Le, Trung

Trung Le: has more than ten years of experience in planning, design, and research on solids and energy projects. His primary roles have involved...

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About Le, Trung

Trung Le: has more than ten years of experience in planning, design, and research on solids and energy projects. His primary roles have involved technical design and biosolids process applications with expertise in digestion, energy, GHG accounting, and decarbonization strategies. He leads BCs Fugitive Methane Taskforce.

Le, Trung

Titles from this speaker

A Techno-Economic Analysis on Biogas Carbon Capture for Implementation at Water Resource Recovery Facilities

Abstract

OBJECTIVE: Especially with arising policies and markets for biogenic or green carbon dioxide (CO2), there are greater incentives for water resource recovery facilities (WRRFs) to implement carbon capture utilization (CCU) and carbon capture sequestration (CCS) strategies. In efforts to mitigate climate change, an increasing number of WRRFs are beneficially utilizing biogas for cogeneration or upgrading to renewable natural gas (RNG). Biogas upgrading to RNG produces a waste gas, or tail gas, that is primary CO2 and is typically vented to atmosphere or disposed of in a thermal oxidizer. While WRRFs have historically treated tail gas as a waste product, this paper will explore the emerging opportunities for CCU and CCS project implementation. The manuscript and presentation will include a market assessment for biogenic CO2 end-uses, funding mechanisms and economic incentives, regulations and policies, technological solutions, and a techno-economic analysis of a case study for carbon capture at a WRRF. BACKGROUND: Biogenic CO2 is associated with the natural carbon cycle and comes from the degradation, combustion, or mineralization of organic matter. Biogenic CO2 is sequestered through new terrestrial growth in a 1:1 ratio, making it effectively carbon neutral and a highly valuable commodity for different industries. Biogenic CO2 is a natural byproduct of both anaerobic digestion and from the combustion of biogas in cogeneration. This paper will focus on the capturing biogas from upgrading programs where CO2 must be removed to produce RNG. WRRFs can utilize two pathways for biogenic CO2: CCS or CCU. CCS is the process in which captured CO2 is compressed and injected in underground geologic formations for permanent storage or sequestration. Geologic formations suitable for sequestration include depleted oil and gas fields, deep coal seams, and saline formations. CCS can be used to offset emissions, meet climate goals, or sold as carbon credits. CCU would sell biogenic CO2 as a commodity to manufacturers to produce electrofuels (e-fuels), bioplastics, cement, dry ice, etc. TECHNOLOGICAL SOLUTIONS: Biogas upgrading includes cleaning and separation to remove CO2, H2S, siloxanes, VOCs, and moisture, resulting in RNG and a CO2 rich tail gas containing 0.1 to 7 percent methane. Industrial plants are utilizing the same technologies for CO2 capture as WRRFs are employing for biogas upgrading such as amine solvents, membranes, and pressure swing adsorption. Historically, the tail gas is a waste product that is vented to atmosphere or combusted in a thermal oxidizer. Participating in CCS and CCU market requires further processing of the CO2 gas, which may include further purification, compression, distillation, and cryogenic storage. Table 3-1 presents a summary of the gas upgrading technologies' compatibility for CO2 capture and processing requirements for end use. FUNDING MECHANISMS The Inflation Reduction Act (IRA) of 2022 includes provisions for CCU and CCS tax credits in the form of a direct payment as part of Section 45Q. Section 45Q provides a production tax credit (PTC) per metric ton of qualified CO2 captured up to $85 (Table 4-1). The captured CO2 can be used in enhanced oil and gas recovery, injected in geological sequestration, or for other qualified uses. Qualified uses include photosynthesis or chemosynthesis, chemical conversion to a material or chemical compound, or commercial markets. The Section 45Q PTC is up to $85 per metric ton of captured CO2 depending on utilization and other requirements in Table 4-1. MARKET ASSESSMENT Several economic incentive programs are available to support the market for biogenic and direct air capture (DAC) CO2. Such programs include the IRA for end-users including sustainable aviation fuel manufacturers, and the Carbon Utilization Procurement Grants Program which offset 50% of the costs to states, local governments, and public utilities or agencies to procure and use products developed through the conversion of CO2. Current market prices for biogenic CO2 range from $100 to 300 per MT while DAC CO2 demands a higher price due to the cost (final submission to include pricing data surveyed from various suppliers and end-users). The other avenue to generate revenues from CCS is to sell the offset as carbon credits through the compliance or voluntary market. Carbon market prices have been highly variable in the voluntary market and for CCS to generate more stable revenues the compliance market would need to be accessed (The techno-economic analysis will include an evaluation of CCS vs CCU in the final submission). TECHNO-ECONOMIC ANALYSIS An initial evaluation of funding opportunities and economic incentives for RNG coupled with CCU is provided based on interpretations of the IRA 2022 and values for RINs, biogenic CO2, and commodity RNG (Figure 6-1). Based on a conservative value for biogenic CO2 ($100/MT) and an IRA tax credit of $65/MT, it is estimated that CCU can provide a 20% increase in revenues from an RNG program that accesses the RFS program. The manuscript and presentation will include a techno-economic analysis for a medium sized WRRF to implement a CCU or CCS project that will support climate change mitigation.

