Chegounian, Parisa

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

Titles from this speaker

Description: Feasibility of Green Hydrogen Production at Lulu Island Wastewater Treatment Plant:...

Feasibility of Green Hydrogen Production at Lulu Island Wastewater Treatment Plant: Final Effluent Pathway and Ammonia Pathway

Abstract

Introduction The production of hydrogen at wastewater treatment plants (WWTPs) is emerging as a promising avenue towards establishing a circular water economy. Electrolysis of water or ammonia can be integrated with wastewater treatment to produce hydrogen that can reduce carbon emissions, for example by powering vehicles using hydrogen as a fuel instead of diesel, and also provide residual heat for various purposes including heating buildings1-2. Metro Vancouver (MV) is conducting a feasibility study on green hydrogen production and utilization at Lulu Island WWTP. Lulu Island WWTP serves a population of 220,000 people and has a total capacity of 155 MLD, with average treated flowrate of 79 MLD. Treatment steps consist of pre-treatment, primary treatment, secondary treatment, disinfection and dechlorination and discharge. Methodology Two pathways were considered for production of green hydrogen by electrolysis of water or ammonia. 1. Final Effluent Pathway. Final effluent prior to chlorination is treated further to produce ultrapure water for electrolysis which in turn produces hydrogen and oxygen. Treatment includes pretreatment by screens, media filtration/DAF/ultrafiltration and then reverse osmosis (RO). Treated water is also passed through an ion exchange system to reduce the ionic concentration. 2. Ammonia Pathway. Ammonia is recovered from the centrate of mesophilic anaerobic digesters to produce nitrogen gas and hydrogen gas. Two technologies are evaluated for the recovery of ammonia from centrate: ion exchange and thermal stripping. (Another option, ammonia cracking using thermal hydrolysis to produce hydrogen and nitrogen, was not included in this study.) Flow diagrams depicting the treatment process for FE pathway (Figure 1) and ammonia pathway (Figure 2) are shown below. The hydrogen production is sized based on the availability of ammonia in the centrate to allow direct comparison between the two pathways. The average ammonia concentration in the centrate is 1,297 mg/L, 95% percentile is 1,390 mg/L, and the average flow ranges from 55,000 L/day to 885,000 L/day with average daily flow of 425,355 L/day. The result is a 1 MW electrolyzer operating at 80% to produce 350 kgH2/day. The carbon intensity of produced hydrogen for both pathways is largely dependent on the electricity demand. Notably, the ammonia pathways evaluated utilize considerably higher electricity consumption than the water electrolysis pathway. Utilizing a grid carbon intensity of 11.3 gCO2e/kWh for 2023 in BC 3, the lifecycle carbon intensity of produced hydrogen is expected to be approx. 5.6 gCO2e/MJ for the electrolysis pathway and between 10.1 to 12.7 gCO2e/MJ for the ammonia pathway, depending on the ammonia conversion technology is selected. The feasibility study is assessing different applications for using the hydrogen. Table 1 summarizes the pros and cons of the utilization options. Conclusions Metro Vancouver is currently evaluating the net present value (NPV) and levelized cost of hydrogen (LCOH) produced for the final effluent and ammonia pathways. Depending on the results, MV intends to build a pilot for the preferred technology onsite with industry partners to produce hydrogen for use in heavy-duty trucks or other end-use. The final effluent pathway distinguishes itself from the ammonia pathway primarily based on its technological readiness level. Technology for the final effluent pathway has reached an advanced stage of development and is readily available at scale. Ammonia separation technology is readily available but is still being developed specifically for hydrogen production. The TRL of the final effluent pathway is 9+ whereas TRL for the ammonia pathway is 5 to 7, contingent upon technology-specific variations. A key advantage of the ammonia pathway over the final effluent pathway is that ammonia can be recovered from the centrate, helping to meet final effluent ammonia regulatory requirements without the need for further investment in side-stream or main-stream ammonia treatment. The next steps will confirm the feasibility of hydrogen production at Lulu Island WWTP by:

*Coordinating with vendors to develop cost estimates for both processes.

*Completing a cost benefit analysis for both pathways.

*Determining NPV and LCOH for both pathways.

