003-2008, plus cost sharing by Salt River Project) See extensive website on T&O
  • AWWARF#2775: Ozone-enhanced Biofiltration for Geosmin and MIB Removal (ASU is PI and co-PIs include University of Colorado (Summers) and Malcolm Pirnie Inc. (Chowdhury) Click here to link

Arsenic Related Projects:

  • Small and inexpensive point of use treatment systems for simultaneous removal of arsenic and nitrate from groundwater, Hristovski, Westerhoff, Brown (Border 2012/EPA, $50,000, 2009-2010)
  • Evaluation of inexpensive sorption technologies for arsenic removal from groundwater in the Arizona-Mexico border region, Hristovski, Westerhoff, Edwards (USEPA/SCERP, $55,000, 2008-2010)
  • Click to link to our USEPA funded final report on the use of Rapid small scale column tests to assess arsenic adsorption media
  • Phase II – Arsenic removal using Iron and Titanium Impregnated Activated Carbon, Westerhoff, Crittenden, Karanfil, Sylvester (AwwaRF funding $115,000; 2006-2009)
  • Regeneration and Performance of Solmetex Xnp Resin, Westerhoff (Solmetex, $15,000, 2004-05)
  • Developing an arsenic sensor, Westerhoff and Tao (Salt River Project, 2004-05)
  • Arsenic Removal Technologies – Phase I: Aerogel & Iron-Oxide Impregnated Granular Activated Carbon Media, Westerhoff (PI), Coleman, Karnafil, Crittenden (AwwaRF/DOE, 2004-2005)
  • Arsenic Removal Technologies – Phase I: Agglomerated Nanoparticle Media, Westerhoff (PI) and Schroder (AwwaRF/DOE, 2004-2005)
  • Verification of Mini-Column Arsenic Test, Westerhoff (PI) (Batelle/USEPA, $60,000; 2004-2006)

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Environmental Nanotechnology:

  • Nanoprospecting: An Approach Towards Environmental Monitoring of Engineered Nanomaterials (NSF, CBET 1336542, $306,000, 2013-2016)
  • 2013 Environmental Nanotechnology GRC, Stove, VT, June 2 – 7, 2013, Westerhoff (NSF CBET1322232), $50,000 (2013)
  • Detection of Engineered Nanomaterials: Semi-Conductor Facilities and Consumer Devices, Westerhoff, Herckes, Ranville (Semiconductor Research Corporation, $300,000, 2012-2014)
  • A New Water Source: Can Fuel Cells Provide Safe & Cost-Effective Potable Water Sources? (AwwaRF, $150,000, 2007-2010)
  • Detection of engineered nanomaterials in drinking water, food, commercial products and biological samples (RC2:Nano-GO), Westerhoff, Halden, Herckes, Hristovski (NIH, $1,272,000, 2009-20100)
  • Biological Fate & Electron Microscopy Detection of Nanoparticles During Wastewater Treatment, Westerhoff, Rittmann, Alford (USEPA, $399,000, 2007-2010)
  • The fate, transport, transformation and toxicity of manufactured nanomaterials in drinking water, Westerhoff (PI), Chen, Crittenden, Capco (USEPA-STAR, $334,000+$120,000 in matching funds, 2004-2007) abstract
  • Arsenic Removal Technologies – Phase I: Agglomerated Nanoparticle Media, Westerhoff (PI) and Schroder (AwwaRF/DOE, $133,000, 2004-2005)

Environmental Sustainability:

