Fitzgerald, Colin

Colin is a Jacobs Globale Principal for Water Resrouce Recovery, located in Denver, CO. His career focusses on nutrient removal, sidestream treatment, tertiary treatment, process control, and wastewater for reuse. Colin holds M.S. and B.S. degrees in Civil Engineering from the University of Wisconsin - Madison and a B.S. in Physics from the University of Wisconsin - Eau Claire.

Titles from this speaker

A Flexible Design Concept for a 180 MGD MBR Facility

Abstract

Background The Metropolitan Water District of Southern California (MWD) and Los Angeles County Sanitation Districts (LACSD) are jointly developing the Pure Water Southern California (PWSC) program to produce up to 150 MGD of purified water at LACSD's A.K. Warren Water Resource Facility (Warren Facility) in Carson, California. The Warren Facility (Figure 1) is a 400 MGD capacity high purity oxygen activated sludge (HPOAS) facility that discharges treated (non-nitrified) secondary effluent (SE) to the Pacific Ocean. Product water from the PWSC Advanced Water Treatment (AWT) facility would be used for indirect potable reuse via recharge of local groundwater basins and possibly direct potable reuse through raw water augmentation of surface water treatment plants (Figure 2). Nitrogen management is a key component of PWSC and a flexible design approach that allows the facility to be optimized for current treatment needs, while preserving expandability to meet future requirements, is needed. As such, a series of Nitrogen Management Studies (Liang et al., 2019, Fitzgerald et al., 2021; Danker, 2022, LACSD 2023) were conducted to evaluate alternative process trains to manage nitrogen in the AWT feed. Based on these studies, the proposed process train for PWSC includes biological nitrogen removal followed by reverse osmosis and an ultraviolet advanced oxidation. The primary process includes a 180 MGD capacity flexible membrane bioreactor (Flex MBR, Figure 3) that would be fed Warren Facility SE. Additional processes that will be integrated into PWSC will include operation of two existing HPOAS reactors to achieve nitrogen removal and implementation of sidestream deammonification. When constructed, the MBR facility will be one of the largest in world. The Flex MBR includes a modular bioreactor design concept (Figure 4) that allows for the ability to operate in either nitrification only or nitrification-denitrification (NdN) mode. NdN can be achieved by addition of supplemental carbon (glycerol) and/or by blending primary effluent (PE) with SE, referred to as hybrid operation. Hybrid operation is intended to reduce supplemental carbon requirements. To further enhance reductions in supplemental carbon requirements, provisions have been included in the design concept to implement partial-denitrification/anammox (PdNA). Additionally, since the basins will be identically designed, the Flex MBR could also be converted to a traditional secondary MBR with PE feed (Figure 5). Pilot-Scale Testing To inform the Flex MBR design concept, pilot testing was conducted (Deco et al., 2023) for approximately one year to validate a pre-anoxic NdN concept (Figures 6 and 7). This concept was developed to mitigate partial NdN (i.e., nitrite accumulation) that was observed during previous demonstration-scale testing in a post-anoxic configuration (Liang et al., 2020) . In addition, initial proof-of-concept testing of the hybrid operating approach was completed. The study concluded that: (1) hybrid operation could result in significant savings in supplemental carbon addition and thus project life-cycle costs; (2) partial NdN can be effectively mitigated with a pre-anoxic configuration designed to control anoxic zone nitrate loading and associated nitrate residual (Figures 8 and 9); and (3) the post-aerobic zone provides a buffer to prevent high effluent nitrite concentrations in the event that anoxic zone nitrite accumulation does occur. Full-Scale Design Concept and Process Modeling Building on the pilot testing, the full-scale Flex MBR concept was developed and refined. A preliminary site plan at the Warren Facility is shown in Figure 5. Major infrastructure will include an influent pump station, fine screen facility, covered bioreactors, membrane tanks and an equipment building, chemical storage and feed facilities, and an odor control facility. The site layout was developed based on a PWSC program phased implementation plan of 115 mgd (Phase 1) and 150 mgd (Phase 2) product water flow. To facilitate the desired operational flexibility, the modular bioreactor design is partitioned into 12 equal zones (Figure 4). The modular concept utilizes a two-pass bioreactor with a multi-purpose central channel and targeted swing zones. The proposed configuration allows for half of a bioreactor train (one pass) to be taken out of service to reduce the out of service volume for maintenance activities. Bioreactor process simulations were completed utilizing BioWin. Design criteria considered for process simulations are shown in Table 1. Simulations were completed considering both the supplemental carbon-based and hybrid operating approaches. Modeling results are shown in Table 2 and Table 3. Key observations from the process simulations include:

