fall 2013 - carollo engineers

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ReseaRch gRoup Jess Brown, R&D practice Directorphone (714) [email protected]

eDIToRerin Mackey

DesIgn anD pRoDucTIonLaura corringtonKim LightnerMatthew parrott

ReseaRch SOLUTIONS

This publication is printed with soy inks on FSC®-certified 60% post-consumer

waste recycled content.

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Phoenix, Arizona Yuma, Arizona Fresno, California Inland Empire, California Los Angeles, California Orange County, California Pasadena, California Sacramento, California San Diego, California San Francisco, California Sunnyvale, California Ventura County, California Walnut Creek, California Denver (Broomfield), Colorado Denver (Littleton), Colorado Broward County, Florida Miami, Florida Orlando, Florida Palm Beach County, Florida Sarasota, Florida Boise, Idaho Chicago, Illinois Kansas City, Missouri Omaha, Nebraska Las Vegas, Nevada Reno, Nevada Oklahoma City, Oklahoma Portland, Oregon Austin, Texas Dallas, Texas Fort Worth, Texas Houston, Texas Salt Lake City, Utah Seattle, Washington

Traci BrooksTraci Brooks received her B.A. in Physics from Austin College and her M.S. in Civil Engineering from the University of Colorado at Boulder. Her

graduate research looked at the degradation of chlorine by UV radiation in the presence of nitrates.

She joined Carollo’s Boise office as a full-time employee in January 2012, after completing a 2-month summer internship. During her internship, she participated in the validation of a Xylem-WEDECO K143 UV reactor. This testing was conducted at flows up to 72 mgd, and was the largest validation of its kind performed to date.

At Carollo, Traci has taken increasing responsibility as the lead validation engineer responsible for testing more than ten UV reactors at Carollo’s Portland UV Validation Facility. She also works on data analysis, report writing, and reviewing for the validation projects. Traci is looking forward to being involved in other UV technology projects with Carollo.

Varun Gandhi, Ph.D.Dr. Varun Gandhi received his B.S., M.S., and Ph.D. in Environmental

Engineering from the Georgia Institute of Technology. His Ph.D. research was on the hydrodynamics and dose delivery in a lab-scale UV reactor using laser-induced fluorescence. Using this technology, he has also analyzed the dose delivery in an ozone contactor and the flow characteristics of dense brine disposal through multi-port and rosette-shaped diffusers. He has authored or co-authored 10 peer-reviewed and conference papers related to various aspects of water treatment.

While at Carollo, Varun has worked on validation testing of multiple UV reactors at Carollo’s Portland UV Validation Facility, along with data analysis and report writing. He has also developed CFD models of UV reactors to compare treatment efficiency and develop action spectra correction factors for utilities around the U.S. In addition, he has developed CFD models for an ozone disinfection reactor.

Bridging the Gap

CommentaryWoodland’s Conversion from Oxidation Ditches to Biological Nutrient Removal

Feature StoryChino II Desalter Concentrate Management Via Innovative Byproduct Resale & Treatment

Project Updates

What’s New

CRG Spotlight

In this Issue

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Carollo will offer a webcast through the WateReuse Research Foundation (WRRF) for WateReuse Project 11-10, Evaluation of Risk Reduction Principles for Direct Potable Reuse.

Date: November 14, 2-3 pm EST.

Value: The webcast will highlight Carollo’s leading edge work in implementing direct reuse. It will also explore the costs and benefits to different risk management alternatives for direct potable reuse and its implications for the future of reclaimed water use.

For more information please go to:http://www.watereuse.org/foundation/webcasts.

Carollo Offers WRRF and WaterRF WebcastsCarollo also offered a webcast on September 19th through the Water Research Foundation (WaterRF) for WaterRF Project 3032, A Decision Tool for Earthy/Musty Taste and Odor Control.

This webcast highlighted Carollo’s expertise in taste and odor (T&O) characterization and management. It also explored the effect of water quality on human sensitivity to earthy/musty odors and public perceptions, and presented a decision-making tool to help utilities develop reasonable and defensible treatment goals for managing T&O events.

This webcast can be accessed at: http://www.waterrf.org/resources/webcasts/Pages/on-demand.aspx.