  • Study of Palo Verde Nuclear Generating Station Evaporation Ponds: Potential for Salinity Management, City of Phoenix, Fox, Westerhoff, Mash ($96,886; 2003-2004)
  • Detection of engineered nanomaterials in drinking water, food, commercial products and biological samples  (RC2:Nano-GO), Westerhoff, Halden, Herckes, Hristovski (NIH, $1,272,000, 2009-20100)
  • Sources for Municipal Disinfection By-Product Control, Westerhoff (SRP, $39,000, 7/1/09-6/31/-10)
  • Regional Water Quality Monitoring and Evaluation for the Metropolitan-Phoenix Area Water Supply, Westerhoff (City of Tempe, $15,000, 1/1/08 – 12/31/11)
  • Small and inexpensive point of use treatment systems for simultaneous removal of arsenic and nitrate from groundwater, Hristovski, Westerhoff, Brown (Border 2012/EPA, $50,000, 2009-2010)
  • Regional Water Quality Monitoring and Evaluation for the Metropolitan-Phoenix Area Water Supply, Westerhoff (City of Phoenix, $155,000, 2007-2010)
  • Evaluation of inexpensive sorption technologies for arsenic removal from groundwater in the Arizona-Mexico border region, Hristovski, Westerhoff, Edwards (USEPA/SCERP, $55,000, 2008-2010)
  • A New Water Source: Can Fuel Cells Provide Safe & Cost-Effective Potable Water Sources? (AwwaRF, $150,000, 2007-2010)
  • John Crittenden, Nancy Grimm, Subhrajit Guhathakurta, Peter McCartney, Elizabeth Corley, Paul Westerhoff, Peter Fox; Title: “P3 Design: A Decision Support Tool for Sustainable Urban Water Management”; Funding Source: EPA; Award Date: 2004-2005; Award Amount: $10,000.
  • Development of a quartz tuning fork sensor for chloroform, Westerhoff, Tao (Arizona Water Institute, $25,000, 2007)
  • Potable water production using hydrogen fuel cells, Westerhoff, Posner (Arizona Water Institute, $75,000, 2007-2008)
  • Cyanobacteria for generating solar-powered, carbon-neutral and cost-effective biodiesel (Science Foundation Arizona and BP, over $2 million, 2007-2009)
  • Monitoring of Trace-Level Pharmaceuticals and Personal Care Products in Salt River Project Waters, Westerhoff, Herkes (Salt River Project, $35,000, 2007-2008)
  • Development of methods for endocrine disruptors and pharmaceuticals in water, Chorover, Westerhoff, Proper (Arizona Water Institute, $50,000, 2007)
  • Biological Fate & Electron Microscopy Detection of Nanoparticles During Wastewater Treatment; Westerhoff, Rittmann, Alford (USEPA, $399,000, 2006-2010)
  • Pathway Generation and Byproduct Estimation for Chemical Oxidation Processes in Water Treatment, Crittenden, Li, Westerhoff (NSF $280,000; 2006-2009)
  • Organic Chloramine Formation in Water Distribution Systems and Influence on Nitrification and Disinfection Efficacy, Westerhoff, Abbaszadegan (AwwaRF $150,000; 2006-2009)
  • Predicting Organic Carbon and Disinfection ByProduct Precursors in Metro-Phoenix Surface Water Reservoirs, Westerhoff (Salt River Project, $40,000; 2006-2007)
  • Phase II – Arsenic removal using Iron and Titanium Impregnated Activated Carbon, Westerhoff, Crittenden, Karanfil, Sylvester (AwwaRF funding $115,000; 2006-2009)
  • Occurrence and formation of nitrogenous DBPs (Project#3014), Mitch, Westerhoff, Pastor, Krasner, Leenheer (AwwaRF total project $400,000; Westerhoff share $100,000, 2006-2009)
  • Arsenic media tests (multiple private company and consulting firms; over $125,000; 2005-2006)
  • Production, Testing and Selection of HIX Media for Simultaneous Perchlorate and Arsenic Removal, Westerhoff (USEPA/Battelle, $50,000, 2005-2008)
  • Regional taste and odor projects, Cities of Phoenix, Tempe, Peoria, Central Arizona Project (Westerhoff and Sommerfeld 2005-2006; $200,000)
  • Strategies for Controlling and mitigating algal growth within water treatment plants, Malcolm Pirnie, Milton Sommerfeld, Paul Westerhoff (AwwaRF, 2006-2008)
  • Oxidative Destruction of Organics in Membrane Concentrates (WRF-05-010), WateReuse Foundation, Paul Westerhoff and John Crittenden (WateReuse Foundation, 2005-2008)
  • Regeneration and Performance of Solmetex Xnp Resin, Westerhoff (Solmetex, $15,000, 2004-05)
  • Development Of A Molecular Fingerprinting Technique For Detection Of Toxic Cyanobacteria In The Salt River Reservoir Water Supply System, Qiang Hu, Milton Sommerfeld, and Paul Westerhoff (NSF Water Quality Center, $15,000, 2004-05)
  • Regeneration and Performance of Solmetex Xnp Resin, Westerhoff (Solmetex, $15,000, 2004-05)
  • Developing an arsenic sensor, Westerhoff and Tao (Salt River Project $53,000, 2004-05)
  • The role of dissolved organic nitrogen in drinking water chloramination – monochloramine loss and by-product formation, Shang (Hong Kong Univ.) and Westerhoff (Co-PI) (HKUST, 2004-2005)
  • The fate, transport, transformation and toxicity of manufactured nanomaterials in drinking water, Westerhoff (PI), Chen, Crittenden, Capco (USEPA-STAR, $334,000+$120,000 in matching funds, 2004-2007)
  • Arsenic Removal Technologies – Phase I: Aerogel & Iron-Oxide Impregnated Granular Activated Carbon Media, Westerhoff (PI), Coleman, Karnafil, Crittenden (AwwaRF/DOE, $133,000, 2004-2005)
  • Arsenic Removal Technologies – Phase I: Agglomerated Nanoparticle Media, Westerhoff (PI) and Schroder (AwwaRF/DOE, $133,000, 2004-2005)
  • Verification of Mini-Column Arsenic Test, Westerhoff (PI) (Batelle/USEPA, $120,000; 2004-2008)
  • Wastewater Contribution to DBP Formation, S. Krasner, G. Amy, P. Westerhoff, Z. Chowdhury (ASU share is $50,000 of $400,000; AwwaRF 2004-2006)
