Lycke, Derek

Derek Lycke was a speaker at the WEFTEC 2024 conference in New Orleans, LA October 5-9, 2024.

Titles from this speaker

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

Hydrothermal Liquefaction: Technical Risks and Mitigation

Abstract

Objective Metro Vancouver is building a continuous flow hydrothermal liquefaction (HTL) demonstration facility using wastewater sludge as its feedstock. HTL operates at subcritical temperature and pressure to convert wet biomass into biocrude oil in minutes. Biocrude is then refined to produce low-carbon transportation fuels. As this will be the first HTL system in North America at an operating wastewater treatment plant (WWTP), it is paramount to address risks including:

*Technical safety: the process operates at high temperature and high pressure not typical for municipal wastewater treatment.

*Design risks: odour control and dispersion, fire protection, and design integration risks.

*Regulatory risks and permitting: oil and gas technical regulations typically do not apply to biocrude as it is an emerging product.

*Operational and business risks: viability of HTL at a WWTP depends on sludge feedstock variability and resulting biocrude yield and quality, and low-cost options for byproduct beneficial use or disposal. Status The project team consists of an HTL technology licensee, HTL equipment supplier (Inside-Battery Limits designer/fabricator) and an engineering consultant serving as Owner's Engineer and Outside-Battery-Limits designer. A risk assessment consultant undertook a Qualitative Risk Analysis (QRA). Design is complete with fabrication scheduled to start Q1 2024, on-site construction in Q4 2024, and operation in Q4 2025. Project partner Parkland Refinery will co-process the biocrude. Methodology The project used a continuous improvement approach that assesses and mitigates risk throughout the design process, via:

*3 stages of Hazard and Operability (HAZOP) reviews in preliminary and detailed designs

*2 stages of QRA of toxicity and flammability dispersion

*Detailed design risk assessments of odour control and dispersion, and fire protection

*Intensive project-wide risk assessment workshops and continuous review and update of risk log

*Detailed characterization of biocrude and aqueous and solid byproducts from processing of sludge in bench-top and mobile HTL units

*Developing beneficial use and disposal options for biocrude/byproducts

*Third-party operation by specifically skilled operators Findings The risk assessment workshops highlighted these top-ranked risks:

*High temperature and high pressure process: need to develop equipment applications, operational procedures, PPE, training, and emergency response plans for safe operation.

*Concurrent engineering: multiple interfaces being designed in parallel that can create risk of interface issues if not carefully managed.

*Experimental technology: HTL of wastewater sludge has not been proven at this scale. Limited information is available on process stream characterization and equipment testing in similar conditions.

*Impacts to WWTP: the HTL plant will return streams to the WWTP, which is located beside the WWTP and warehouses, and produces flammable and toxic substances. Abnormal releases or spills could present risks to WWTP operation and human health. The second stage of QRA took into consideration the volume of products and lower potential for run-away reactions based on more accurate product characterization in order to optimize the results obtained by the first stage QRA that has used more conservative assumptions and inputs. The updated QRA showed a significant reduction in dispersion radius for both toxicity and flammability impacts, with all risk contours (location specific individual risk) contained within site and a probability of 0.3 fatalities in 1 million years. This is considered extremely low according to MIACC guidelines as shown in Figure 2. Mitigation of risks during design will be discussed in this paper:

*Design changes to feedstock preparation and delivery (pressure regulation, heat exchanger technology)

*Corrosion assessment plan was developed to use tokens and targeted sampling during operation.

*Bench-scale HTL by academic partner produced biocrude and byproducts for characterization.

*analogous sludge was sourced for processing in mobile HTL unit by technology licensee, providing biocrude for evaluation by refinery partner.

*Feedstock, biocrude and byproduct characterization methods were developed.

*Laboratories that conduct testing across both municipal wastewater treatment and hydrocarbon sectors were identified.

*Aqueous byproduct characterization identified potential issues with loading (Table 1) and toxicity (Figure 3) that could prevent return of the stream to the WWTP.

*UBC researchers screened physical, aerobic, and anaerobic methods for treatment of aqueous byproduct.

*Due to high disposal cost for the aqueous byproduct, pretreatment may be favored to remove visible oils, odour, nitrogen (ammonia) and carbon to allow the stream to be returned to the WWTP.

*Identifying disposal and beneficial use options for solid byproduct prompted changes to solid byproduct handling, required further byproduct characterization and navigating permits at local landfill and waste-to-energy facility (Table 2).

*Biocrude and byproduct management plans influenced storage and transportation design. Significance HTL is a promising solution for wastewater utilities seeking alternatives for biosolids management. Lessons learned from design and operation of this demonstration will inform scale-up of HTL with wastewater sludge, improving the probability of success in future

Metro Vancouver is building a continuous flow hydrothermal liquefaction (HTL) demonstration facility using wastewater sludge feedstock. HTL operates at subcritical temperature and pressure to convert wet biomass into biocrude oil in minutes. Biocrude is then refined to produce low-carbon transportation fuels. As this will be the first HTL system in North America at an operating wastewater treatment plant (WWTP), it is paramount to address risks.

SpeakerCotter, Lucy

Presentation time

14:30:00

14:50:00

Session time

13:30:00

15:00:00

SessionDevelopments in Hydrothermal Liquefaction for WRRFs

Session number401

Session locationRoom 256

TopicBiosolids and Residuals, Circular Water Economy, Energy Production, Conservation, and Management, Intermediate Level, Research and Innovation

Author(s)

Cotter, Lucy, Lycke, Derek, Richards, Shantell, Wong, Stephenie, Farinelli, Zeno, Eskicioglu, Cigdem, Zaremba, Lillian, Archer, Gregg, Blair, David, Taponat, Marie, Li, Huipeng, Roxburgh, Ruth

Author(s)L. Cotter1, D. Lycke2, S.M. Richards3, S. Wong2, Z. Farinelli4, C. Eskicioglu5, L. Zaremba6, G. Archer7, D. Blair6, M. Taponat8, H. Li9, R. Roxburgh1

Author affiliation(s)1Jacobs, British Columbia, 2Jacobs, BC, 3Jacobs Engineering, BC, 4Metro Vancouver Reg'L Dist, BC, 5University of British Columbia Okanagan, DC, 6Metro Vancouver, BC, 7Metro Vancouver, British Columbia, 8, BC, 9Jacobs

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159541

Volume / Issue

Content sourceWEFTEC

Word count7

Base text size -

Lycke, Derek

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