WRRFs with AD can implement CO2 capture alongside RNG programs to enhance resource recovery and generate additional revenues. WRRFs are one of the few sources of biogenic CO2 and the high concentration of CO2 in biogas upgrading can generate a green CO2 product for decarbonization. A TEA found that CO2 capture systems larger than 1,200 of biogas with IRA funding can result in a NPV that is positive. However, there are still many significant challenges that need to be addressed.

SpeakerNojima, Alison

Presentation time

16:30:00

16:50:00

Session time

15:30:00

17:00:00

SessionWhat Will You Make of Your Biogas?

Session number430

Session locationRoom 346

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Intermediate Level, Sustainability and Climate Change, Utility Management and Leadership

Author(s)

Nojima, Alison, Le, Trung, Guo, Peibo, Valenti, Alexis, Ross, Adam

Author(s)A.C. Nojima1, T. Le2, P. Guo2, A. Valenti1, A. Ross1

Author affiliation(s)1Brown and Caldwell, CA, 2Brown and Caldwell, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159687

Volume / Issue

Content sourceWEFTEC

Word count15

Description: A techno-economic analysis on water resource recovery facilities employing carbon...

A techno-economic analysis on water resource recovery facilities employing carbon capture strategies in biogas upgrading practices

Abstract

OBJECTIVE: The increasing emphasis on circular economies has led wastewater treatment in recent years to become a renewable source for energy, heat, water, fertilizers, carbon products, and soil amendments. Despite these advancements, one significant and potential resource that remains unrealized is biogenic CO2, which can be used for geological sequestration or other manufacturing. Given the arising climate change policies and markets for biogenic, or green CO2, there will be greater financial incentives in the future for WRRFs to implement bioenergy programs with carbon capture, utilization, and sequestration (BECCUS) strategies. This paper will explore a market assessment for biogenic CO2 end-uses, funding mechanisms and economic incentives, regulations and policies, technological solutions, and a techno-economic analysis (TEA) of a case study for carbon capture at a WRRF. CURRENT CO2 MARKET In 2022, commodity CO2 demand in the United States was estimated at 10.3 million MT per year with over 64% of that sourced from fossil fuel derivatives (Figure 1). About 25 percent of CO2 are mined, with the remaining demand supplied as a byproduct from chemical manufacturing processes (ammonia, ethanol, hydrogen, and natural gas processing). While most of the CO2 is used in enhanced oil recovery (EOR), which is the process of injecting CO2 into the oil reservoir to increase the mobility of the oil, the second most common use of CO2 is for the food/beverage industry (approximately 30% of all CO2 demand). THE VALUE OF BIOGENIC CO2 AND THE FUTURE CO2 MARKET CO2 can be categorized by its sourcing as traditional CO2 or green CO2. Traditional CO2 mainly comes from the burning of fossil fuels and results in an accumulation of CO2 in the atmosphere. As climate-driven initiatives and regulations become more pressing, the CO2 market will need to evolve to more sustainable alternatives. Green CO2 is a sustainable type of CO2 as it is sourced from the natural carbon cycle making it effectively carbon neutral. The two main sources of green CO2 are direct air capture (DAC) CO2 and biogenic CO2. DAC is a technology that separates CO2 from the atmosphere through chemical reactions and is not limited to point of emission locations. However, DAC is both an expensive and energy intensive method of capturing CO2, as it requires concentrating the dilute stream of CO2 from the atmosphere (Figure 2). Biogenic CO2 is a favorable alternative as it comes from the degradation (digestion/fermentation), combustion, or mineralization of organic matter, and tends to result in a higher concentrated CO2 stream. Currently, ethanol plants provide up to one quarter of the existing biogenic CO2 market's supply in the U.S., but its production is limited to the midwest region. For WRRFs, biogenic CO2 is a natural byproduct of both anaerobic digestion and from the combustion of biogas in combined heat and power systems (CHP), making it a prime point of emission location. Over 1,300 WRRFs are equipped with anaerobic digestion