select areas of focus bridging the gap…in uv …on bridging the gap between fundamental research...

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The Carollo Research Group (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 the water industry. We believe that creativity, science, and technology must be integrated with sound engineering to meet the complex challenges facing the water 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 develop-ment to the application of advanced processes, technologies, and tools for real world solutions.

SELECT AREAS OF FOCUSBridging the Gap…in UV Technology and Treatment

UV disinfection has emerged over the last 15 years as the best avail-able technology for the inactivation of Cryptosporidium, Giardia, and other pathogens that are resistant to chemical disinfection. Carollo has contributed to the successful development and implementation of UV disinfection in North America by providing leadership in UV regulations, modeling, validation, and design. Underlying our indus-try-leading UV expertise is an extensive portfolio of UV research. Since 1990, the Water Research Foundation has funded 38 projects on drinking water UV disinfection and advanced oxidation. Carollo has been/is the principal or co-principal investigator for 13 of those projects and a Project Advisory Committee member or participant on three others. Projects like the Development of a UV Disinfection Knowledge Base, Evaluation of CFD as a Cost-Effective Tool for Assessing UV System Performance, Optimization of UV Validation, and others have defined the state-of-the-art in drinking water UV disinfection.

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Bridging the Gap…in Reuse

CRG has been active in potable water reuse research since 1998. Select examples of this work include: 1) the very first WateReuse Research Foundation (WRRF) funded project, which examined N-nitrosodimethylamine (NDMA) formation and destruction through advanced treatment facilities; 2) two early-state and key WRRF grants on using advanced treatment to remove trace pollutants and pathogens from reuse water; 3) WRRF’s first-ever direct potable reuse (DPR) research project, which was a collaborative effort with NASA and focused on methods for reducing DPR risk; and 4) a WRRF project on how to replace an environmental buffer with engineered storage for DPR applications. This seminal research affords Carollo expertise that is critical to the success of municipal reuse projects with which we’re involved in California, Oregon, Texas, and Florida.

Bridging the Gap…in Biological Drinking Water Treatment

Biological drinking water treatment? Naturally. Due largely to the rising costs and increasing complexities of handling high-strength water-treatment residuals, biological treatment is rapidly gaining traction in the drinking water industry. CRG has pioneered key developments in this arena, developments which are quickly becoming the standard practice in the industry. For example, Carollo’s Engineered Biofiltration concept shifts biofiltration from a passive process to an intentional process, engineered to enhance both filtration and the biological removal of contaminants like DBP precursors, T&O, iron, manganese, and ammonia. CRG also developed a two-stage, fixed-bed biological process (biottta®) that efficiently removes multiple groundwater contaminants like nitrate, perchlorate, hexavalent chromium, and volatile organic chemicals. Our biological treatment includes not only macro-level process testing, development, and design but also micro-level analyses (e.g., ATP quantification, scanning electron microscopy, tracer studies, molecular microbial community analysis) that have improved process understanding and treatment performance.

Bridging the Gap…in Planning

Blue Plan-it® is a dynamic decision support tool that allows utilities to develop a virtual roadmap to the future so they can see the potential

impacts of the decisions they make today as they deploy water resources to serve their customers. Blue Plan-it® integrates water, wastewater and reclaimed water systems in a single model to provide a complete assessment of water resource allocation strategies, treatment options, and associated financial impacts. The tool was developed with input from Carollo’s experts in water resources, water treatment, and integrated water resources

master planning, and uses state-of-the-art process simulation and optimization tools. It also includes a customizable dashboard that

presents technical, financial, and environmental evaluation results right at a utility’s fingertips.

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Bridging the Gap…in Communication

Published quarterly, Research Solutions includes technical articles that highlight Carollo’s involvement with the development and implementation of cutting-edge advanced processes, technologies, and tools in the water industry. You’ll also find commentary articles addressing new regulations and industry trends, and announcements about recent publications, awards, and new staff.

Bridging the Gap…in Field Testing

Good field-testing data lead to robust solutions and cost-effective and reliable full-scale designs. To that end, the CRG has developed a Pilot Testing Services Program, leveraging our extensive experience with applied research projects. Pilot Testing Services is a company-wide resource that incorporates quality control review of field testing projects, management of over $3 million in custom-made, bench- and pilot-scale equipment, and training and support for our field operators. The result is a formula for quality and service, unique in the industry, for delivering applied research and other field testing projects.


Representative Projects - Carollo Research GroupCategory Client/ProjectUV Disinfection Water Research Foundation - UV Disinfection Knowledge Base

Carollo Engineers - UV Disinfection Portland Validation Facility

EPA/Cadmus - Implementing UV Systems for Treatment of Groundwater in Small-Medium Sized Utilities

Water Research Foundation - Design and Performance Guidelines for UV Sensor Systems

Water Reuse WateReuse Research Foundation - Low-Energy Treatment Schemes for Water Reuse Phase I

WateReuse Research Foundation - Innovative Treatment for Reclaimed Water

WateReuse Research Foundation - Risk Reduction for Direct Potable Reuse

WateReuse Research Foundation - Framework for Informed Planning Decisions Regarding Indirect Potable Reuse and Dual Pipe Systems

WateReuse Research Foundation - Demonstrating the Benefits of Engineered Direct vs. De facto Reuse Systems

Wastewater Colorado School of Mines - Modifying Treatment to Increase Nitrogen Removal in Conventional Side-Stream Treatment

Multiple Clients Across the Country - Biogas Scrubbers

Water Environment Research Foundation - Co-Digestion of Organic Waste - Addressing Operational Side-effects

Biological Drinking Water Treatment

Water Research Foundation - Development of a Biofiltration Knowledge Base

Chino Basin Desalter Authority, California - Pilot Testing and Design of the biottta® System for the Removal of Nitrate and VOCs from Chino Basin Groundwater

Water Research Foundation/City of Arlington, Texas, Tailored Collaboration (TC) Project - Engineered Biofiltration for Enhanced Hydraulic and Water Treatment Performance

Water Research Foundation/Trinity River Authority TC Project - Optimizing Biofilter Conditions for Improved Manganese Removal

Pilot and Bench-Scale Testing

Water Research Foundation DBP Control using Advanced Water Treatment Processes

University of Michigan - Waste Activated Sludge Anaerobic Contact (WASAC [Patent No. 6,921,486]) Pilot Plant Project

Membranes Water Research Foundation - Seawater Intake Systems for Desalination Plants

Water Research Foundation - Desalination Product Water Recovery and Concentrate Volume Minimization

Indian Wells Water District, California - Pilot Testing of Zero Liquid Discharge Technologies

Water Research Foundation/Phoenix TC Project - Lowering Chemical and Energy Usage for Inland Desalination

CFD Modeling King County, Washington - West Point Treatment Plant CFD Model of Sludge Digester Gas Mixing System

Water Research Foundation - UV Reactor Design Assessment and Installation

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WATER RESEARCH FOUNDATION, DENVER, CO

UV Disinfection Knowledge Base

UV disinfection has evolved considerably over the last 10 years in terms of regulations, commercial technologies, design and operation, and fundamental understanding. Thus, utilities, engineers, and regulators see UV disinfection as an emerging technology and have questions that include: How much lamp aging and fouling occurs? Are UV systems properly sized? How reliable are UV systems? How much do they cost in terms of capital and O&M? Is mercury release an issue? How do they comply with guidance and regulations? What are the lessons learned implementing UV disinfection?