*Selecting a technology to advance to pilot project definition stage.

Wastewater treatment plants can leverage existing infrastructure and byproducts to produce green hydrogen. This study compared three methods of hydrogen generation at Lulu Island wastewater treatment plant: electrolysis of water from purified final effluent, and electrolysis of ammonia recovered from centrate by ion exchange and by thermal stripping. The study evaluated the technical feasibility, carbon intensity, revenue and operating costs.

SpeakerChegounian, Parisa

Presentation time

14:00:00

14:20:00

Session time

13:30:00

15:00:00

SessionBuilding a Hydrogen Future

Session number206

Session locationRoom 244

TopicEnergy Production, Conservation, and Management, Intermediate Level, Research and Innovation

Author(s)

Chegounian, Parisa, Zaremba, Lillian, McCoy, Alan, Hildebrandt, Shannon, Saffron, Ben, Robertson, John, Dunn, Gemma

Author(s)P. Chegounian1, L. Zaremba1, A. McCoy2, S. Hildebrandt3, B. Saffron3, J. Robertson3, G. Dunn4

Author affiliation(s)1Metro Vancouver, BC, 2GHD, Alberta, 3GHD, 4GHD Ltd., BC

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159583

Volume / Issue

Content sourceWEFTEC

Word count18

Description: Innovation Portfolio Management for Retrofitting Advanced Biotechnologies for...

Innovation Portfolio Management for Retrofitting Advanced Biotechnologies for Anaerobic Digestion Process at Lulu Island Wastewater Treatment Plant

Abstract

Metro Vancouver recently commissioned the Pilot Digestion Optimization Facility (PDOF) at its Lulu Island Wastewater Treatment Plant (LI WWTP) to facilitate the evaluation of different digestion optimization technologies without risk to full-scale plant operation. This study summarizes the integrated approach adopted at the pilot-scale preliminary design stage for two of these technologies. The first technology aims to increase biogas production rates by testing the Direct Interspecies Electron Transfer (DIET) process using electroconductive materials. The second technology utilizes a biological hydrogen methanation (BHM) process to convert the carbon dioxide portion of biogas into renewable natural gas (RNG) using hydrogen. Cost-effective pilot-scale conceptual designs are developed for testing the in-situ and ex-situ configurations of these technologies in order to reach a go/no-go decision quickly, while still producing replicable results for further scale-up. To guide the decision-making process for selecting these technologies for pilot testing, GHG emission reduction calculations and an energy balance model are used to evaluate the environmental impacts of implementing these technologies at full-scale. A Sumo model is used to evaluate the effects of implementing these technologies on process intensification.

Metro Vancouver, in collaboration with its partners, is developing innovative technologies that reduce greenhouse gas emissions and intensify existing digestion processes. Metro Vancouver will first assess the effectiveness and scalability of these technologies at the Lulu Island Pilot Digestion Optimization Facility. Metro Vancouver intends to incorporate these technologies into one of its treatment facilities if the technologies prove successful at pilot-scale.

SpeakerChegounian, Parisa

Presentation time

15:30:00

15:50:00

Session time

15:30:00

17:00:00

SessionImproving Biosolids Treatment Efficiency

Session locationRoom S403b - Level 4

TopicEnergy Production, Conservation, and Management, Intermediate Level, Research and Innovation

Author(s)

Kakar, Farokh Laqa

Author(s)F. Kakar 1; C. Muller 2 ; T. Barber 3; F. Kakar 1; P. Chegounian 4; L. Zaremba 4; T. Gregonia 4; P. Kadota 4; S. Sorensen 4; A. Al-Omari 5;

Author affiliation(s)Brown and Caldwell 1; Brown and Caldwell 2 ; Brown and Caldwell 3; Brown and Caldwell 1; Liquid Waste Services Department, Metro Vancouver, Burnaby, BC, Canada 4; Liquid Waste Services Department, Metro Vancouver, Burnaby, BC, Canada 4; Liquid Waste Services Department, Metro Vancouver, Burnaby, BC, Canada 4; Liquid Waste Services Department, Metro Vancouver, Burnaby, BC, Canada 4; Liquid Waste Services Department 4; Brown and Caldwell 5;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2023