systems, and many are located in urban centers. OPPORTUNITIES AND CHALLENGES FOR BIOGENIC CO2 WRRFs can utilize two pathways for biogenic CO2: carbon capture and utilization (CCU) or carbon capture and storage (CCS). Figure 3 shows a general diagram of the two paths. A national survey was performed to examine the prospects for captured biogenic CO2 from WRRFs to be utilized in the food/beverage, e-fuels, or sold to a distributor. Partial details of the survey are included below; full details will be included in the paper: -E-Fuels -- also known as 'electrofuels', are a class of synthetic fuels that are produced from combining the carbon in CO2 with green or blue hydrogen. Twelve, a carbon transformation company and E-Jet fuel supplier, stated that they source their biogenic CO2 for $20-100 per ton from the ethanol industry. - E-Chemistry -- similar to e-fuels, e-chemicals use electrosynthesis to produce chemicals through more sustainable avenues. This sector is still developing but may become a major user of CO2 in the future. Biogenic CO2 would be highly compatible with this end-use. - Cement manufacturing -- biogenic CO2 can be used as a direct replacement for traditional CO2 which is used for the manufacturing of concrete. Scale and size may limit acceptance. CCS is the process in which captured CO2 is compressed and injected in underground geologic formations for permanent storage or sequestration. WRRF would partner or contract with a regional or local CCS service provider, and the credits can be used to offset a utility's emissions or sold in the voluntary or compliance carbon market. FUNDING MECHANISMS AND ECONOMIC INCENTIVES The Inflation Reduction Act (IRA) was passed in 2022 and provided over $369 billion dollars in climate-related funding for domestic clean energy production, decarbonization technologies, climate change mitigation, and resiliency programs. Within Section 45Q of the IRA, provisions for CCU and CCS provide the financial incentives for utilities with bioenergy programs to invest in CO2 capture technologies (Table 1). TECHNOLOGICAL SOLUTIONS The biogas upgrading to RNG process includes cleaning and separation to remove CO2, H2S, siloxanes, VOCs, and moisture, resulting in RNG and a CO2-rich tail gas that contains 93 to 99.9 percent CO2. This tail gas can be further processed to recover biogenic CO2 rather than vented to atmosphere. Each of these technologies have varying levels of compatibility with CO2 recovery in the tail gas as shown in Table 2. TECHNO-ECONOMIC ANALYSIS A TEA was developed to evaluate the financial feasibility of two different CO2 capture program sizes with and without IRA eligibility. This TEA only considered the CO2 capture program as an add on and not a full CO2 and RNG program which may change the economics. Interviews with various CO2 capture equipment manufacturers, CO2 commodity suppliers and distributors, and CO2 end-users provided economic information for this TEA. The key assumptions that drove the economic model are summarized in Table 3. The results of the TEA illustrates that a 'no distributor model' with IRA funding reflected a positive NPV. The other modelled scenarios are illustrated in Figure 5. Note that the current IRA 45Q guidelines provides credits for only 12 years and that CO2 pricing, transportation costs are highly region dependent and may change the economics (Smith et al. 2021). CONCLUSIONS Capturing CO2 from municipal bioenergy programs is a significant opportunity for resource recovery and carbon management and stands out for its practicality and effectiveness. One advantage of CO2 capture from biogas is its high concentration in the airstream, with purity typically ranging from 30-50% and up to 99.9% from biogas upgrading to RNG. There are several end-uses for biogenic CO2 in the CCS (sequestering and selling credits to the voluntary or compliance carbon market) and CCU market (i.e. food/beverage, industrial uses, e-fuels). However, a limitation for WRRFs-sourced biogenic CO2 is its scale and size as many require a production of a minimum of 30,000 to 50,000 tons of CO2 per year for partnership. We anticipate that the competition for green CO2 sources will drive these end-users to seek WRRFs in the future. The future paper and presentation will explore additional sources of CO2 from WRRFs such as from post-combustion capture, and aeration tanks.