  • Groundwater Quality in the US-Mexico Border Region: Arsenic Occurrence and Treatment, Westerhoff (PI) and Mata ($75,000, SCERP/USEPA, 2003-04)
  • Using DNA Fingerprints to track MIB/Geosmin-producing cyanobacteria in the SRP water distribution system-II, Salt River Project, Hu, Q., Sommerfeld, M., Westerhoff, P. ($35,000; 2003-2004)
  • Reducing 2-Methylisoborneol (MIB) and Geosmin in the Metropolitan-Phoenix Area Water Supply, City of Phoenix through NSF WQC, Westerhoff (PI) and Sommerfeld ($225,000; 2003-2004)
  • Study of Palo Verde Nuclear Generating Station Evaporation Ponds: Potential for Salinity Management, City of Phoenix, Fox, Westerhoff, Mash ($96,886; 2003-2004)
  • Comparison of pilot and RSSCTs for GFH and E33, NSF Water Quality Center ($7500) (2003)
  • Dissolved organic nitrogen in drinking water and reclaimed waste water, AWWARF, Westerhoff (PI), Mash, Fox, Amy, Croue, Gallard ($170,000) (2002-2004).
  • Water Quality Center Support from City of Tempe for T&O Monitoring, City of Tempe, Westerhoff (PI), Sommerfeld ($23,100) (2002).
  • Development of gene probes for monitoring occurrence and distribution of MIB/Geosmin producing cyanobacteria in SRP water systems-I, Salt River Project, Westerhoff (PI), Hu, Sommerfeld ($35,000) (2002-2003)
  • MIB/Geosmin Monitoring for Summer/Fall 2002, City of Tempe through NSF Water Quality Center ($26,000) (2002)
  • Arsenic Testing Project, Damon S. Williams Associates through NSF Water Quality Center ($25,000) (2002-2004)
  • Design models for sorption-based arsenic treatment systems, NSF Water Quality Center ($15,000) (2001-2002).
  • Powder Activated Carbon Screening for MIB/Geosmin Removal, City of Tempe through NSF Water Quality Center ($4000) (2002)
  • Ozone-enhanced biofiltration for MIB and Geosmin removal, AWWARF, Westerhoff (PI), Chowdhury, Summers ($300,000) (2001-2004)
  • Conventional and Advanced treatment processes for Endocrine Disruptor, Personal Care Products, and Pharmaceuticals, AWWARF, Snyder (PI), Westerhoff, Song, Levine, Long (2001-2004)
  • Customer perception of algal metabolites: perceived (taste and odor) or actual (biotoxin) risk, City of Phoenix/AWWARF (2001-2004; $125,000).
  • Transient arsenic occurrence and wellhead arsenic treatment, Salt River Project (2000-01). Westerhoff ($38,000)
  • Arsenic treatment project, Motorola SPS (2000), Westerhoff ($11,000).
  • Pre-oxidation studies on CAP water, Carollo Engineers / City of Phoenix (2000), Westerhoff ($28,727)
  • Photosynthetic microalgal mass culturing – Phase II+III, Salt River Project/ASU (1999-2000). Westerhoff (PI), Vermaas, and Quang ($35,000+$7,500).
  • Reducing Taste and Odor and Other Algae-related problems for surface water supplies in arid environment (1999-2002), Sommerfeld (PI) and Westerhoff ($1,236,121).
  • Development of a Kinetic DBP Model, USEPA (1998-2000) Westerhoff (PI), Reckhow, Amy, Chowdhury ($344,000).
  • Modeling Bromate formation in the presence of NOM, USEPA (1998-2000). Westerhoff (PI) ($100,000).
  • A Zero-Valent Iron Packed Bed Reactor for Nitrate Removal, AWWARF (1998-2000). Westerhoff (PI) and Johnson ($90,000).
  • Preparing for regional changes in groundwater quality at GRUSP and other recharge projects, Salt River Project (1998-1999). Westerhoff (PI) and Knauth ($33,000).
  • Photosynthetic microalgal mass culturing, Salt River Project/ASU (1998-1999). Westerhoff (PI), Vermaas, and Quang ($35,000).
  • Taste and Odor and DOC Algae-Related Issues in the Verde River System, Salt River Project/Phoenix/Tempe/ Chandler (1997-1998). Baker (PI), Westerhoff, and Sommerfeld ($50,000).
  • Low-cost wastewater treatment processes (1996-1999). Baker (PI), Westerhoff, Fox, Houston, Johnson ($250,000).
  • Investigation of Soil Aquifer Treatment for Sustainable Water Reuse, USEPA (1998-2000). Fox (PI), Houston, Westerhoff ($1,000,000 + $900,000).
  • “Isolation and characterization of organic carbon from CAP water” (Malcolm Pirnie, Inc.) for $2,051 (sole PI in 1997).
  • “Chemical analysis at Gilbert Water Reclamation Site” (Town of Gilbert) for $7,294 (Sole PI in 1997/98).
  • “Algae-related Water Quality Issues in the Verde River Reservoirs” (Salt River Project) for $48,731 (Second PI of 3-investigators in 1997/99)
  • “Source and transport of aquatic organic material in arid systems” (WEAL/ASU) for $9,600 (first PI of 3-investigators in 1996).
  • “Development of a photosynthetic bioreactor and UV-oxidation system for remediating inorganic and organic pollutants” (Project Ingenhousz/ASU) for $70,050 (first PI of 2-investigators in 1997/98/99).
  • “Investigating the effects of metal-salt addition to lime/soda ash softening processes for improved hardness control, cost reduction, and sludge quality at the Coronado Generating Station, St. Johns, AZ” (Salt River Project) for $26,000 (sole PI in 1997/98).
  • “Low-cost strategy for treating wastewater” (USEPA/SCERP) for $135,000 (Second PI of 5-investigators in 1996/97).
  • “Low-cost strategy for treating wastewater” (USEPA/SCERP) for $87,990 (Second PI of 5-investigators in 1997/98).
  • “Linking nitrate models to existing SRP canal hydraulic models to predict water quality impacts of well pumping” for $25,358 (Salt River Project) (first PI of 3-investigators in 1996/97).
  • “Evaluation of Physical-chemical processes in removing chemically distinct fractions of NOM” (ASU) for $6,000 (sole PI in 1996).
  • “Predicting DBPs in the Paris-Area Water Treatment Plants and Distribution System” (confidential client) (Co-PI in 1995/96/97).