Jess Brown, Ph.D., P.E.R&D Practice Director

Welcome to the Fall 2013 issue of Research Solutions, a quarterly publication of the

Carollo’s R&D Practice, also known as the Carollo Research Group (CRG). CRG, a diverse team of engineers, scientists, and researchers located throughout the country, is focused on bridging the gap between fundamental research and practical, innovative, and reliable solutions for those we serve. Research Solutions features articles that demonstrate Carollo’s capabilities to develop and implement advanced processes, technologies, and tools in the water industry. You’ll also find commentary about industry developments and announcements about recent publications, webcasts, awards, and new staff. The Fall 2013 issue discusses:

• Cost-effective conversion to biological nutrient removal.

• An innovative approach for leveraging RO concentrate residuals.

• A new, comprehensive study of the nation’s first direct potable reuse system.

• How a pipe loop, pilot study, and blending analysis helped address one utility’s water quality and conveyance challenges.

Research Solutions reflects our belief that creativity, science, and technology must be integrated with sound engineering to meet the complex challenges facing our industry. Challenges like aging infrastructure, increasingly stringent water quality and discharge requirements, the movement toward sustainability, and growing water supply shortages require innovative thinking: thinking that bridges the gap from research and development to real world solutions.

We hope that Research Solutions provides you with new ideas and case studies that help you address your water needs. Please do not hesitate to contact the primary authors or me directly for more information on any of these articles.

cOMMeNTaRY

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Bridging the Gap

BNR alternatives included constructing new tanks to serve as anoxic zones in a Modified Ludzack-Ettinger (MLE) process configuration, retrofitting the existing ditches to MLE without constructing new tanks, and operating the ditches in a simultaneous nitrification-denitrification mode. The aeration alternatives included adding more brush rotors, installing fine bubble diffusers to supplement the rotors, and replacing the rotors with a diffused aeration system. The best approach for the City was to retrofit the existing ditches to MLE and replace the rotors with fine bubble diffusers supplied by high-efficiency turbo blowers. This approach was selected because: 1) retrofit to MLE does not require constructing costly new tanks; and 2) converting to diffused aeration provides operational flexibility for successful nutrient removal and significant energy savings. Figure 1 illustrates the anticipated energy savings, which translates to approximately $160,000 per year in reduced costs at startup.

Aeration and Mixing Challenges in Basins with SideslopesConverting to MLE means the ditch will be partitioned into discrete aerobic and anoxic zones with weir walls and the mixed liquor return will be pumped from the last aerobic zone to the anoxic zone. The design of the mixing and aeration system was unique due

Woodland’s Conversion from Oxidation Ditches to Biological Nutrient Removal

By Andre Gharagozian, P.E. ([email protected]), Katy Rogers, P.E., Rob Hunt, P.E., and Ed Wicklein, P.E.; and Mark Cocke

[City of Woodland, CA]

The City of Woodland, CA, serves a population of 56,000 and owns, operates, and maintains a wastewater collection system and Water Pollution Control Facility (WPCF). The WPCF is permitted for tertiary treatment of 10.4 million gallons per day (mgd) using oxidation ditches with brush rotor aeration and cloth media filters. However, at current dry weather flows of 5.5 mgd, the aeration equipment cannot deliver sufficient oxygen when 3 of the 4 ditches are in service. Additionally, the City is planning for an effluent nitrate limit of 10 mg/L in their next NPDES discharge permit, requiring conversion to biological nutrient removal (BNR). Carollo is currently designing modifications to convert to BNR and address the aeration deficiency. The project is at 90-percent design and will advertise for bids at the end of the year.

BNR Process and High-Efficiency Turbo Blowers Selection Several aeration and BNR alternatives were considered during predesign. The

Figure 1. The City will reduce power usage by almost 200 hp with this project.

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to the unorthodox ditch geometry—the walls are not vertical and instead have a 1:1 sideslope. The area directly above the sideslopes contains 40 percent of the ditch volume, which raised several questions: 1) Are diffusers needed on the sideslopes to maintain sufficient dissolved oxygen? 2) Will the sideslopes affect the performance and efficiency of the diffusers? and 3) Are mixers needed on the sideslopes to prevent solids deposition? Of particular concern were the ends of the ditch, where the 180-degree bend means an even higher percentage of the volume is above the sideslope.