*Nitrogen targets can be met without the use of an internal nitrate recycle

*Hybrid operation requires slightly higher return activated sludge rates, as compared to carbon based operation, to stay below the maximum design membrane tank MLSS concentration of 10,000 mg/L

*To meet the Phase 1 nitrogen target under current average day loading conditions, NdN, and thus carbon or PE feed, is projected to be needed on only 40% of days

*Hybrid operation is projected to result in significant savings in supplemental carbon

*Carbon-based operation simulations indicate that anoxic zone nitrate loading is predicted to align with pilot-scale testing

The Metropolitan Water District of Southern California and Los Angeles County Sanitation Districts are jointly exploring the potential of implementing the Pure Water Southern California program. This paper focuses on summarizing the preferred design concept, which incorporates a flexible MBR that would initially be operated in tertiary mode and fed Warren Facility secondary effluent.

SpeakerFitzgerald, Colin

Presentation time

14:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionOptimization of MBR Technology

Session number210

Session locationRoom 343

TopicAdvanced Level, Facility Operations and Maintenance, Municipal Wastewater Treatment Design

Author(s)

Fitzgerald, Colin, Constantine, Tim, Swaim, Paul, Melitas, Nikos, Natanom-Harrold, Nan, Deco, Rachel, Liu, Michael, Mansell, Bruce

Author(s)C.M. Fitzgerald1, T. Constantine2, P. Swaim3, N.T. Melitas4, N. Natanom-Harrold5, R.M. Deco5, M. Liu5, B.O. Mansell6

Author affiliation(s)1Jacobs, CO, 2Jacobs, MT, 3Jacobs, 4Jacobs Engineering Group, Inc., CA, 5Los Angeles County Sanitation Districts, CA, 6LA County Sanitation District, CA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159646

Volume / Issue

Content sourceWEFTEC

Word count11

Description: Ann Arbor Tackles Stringent Effluent Phosphorus Limits with a Cost-Effective...

Ann Arbor Tackles Stringent Effluent Phosphorus Limits with a Cost-Effective Side-Stream Phosphorus Removal Solution

Abstract

BACKGROUND The Ann Arbor WRRF is a 29.5 MGD advanced secondary treatment wastewater facility owned and operated by the City of Ann Arbor, MI. The liquids treatment includes headworks, primary clarification, enhanced biological phosphorus removal (EBPR) , nitrification, final clarification, granular media filtration, and UV disinfection prior to discharge to the Huron River. The solids treatment has been dependent upon the ability to land apply the biosolids for nearly half of the year. During this period, primary sludge (PS) was thickened using gravity thickeners and waste activated sludge (WAS) was thickened by a gravity belt thickener (GBT). Together thickened PS (TPS) and thickened WAS (TWAS) were combined and the biosolids were lime stabilized prior to hauling to local fields. During the rest of the year, when land application was not possible, PS and TWAS were combined in holding tanks before being dewatered by centrifuges. Centrate from the centrifuges was returned to the plant influent, and the dewatered biosolids were hauled to a landfill for disposal. Combining PS and TWAS without the addition of lime, caused phosphate removed by the EBPR process to release into solution and concentrate in the dewatering centrate. For these months, this returned phosphate load reduced the efficiency of the EBPR process, and ultimately increased the effluent Total Phosphorus (TP) concentrations. Ann Arbor is facing challenges associated with increasingly stringent National Pollutant Discharge Elimination System (NPDES) permit limits for effluent phosphorus, with May to December effluent loadings limits reduced from 200 to 50 - 60 lbs total phosphorus (TP)/d. In addition, land application has become more difficult (i.e., farm field availability, transportation issues) causing Ann Arbor to dewater and landfill solids year-round until a longer term biosolids management strategy is developed. To consistently meet the new NPDES permit limits for phosphorus, the City of Ann Arbor engaged a team of consulting engineers to study options for treatment of the high phosphorus centrate side stream resulting from centrifuge dewatering of WRRF sludge. METHODOLOGY The first task in this study was to develop a whole plant process model, which was used to understand the impacts of centrate phosphate loading and evaluate the efficacy of possible mitigation approaches. The project team then identified four alternatives to be considered for mitigation of centrate phosphate loading concerns: 1.Segregated and aerated storage of WAS to prevent phosphorus release. 2.Lime addition to sludge holding tanks to precipitate phosphorus prior to dewatering. 3.Phosphate recovery from the dewatering centrate. 4.Chemically enhanced primary treatment (CEPT) to minimize secondary phosphorus loading. The alternatives were evaluated based on:

*Ability to meet the NPDES limit for TP loading

*Capital and operating costs

*Ease of implementation and operation

*Secondary impacts to plant processes, such as EBPR Following evaluation, bench scale testing was performed for preferred alternatives to validate modeling results and examine operational feasibility. This resulted in one preferred alternative being implemented and optimized at full scale. FINDINGS Simulation results from the whole plant model (Figure 1) demonstrate Alternatives 1, 2 and 4 show the most promise in meeting the strictest year-round final effluent TP load (50 lb/d). Cost analysis, however, showed that the chemical demand associated with Alternative 4 would add nearly $2 million in annual operating cost for Ann Arbor, whereas Alternatives 1 and 2 could be implemented with the fewest operational and infrastructure changes. These alternatives also presented no negative impacts on other plant operations (e.g. EBPR). Benchtop testing for Alternative 1 (Figure 2) demonstrated that it is unlikely that aged PS and aerated TWAS could be mixed for more than a few minutes without releasing more than 20% of the stored phosphate into the centrate stream. Testing observations also identified potential full-scale difficulties with aerating TWAS. Testing for Alternative 2 (Figure 3) predicted a lime dosing rate of 2.3% (18% lime slurry) would provide 90% PO4-P removal in the centrate. Based on this analysis, Alternative 2 — Lime addition to sludge holding tanks, was implemented at the full scale using existing assets in 2023, one year ahead of permit limit reductions taking effect. The plant has met their new NPDES limits (Figure 4) and has been able to optimize the lime dosing operation. Since the initial lime dosing rate of 2.3% was exceeding the targets of 90% PO4-P removal in the centrate (Figure 5), systematic reductions in dosing rate to 1.6% have been completed, resulting in a final sidestream PO4-P removal cost of less than $0.25/lb TP. Under the lower dosing rates, targeted PO4-P removal and daily plant effluent TP limits are still being met on an average basis, however, there is increased variability in daily centrate PO4-P removal rates. This variability has been linked to the final centrate pH, which is thought to be primarily influenced by pre-liming sludge age. The City and its team of consulting engineers is currently investigating and optimizing the sludge holding and lime dosing strategy to reduce this variability. Findings from this optimization will also be included in the final paper.

Ann Arbor and their team of consulting engineers reviewed several sidestream treatment options to treat a high phosphate concentration centrate stream that was impeding the plant's ability to meet new NPDES limits. The team has implemented lime dosing in the sludge stream upstream of the centrifuge, reducing phosphate return loads by over 90%, and allowing the city to meet their permit.

SpeakerLycke, Derek

Presentation time

14:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionInnovations in Phosphorus Management: From Models to Solutions

Session number603

Session locationRoom 340

TopicFacility Operations and Maintenance, Intermediate Level, Municipal Wastewater Treatment Design, Nutrients, Research and Innovation

Author(s)

Lycke, Derek, Stewart, Heather, Li, Mengfei, Fitzgerald, Colin, Gelderloos, Allen, Drinan, Jennifer, Sanders, Keith, Jaworski, Nicholas

Author(s)D. Lycke1, H.A. Stewart2, M. Li3, C.M. Fitzgerald4, A.B. Gelderloos5, J.B. Drinan6, K.E. Sanders7, N. Jaworski8

Author affiliation(s)1Jacobs, BC, 2Jacobs, PA, 3Jacobs Engineering Group, MI, 4Jacobs, CO, 5Jacobs Engineering Group, Inc., MI, 6OHM, MI, 7City of Ann Arbor WWTP, MI, 8, MI

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159589

Volume / Issue

Content sourceWEFTEC

Word count15

Description: Assessing N2O production and short-cut nitrogen removal in Post Aerobic Digestion...