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A Zero-Valent Iron (FE0) Packed-Bed Treatment Process
Groundwater contamination by nitrate has become widespread in the U.S. (Nielsen and Lee, 1987). In the Phoenix, AZ area for example, over 60% of the production wells have nitrate levels that exceed the United States Environmental Protection Agency (USEPA) drinking water Maximum Contaminant Level (MCL) of 10 mg-N/L. Contaminated groundwater, agricultural drainage, and municipal wastewater, once considered unusable, are now being seriously considered as sources of municipal water in order to meet current and future demands (Andrews et al., 1994). Nitrate was the most frequently reported contaminant of concern in groundwater, reported by more than 40 state nationwide (Fetter, 1993; USEPA,1990). The USEPA has also recognized the health effects from oxo-anions other than nitrate (e.g., bromate, chlorate, chlorite, perchlorate).

Many communities throughout the Midwest and southwest that had shut down nitrate-contaminated wells are now finding that those wells must be re-activated to meet growing water demands (Clifford and Liu, 1993). Current methods of nitrate treatment (e.g., membrane separation, ion exchange, biological treatment) are costly, difficult to maintain, and can generate concentrated wastestreams. There is need for a low-cost, low-maintenance, but efficient method to treat nitrate contaminated groundwater.
The goal of the proposed research is to develop and test a zero-valent iron (ZVI) packed bed treatment process for electrochemically reducing problematic inorganics in groundwater. The process will be optimized for nitrate removal, and will evaluate the removal of other oxo-anions (e.g., perchlorate, bromate, chlorate). The use of elemental iron (Fe0) for in-situ, sub-surface, groundwater treatment of halogenated organics has recently received strong interest. A few studies have indicated that Fe0 can remove oxo-anions, such as nitrate. This project represents an initial step in assessing the feasibility of an above-ground water treatment process for treating problematic inorganic ions. The project has the following specific objectives and corresponding general technical approaches:

  • Optimize iron source for removal of nitrate. Batch and column tests will be conducted with several sources of iron with model solutions and native groundwater spiked with nitrate. The best performing iron source(s) will be used in subsequent studies.
  • Study the effects of water quality (pH, nitrate concentration, temperature, ionic strength, dissolved oxygen) and water treatment parameters (contact time, iron source) on nitrate removal from groundwater through an orthogonal experimental design.
  • Design, construct, operate, and monitor a field-scale ZVI system for removing nitrate from groundwater. Variable contact times and treatment optimization parameters will be studied. Reductive by-products (e.g., ammonia), soluble/particulate iron, scale formation, and bacterial released from the ZVI system will be monitored.
  • Screen lab-scale ZVI systems for removal capabilities of problematic oxo-anions, such as perchlorate, bromate, chlorite, chlorate, and arsenic.
  • Integrate experimental results and assess the feasibility and applications for ZVI systems for ground and surface water systems.

Funding Source: American Water Works Association Research Foundation ($90,000 over 1998-2001)

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Mechanistic-based Disinfectant and Disinfectant By-Product Models

Principal Investigator:
Paul Westerhoff

Co-Investigators:
David Reckhow (University of Massachusetts, Amherst)
Gary Amy (University of Colorado, Boulder)
Zaid Chowdhury (Malcolm Pirnie Inc.)

We will develop a mechanistic-based numerical model for chlorine decay and regulated DBP (THM and HAA) formation derived from (free) chlorination; the model framework will allow future modifications for other DBPs and chloramination.

Funding source: USEPA ORD/NCERQA STAR GRANTS PROGRAM ($330,000 over 1999-2001)

Click Here to link with webpages for the final report and model

Kinetic-Based Models for Bromate Formation in Natural Waters
Ozone (O3) is an effective disinfectant, but it can form by-products (e.g., bromate). Bromate forms via oxidation of naturally occurring bromide through a series of steps (Figure 1). There is a need to develop tools to understand and predict bromate (BrO3) formation while still achieving high levels of microbial disinfection. The central hypothesis is that a kinetic-based understanding of natural organic matter (NOM) reactions with hydroxyl (HO) radicals and aqueous bromine (HOBr/OBr) over a range of temperatures is necessary to develop mechanistic-based models for bromate formation in bulk waters. Objectives include:

  • Develop a comprehensive database of BrO3, O3, and HO radical concentrations
  • Determine rates of reaction between HOBr and OBr and NOM
  • Calibrate and verify a BrO3 formation mechanistic-based model that includes NOM
  • Simulate BrO3 control measures necessary to meet proposed and future MCLs
  • Link the numerical BrO3formation model with hydraulic and CT disinfection models