To answer these questions, 3D computational fluid dynamic (CFD) modeling was used. The CFD model included user-defined functions for solids transport and aeration. This was necessary for the model to properly account for the density effects of having solids and air in the wastewater, which significantly influences the fluid flow pattern. Figure 2 depicts the velocity and air outputs for one of the simulations, showing that the upward velocity from the diffused aeration system creates a strong mixing and recirculation pattern over the side slope. Therefore, diffusers or mixers above the sideslopes are not needed. See the Winter 2013 issue of Research Solutions for a more detailed description of the CFD modeling and different types of mixers evaluated.

While the strong recirculation pattern is good for mixing, there are concerns that it accelerates the upward velocity of the air bubbles, reducing contact time and oxygen transfer efficiency. Field test data provided by a major diffuser manufacturer were used to assess this concern. Results showed that

diffuser efficiency was inversely proportional to the depth and diffuser flux rate. Deeper basins and higher diffuser flux rates create stronger recirculation patterns. Figure 3 illustrates this relationship, which was accounted for in the design. Since there is some uncertainty in the performance, diffuser specifications will require that blanks be provided to facilitate adding diffusers in the future, if needed.

Water Conservation and a Changing Supply Means Flexibility Is NeededLike many communities, the City is implementing measures to promote water conservation. Water conservation will increase the concentration of nutrients in the WPCF influent over time. Therefore, the process will need to operate at higher efficiencies in the future to meet the fixed effluent nitrate limit of 10 mg/L. For example, with an influent total nitrogen (TN) concentration of 40 mg/L today, the BNR process needs to perform at 75-percent efficiency to meet its effluent limit. In the future, TN concentrations may approach 60 mg/L and the process would need to perform at 85-percent efficiency and potentially require enhancements, such as adding supplemental carbon. Space was left on the site if this change is required.

The City’s water supply will be changing from groundwater to surface water sources in the next 5 years. This will significantly reduce the wastewater alkalinity, which is needed to support the biological reactions in a BNR process. To mitigate this, the project includes storage and feed facilities for magnesium hydroxide.

Constructability and ImplementationLike all wastewater treatment plants, the modifications will be constructed while the WPCF is in operation. In addition to the regulatory and capacity drivers, project constructability is also a factor. The City currently operates with 3 of the 4 ditches in service; therefore, improvements can be made one ditch at a time with minimal operational impact. However, the aeration system is at capacity, so any delays in implementation or increase in flow or load would require supplemental aeration during construction, adding complexity and cost.

The project cost related to BNR upgrade and improved aeration capacity is approximately $12 million, amounting to roughly $1 per gallon. The City’s ability to implement this BNR conversion at such a low cost is primarily through reusing existing infrastructure. While basins with sideslopes pose challenges for mixing and aeration, they are definitely worth salvaging!

Figure 2. CFD modeling shows that aeration creates a strong recirculation pattern and supplemental aeration or mixing is not needed on the sideslopes.

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Figure 3. The tank depth and air flow rate appears to affect the diffuser transfer efficiency.

Source: Adapted from Redmond Engineering Company, Denton Creek, Texas - Report of the Clean Water Test Results – Sanitaire/ABJ Project 02-5130a – SBR Basin #1, July 16, 2004.

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IntroductionWith more than 800 wells, the Chino Groundwater Basin in Southern California provides a critical water supply for agriculture, industry, and public drinking water suppliers. Although over pumping of groundwater has resulted in subsidence in some areas of the Chino Basin, there is also a hydraulic surcharge that results in overflow of contaminated groundwater to the Santa Ana River. The primary groundwater contaminants of concern are total dissolved solids (TDS), nitrates, and volatile organic compounds (VOCs).