Assessing N2O production and short-cut nitrogen removal in Post Aerobic Digestion through enhanced monitoring and advanced process modeling

Abstract

Nitrous Oxide (N2O) is a greenhouse gas emitted from resource recovery facilities (WRRFs) utilizing biological nutrient removal (BNR) at a rate between 0.1-1.8 percent of the influent total kjeldahl nitrogen (TKN) loading. In addition to having a global warming potential more than 300-times that of Carbon Dioxide, N2O is a precursor to ground-level ozone formation. With the Environmental Protection Agency (EPA)'s reclassification of the Denver Metro/North Front Range ozone nonattainment area from Moderate to Serious nonattainment in December 2019, the City of Boulder (city) has become increasingly interested in understanding the impact that the Boulder WRRF (BWRRF) has on GHG emissions. One such concern is the continued use of the BWRRF's Post Aerobic Digester (PAD), which utilizes operating conditions similar to those identified to increase N¬2O production in secondary processes (e.g. low dissolved oxygen, transient anoxia, etc.). Enhanced sampling around PAD and process modeling on with improved nitrogen biokinetics was completed to better predict nitrogen removal pathways occurring within PAD and the potential for N2O release. Initial results indicate minimal N2O generation through steady state loading conditions (<0.05 percent of PAD loading). There are, however, likely intermittent excursions of N2O and possibly nitric oxide (NO) that may require further evaluation. It is expected that N2O emissions from PAD represent a small portion of the overall GHG footprint of the WRRF. In addition, N2O emissions from PAD through this initial monitoring period appear to be significantly less than those reported for alternative sidestream nitrogen removal processes (e.g. anammox). The study was completed between January and February of 2020 at the BWRRF. The study included the installation of an online N2O sensor (Unisense, Aarhus, Denmark) to monitor aqueous N2O and nitrogen sampling as noted in Table 1. Gaseous emission rates of N¬2O and NH3 were estimated utilizing the transfer coefficient (kLa). Estimates based on lab collected data were compared to the values predicted within the Sumo© process model (data not shown). Process modeling using enhanced nitrogen biokinetics was completed to provide further insights into the possible nitrogen pathways occurring within the PAD process. A process flow diagram of the model can be seen in Figure 1. The model base is denoted as Sumo4N and includes two primary ammonia oxidizing bacteria (AOB) pathways for N2O/NO generation described by the 2-P model (Pocquet et al. 2016) along with heterotrophic reactions related to NO and N2O. The 2-P model includes the nitrifier denitrification pathway (ND) and incomplete oxidation of hydroxylamine pathway (NN). The matrix adds seven nitrogen related state variables, including intermediates in ammonia oxidation (NH2OH and NO) and twelve reactions related to nitrogen transformations. Figure 2 shows a comparison between conventional 2-step nitrification/denitrification (Henze et al. 2000) and the Sum4N approach.

Enhanced sampling, in-situ N2O monitoring, and process modeling on the Sumo platform with an improved nitrogen matrix was completed to better predict nitrogen removal pathways occurring within the City of Boulder’s PAD Process to better understand the potential for N2O release. Initial results indicate minimal N2O generation by PAD through steady state loading conditions (<0.05 percent of PAD loading). There are, however, likely intermittent excursions of N2O and possibly nitric oxide (NO) that may require further evaluation. It is expected that N2O emissions from PAD represent a small portion of the overall GHG footprint of the WRRF.

SpeakerFitzgerald, Colin

Presentation time

11:45:00

12:00:00

Session time

11:00:00

12:00:00

SessionN2O Emissions from Water Resource Recovery Facilities

Session number415

TopicFacility Operations and Maintenance, Municipal Wastewater Treatment Design, Nutrients, Sustainability and Climate Change

Author(s)

Colin Fitzgerald

Author(s)C.M. Fitzgerald3; C. Sigmon2; C.A. Marks1;

Author affiliation(s)City of Boulder, Boulder, CO 1,2Jaocbs, Denver, CO3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158126

Volume / Issue

Content sourceWEFTEC

Word count19

Description: Embracing the Uncertain: Fundamentals and Applications of Uncertainty Analysis at...

Embracing the Uncertain: Fundamentals and Applications of Uncertainty Analysis at Water Resource Recovery Facilities

Abstract

Planning and designing for future conditions are challenging propositions in the wastewater treatment industry. Both practices include inherent uncertainties surrounding existing performance, performance of new processes, growth within the service area, future regulations, and economic conditions. In conventional planning and design, the risk surrounding these uncertainties is avoided by implementing conservative assumptions around key criteria to ensure adequate planning funds are allocated and processes are sized with sufficient safety factors to operate under a wide range of conditions. While this approach has historically served the needs based on industry averages, increasing demands are being placed on utilities, thus requiring a revised approach to wastewater treatment planning and design. This interactive session explores the key findings of IWA’s Design and Operations Uncertainty Task (DOUT) work group who has been working on uncertainty analysis principles for the last 10 years. Select case studies and speakers have been identified to demonstrate the effectiveness of uncertainty analysis-based approaches through design and planning.