Funding source: USEPA ORD/NCERQA STAR GRANTS PROGRAM ($90,000 over 1999-2001)

Click Here for Links to Executive Summary and Final Report

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Soil Aquifer Treatment & Sustainable Water Supply
The National Center for Sustainable Water Supply (http://www.eas.asu.edu/~civil/ncsws/NCSWS.html ) has been created at Arizona State University. The NCSWS is a collaborative effort between Arizona State University, the University of Arizona, Stanford University and the University of Colorado-Boulder. The Center will address fundamental problems with the sustainability of present and proposed water reuse and management practices. NCSWS is funded by the United States Environment Protection Agency and the American Water Works Association Research Foundation (AWWARF). The role of two PhD students working with me is to

  • Develop fluorescence spectroscopy techniques to quantify DOC of wastewater origin
  • Develop techniques to isolate and characterize DOC
  • Compare the performance of reverse osmosis treatment to soil aquifer treatment (SAT)

Funding source: USEPA/AWWARF for multiple years

Preparing for Regional Changes in Groundwater Quality Due to GRUSP and Other Recharge Projects
The purpose for this project was to better understand localized and regional impact of groundwater recharged by SRP and other entities on the groundwater quality that will serve future water users throughout the Metropolitan area. Key issues regarding metals contamination are regulated by ADEQ, but other water quality constituents are typically not regulated and not measured (e.g., salts, organic carbon). SRP currently recharges up to 200,000 ac-ft per year of primarily Salt and Verde River water at the Granite Reef Underground Storage Project (GRUSP). SRP is also in the process of demonstrating direct groundwater recharge using existing wells along its canal system as dual-use (recharge-recovery) wells. In addition to SRP, there are nearly 30 other recharge projects that vary in magnitude around the Valley, and many more are planned. SRP should consider assessing the current state of un-impacted groundwaters, understanding the impact of current groundwater recharge practices, and be capable of monitoring and predicting future changes in groundwater quality.

This project provides SRP with information and tools that can be used to assess the impact of recharge on SRP customers. Along with the water resources expertise obtained by GRUSP and the Rio Salado Town Lake Project, this project will allow SRP to establish itself as an expert in large-scale recharge projects. The project was designed to address the following key questions:

  • What is the best indicator for recharged water in a recovery or monitoring well?
  • To what extent have water quality changes already been observed at GRUSP and other recharge facilities?
  • What is the potential extent for recharge projects other than GRUSP to affect SRP operated wells?

Funding Source: Salt River Project ($35,000 over 1998-1999)

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Application of Photosynthetic Algal Culture Technology for Carbon Dioxide Emission Control and Nitrate Reduction
Raising worldwide atmospheric carbon dioxide (CO2) levels may be responsible for global warming. Industrial gas emissions have been recognized as a major input of CO2 into the atmosphere. Many industries that produce carbon dioxide have been controlling their emissions, but will continue to produce carbon dioxide as long as fossil fuels are used as an energy source. To this end, industries are purchasing CO2 credits. One such CO2 credit strategy includes purchasing stands of trees; photosynthetic plants fix atmospheric CO2 and convert it to organic matter through solar energy. Over the past twenty years, other applications of photosynthesis for CO2 removal have been considered and are now emerging as viable technologies that have multiple benefits. One such application is to use the natural photosynthetic process in microalgae (including green algae and cyanobacteria) to remove CO2 from atmospheric gases or power-plant off-gases, while producing biomass that has an economic benefit (e.g., fuel source, food source, etc.). Microalgal photosynthesis in engineered photobioreactors has much higher CO2 uptake rates and efficiencies than higher plant photosynthesis (e.g., trees, water hyacinth).