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerNojima, Alison

Presentation time

08:50:00

09:10:00

Session time

08:30:00

10:00:00

SessionInnovations in Waste-to-Value Technologies: Carbon Management and Resource Recovery

Session number22

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicAcidogenic fermentation, Anaerobic Digestion, Biogas, business case evaluation, Circular Economy, Compost, Energy and Carbon Neutrality, Nitrogen Removal, Nutrient Removal, Phosphorus recovery, struvite, electrochemical, Phosphorus Removal and Recovery, Resource Recovery

Author(s)

Guo, Peibo, Nojima, Alison, Le, Trung, Valenti, Alexis, Ross, Adam

Author(s)P. Guo1, A. Nojima1, T. Le1, A. Valenti1, A. Ross1

Author affiliation(s)Brown and Caldwell, 1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159758

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count17

Description: Continuous Monitoring of Fugitive Methane in Wastewater Treatment Plants Using...

Continuous Monitoring of Fugitive Methane in Wastewater Treatment Plants Using Ground Sensors

Abstract

Introduction Greenhouse gas (GHG) emissions, primarily comprising carbon dioxide (CO2), methane (CH), and nitrous oxide (N2O), are a major contributor to climate change, driving global warming and environmental instability (Gautam et al., 2021). These gases originate from various human activities, including energy production, transportation, agriculture, oil and gas industry, wastewater treatment, and waste management (Varon et al., 2021). Among these sources, methane is particularly potent, having a global warming potential significantly higher than CO2 over a 20-year period. This makes methane emissions a critical target for mitigation efforts, as reducing them can have an immediate impact on curbing climate change and its negative influence on the environment (Liu et al., 2019). Wastewater treatment plants (WWTPs) are considered an active source of GHG emissions, especially methane, which is generated during the biological processes that involve breaking down the organic matter during the anaerobic digestion processes (Khalil et al., 2024). There are multiple key emission hotspots within WWTPs including the sludge treatment areas, anaerobic digesters, and equalizer tanks, where anaerobic conditions can lead to significant methane release. In addition, there might be additional unexpected sources of GHG emissions that may contribute to the overall emissions from these WWTPs such as aeration tanks. As these emissions can be episodic and location-specific, continuous monitoring is essential for capturing real-time data on emission patterns and variabilities. Despite its significance, a major limitation in the wastewater sector is developing an affordable and continuous methane monitoring systems. Therefore, the use of advanced sensing technologies, such as ground and drone-mounted sensors, has been gaining greater attention during recent years. These technologies enable more precise and continuous monitoring, allowing for effective detection of fugitive methane emissions and identification of the hotspots that might otherwise go unnoticed. Continuous monitoring not only provides critical insights into emission dynamics but also supports timely interventions, helping to reduce the carbon footprint of WWTPs and contribute to broader climate goals. Objectives The main objectives of the current study are to: (1) install a group of ground sensors to isolate the methane emissions from different wastewater treatment processes; (2) identify the hotspots of methane emissions within the wastewater treatment facility based on continuous timeseries of fugitive methane emissions from different sources; and (3) compare the methane emissions from the ground sensors with other sensing technologies such as drone-based techniques. Methods and Materials In the current study, 16 ground sensors were installed in a local wastewater treatment facility (WWTF) in Ontario, Canada. The WWTF comprises the typical treatment processes including the primary and secondary treatment, anaerobic digesters, and solids management facilities. In addition, this WWTF receives high organic loading rates which can contribute to the fugitive methane emissions. The ground sensors were distributed around the treatment processes and building to continuously monitor the fugitive methane from these processes. For example, four ground sensors were installed around the aeration tanks to continuously monitor the methane concentrations and emissions from the basins. It should be noted that the observation period started in June 2024 where the ground sensors observed the methane concentrations on a 15-minute interval. Besides the ground sensors, a drone and Optical Gas Imaging (OGI) sensing campaigns were carried out in the WWTF in Summer 2024 to compare the methane concentrations and emissions from different monitoring levels including the ground and aerial sensing techniques. Results According to the preliminary insights from the time-series of methane concentrations using the ground sensors, it was observed that there are multiple hotspots for methane emissions within the WWTF. The average methane concentration at each ground sensor varied according to the location of sensor, the isolated process, and wind properties that play a crucial role in conveying the methane plume. For example, the average methane concentration over four months (i.e., from beginning of June until the end of September) ranged between 7.2 to 11.4 ppm for the sensors surrounding the aeration tanks (Fig. 1), indicating that these basins are a potential source of methane emissions. In addition, the average methane concentration was approximately 10.3 ppm near the primary clarifiers (Fig. 2a). Moreover, the range of the average methane concentration of the sensors installed around the sludge treatment facilities was 5.7 -- 11.2 ppm. Based on these observations, it can be emphasized that most of the treatment processes are considered hotspots for fugitive methane emissions with the WWTF. These findings were validated using the drone and OGI sensing approaches where the drone flights and OGI camera confirmed the locations of the hotspots for emitting methane within the treatment processes (Fig. 2). Conclusions and summary The deployment of ground-based sensors for the quantification and detection of fugitive methane emissions at the WWTF provided valuable insights into the spatial and temporal distribution of emissions. The sensors, strategically placed near the expected and unexpected emitters such as sludge handling units, anaerobic digesters, and aeration tanks, captured real-time data on methane concentrations, enabling the identification of persistent emission sources. Over the monitoring period, fluctuations in emission levels were observed that were linked to the operational activities and environmental conditions. This data underscored the variability of methane emissions and emphasized the importance of continuous monitoring to capture short-term spikes and long-term trends. Ultimately, the ground sensor campaign highlighted the potential for such technology to complement aerial sensing, providing granular, location-specific data critical for effective emission mitigation strategies in wastewater treatment operations.