Planning and design include inherent uncertainties surrounding performance, growth within the service area, regulations, and economic conditions. The risk surrounding these uncertainties has historically been avoided by implementing conservative assumptions to ensure processes are sized with sufficient safety factors to operate under a wide range of conditions. While this approach has historically served the needs of the industry, increasingly stringent effluent limits and financial pressures warrant a revised approach that manages risk, rather than avoids risk. This session includes select speakers and case studies to demonstrate the effectiveness of utilizing uncertainty analysis-based approaches through design and planning to manage risk.

SpeakerFitzgerald, Colin

Presentation time

13:30:00

15:00:00

Session time

13:30:00

15:00:00

SessionEmbracing the Uncertain Part I: Fundamentals of Uncertainty Analysis at WRRFs

Session number309

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Nutrients, Resilience, Disaster Planning and Recovery

Author(s)

Colin Fitzgerald

Author(s)C.M. Fitzgerald5; L. Belia3; E.D. Redmond2; N. Qualls6; R.W. Angelotti7; P. Vanrolleghem1; L. Benedetti4;

Author affiliation(s)modelEAU, Université Laval, QC, CA1Black and Veatch, Des Moines, IA2Primodal Inc, QC, CA3Water Ways, CR4Jacobs, Denver, CO5UOSA, Centerville, VA7Jacobs8

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2021

DOI10.2175/193864718825158049

Volume / Issue

Content sourceWEFTEC

Word count15

Description: Pilot-scale Validation of Tertiary MBR Design Concepts for Potable Reuse in Southern...

Pilot-scale Validation of Tertiary MBR Design Concepts for Potable Reuse in Southern California

Abstract

The Metropolitan Water District of Southern California (Metropolitan) and Los Angeles County Sanitation Districts (LACSD) are jointly exploring the potential of implementing the Pure Water Southern California (PWSC) program, which would include building an Advanced Water Treatment Facility (AWTF) capable of producing a 568 MLD (150 mgd) of purified water at LACSD’s Joint Water Pollution Control Plant (JWPCP) in Carson, CA. A series of studies conducted by both agencies have identified the application of a tertiary membrane bioreactor (tMBR) as a promising approach to provide nitrogen removal downstream of the JWPCP. This pilot study focused on evaluating tMBR design concepts with an emphasis on demonstrating successful operation of nitrification-denitrification (NDN) tMBR concepts. This study showed that NDN operated in a pre-anoxic configuration either utilizing supplemental carbon or primary effluent provides a promising approach for PWSC and potential future ocean discharge requirements for JWPCP

Pure Water Southern California is a potential reuse program to provide substantial water resiliency to Southern California. A series of studies identified use of a tertiary membrane bioreactor as a promising approach to manage nitrogen prior to advanced water treatment. The Los Angeles County Sanitation Districts initiated this pilot study to refine design and operational characteristics of the process.

SpeakerDeco, Rachel

Presentation time

16:00:00

16:20:00

Session time

15:30:00

17:00:00

SessionRefining Wastewater Effluent for Purification: Reuse-nutrient Removal-nexus II

Session locationRoom S404a - Level 4

TopicIntermediate Level, Municipal Wastewater Treatment Design, Nutrients, Potable Reuse, Water Reuse and Reclamation

Author(s)

Deco, Rachel

Author(s)R. Deco 1; B. Mansell 2 ; M. Liu 3; N. Melitas 3; C. Fitzgerald 4; T. Constantine 5; P. Swaim 6; R. Deco 1;

Author affiliation(s)Los Angeles County Sanitation Districts 1; Los Angeles County Sanitation Districts 2 ; Los Angeles County Sanitation Districts 3; Los Angeles County Sanitation Districts 3; Jacobs Engineering Group 4; Jacobs Engineering 5; Jacobs Engineering 6; Los Angeles County Sanitation Districts 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159134

Volume / Issue

Content sourceWEFTEC

Word count14