DOI10.2175/193864718825159034

Volume / Issue

Content sourceWEFTEC

Word count18

Performance Evaluation of Pilot Digestion Optimization Facility (PDOF) for Digestion Intensification of Metro Vancouver Anaerobic Digestion Facilities

Abstract

Introduction Anaerobic digestion has proven effective and reliable for stabilizing sludge for decades1. As municipalities grow, digestion intensification can offset or defer major capital expenditures. Testing operational limits for existing systems and trialing new technologies at full-scale carries considerable risk as potential process failures can lead to long recovery times or not meeting regulatory requirements. One approach to address these challenges is conducting bench-scale tests; however, a direct transition to full-scale can impose risks that were not fully considered at bench-scale. Metro Vancouver has built a Pilot Digestion Optimization Facility (PDOF) to conduct tests at a representative scale without risk to full-scale operations. The PDOF consists of three 8 m3 digesters that can be fed with mixed sludge or any combination of primary and secondary sludge. This paper presents results of the first three tests of a multi-year test plan: baseline digestion, thermophilic digestion and temperature-phased anaerobic digestion (TPAD). The test plan for 2023—2024 is outlined in Figure 1. Baseline digestion aimed to replicate the full-scale mesophilic digesters and achieve stable PDOF operation at various hydraulic retention times (HRTs) to identify the most comparable HRT to the full-scale digesters and to develop a volatile solids removal (VSr) performance curve. Thermophilic digestion will run two pilot digesters at 55 degrees C and 60 degrees C while the third runs at 38 degrees C as a mesophilic control. Stress tests will determine HRT operating limits. TPAD involves separating the digestion process into a fermentation phase in a separate tank from methane production. Higher temperatures (55 degrees C) in the first stage increase the rate of hydrolysis, while lower temperatures (38 degrees C) for the methane forming stage reduce energy input and maximize process stability2. The results of baseline digestion test are complete and discussed here. Results for the other tests will be available at the time of paper submission. Methods The PDOF is located at Lulu Island Wastewater Treatment Plant (LIWWTP) in British Columbia, Canada where two 5,400 m3 mesophilic anaerobic digesters operate with 25-to-30-day HRT. The PDOF feeds the same mixed sludge as the full-scale digesters to three 8 m3 pilot digesters. The PDOF was commissioned in June 2023 and achieved steady state mesophilic digestion after 8 weeks. Baseline digestion testing was conducted from July to September 2023. Performance data includes organic loading rate (OLR), VSr and destruction (VSD), biogas and methane yields, volatile fatty acids (VFA), alkalinity, ammonia, and microbial consortia. Genomic samples are collected, extracted and sequenced using shallow shotgun sequencing. Results Baseline Digestion Key process parameters for the pilot digesters were within 5 to 15 % of the full-scale digesters, suggesting direct scalability between the two. Figures 2—4 highlight the similarity between TS, VFA, and ammonia concentrations. The start-up period used diluted digested sludge and can be seen from June 2023 to mid-August 2023 when the digesters achieved steady-state operation. PDOF metrics including VSr and biogas yield were comparable to the full-scale digesters (Table 1). As biogas data from the test was not completely reliable due to condensate issues, the data reported here relies on measured chemical oxygen demand (COD) and a theoretical conversion of 0.35 standard litres of methane per gram of COD destroyed3. Following baseline digestion, modifications to the gas meters improved the accuracy for further tests. There was good agreement between the microbial consortia population in the pilot and full-scale digesters (Figure 5). Thermophilic digestion with LIWWTP sludge in the PDOF is expected to develop a completely new population as it is not seeded from thermophilic digesters. Thermophilic Digestion A single digester was transitioned to thermophilic temperatures (55 degrees C) without a thermophilic digestate seed by increasing the temperature instantly, with no added feed. To ensure that the thermophilic transition was progressing as expected, VFA and alkalinity were monitored daily (Figure 6). A second digester will be converted to 60 degrees C using different methods where mixed mesophilic sludge will be continuously fed to the digester. The two transition methods will be compared once complete. TPAD The test for TPAD is anticipated to be complete by the time of paper submission. Conclusions The three PDOF digesters demonstrated distinct individual performances according to their HRT during the steady-state period. All three digesters were stable throughout the tests based on digested sludge characterization. The VSr results for Digester B with 20-day HRT were closest to the full-scale digester with 28-day HRT. This may indicate that a scalability factor or inefficiencies at full-scale need to be considered in future tests. With the shorter HRT of Digester C (15 days), the product still meets the Organic Matter Recycling Regulation (OMRR)4 requirements for Class B Biosolids. In addition, this study provides valuable insights into the performance and scalability of the PDOF, operational limits for various digestion processes at reduced HRTs, and potential redefines the minimum requirements to achieve biosolids reguirements.