To answer these questions, the Water Research Foundation and 10 utilities across North America funded WaterRF Project 3117, Development of a UV Disinfection Knowledge Base. This $720,000 project collected and analyzed data on the design, validation, performance, costs, and lessons learned from installed UV systems across North America. Data was stored within a Microsoft Access database and can be evaluated using software tools specifically designed to answer questions on the application of UV disinfection. The project team also conducted onsite evaluations of UV system performance at nine UV installations representing the four top UV vendors. At each site, Carollo evaluated the UV dose monitoring and control algorithm, and the performance of UV system components, including lamps, ballasts, quartz sleeves, UV sensors, and UVT monitors using a custom optics bench and instrumentation. Results from those evaluations were used to develop standard methods for evaluating and troubleshooting UV system performance. Finally, Carollo conducted a pilot study to evaluate mercury release following breakage events with MP and LPHO lamps. The results were used to develop approaches utilities can take to minimize the risk and impact of lamp breakage events with UV system operation.

Thirty participating utilities.

Onsite evaluations of nine installed UV systems.

Answered the important questions about UV system

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The UV Disinfection Knowledge Base project benchmarked the state-of-the-

art in drinking water disinfection in North America.

Calgon Carbon CorporationOndeo Degremont

Trojan Technologies, Inc.Severn Trent Services WEDECO UV Technologies

Ultra Dynamics

Hanovia

LEGEND


CAROLLO ENGINEERS, PORTLAND, OR

UV Disinfection Validation Facility

To receive inactivation credits with UV disinfection, the USEPA requires that UV systems undergo validation testing. Before 2003, UV systems installed in the U.S. were validated either onsite or at a facility in Europe. Recognizing a need for a U.S. facility, Carollo developed the Portland UV Disinfection Validation Facility in Portland, Oregon. The facility is located near the groundwater pumping station of Portland’s South Shore Well Field. The wellfield can provide up to 90 mgd of chlorine-free, low UV-absorbance groundwater.

Carollo obtained funding for facility development from four UV system suppliers: Calgon Carbon Corporation, Trojan Technologies, WEDECO, and Aquionics. The design and construction of a 30-inch test train was completed in February 2003. A second 12-inch test train was added to the facility in December 2005. The facility was expanded in 2011 to provide validation at flows up to 70 mgd.

Carollo commissioned the site in March 2003 with the testing of a 40-mgd, medium-pressure (MP) UV system supplied by Calgon. Carollo has since tested over 50 commercial UV reactors for drinking water and reuse applications at flowrates ranging from 1 to 70 mgd and UV transmittance values ranging from 50 to 98%. Since facility startup, over 4,000 challenge tests using MS2, Qβ, T1UV and T7 coliphage and B. pumilis spores have been used to demonstrate UV doses ranging from 5 to 200 mJ/cm2.

The test train provides highly accurate validation test results: (1) flow is controlled to within 1% of target flow, (2) UV transmittance (UVT) is controlled within 0.3% of target UVT, and (3) influent and effluent concentrations are typically measured with a standard deviation of 0.04 log. Through analysis of the validation data, Carollo has developed efficient and simple dose-monitoring algorithms that predict UV dose within ±1 mJ/cm2. The dose-monitoring algorithms are used by UV systems across North America and have been adopted by the UV Desinfection Guidance Manual as a standard method for the UV industry.

The facility has also validated UV systems for UV advanced oxidation processes (AOP) applications. Carollo measured the destruction of methylisoborneol (MIB), geosmin, and caffeine as a function of UV dose, hydrogen peroxide concentration, and hydroxyl scavenger demand. Results were used to demonstrate scaleup of advanced oxidation from bench- to full-scale applications.

Validation of over 50 commercial UV reactor

product lines.

Development of optimized validation techniques using MS2, T1UV, and T7 phage that accounts for the UV

reactor’s dose distribution.

First full-scale validation of advanced oxidation using

UV light and hydrogen peroxide.

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Validation of 40-mgd UV reactors allows for accurate, bioassay

validated scale-up from test site to installation.

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UNITED STATES EPA/CADMUS, WASHINGTON, D.C.

Carollo is working with The Cadmus Group and USEPA to develop simplified approaches for validating UV reactors for small- and medium- sized drinking water systems to meet the virus inactivation requirements of the Ground Water Rule.

Implementing UV Systems for Treatment of Groundwater in Small to Medium-Sized Utilities

Carollo is working with The Cadmus Group, Inc. and USEPA to develop simplified approaches for validating UV reactors for small- and medium- sized drinking water systems to meet the virus inactivation requirements of the Ground Water Rule (GWR). Carollo is evaluating UV reactors equipped with low-pressure high-output (LPHO) and MP lamps. The UV reactors were installed within a test train located in Portland, Oregon, and validated using MS2 phage, B. Pumilus spores, and live adenovirus.

A key objective of the project is to show that 4-log inactivation of adenovirus can be predicted using 4-log MS2 inactivation, provided the validation data is analyzed using a combined variable, S/S0/Q/DL, where S/S0 is the relative lamp output indicted using the UV sensors, Q is the flow and DL is the UV sensitivity of the microbes defined as the UV dose required per log inactivation. A second objective is to demonstrate a simplified UV sensor setpoint approach for adenovirus credit and a simplified calculation of the validation factor. An additional objective with the MP reactor is to account for the contribution of low- and high-wavelength UV light generated by MP lamps using low- and high-wavelength UV sensor technologies, develop low and high-wavelength action spectra correction factors (ASCFs) that account for differences in the wavelength response of MS2 and adenovirus, and to develop UV dose-monitoring algorithms that account for low- and high-wavelength contributions for adenovirus inactivation.

The findings from this work will be used to develop updated guidance document for applying UV disinfection for pathogen inactivation credit. The update will also address current issues with the 2006 UV Disinfection Guidance Manual.

Updated UV guidance.

New low-wavelength UV sensors for medium-

pressure UV.

Simplified UV monitoring and validation.

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Design and Performance Guidelines for UV Sensor Systems

Carollo completed the WaterRF Project, Design and Performance Guidelines for UV Sensor Systems. This $580,000 project quantified the capabilities and limitations of commercial UV sensors, evaluated the impacts of UV sensor properties on dose monitoring, and developed guidelines for UV sensors and dose monitoring with stakeholder buy-in. The project team included the Veterinärmedizinische University in Vienna, Austria; the National Institute of Standards and Technologies in Maryland, U.S.; 9 European utilities; and 8 UV system and UV sensor manufacturers.

Field and laboratory studies showed significant variability with UV sensor performance, especially with UV sensors used with MP UV systems. In particular, the data analysis showed that spectral and angular response criteria specified by current guidance can be a significant cause of variability. UV sensor accuracy can be significantly improved by controlling the angular orientation of sensors within the sensor port, field calibration of duty sensors using the average reading of three reference sensors, and calibrating MP reference sensors using polychromatic light.

Using dose delivery models based on CFD, the team analyzed how UV sensors are used for UV dose monitoring. New approaches were developed for analyzing UV validation data obtained using MS2 phage that predict UV dose distributions. The new approaches eliminate the need to apply a reduction equivalent dose (RED) bias uncertainty factor to the sizing and operation of UV systems, thereby significantly reducing the capital and operating costs of UV disinfection.

International coalition of UV system manufacturers,

utilities, regulators, and standards organizations.

UV sensor guidance endorsed by the UV system

manufacturers.

New dose monitoring algorithms determine UV dose distributions from

validation data.

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The National Institute of Standards and Technology's Spectral Comparator

Facility is used to calibrate all UV sensor measurement standards for U.S.