The Chino II Desalter (Chino II) began operation in 2006 to expand the capacity of the groundwater treatment system with a combined ion exchange (IX) and reverse osmosis (RO) treatment capacity of 10 mgd. The Chino II is managed and operated by the Chino Basin Desalter Authority (CDA). The IX and RO treatment trains in Chino II are used to treat brackish groundwater from eight wells that also have elevated nitrate concentrations. A 6.5-mgd expansion of the Chino II RO plant has been constructed. However, due in part to the high cost of waste brine disposal, the CDA is evaluating means of maximizing the efficiency of the RO treatment system at Chino II to reduce brine disposal costs and increase permeate production.

Basis of DesignRO recovery is typically limited by precipitation of sparingly soluble salts on the surface of the membranes. With the

current mineral content of the groundwater treated at the Chino II RO facilities, the primary RO recovery is 83.5 percent. The remaining 16.5 percent is discharged into the Inland Empire Brine Line (IEBL) line as RO concentrate. The heart of the design of the Chino II Concentrate Reduction Facility (CRF) is a high-rate pellet softening and solids contact clarifier system to remove the limiting foulants (specifically calcium and silica) from the primary RO concentrate. Seeded calcite precipitation occurs in the fluidized pellet reactors, where hard and durable pellets are generated, as shown in the photo above. The pellets naturally dewater and can be easily transported compared to the thick, heavy, wet sludge produced by a conventional softening process. The produced pellets are a value-added product that can be used in a variety of industrial

applications, thus converting a waste stream of the Chino II process into a usable commodity.

Due to the turbid nature of the pellet reactor effluent solids, contact clarification is required to remove magnesium solids that are formed in the pellet reactors and carry over due to their lower density. After the fouling compounds are reduced in the pellet reactor and the clarifier, the softened primary RO concentrate is polished with dual media filters. The filtered effluent is sent as feed to the secondary RO (SRO) systems. Treated water will be blended with the primary RO permeate, and SRO concentrate will be disposed of into the IEBL. Using this approach, total water recovery from the RO system at Chino II will be increased from 83.5 percent to as high as 95 percent, substantially reducing

the volume of brine disposed into the IEBL, while increasing permeate production.

Chino II CRF Overall ProcessA process flow diagram for the proposed concentrate reduction facility is shown in Figure 1. The schematic shows the following major process elements:

• An energy recovery system upstream of the pellet reactor to recover excess energy from the primary RO concentrate.

• Pellet reactor softener system to remove calcium carbonate and some silica from the primary concentrate.

• Solids contact clarifier to remove the carryover of calcium, magnesium, and silica particles.

• Granular media filters to polish the clarifier effluent.

• SRO system to treat the softened and filtered primary RO concentrate to produce permeate (product water) and brine (SRO concentrate).

• Filter waste washwater basin to collect media filter spent backwash water, gravity thickener supernatant, pellet storage hopper drainage, and supernatant from the dewatering process. The waste washwater is pumped to the clarifier influent for treatment and recovery.

• Backwash basin to store backwash and surface wash water for the granular media filters and equalize SRO feed.

• Gravity thickener and mechanical dewatering to treat clarifier sludge.

• The following chemicals and materials are required:

Q Lime and caustic soda are used to raise the pH and cause precipitation of the dissolved solids within the pellet reactor and clarifier.

Q Seed material (silica sand or calcium carbonate) is fed to the pellet reactor to act as the nucleus for calcium carbonate precipitation.

By Brandon Yallaly, P.E. ([email protected]), Winnie Shih, Ph.D., and John Meyerhofer; Jack Safely [formerly with Western Municipal

Water District], Curtis Paxton [Chino Basin Desalter Authority], and Issam Najm, Ph.D., P.E. [WQTS]

Chino II Desalter Concentrate Management Via Innovative Byproduct Resale & Treatment

FeaTuResTORY

Q Ferric chloride is applied as a coagulant in the clarifier to improve solids settleability.

Q Polymer is added in the clarifier as a gravity thickener to improve solids settleability, and ahead of the mechanical dewatering process to improve the performance of the centrifuge.

Q Threshold inhibitor is applied to the SRO feed to control precipitation of silica and calcium carbonate.

Q Sulfuric acid is fed to the clarifier effluent to prevent continued calcium carbonate precipitation in the media filters and SRO systems.

Q Soda ash is added upstream of the pellet reactors and is used to provide a source of carbonate alkalinity.