Anaerobic digestion stabilizes sludge effectively, and optimizing this process can save costs as municipalities grow. Intensified anaerobic digestion enhances efficiency, biogas production, and pathogen reduction via thermophilic digestion, advanced reactor designs, and pre-treatment methods. To test these processes, Metro Vancouver built the Pilot Digestion Optimization Facility (PDOF) at Lulu Island WWTP. This paper summarizes the early results from thermophilic digestion at 55 and 60 degrees Celsius.

SpeakerChegounian, Parisa

Presentation time

16:30:00

16:50:00

Session time

15:30:00

17:00:00

SessionAdvances in Anaerobic Digestion

Session number219

Session locationRoom 344

TopicBiosolids and Residuals, Intermediate Level, Research and Innovation

Author(s)

Chegounian, Parisa, Barber, Tyler, Kakar, Farokh Laqa, Martin, Kelly, Choy, Chris, Zaremba, Lillian, Gregonia, Theresa, Muller, Christopher, Yesin, Michael, Flibotte, Stephane, Yik, Susanna

Author(s)P. Chegounian1, T. Barber2, F. Kakar3, K. Martin4, C. Choy5, L. Zaremba1, T. Gregonia1, C. Muller6, M. Yesin2, P. Chegounian1, T. Barber2

Author affiliation(s)1Metro Vancouver, BC, 2Brown and Caldwell, British Columbia, 3, ON, 4Metro Vancouver, 5Metro Vancouver, 6Brown and Caldwell, MA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159667

Volume / Issue

Content sourceWEFTEC

Word count18

Description: Scalability of Anaerobic Digestion: Evaluating pilot scale operations for full-scale...

Scalability of Anaerobic Digestion: Evaluating pilot scale operations for full-scale implementation for Metro Vancouver's advanced digestion concepts