Nitrate contamination of groundwater, and its remediation, also poses a significant challenge for SRP customers and users of groundwater worldwide. Nitrate is a predominant contaminant of drinking well water in many urban areas. Wastewater, fertilizers, and livestock farming are major sources of nitrate (Hem, 1992), and nitrate contamination is widespread throughout the world. Nitrate poses a potential risk to public health, particularly to infants (Gangolli et al., 1994). In the USA, the Environmental Protection Agency has maximum contaminant concentration (MCL) for nitrate in drinking water of 10 mg-N/l (0.71 mM). Canada has set the same maximum acceptable level as the US, while the European Community established a MCL of 50 mg-NO3/L (0.80 mM) and a recommended level of 25 mg-NO3/L (0.40 mM) (European Community, 1980). In many agricultural areas, the amount of nitrate in well water is 3-7 fold higher than the allowed upper limit. Removal of relatively low concentrations of nitrate by biological (denitrification), physical (reverse osmosis, electrodialysis), or chemical (ion exchange, catalytic denitrification) means is expensive (see review by Kapoor and Viraraghavan, 1997).

One very attractive and environmentally friendly alternative to remove nitrate from well water is to utilize photosynthetic microalgae such as cyanobacteria that require mostly nitrate and light for growth. Light is used as an energy source for carbon fixation as well as a source for generation of ATP and reducing power, and nitrate is used as the main source of fixed nitrogen. Other compounds that are required in smaller amounts include phosphate and trace minerals, but these are also present in water from most wells. Therefore, we have started to explore the concept of utilization of cyanobacteria for nitrate removal from ground water, and the preliminary data are very encouraging. Figure 1 presents a graph of removal of nitrate from ground water samples by different strains of cyanobacteria, and proves the concept that such nitrate removal is efficient and relatively fast. Within a day the nitrate level has dropped below the 10 mg-N/l level.

Warm temperatures and frequent sunny days in Arizona offer an opportunity to apply natural photosynthetic processes in a state-of-the-art setting for controlling CO2 emissions. This project would represent a continuation of a first year of funding through the SRP/ASU cooperative research program. During this first year of study, and research on related projects, the following key milestones were reached:

  • A collection of several algal species from Montezuma Well and Wet Beaver Creek (AZ) were found to grow rapidly under high-CO2 conditions (20%) that represent levels found in flue-gas from power plants
  • A lab-scale tubular reactor was designed and is currently under construction to monitor the uptake of CO2 from a mixed CO2/air gas-stream. A process biomass growth model / CO2 uptake model has been developed. Winter and summer growth conditions will be simulated during 30 day continuous flow operation cycles over the next few months
  • Nitrate removal by photosynthetic algal cultures has been measured, with 20 mg-N/L levels being reduced to less than 1 ppm (see Appendix A)
  • Several external proposals written and submitted to research agencies for pursuing related biomass work

Funding source: Salt River Project ($70,000 over 1998-2000)

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Other Projects:
“Isolation and characterization of organic carbon from CAP water” (Malcolm Pirnie, Inc.) for $2,051 (sole PI in 1997).
“Chemical analysis at Gilbert Water Reclamation Site” (Town of Gilbert) for $7,294 (Sole PI in 1997/98).
“Algae-related Water Quality Issues in the Verde River Reservoirs” (Salt River Project) for $48,731 (Second PI of 3-investigators in 1997/99)
“Source and transport of aquatic organic material in arid systems” (WEAL/ASU) for $9,600 (first PI of 3-investigators in 1996).
“Development of a photosynthetic bioreactor and UV-oxidation system for remediating inorganic and organic pollutants” (Project Ingenhousz/ASU) for $70,050 (first PI of 2-investigators in 1997/98/99).
“Investigating the effects of metal-salt addition to lime/soda ash softening processes for improved hardness control, cost reduction, and sludge quality at the Coronado Generating Station, St. Johns, AZ” (Salt River Project) for $26,000 (sole PI in 1997/98).
“Low-cost strategy for treating wastewater” (USEPA/SCERP) for $135,000 (Second PI of 5-investigators in 1996/97).
“Low-cost strategy for treating wastewater” (USEPA/SCERP) for $87,990 (Second PI of 5-investigators in 1997/98).
“Linking nitrate models to existing SRP canal hydraulic models to predict water quality impacts of well pumping” for $25,358 (Salt River Project) (first PI of 3-investigators in 1996/97).
“Evaluation of Physical-chemical processes in removing chemically distinct fractions of NOM” (ASU) for $6,000 (sole PI in 1996).
“Predicting DBPs in the Paris-Area Water Treatment Plants and Distribution System” (confidential client) (Co-PI in 1995/96/97).
students: AQWA Draft Report