The Optical Division of NIST worked with Carollo to develop UV sensor

guidelines.

CFD-based dose models evaluated the impact of UV sensor properties on

UV dose monitoring.

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WATEREUSE RESEARCH FOUNDATION, ALEXANDRIA, VA

Using a combination of cited literature and internal

knowledge, the members of the Carollo team sorted through

conventional treatment systems, emerging treatment systems, and innovative treatment concepts for low-energy wastewater treatment

and wastewater reclamation.

Low-Energy Treatment Schemes for Water Reuse Phase 1

The production of reclaimed water from municipal wastewater is now standard practice and almost universally accomplished using primary treatment (discretionary), secondary treatment with activated sludge, filtration, and disinfection with chlorine, sodium hypochlorite, or UVlight. Sludge produced by liquids treatment is often stabilized with aerobic digestion. These conventional processes are energy-intensive.

Lower-energy treatment alternatives exist in varying degrees of market readiness. Collectively, many of these represent the future of wastewater and reclaimed water treatment.

There are a number of different process schemes and technologies that can potentially fit the ‘low-energy’ reuse label, ranging from anaerobic membrane bioreactors (MBRs) to non-biological treatment and nutrient and energy-recovery systems, among many others.

This project had two main objectives:

XX Identify emerging low-energy treatment technologies, ranging from alternatives to existing treatment processes to innovations in energy recovery systems.

XX Evaluate the market readiness of these new ideas and products to identify the most promising ideas to bring forward for potential Phase II testing. These ideas would have the highest potential to save energy and cost, and would be close to being ready for use at full scale.

Using a combination of cited literature and internal knowledge, the members of the project team sorted through conventional treatment systems, emerging treatment systems, and innovative treatment concepts for low-energy wastewater treatment and wastewater reclamation.

The project team concluded that several key treatment technologies (from the emerging treatment systems category) should be carried forward for Phase II research. Recommended Phase II technologies included full-stream Anammox (AnMBR); pasteurization; gasification; Water Tectonics’s Electrocoagulation; Emefcy’s SAVRA process; and UASB. The report also provided projections of potential savings from these emerging technologies.

Evaluation of the next generation of low-

energy treatment and recommending a path

forward for the industry.

Evaluation of optimal solutions for treatment which include nutrient

removal/recovery schemes and alternative schemes

which leave the nutrients in the water.

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Innovative Treatment for Reclaimed Water

The WateReuse Research Foundation (WRRF) evaluated a wide range of conventional and emerging technologies for their ability to cost-effectively reduce various hormones, pharmaceuticals, and pathogens in secondary effluent. The project was funded by the WRRF, the U.S. Bureau of Reclamation, and the Southwest Florida Water Management District. Substantial financial and in-kind support was also provided by utilities and manufacturers. The team included researchers from Duke University, the University of Colorado at Boulder, the U.S. Department of Agriculture, and Carollo.

AOP were evaluated based on disinfection capacity and ability to oxidize organic pollutants. Ozone (O3) and UV with and without H2O2 provided “fair” to “excellent” disinfection of a range of pathogens. The TiO2/UV process is also expected to perform equally well, but at a higher cost. The other technologies tested had one or more pathogen groups in which performance was deficient.

The major findings of this study were as follows:

XX Free chlorine provided substantial virus and bacteria destruction and had mixed results for destruction of chemical constituents. Chloramination provided substantial destruction of bacteria, but not virus and chemical constituents.

XX Peracetic acid (PAA) can be a substitute for chlorine if coliform bacteria are the primary target, though PAA performance for other targets was limited.

XX Ultrafiltration (UF) and microfiltration (MF) are proven barriers to most of the microorganisms tested in this study.

XX UV and O3 are robust disinfectants, with particularly high effectiveness against parasitic protozoa for UV and viruses for O3. Adding H2O2 had no consistent impact on disinfection.

XX Ozonation mitigates the overall estrogenic effect of EDCs, but reacts slowly with NDMA, TCEP, and other compounds with electron-withdrawing characteristics. Addition of H2O2 improves performance.

XX UV photolysis is an especially important component of UV/ H2O2 when target compounds are photoliable (e.g., NDMA and triclosan). Where direct photodegradation is not effective, hydroxyl radicals can destroy target compounds.

Evaluated a wide range of conventional and emerging

technologies for their ability to cost-effectively

reduce various hormones, pharmaceuticals, and

pathogens in secondary effluent.

Advanced oxidation processes (AOP) were evaluated based on

disinfection capacity and ability to oxidize organic

pollutants.

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This project evaluated a wide range of conventional and

emerging technologies for their ability to reduce various hormones, pharmaceuticals, and pathogens in

secondary effluent.

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Risk Reduction for Direct Potable Reuse

Direct potable reuse (DPR) is the planned introduction of recycled water either directly into a public water system or into a raw water supply immediately upstream of a water treatment plant. DPR is a reality in the United states, with projects now operating in Texas and New Mexico. Because of logistical barriers (poor quality or inaccessible groundwater basins, no available receiving surface waters), indirect potable reuse (IPR) is not always reasonable or possible. Thus, the need for DPR is growing.

The potential impact of DPR treatment process upsets can be far greater than for IPR or traditional drinking water treatment of a less impaired source. Ideally, DPR systems should be fail-safe. However, the water and wastewater industry has yet to determine how and where fail-safe design and operation might be appropriate.

The goal of this project was to review existing engineering practices for IPR and consider what additional treatment and monitoring and operational issues could be necessary to implement DPR. Further, this study reached outside of our industry (structural/bridge, aviation/NASA) to understand fail-safe engineering as it was applied to critical engineering projects and combined this information into a risk reduction framework for evaluation the pros, cons, and costs of the identified DPR approach alternatives. The recommendations developed in this work were used to develop case studies for the cities of Escondido and San Diego, California.

The results of this study provide new perspectives on how to think about risk management and an understanding of what engineering practices could be incorporated into our approach to the design, control, operation, and maintenance of advanced treatment systems (e.g., MBRs, MF, UF, reverse osmosis [RO], and UV- or ozone-based advanced oxidation).

The goal of this project was to review existing

engineering practices for IPR and consider what additional treatment,

monitoring, and operational issues could be necessary to

implement DPR.

This study investigated other industries' approaches

to mitigating risk and combined this information

into a risk reduction framework.

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This WRRF report evaluated risk reduction principles for direct

potable reuse (DPR).



Framework for Informed Planning Decisions Regarding IPR and Dual Pipe Systems

The objective of this project was to develop a structured framework that supports water resource managers and those responsible for the deployment of available water supplies in making informed decisions regarding appropriate investments in water resources development and capital projects necessary to meet water demands at the project, municipal, or regional level of planning.

The focus of the decision support tool was on the development and deployment for beneficial use of alternative sources. Deployment schemes included one or more separate piping systems for meeting demands requiring specific water qualities, augmentation of surface water or groundwater that serve as potable supplies, or combinations thereof. Having a decision support tool that provides a structured and robust framework to guide the decision-making process among multiple variables of varying degree of priority, weight, or influence helped water resources managers sufficiently consider everything that is important about such decisions with respect to the social, economic, and environmental needs of the community being served. The use of such a tool could serve as demonstration to regulators, the authorizing (and investing) public, and other stakeholders that a wide range of options have been considered. Carollo provided the following services:

XX Background Review and Data Collection. We supplemented our existing body of knowledge with utility profiles (type of alternative resource, extent of treatment, and number/type of customers) for newer, high profile projects, and then described and characterized the “common characteristics” among the 14 case studies that were considered in the framework development.