The concentrate reduction process reduces the overall dissolved solids mass loading to the IEBL pipeline through the removal of calcium carbonate, magnesium hydroxide, and silica from the brine stream as solid precipitates. Figure 2 shows the 3-D rendering of the Dewatering Building at the Chino II CRF, where the pellet softening, solids clarification, and mechanical dewatering process are located. While Chino II continues to remove the same amount of dissolved solids from the groundwater basin, a smaller portion is discharged to the IEBL pipeline as a liquid waste and a significant amount of solids leave the Chino II site by truck in the form of pellets and dewatered sludge.

Figure 1. Chino II CRF process flow diagram.

Calcium carbonate pellets generated from the pellet softener.

Figure 2. Chino II CRF dewatering building.

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Carollo is pleased to announce the publication of WateReuse Report 10-06A, Challenge Projects on Low Energy Treatment Schemes for Water Reuse, Phase 1, authored by Andrew Salveson, Erin Mackey, Graham Juby, Rudy Kilian, and Rod Reardon (Carollo); Julian Sandino (CH2MHill); Jean Debroux (Kennedy/Jenks Consultants); Perry McCarty (Consultant); Laura Shenkar (The Artemis Project); and Paul O’Callaghan (O2 Environmental).

This study evaluated conventional treatment systems, emerging treatment systems, and innovative treatment concepts for low-energy wastewater treatment and wastewater reclamation. The study identified two key treatment technologies from the Emerging Treatment Systems

category based on market readiness, having the highest potential to save energy

and costs, and being ready for use at full-scale. The recommended technologies for Phase II research were: the anaerobic MBR (AnMBR) and the main-stream anammox process. Other processes also recommended for testing, should outside funding become available, were pasteurization, gasification, WaterTectonics electrocoagulation, and the Emefcy’s SABRE process. Each process is briefly described in the report.

This report was jointly sponsored by the WRRF, the Water Environment Research Foundation, and the U.S. Department of Interior Bureau of Reclamation.

WRRF Publishes Low Energy Treatment Schemes ReportKeY TeaM MeMbeRandrew salveson, P.e. ([email protected])

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This report is available through the WRRF website (www.watereuse.org).

KeY TeaM MeMbeRsJustin sutherland, Ph.D., P.e. ([email protected])Greg Pope, Ph.D., P.e.hutch Musallam, P.e.

Faced with an extended drought in the State of Texas, the City of San Angelo began to explore its best available water supply option: the Hickory Aquifer well field. However, there were some challenges to overcome: the well field is approximately 60 miles away from the City’s treatment plant and the water contains significant amounts of radium and iron.

The challenges presented by the water quality had potential impacts on the design of treatment and raw water conveyance systems and distribution of the finished water. In each of these cases, data were either limited or site-specific information was needed. Bench and pilot studies were invaluable tools to develop good design and operational criteria for treatment, raw water conveyance, and blending the finished groundwater with the existing finished surface water.

Raw Water Conveyance. A pipe loop study was conducted on the raw groundwater to evaluate whether radium may co-precipitate with other inorganic constituents in the raw

San Angelo’s Hickory Water Supply Project Develops Criteria for Treatment, Raw Water Conveyance, and Blending of Groundwater and Surface Water

water pipeline to a point at which the waste from a pipe pigging operation would require disposal in a low-level radioactive waste site. An interesting finding of this study was that the use of a phosphate inhibitor appeared to slightly increase pipe scale weight and significantly increase the radium concentration in the pipe scale and, therefore, should be avoided for pipeline operation. Otherwise, the results of the study demonstrated that there was no valid concern about significant levels of radium depositing on the pipe wall.

Treatment. Carollo worked with the City to design, construct, and operate pilot testing facilities to evaluate three IX resins for radium removal from the groundwater. Two of the resins were viable options. The City wished to evaluate other treatment technologies, and Carollo led a second pilot plant investigation that tested three RO membrane systems. Both technologies

worked well, but the City opted to select the single use IX technology to remove radium because it offered the operational flexibility and waste disposal alternatives that the City desired.