Abstract

Anaerobic digestion is a process central to the stabilization of sewage sludges while also proven to be the effective first step in many resource recovery programs. Mesophilic anaerobic digestion has proven efficient, effective, and reliable process for decades. However, with increasing capital costs, increased value of recovered resources and a societal push toward decarbonization, in an attempt to limit the impacts of climate change; interest in intensification of the digestion process has grown. In the past decade the adoption of intensified or advanced digestion processes has increased. Processes like thermal hydrolysis, thermophilic digestion and co-digestion have demonstrated that conventional process limits, performance and stability indices need to be reassessed and defined for the next generation of water resource recovery facility. Metro Vancouver, has experience with advanced digestion technologies, like its Class A series thermophilic anaerobic digestion system at Annacis Island, pioneering its adoption in the late 1990's. However, since its adoption and nearly 20 years of effective operations the true capacity limits of this process have yet to be defined. To define the operational limits of a biological process, a range of process metrics must be considered these include: - Substrate loading capacity. -Minimum solids retention time - Acclimation potential to inhibitory compounds - Process reaction rates - Dynamic stress responses and recovery (load, temperature, feed composition, toxicity, etc.) To elucidate these metrics at scale is possible, but the impacts of potential process failure can be significant, including long recovery times, process restart, loss of treatment and odors. Any of which can represent significant costs when managing thousands of cubic meters of material (millions of gallons). These risks further increase when new processes are being implemented and/or augmenting an existing digestion process. Further, testing new unproven technologies at scale that on paper would appear to be effective often prove to be more complicated than first envisioned, resulting in increased costs. These costs could result in a premature cessation of process development. One approach researchers and early adopters have addressed these challenges is through the bench testing, on-site and at universities. While these often provide evidence for proof of concept, they are limiting in scale and scope; often not integrating the true variability in operation that a full-scale facility, leading to conservative designs or non-adoption due to risk avoidance. Ultimately this slows the progression of technology advancement. Metro Vancouver, has elected to accelerate the testing and adoption of new processes for its wastewater treatment plants through the construction of the Pilot Digestion Facility (PDOF). This facility consists of three 8 cubic meter digesters, and a feed skid. The digesters are capable of operating at range of temperatures, retention times, mixing strategy and process phasing strategies. The PDOF not only allows for new processes to be tested but also existing systems to be stress tested to defined the maximum capacity of their existing assets. Further, at this scale, it is possible to test processes under real-world conditions, to better assess implementation at scale and process viability at scale. In June of 2023, the PDOF completed construction and commissioning and was started-up at the Lulu Island Wastewater Treatment Plant, in Richmond, BC. One of the first test plans implemented was to evaluate the reproducibility of pilot results relieve to the full-scale operating digesters. Three PDOF digesters were operated at solids retention times of 15, 20 and 28 days respectively on a mix of thickened primary (TPS) and waste secondary sludge (TWSS). Core process metrics were monitored to determine, system performance and compared to the full-scale operating digesters. Figure 1, shows the relationship between digester operating SRT and volatile solids destruction, after each of the three test digesters had reached stead-state and compared it to reference data and LIWWTP's current digester operations. What is apparent from the PDOF and the reference data is that 15 days SRT appears to be an inflection point around which further reduction in operating residence time will result in notable reduction in solids destruction which ties directly to biogas production. The current industry primary practice for resource recovery is biogas generation and methane utilization. Understanding this inflection point and being able to accurately test around this point will provide significant understanding of the total benefit of future process optimizations. Further what is also apparent is that the sludge a LIWWTP is more degradable than a 'typical' sludge, based on the reference data information. This is likely due to a combination of very low industrial input, high volatile content and a low overall residence time in the secondary system, a trickling filter solid contact system. The fact that the PDOF system produced similar VSr to the full-scale, suggests the system is performing in a similar manner to the full-scale digester, making extrapolations to full-scale relatively direct. In terms of reproducing the performance of the anaerobic digesters at LIWWTP, there was generally good agreement in the data, between the pilot and the full-scale digesters in terms of solids destruction, volatile acids, alkalinity and ammonia, Table 1. Biogas data was not completely reliable during this time as condensate was impacting meter accuracy on the pilot units. Modifications to the meter orientation, appears to have improved the response. As part of understanding the overall potential of anaerobic digestion and to gather further in-sites as to the fundamental mechanisms driving the observed results, microbial ecology analysis was conducted to understand changes in the consortia present. As part of this baselining observation the result of these efforts will be discussed. Figure 2, presents the relative abundance of different phylum level populations with time for each of the PDOF digesters and a single steady-state point for the LIWWTP digesters. Figure 3, further refines that focusing Euryarchaeota, which contain the methanogens. With the successful demonstration of the mesophilic operation of the PDOF facility, completing commissioning, the first tests of intensified digestion have commenced. The process being converted over to thermophilic operations to evaluate the limitations of the process. As of authoring the digester temperature has been increased and the microbial population is transitioning to thermophilic, as denoted by the significant increase in volatile acids and deterioration of biogas production. A process condition understood to be typical. Once steady thermophilic operation has been reached a range of process conditions will be tested. These include, reduced SRT and increased organic loading rate. This not only will demonstrate the potential for LIWWTP to utilize thermophilic digestion to increase capacity but also further define the capacity at the larger Annacis Island WWTP. This paper will discuss the results of the completed baselining operations, including lessons learned, and observation due to different operating retention times for mesophilic digestion. It will further present relevant observations from the conversion to thermophilic, which are in progress now.

This paper was presented at the WEF Residuals and Biosolids Conference, June 18-21, 2024.

SpeakerMuller, Christopher

Presentation time

09:30:00

10:00:00

Session time

08:30:00

11:45:00

SessionAdvancing Anaerobic Digestion

Session number12

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicAdvanced Treatment, Anaerobic Digestion, Intensification