XX Case Studies. The data from 3 case studies was used to “calibrate” the tool and its data inputs to check that it produced reliable results.

XX Framework Development. The framework developed for this project provided: 1) an easy-to-navigate guide through the important issues and the most current information needed to evaluate IPR and dual piping projects; 2) a master planning template that utilities can use to assess and record the range of planning issues relevant to their local situation; and 3) identification of existing tools and resources that can be used to complete quantitative sustainability analyses, with specific guidance on how those tools and resources can be used to support the master planning process, as recorded in the template provided in the framework.

XX Final Toolkit. We developed an easily modifiable and customizable sustainable master planning framework that guides the user to consider important influences related to choosing a distribution system or an IPR program, or a combination of both for the deployment of recycled water. We employed an Excel-based program because of its wide familiarity and ease of use.

The decision support tool aids water resource

managers in their decision when considering multiple variables—socio-economic factors and the

environmental needs of the community being served.

The focus of the decision support tool was on

the development and deployment for beneficial use of alternative sources.

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The goal of this project was to create a planning framework to compare IPR and dual pipe reclaimed water

distribution system alternatives, thereby enabling utilities to make an informed

decision about investment in reuse options.

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Demonstrating the Benefits of Engineered Direct vs. De facto Reuse Systems

"De facto reuse" describes the process by which treated wastewater effluent is released into groundwater or surface water bodies that serve as drinking water sources of supply, without specific plans or permits for augmenting these water supplies with treated wastewater. All drinking water utilities in the U.S. are required to provide potable public water supplies that meet EPA's enforceable primary and secondary drinking water standards, set in accordance with the Safe Drinking Water Act. As a result, de facto reuse historically has not been considered a scenario of public health concern in the U. S.

This research investigates the downstream impacts on drinking water quality from upstream releases of treated wastewater into surface water bodies. The aim of this project is to evaluate whether these impacts pose a threat to drinking water quality downstream and if, in such cases, a more engineered approach provides more reliable water quality. Case studies were developed for three selected utilities, serving different population sizes, representing different geographic regions, and located in different land use settings: Greater Cincinnati Water Works (Ohio); Frederick County Utilities (Maryland); and Philadelphia Water Department (Pennsylvania). Water quality and other data on these systems were collected from drinking water utilities, wastewater utilities, and other regional water organizations and from publicly available data sets (e.g., U.S. Geological Survey stream gauges). A quantitative model was developed to estimate the impacts of effluent discharges on the water quality of the receiving water bodies, which is representative of de facto reuse. Water quality parameters considered in the model were dissolved oxygen (DO), indicator bacteria, and trace organic compounds (TOCs). The model results were used to compare the de facto reuse scenario with water quality resulting from more fully engineered approaches, such as intentional IPR and DPR.

The findings of this study indicated that predicted concentrations at intakes were largely dependent on dilution, background concentrations of contaminants in surface water, ambient temperature, and the residence time of the contaminants in the system. However, the impact of effluent discharges on water quality at intakes was considered negligible for these case studies. The selected analytical approach was appropriate for understanding system behavior in the selected de facto reuse cases and allowed for a consistent comparison of water quality impacts among different systems where data were limited. This approach may be adopted by other potable water utilities that are located only a short distance downstream from the nearest wastewater treatment discharge point, have a limited number of nonpoint source discharges in that distance, and have adequate data on TOCs to assess the concentrations at the water intake.

Predicted concentrations at intakes were largely dependent on dilution,

background concentrations of contaminants in surface

water, ambient temperature, and the residence time of the contaminants in the

system.

The impact of effluent discharges on water quality at intakes was considered negligible for these case

studies.

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This research investigated the downstream impacts on water quality

from upstream releases of treated wastewater into surface water bodies.


COLORADO SCHOOL OF MINES, GOLDEN, CO

Modifying Treatment to Increase Nitrogen Removal in Conventional Side Stream Treatment

High ammonia wastewater streams from dewatering after anaerobic digestion can negatively impact the performance of mainstream treatment. In an 18-month research collaboration with the Colorado School of Mines and a Front Range wastewater utility, Carollo investigated operational strategies that may help increase the removal of nitrogen in a side stream treatment (SST) reactor treating ammonia-laden centrate.

Full-scale testing was conducted at a facility that operates a Modified Ludzack-Ettinger (MLE) process for nitrification and denitrification. Centrate from the common solids handling facilities is treated in centrate and return activated sludge (RAS) SST basins under aeration. Under traditional operation, centrate ammonia is removed by 50-80%. Nitrate or nitrogen removal was found to be limited to about 10-20% as very little carbon is available to support denitrification in RAS or centrate.

The objective of this study was to increase nitrogen removal in the sidestream through operational changes alone, without capital improvements or chemical addition, and without compromising nitrification performance.

Early laboratory batch tests conducted in this study suggested that free ammonia (FA, or NH3) can be used to control the activity of ammonia and nitrite oxidizers in the SST reactor. Stopping the nitrification process at nitrite opens up alternative nitrogen removal pathways compared to conventional denitrification. Two such processes that we know occur in wastewater treatment under specific conditions are:

1. Denitritation (nitrite is directly converted to nitrogen (N2) by denitrifiers).

2. Nitrifier Denitritation (Ammonia and nitrite are converted to gas (nitric oxide [NO], nitrous oxide [N2O], and nitrogen [N2]).

Both of these pathways require little to no organic carbon for nitrogen removal compared to conventional denitrification—a major advantage in SST. Full-scale testing indicated that the nitrogen removal in the SST test reactor approached 50% while the FA concentration was kept at about 1 to 2 mg/L in the basin, which is lower than the optimum indicated in batch tests. The target FA concentration in the test reactor was dialed in by adjusting the RAS to centrate flow ratio to the SST test basin. The air supply to the tank was reduced to promote transient anoxia. The ammonia removal remained between 60-70% during the same period.

These initial results are promising in that SST processes that are primarily designed for nitrification may have a higher ability to also remove more nitrogen than so far assumed.

This research project was conducted in partnership with a local university and

utility.

It focused on operational optimization of side-stream

treatment to enhance nitrogen removal.H

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Nitrogen removal monitoring under modified operational conditions in

the side stream basins was completed through offgas testing in the basins

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Biogas Scrubbers

One of the biggest challenges to the beneficial reuse of natural biogas has always been the contaminants it carries along with it. Newer air quality regulations and more efficient combustion processes have required that the gas produced from anaerobic digestion be cleaned before it is used in cogeneration equipment. In setting out to change the status quo, Carollo identified the key assets at a wastewater treatment plant that differ from other industries that deal with hydrogen sulfide in gas. The biggest difference is WATER. We have a steady supply of water, typically under high pressure from the washwater or plant water systems. What allows our invention to work is the differential solubility of the hydrogen sulfide and carbon dioxide to methane. When we introduce these gases under pressure to water, the carbon dioxide and the hydrogen sulfide preferentially dissolve into the water leaving behind the methane.

The concept is simple: Using the water, of which we have an abundant supply, we generate a vacuum using a Venturi to draw the gas into the system. The gas/water mixture is separated in a gas separator, and the cleaned gas is collected at the top in the degas valve. The water now containing the hydrogen sulfide and the carbon dioxide is drained to the aeration basins where the carbon dioxide is released and the sulfide is converted into sulfate and leaves the plant in solution with the effluent.