Finished Water Blending. Since the low TDS groundwater from the Hickory Aquifer will be blended with the City’s high TDS surface waters, it was necessary to investigate the effect of blending both waters on the distribution system. Results of the blending study showed that the surface water and groundwaters blend well and that the chloramines stability improved with increased groundwater in the blend.

The results of the studies conducted by Carollo—viable options for radium and iron removal, waste disposal, water blending, and the impact of radium on the conveyance system, among others—were invaluable guides to the final design and construction phases of the project. This work is scheduled for final completion in 2014.

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Carollo Awards 2013 Scholarship to ASU Student

Carollo awards a $10,000 scholarship annually to a master’s student engaging in water-energy nexus issues for water, wastewater, or reuse. Alexandra (Allie) Bowen, E.I.T., was awarded the 2013 Carollo Engineers Scholarship at the AWWA Annual Conference & Exhibition in Denver, CO.

Allie is a graduate research assistant at Arizona State University’s School of Sustainable Engineering and the Built Environment. At ASU, she’s been involved with research focused on the occurrence and speciation of metals throughout potable water treatment plants and power

generating systems. She’s also developing an in-situ passive sampler for water treatment plants and is co-founder of the ASU student group Graduate Students for the Environment.

Prior to ASU, Allie was an undergraduate research assistant at the University of New Hampshire, where she investigated the use of UV for RO pretreatment and also studied oxidative degradation mechanisms of pharmaceuticals and personal care products.

Congratulations, Allie!

Jess Brown (left) and former AWWA President Charlie Anderson (right) awarded the 2013 Carollo Engineers Scholarship to Allie Bowen, a graduate research assistant at Arizona State University.

direct measurement of pathogens (virus, protozoa, and bacteria) and trace chemicals (pharmaceuticals and personal care products, hormones, flame retardants, and others) as well as a number of indicator and surrogate measurements that can be used to monitor treatment performance. To support development of a robust monitoring approach that is practicable for utilities of various sizes and financial means, our testing protocol will include measurement of less costly surrogates wherever possible to complement the testing for primary parameters, and will define correlations between primary parameters and surrogates.

KeY TeaM MeMbeRseva steinle-Darling, Ph.D., P.e. ([email protected])andrew salveson, P.e.

Across the country, successful indirect potable reuse (IPR) projects are now creating more than 100 mgd of potable water; several have been doing it safely for nearly half a century, with no ill effects on public health. These include the Orange County Water District, CA; West Basin Municipal Water District, CA; El Paso Water Utilities, TX; Upper Occoquan Services Authority, VA; and the City of Scottsdale, AZ. In May of this year, the first of several Texas projects exploring the path towards direct potable reuse (DPR), implemented by the Colorado River Municipal Water District (CRMWD) in Big Spring, TX, began augmenting raw water supplies directly with advanced treated reclaimed water.

The advanced treatment processes implemented at the Raw Water Production Facility (RWPF) in Big Spring include microfiltration, RO, and UV-peroxide based advanced oxidation, a configuration that is similar to several of the IPR projects listed above. What makes Big Spring unique among potable reuse projects is the lack of an environmental buffer, which in conventional IPR projects provides additional treatment and response time in case of a water quality failure.

Texas Water Development Board Study to Examine Nation’s First Direct Potable Reuse System

A team led by Carollo was recently selected by the Texas Water Development Board to perform a

comprehensive evaluation and monitoring study of the RWPF in Big Spring. An overarching goal of the study is to determine the efficacy and reliability of DPR treatment for implementation across the State of Texas, and ultimately support the development of DPR projects across the nation.

Our study will include:

• A comprehensive and independent evaluation of RWPF process performance.

• Development and implementation of a detailed testing protocol.

• A guidance document that recommends monitoring approaches for DPR.

For this study, Carollo will build upon its nation-leading research efforts on treatment and monitoring for potable reuse applications, developed in partnership with both research agencies and utility clients. Our team will develop and implement a testing protocol that includes

Big Spring Wastewater Treatment Plant

Raw Water Production Facility

CRMWD Raw Water Pipeline

Water Treatment Plants

IPR and DPR involve the use of additional advanced treatment processes to further purify the water for reuse as a potable water source.