Since methane is soluble in water, a mass balance was developed to identify the amount of methane that would be “lost” to the water in this process. Based on the solubility of methane, less than 1.8% of the methane treated by the system would be lost to the water, making the system 98.2% efficient in methane recovery.

While additional work is still required to optimize the system and demonstrate its full benefits, the preliminary applications of this technology suggest it has a promising future in wastewater treatment resource recovery. Pilot tests conducted at wastewater treatment plants across the U.S. have demonstrated that this system provides excellent hydrogen sulfide, carbon dioxide, and siloxanes removal (Table 1).

The Mazzei® Injector Company provided Carollo with the equipment necessary for the four treatment facilities that hosted the demonstration of this equipment.

Clean methane.

No chemicals or media required.

Low capital and O&M costs.

No moving parts.

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Carollo’s bioscrubber is a new digester gas cleaning technology with low capital and O&M costs.

Scrubber InletScrubber Outlet

Removal %

Methane (CH4), % 62 98 Not Applicable

Carbon Dioxide (CO2), % 36 to 40 Less than 3 98

Hydrogen Sulfide (H2S), ppm Up to 12,000 Less than 5 99.5 to 100

Siloxanes (H2S:O), ppb Up to 3,700 Less than 100 97 to 98

Table 1. Pilot Test Results

MULTIPLE CLIENTS ACROSS THE COUNTRY


WATER ENVIRONMENT RESEARCH FOUNDATION, ALEXANDRIA, VA

Co-Digestion of Organic Waste - Addressing Operational Side-effects

The objective of this project were to advance the knowledge of “real-world” co-digestion facility design, operations, performance, and maintenance for other treatment facilities evaluating co-digestion for increased energy recovery.

This study compiled and summarized performance, operations, and maintenance experience of full-scale co-digestion facilities and communicate this information for the benefit of owners and engineers considering, planning, or designing this technology. The project also evaluated extensions of bench-scale anaerobic treatability testing to provide estimates of increased sludge production and final effluent nitrogen concentrations for proposed supplemental organic waste(s).

The project consisted of two major phases.

XX The first phase focused on analysis of available operations and maintenance data and identification of O&M issues at each of the participating treatment facilities.

XX The second phase focused on sampling at selected participating treatment facilities and bench-scale testing to identify variability in as-received supplemental organic waste characteristics. An additional focus of the second phase was extending a typical anaerobic treatability test to provide additional data to better estimate the impacts of supplemental organic waste(s) on dewatered sludge production and final effluent nitrogen concentration.

This project provided specific benefits to municipal wastewater treatment facilities, food-processing industries, and the dairy industry within the state of New York.

Project objectives were to advance the knowledge of “real-world” co-digestion facility design, operations,

performance, and maintenance for treatment

facilities evaluating co-digestion for increased

energy recovery.

This study compiled and summarized performance,

operations, and maintenance experience of full-scale co-digestion

facilities.

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This project provided specific benefits to municipal wastewater

treatment facilities, food-processing industries, and the dairy

industry within the state of New York.

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Development of a Biofiltration Knowledge Base

Though there are a wide variety of design, operational, and monitoring strategies that can be considered for biofiltration, knowledge of these strategies is disperse and unorganized, and links need to be established between these strategies and treatment performance. This project catalogued and summarized design, operation, and monitoring strategies and experiences of North American biofiltration facilities. The overall objective of this project was to develop a dynamic, user-friendly Biofiltration Knowledge Base to aid water utilities in the evaluation of biofiltration as a viable and proven approach for drinking water treatment. Results from this project are being used to widely communicate information and direction to the user about:

XX The benefits of biofiltration.

XX Mitigating negative impacts.

XX Solutions for improving initial design, operations, and monitoring of biofiltration facilities.

XX Opportunities for future research.

To achieve the project objective and communication goals, Carollo developed a project approach that involved:

XX Stakeholder-informed development of a survey and Knowledge Base tool.

XX Alpha- and beta-testing of the Knowledge Base tool by participating utilities.

XX Implementation of a comprehensive industry-wide Knowledge Base rollout.

XX Development of a companion biofiltration guidance document.

Important deliverables from this project included:

1. A Biofiltration Knowledge Base tool for cataloging and analyzing design, operational, and monitoring data.

2. A companion guidance document to inform decisions related to the design, operation, and monitoring of biofiltration systems.

3. Multiple workshops and webcasts to expand input to the Knowledge Base tool and to broaden the dissemination of project results.

This project catalogued and summarized the design,

operation, and monitoring strategies and experiences

of North American biofiltration facilities.

The overall project objective was to develop a dynamic, user-friendly Biofiltration Knowledge Base to aid

water utilities in the evaluation of biofiltration as a viable and proven

approach for drinking water treatment.

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The Biofiltration Knowledge Base tool provides ready access to

biofiltration utilities’ experiences across North America.


CHINO BASIN DESALTER AUTHORITY, ONTARIO, CAPilot Testing and Design of the biottta® System for the Removal of Nitrate and VOCs from Chino Basin Groundwater

Groundwater often contains multiple contaminants, such as nitrate, perchlorate, hexavalent chromium, and/or volatile organic chemicals (VOCs). Physical-chemical processes such as reverse osmosis, ion exchange (IX), activated carbon adsorption, and air stripping are typically used to remove these contaminants for drinking water distribution. However, these processes separate and concentrate groundwater contaminants into a waste stream that can be costly and difficult to manage. In contrast, biological treatment converts many groundwater contaminants into innocuous or less toxic end-products. For almost two decades, Carollo has been pioneering the development, design, and implementation of two-stage fixed-bed biological drinking water treatment (we call it biottta®) for removing multiple groundwater contaminants. This work has shown that:

XX 55 ug/L perchlorate and over 75 mg/L nitrate can simultaneously be converted to chloride, water, and nitrogen gas using empty-bed contact times (EBCTs) as low as 4 minutes.

XX 30 mg/L nitrate, 400 ug/L perchloroethylene, 600 ug/L trichloropropane, 50 ug/L dibromochloropropane, and 40 ug/L hexavalent chromium can simultaneously be reduced to below detectable levels.

XX 200 mg/L nitrate, 200 ug/L TCE, 4 ug/L 1,1-DCE, and 6 ug/L 1,2,3-TCP can simultaneously be reduced to below detectable levels.

XX Treatment performance is minimally impacted by fluctuations in raw water quality or various operational upsets such as backwashes, system shut-downs, and chemical feed failures.

XX Low-energy demand, the lack of salt regeneration, and the avoidance of a high-strength, contaminant-laden brine stream contribute to low O&M and life-cycle costs.

The treatment system has received approval from the California Division of Drinking Water and the Minnesota Department of Health for full-scale treatment, and multiple full-scale systems are under design in California and Minnesota.

Conventional drinking water treatment typically requires the application of several unit processes to meet multiple water quality objectives. This work has shown that tailored, two-stage fixed-bed biological treatment can provide an alternative to

the unit process add-on approach by eliminating multiple organic and inorganic contaminants in a single system using reasonable contact times without generating cumbersome concentrate waste, thereby potentially minimizing costs and plant footprint. These characteristics make it a highly efficient and environmentally sustainable process that could garner increased utility attention as the gap between water supply and water demand continues to widen.

biottta® (biologically tailored, two-stage,

treatment approach) was developed by Carollo to help municipalities and public agencies cost-effectively treat

contaminated groundwater sources to improve local

and regional water supplies.

The overall goal of this project is to develop final design criteria and obtain

permits for the biottta® system to remove nitrate, TCE, and TCP from Chino

Creek Well 18 and to produce water that meets all regulatory standards.

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Carollo’s biottta® 1 skid is fully automated and consists of a bioreactor, a degas column, and a

biofilter along with five chemical feed systems and in-line water quality analyzers.

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WATER RESEARCH FOUNDATION (CO)/CITY OF ARLINGTON (TX)

Engineered Biofiltration for Enhanced Hydraulic and Water Treatment Performance

The City of Arlington, Texas, is faced with both operational and water quality complications at their John Kubala and Pierce-Burch water treatment facilities. Both facilities installed ozone and biofiltration in 1999 primarily to help remove taste and odor (i.e., MIB and geosmin), iron and manganese, and turbidity, and to minimize disinfection by-product formation (DBP). While the ozone/biofiltration systems performed well for many years, recently observed performance disruptions and the detection of endocrine disrupting compounds (EDCs) require that the City of Arlington evaluate their ozone/biofiltration systems to identify potential modifications to enhance process performance.

This project focused on evaluating methods for restoring and enhancing the performance of the existing ozone/biofiltration process, which entails: 1) A characterization, evaluation, and enhancement of the biological activity in the filters; 2) An assessment of enzymatic oxidation potential in the treatment system; and 3) An examination of inorganic particle formation and filtration. The overall objective of this work is to identify and refine operational modifications to the ozone/biofiltration process that will yield sustained and robust attainment of the City’s water treatment objectives.

This work investigated process fundamentals (e.g., microbial ecology, bacterial metabolism, and contaminant removal mechanisms) to understand how: 1) TOC, MIB, geosmin, EDCs, iron, and manganese can be more efficiently removed in a single treatment step; 2) Biological clogging can be minimized; and 3) Overall process robustness can be improved. The approach included over 10 months of focused bench- and pilot-scale testing to evaluate ozone/biofiltration enhancement strategies. In addition, microbial tracking was performed throughout the project to gain a better understanding of the microorganisms present in the biofilters under a variety of operating conditions, as the type of microbial populations present will affect hydraulics and process performance.

The results included recommended operating parameters that could be implemented at full-scale water treatment facilities for enhanced ozone/

biofiltration performance. The proposed research would benefit the drinking water industry by augmenting the existing body of knowledge by providing operational strategies to meet both emerging and existing treatment objectives.

This project focused on evaluating methods for

restoring and enhancing the performance of the existing ozone/biofiltration process.

Decreased biofilter headloss by 15%.

Improved MIB removal by >75%.

Improved manganese removal by >96%.

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Phosphorus addition improved biofilter headloss profiles.

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Head

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Filter Run Time (hours)

Without Phosphorus

With Supplemental Phosphorus

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00 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

Filter with Phosphoric Acid

Filter under Baseline Conditions

15% decreasein terminal headloss

15% increasein filter run time


WATER RESEARCH FOUNDATION (CO)/TRINITY WATER AUTHORITY(TX)

Optimizing Biofilter Conditions for Improved Manganese Removal

The Trinity River Authority (TRA), which operates a conventional water treatment plant with intermediate ozonation (ozone applied to sedimentation effluent), plans to convert their conventional filters to biological filters to improve treated water quality and stability. In order to operate the filters in a biological mode, chlorine, which is currently applied to the filter influent, must be moved downstream. Application of chlorine downstream of filtration will allow the filters to operate in a biological mode, but will also eliminate a common and effective means of removing dissolved manganese. This physical chemical removal process, which has been extensively studied, removes dissolved manganese using granular filter media coated with manganese oxides in the presence of chlorine. This removal strategy requires continuous maintenance of the applied chemical oxidant (typically free chlorine) to oxidize the absorbed manganese and regenerate adsorption sites. The elimination of chlorine residual to promote biological filtration will cause a decrease in filter feed oxidation-reduction potential and may result in release of manganese adsorbed to the filter media.

Carollo conducted bench- and pilot-scale studies to investigate the conversion from conventional filtration to a biological filtration process. These studies assessed biofilter startup/acclimation and steady-state operational strategies to enhance biological manganese treatment and minimize manganese release from the filter media. The strategies tested included:

XX Nutrient addition (addition of orthophosphate and ammonia).

XX Substrate addition (ethanol).

XX pH adjustment (elevated pH conditions may increase the manganese adsorption capacity).

When compared to conventional biofiltration (biofiltration without nutrient addition, substrate addition, or pH adjustment), Engineered Biofiltration (conventional biofiltration enhanced with one or more of the strategies) resulted in significantly better manganese removal. Both pH adjustment and nutrient addition prevented filter manganese breakthrough and improved filter hydraulics and were selected for demonstration full-scale.

To complement this study, DNA was also periodically extracted from the pilot-scale filter samples for 16S rRNA gene sequencing analysis to provide information about the impacts of process enhancements on community composition.

The project included bench- and pilot-scale studies.

Assessed strategies to minimize manganese

release during conversion to biofiltration.

Studied strategies to enhance manganese

removal with biofiltration.

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Carollo demonstrated with pilot-scale studies that conversion to Engineered Biofiltration, when

compared to conventional biofiltration, minimized manganese

release during the startup/acclimation period and enhanced

manganese removal after the filters were acclimated.

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DBP Control Using Advanced Water Treatment Processes

California’s Sacramento-San Joaquin River Delta is a major estuarine drinking water supply for more than 3 million people in the San Francisco Bay Area, as well as approximately 19 million people in Southern California, via the California State Water Project (SWP) aqueducts. Transport of the water through the aqueducts results in an estuarine water characterized by low turbidity (2 to 20 NTU), moderate organic matter concentrations (2 to 6 mg/L), and high bromide concentration (0.2 to 0.4 mg/L). This water tends to readily form chlorinated DBPs, especially when free chlorine is used as the secondary disinfectant. For some utilities, alternative disinfectants, such as chloramines, are not an attractive long-term option due to high temperatures, long distribution system residence times, and the need to feed ammonia at numerous (30 or more) entry points to the distribution system. The purpose of this study was to evaluate treatment options for this supply to comply with Stage 1 and 2 DBP regulations, while maintaining a free chlorine residual in the distribution system.

A preliminary feasibility study identified the following advanced treatment processes for DBP precursor removal: GAC adsorption, MIEX® resin, and fixed-bed IX. The goal of this project was to evaluate integration and potential synergies among the processes. The study determined the performance of combinations of these processes, regeneration frequencies, residuals disposal requirements, and costs to achieve compliance with the Stage 1 and 2 DBP Rules. Testing employed bench- and pilot-scale systems designed to simulate full-scale performance with the following specific objectives:

XX Characterize organic DBP precursors in raw and treated waters using size exclusion chromatography and XAD-8/-4 resin fractionation to fully evaluate performance.

XX Determine practical operating conditions and limitations of the process combinations tested, and identify obstacles which may limit their ability to achieve DBP regulatory compliance.

XX Develop practical design criteria and a comparative cost analysis for feasible process combinations.

Carollo completed the pilot study phase in mid-November 2004. The report was published in 2006.

Bench- and pilot-scale testing of advanced treatment processes

including MIEX®, GAC, and fixed-bed IX.

Developed design criteria and operating conditions to achieve Stage 2 DBP

compliance for treatment of State Water Project water.

Developed performance and cost data for novel application of GAC for

THM adsorption.

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MIEX® is one of several treatment processes tested to reduce DBPs

at water treatment plants treating California State Water Project water.