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ReseaRch gRoup Jess Brown, R&D practice Directorphone (714) [email protected]

eDIToRerin Mackey

DesIgn anD pRoDucTIonLaura corringtonKim LightnerMatthew parrott

ReseaRch SOLUTIONS

This publication is printed with soy inks on FSC®-certified 60% post-consumer

waste recycled content.

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Phoenix, Arizona Yuma, Arizona Fresno, California Inland Empire, California Los Angeles, California Orange County, California Pasadena, California Sacramento, California San Diego, California San Francisco, California Sunnyvale, California Ventura County, California Walnut Creek, California Denver (Broomfield), Colorado Denver (Littleton), Colorado Broward County, Florida Miami, Florida Orlando, Florida Palm Beach County, Florida Sarasota, Florida Boise, Idaho Chicago, Illinois Kansas City, Missouri Omaha, Nebraska Las Vegas, Nevada Reno, Nevada Oklahoma City, Oklahoma Portland, Oregon Austin, Texas Dallas, Texas Fort Worth, Texas Houston, Texas Salt Lake City, Utah Seattle, Washington

Traci BrooksTraci Brooks received her B.A. in Physics from Austin College and her M.S. in Civil Engineering from the University of Colorado at Boulder. Her

graduate research looked at the degradation of chlorine by UV radiation in the presence of nitrates.

She joined Carollo’s Boise office as a full-time employee in January 2012, after completing a 2-month summer internship. During her internship, she participated in the validation of a Xylem-WEDECO K143 UV reactor. This testing was conducted at flows up to 72 mgd, and was the largest validation of its kind performed to date.

At Carollo, Traci has taken increasing responsibility as the lead validation engineer responsible for testing more than ten UV reactors at Carollo’s Portland UV Validation Facility. She also works on data analysis, report writing, and reviewing for the validation projects. Traci is looking forward to being involved in other UV technology projects with Carollo.

Varun Gandhi, Ph.D.Dr. Varun Gandhi received his B.S., M.S., and Ph.D. in Environmental

Engineering from the Georgia Institute of Technology. His Ph.D. research was on the hydrodynamics and dose delivery in a lab-scale UV reactor using laser-induced fluorescence. Using this technology, he has also analyzed the dose delivery in an ozone contactor and the flow characteristics of dense brine disposal through multi-port and rosette-shaped diffusers. He has authored or co-authored 10 peer-reviewed and conference papers related to various aspects of water treatment.

While at Carollo, Varun has worked on validation testing of multiple UV reactors at Carollo’s Portland UV Validation Facility, along with data analysis and report writing. He has also developed CFD models of UV reactors to compare treatment efficiency and develop action spectra correction factors for utilities around the U.S. In addition, he has developed CFD models for an ozone disinfection reactor.

Bridging the Gap

CommentaryWoodland’s Conversion from Oxidation Ditches to Biological Nutrient Removal

Feature StoryChino II Desalter Concentrate Management Via Innovative Byproduct Resale & Treatment

Project Updates

What’s New

CRG Spotlight

In this Issue

2

6

6

8

4

2

WhaT’sNeW

Carollo will offer a webcast through the WateReuse Research Foundation (WRRF) for WateReuse Project 11-10, Evaluation of Risk Reduction Principles for Direct Potable Reuse.

Date: November 14, 2-3 pm EST.

Value: The webcast will highlight Carollo’s leading edge work in implementing direct reuse. It will also explore the costs and benefits to different risk management alternatives for direct potable reuse and its implications for the future of reclaimed water use.

For more information please go to:http://www.watereuse.org/foundation/webcasts.

Carollo Offers WRRF and WaterRF WebcastsCarollo also offered a webcast on September 19th through the Water Research Foundation (WaterRF) for WaterRF Project 3032, A Decision Tool for Earthy/Musty Taste and Odor Control.

This webcast highlighted Carollo’s expertise in taste and odor (T&O) characterization and management. It also explored the effect of water quality on human sensitivity to earthy/musty odors and public perceptions, and presented a decision-making tool to help utilities develop reasonable and defensible treatment goals for managing T&O events.

This webcast can be accessed at: http://www.waterrf.org/resources/webcasts/Pages/on-demand.aspx.

fall 2013 - carollo engineers

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