UNIVERSITY OF MICHIGAN, ANN ARBOR, MI

Waste Activated Sludge Anaerobic Contact (WASAC

[Patent No. 6,921,486]) Pilot Plant Project

Organic carbon in wastewater (measured as biochemical oxygen demand [BOD] or chemical oxygen demand [COD]) has traditionally been regarded as a primary pollutant. This perspective is rapidly changing as utilities recognize the critical value of organic carbon for nitrogen and phosphorus removal, and increasing energy recovery from biosolids.

As we recognize carbon as the fuel for wastewater treatment performance and a reduced energy footprint, different, more flexible process configurations are needed to allow operations to actively distribute influent carbon between processes that compete for its use. The WASAC (Patent No. 6,921,486) process developed by Carollo is such a process. Key to this process is to contact influent carbon under anaerobic conditions with solids from the main stream biological nutrient removal (BNR) treatment. Very short exposure times are sufficient for the biomass to sorb or uptake carbon. The solids are then directly transferred to anaerobic digestion for biogas production.

In Spring 2013, Carollo and the University of Michigan began a series of studies to demonstrate the benefits of WASAC (Patent No. 6,921,486). The key process benefits to be demonstrated are:

XX Reducing the carbon load onto the mainstream process increases treatment capacity.

XX Reducing energy input for aerobic BOD removal.

XX Increasing methane recovery during anaerobic sludge digestion.

A pilot system was constructed at a BNR facility (shown in the figure below). Solids conveyed from the mainstream aerobic/oxic process to the pilot are contacted with primary effluent in one of two parallel, identical treatment trains, simulating the WASAC (Patent No. 6,921,486) process.

Experiments revealed that the WASAC (Patent No. 6,921,486) process uses phosphorus accumulating organisms (PAOs) present in BNR plants as bio-vehicles to transport carbon from the wastewater influent to anaerobic digestion for biogas generation.

Pilot and batch experimentation confirms that approximately 30-50% of soluble COD is removed in the anaerobic contactors in a very short retention time of 15-20 minutes. Approximately 80% of particulate COD and 55% of colloidal COD is also removed, indicating that colloidal sorption and particulate enmeshment are important COD removal mechanisms.

Anaerobic digestion of WASAC (Patent No. 6,921,486) solids increased methane production by approximately 10% compared to the methane yield from digesting BNR waste from the full-scale facility without observed negative impacts on the final effluent quality.

The WASAC (Patent No. 6,921,486) process developed by Carollo provides utilities the

flexibility to distribute incoming carbon between biological nutrient removal and anaerobic digestion for biogas generation,

while reducing the footprint needed for mainstream

treatment.

Anaerobic digestion of WASAC (Patent No.

6,921,486) solids increased methane production by

approximately 10%.

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Pilot testing reveals the mechanisms of recovering energy by redirecting wastewater

carbon to anaerobic digestion.

Treatment Train A

Treatment Train B

PrimEff andWAS Pumps

WAS OverflowBasin

PrimEff OverflowBasin

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Seawater Intake Systems for Desalination Plants

Of the three components of a seawater desalination plant (intake, treatment, and brine disposal), intake location and design is often the most challenging aspect of the system in terms of technical strategy, regulatory challenges, and public perception. These challenges are due, in part, to the relatively limited experience many managers and other decision makers have with desalination technology, the fact that ocean intakes are uncommon facilities for traditional water agencies, and the lack of a methodology to share experiences, success stories, and lessons learned with other agencies.

While it is important to have a clear understanding of what intake alternatives are technically feasible, it does not always mean that these options can be implemented. Ocean desalination projects often fail to become reality because ocean intake alternatives: 1) may adversely impact the environment (e.g., entrainment, impingement, sustainability, safety of other water sources); and/or 2) may not adequately address stakeholder values (e.g., water rates, water quality specifications, ecological issues).

The "best solution" is usually a negotiation between competing interests of providing a cost- and operations-optimized system with the needs of the local ecology and community's values.

The objective of this study was to develop a user decision methodology by which managers, regulators, and stakeholders would be able to assess the viability of various seawater intake options based upon these competing interests. The platform for this decision methodology is an automated database platform that leads the user through the decision process, answering questions and/or identifying data gaps where additional studies may be required. This automated decision methodology platform is linked to a "state-of-the-science report" that Carollo developed, which helps the user easily access background information to help inform the decision process.

Developed "state-of-the- science report" for ocean

intakes.

Automated decision methodology platform

helps walk the user through the decision process.

Survey of current intake practices.

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Carollo developed a user-friendly decision tool to help guide users through the complex process of selecting an intake for seawater

desalination plant.

Assessing Seawater Intake

Systems for Desalination Plants

Subject Area: Water Resources and Environmental Sustainability



Desalination Product Water Recovery and Concentrate Volume Minimization

The overall project objective was a state-of-the-science assessment and development of technologies for maximization of system energy recovery and minimization of concentrate volume. The study was organized in two phases. Phase I focused on state-of-science assessment and the development of an innovative approach. Phase II focused on the testing of the innovative approach. Key points of this research included:

XX Literature Review and International Survey. Extensively document state-of-the-science of desalination technologies as well as promising and emerging technologies for recovery enhancement and concentrate management via literature reviews and international survey.

XX Validate Innovative Approach and Possible Improvements. Perform bench- and pilot-scale tests of innovative approach to validate anticipated performance and conduct QA/QC functions.

XX Guidance Tool. Develop a guidance tool for the end user to select a viable desalting technology with improved recovery and/or decreased concentrate volume that may be preferred under specific site and geographic conditions.

To assure practical assessment and implementation of the work, our approach included expert input and validation utilizing several distinguished desalination specialists, comparative testing of developing and emerging concepts based on available equipment, and input from large utilities and agencies.

Literature review and international desalination

survey.

Performance validation of innovative desalination approach and possible

improvements.

Development of a guidance tool for selecting a viable desalting technology with improved recovery and/or lower concentrate volume.

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Carollo is leading the industry in the development and application of innovative

desalination technologies that reduce concentrate volume and disposal costs.

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INDIAN WELLS VALLEY WATER DISTRICT, RIDGECREST, CA

Evaluated pilot-scale ZLD system with RO followed

by EDR.

Established CDPH permitting—and the

Regional Water Quality Control Board—

requirements for the disposal of concentrate.

Combined RO and EDR system produced a high-

quality and low-TDS water with an overall recovery

of 92%.

Reversible RO configuration improved RO performance.

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Carollo was selected by the Indian Wells Valley Water District to carry out the preliminary design of a new brackish water desalting facility. The Indian Wells Valley contains brackish groundwater that, apart from its moderate total dissolved solids (TDS) levels, is also contaminated with a range of constituents including hardness (around 1,100 mg/L as CaCO3), nitrate (over 200- mg/L), arsenic, selenium, iron, and manganese.

The groundwater was fully characterized to evaluate the presence of chemical species of concern, such as silica, that may affect the selection of the treatment process. Zero liquid discharge (ZLD) pilot-scale testing was conducted with an RO and EDR in series for 7 months. During this period, the RO unit was operated for a total of 4,400 hours (2,100 hours in conventional mode and 2,300 hours in reversible mode). A total of 1,600 hours of operation were achieved with the EDR, which exceeded the initial goal of 1,000 hours.

The reversible configuration of RO improved performance of the RO system. The combined system of RO followed by EDR achieved an overall recovery of 92%. The final effluent contained 140-mg/L TDS with 90% removal of the influent TDS. Similarly, approximately 90% removal was achieved for all other contaminants of concern, including As, Se, U, Fe, and Mn, with the exception of boron. All other water quality objectives were met. The study suggested that a treatment train consisting of primary RO followed by concentrate treatment with EDR was a cost-effective process train for the treatment of the groundwater sources. Data collected during the pilot study will be useful for any future design of a full-scale ZLD.

In addition, the project established the CDPH permitting requirements for the treatment system, as well as the Regional Water Quality Control Board requirements for the disposal of any waste streams from the process, including brine (concentrate). After the completion of the Preliminary Design Report, Carollo worked with the District to design and construct a pilot-testing facility for the treatment of well water with the combined system of RO and EDR.

Carollo designed and constructed a pilotfacility for the testing of upfront ZLDprocesses.


CITY OF PHOENIX (AZ)/ WATEREUSE RESEARCH FOUNDATION (VA)/USBR (CO)Salinity Research on Concentrate Management Pilot Demonstration StudyBench-scale testing and

pilot-scale demonstration of cutting edge concentrate management technologies.

Challenging water quality requires multiple

pretreatment steps, including new applications

of ozone, biological filtration, and IX.

Demonstrated alternative concentrate management

strategies that could provide up to 41% savings in total

water costs compared to the baseline alternative using

brine concentrator.

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Ozone (front), biological filter (middle), and EDR (back) skids were

tested at demonstration-scale.

High salinity in wastewater poses challenges for water reuse and desalination concentrate disposal for the southwest region of the U.S. Advanced treatment technologies, such as RO, are often used to improve the quality of the reclaimed water. These technologies are effective and well established, but feasible and sustainable solutions for disposing of the resultant concentrate are limited, especially for inland communities. Current solutions are either unsustainable (i.e., sewer discharge), land-consuming (i.e., large-scale evaporation ponds), energy-intensive (i.e., brine concentrators), or unavailable (i.e., deep well injection for Arizona).

Carollo recently completed a concentrate management study co-funded by the Sub-regional Operation Group ([SROG], which includes Glendale, Mesa, Phoenix, Scottsdale, and Tempe, AZ), the WateReuse Research Foundation, and the U.S. Bureau of Reclamation. This study demonstrated the feasibility of reducing tertiary reclaimed water RO concentrate volumes and improving overall RO recovery from 85 to 94.3% by using EDR with organic matter pretreatment (ozone [O3] and biologically-activated filtration [BAF]), and to 98.2% with the addition of inorganic pretreatment as well (e.g., IX or lime softening). EDR reliably recovered 62% of the RO concentrate with organic pretreatment alone, and 89% with both organic and inorganic pretreatment. This means that the proposed concentrate treatment schemes could improve the overall recovery from 85 to 94.3 and 98.2%, respectively.

The SROG concentrate minimization demonstration project delivered new brine management solutions that have reshaped the inland desalination and concentrate management. The overall recovery and the total water costs associated with concentrate management system (i.e., ozone, BAF, IX plus EDR with regular membranes) provided ~41% cost saving in the total water costs compared to the baseline alternative using brine concentrator, with only 0.7% difference in overall recovery. Compared to secondary RO with organic pretreatment and lime softening, the demonstrated solution offers ~31% cost reduction while achieving a slightly higher overall recovery.

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KING COUNTY DEPARTMENT OF NATURAL RESOURCES AND PARKS, SEATTLE, WA

West Point Treatment Plant CFD Model of Sludge Digester Gas Mixing System

CFD model used to investigate the performance

of the mixers.

Two-phase liquid-gas model.

Developed rating curve for system that would be

difficult to measure.

Provided better operational guidance for plant.

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digesters. Recycled digester gas is injected into four draft tubes located in the quadrants of the digesters. The digester lids are floating with levels varying by 8 feet, changing the elevation of the lances in the draft tubes during operation. Over time, the system performance had been affected by reduced gas flow rates and gas lance functionality. Temperature profiles and tracer testing had been undertaken to evaluate the reduction in system performance due to these factors, but tests were inconclusive. Therefore, a CFD model was used to further investigate the performance of the mixers for a range of gas injections rates, operating levels, and the impact of gas lance plugging. The aim of the model was to evaluate impacts of the process operating conditions, including the lance location and lance plugging.

The model was run with the digester lid at the maximum and minimum levels (maximum and minimum sludge depths) for 5 air flows ranging from 100-cubic feet per minute (cfm) to 500 cfm with all lances

operating. A second condition was modeled to evaluate the operation with plugged lance heads with an air flow was 400 cfm.

For all runs made, the flow rate into the draft tube was monitored. The CFD modeling showed that the flow through the draft tube mixer was 45% higher at the low sludge depth as compared to the high sludge depth. This was due to the lower position of the lances within the draft tube at low sludge levels. Further, plugged lances showed a more significant reduction of flow at high sludge levels, as compared to low sludge levels.

Several conclusions can be drawn from the study. The rating curve developed can allow operators of this system to optimize the gas injection rate at different sludge levels to improve mixing. Second, plugging of the lance head will decrease the digester mixing for a given gas flow. Finally, the mixing would probably be more uniform if the lances were always located at the same elevation within the draft tube, which could be achieved by either attaching the draft tube to the floating lid, or the lances independent of the lid.

The velocity at a section through the draft tube for the 400-cfm run at high sludge depth

showed low velocity, but good circulation.



UV Reactor Design Assessment and InstallationCFD models showed a good match in predicting

headlosses.

The UV dose models showed a good match in

RED.

The work has led to improved application of

CFD modeling to UV facility design.

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The use of UV disinfection for drinking water treatment is increasing as a result of the Long-Term 2 Enhanced Surface Water Treatment Rule (LT2ESWTR) and Stage 2 Disinfection/Disinfection Byproducts Rule. In order for utilities to receive inactivation credits for UV under the LT2ESWTR, systems must first be validated using costly biodosimetry methods under the specific design configuration and operating conditions planned for full-scale treatment. CFD is a modeling tool that has been shown to successfully determine relative differences in UV reactor performance as the model provides detailed information on flow-field characteristics that can aid in identifying hydraulic-based reasons for variations in reactor performance.

In many cases, utilities will be retrofitting UV systems into existing treatment processes, so they will be limited in their available inlet/outlet configurations and may not be able to achieve optimal configurations. Thus, a tool is needed to assess hydraulic impacts on UV disinfection performance and evaluate alternative configurations early in the design process. Moreover, a better understanding of the effects of inlet/outlet hydraulic configurations on UV disinfection performance will result in more pragmatic design recommendations with potential to significantly reduce capital costs in future UV installations.

The goal of this work was to evaluate whether CFD-based models could be used to accurately model the hydraulics, UV intensity distribution, and RED in commercial UV reactors with different reactor and piping configurations. In particular, the primary objective was to demonstrate whether CFD-based models could be used to compare the performance of installed UV disinfection systems relative to validated systems with different piping configurations (potentially caused by retrofits or space limitations at the installed site).

Three different commercial reactors, some with multiple piping and baffling arrangements, were simulated for the validation configurations. The results of the modeling showed that CFD-based simulations were able to capture the salient trends measured as a function of different flow rates, UV transmittances, and lamp power. In addition, the use of different pipe sizes and the comparison of runs with and without a baffle plate showed notable impacts on the measured RED in the validation tests. The simulated performance of these different reactors and configurations showed good matches between simulated and measured data for a wide range of operating conditions.

One of the reactor geometries modeled, including an S-bend, baffle plate, and a

six-lamp reactor.

select areas of focus bridging the gap…in uv …on bridging the gap between fundamental research...

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