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerElsayed, Ahmed

Presentation time

09:30:00

09:50:00

Session time

08:30:00

10:00:00

SessionDrones, Satelites, Sensors, Oh My!: Advances in Fugitive Methane Monitoring

Session number11

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicBiosolids To Energy, Climate Change Mitigation, Energy and Carbon Neutrality, Greenhouse Gases, Odor/Air Emissions, Regulatory Requirements, Sensors, wastewater

Author(s)

Alsayed, Ahmed, Elsayed, Ahmed, Abdelrahman, Omar, Khalil, Mostafa, Zaghloul, Mohamed, Kakar, Farokh, Bell, Katherine, Le, Trung, Willis, John, Elbeshbishy, Elsayed

Author(s)A. Elsayed1, A. Alsayed2, O. Abdelrahman1, M. Khalil1, M. Zaghloul3, F. Kakar4, K. Bell4, T. Le4, J. Willis4, E. Elbeshbishy1

Author affiliation(s)Toronto Metropolitan University, 1Northwestern University, 2United Arab Emirates University, 3Brown and Caldwell, 4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159805

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count13

Developing a Regional Biosolids Master Plan for the North Shore Water Reclamation District

Abstract

In 2023, the North Shore Water Reclamation District (NSWRD) developed a comprehensive Biosolids Master Plan (BMP) to leverage opportunities for the regionalization of solids handling facilities that were in need of renewal and modernization. The BMP addressed operational and maintenance challenges, optimized resource recovery, and made plans for current and future regulations, within the framework of stakeholder goals and values. The NSWRD BMP planning process is complete, and a discussion of the planning approach, considerations, and the selected alternative will be presented. This approach to biosolids master planning could be implemented by any water resource reclamation facility seeking to take a holistic approach to their biosolids management program, solids handling technology, and the operational requirements of their solids processing. The NSWRD serves around 300,000 residents north of Chicago and processes a total average of 63 million gallons and 7,785 dry tons of Class A Exceptional Quality (EQ) biosolids per day. The NSWRD is composed of three water reclamation facilities (WRFs), Gurnee WRF, Waukegan WRF, and Clavey Road WRF, and a regional biosolids drying facility (Figure 1). The drivers for completing this BMP included the following: Capacity constraints , aging assets, operational challenges associated with the drying and marketing of unstabilized solids, and other regulatory considerations. At the onset of the planning effort, a collaborative effort was undertaken by the NSWRD and the Brown and Caldwell team to develop a set of guiding principles to keep the plan aligned with the long-term goals of the NSWRD's. Those program goals and objectives are listed below:

*Modernize NSWRD's aging solids handling assets in a cost-effective manner that balances program goals with stakeholders' financial interests.

*Create solids handling solutions that can incorporate innovation and are operation and maintenance (O&M) friendly/easy to own.

*Improve regulatory and market resiliency by creating solutions that lend themselves to program flexibility and redundancy.

*Set a course that supports environmental stewardship, including reduction or recovery of energy, and the creation of marketable biosolids products.

*Create an adaptable plan that can be implemented to leverage current assets and address near-term challenges, while prioritizing those projects that address the NSWRD's goals for the future. The preferred alternative was selected through a two-phase planning process, with numerous collaborative and iterative rounds of analysis and screening. In Phase I of the planning process, the planning team established the operational, economic, and environmental baseline for the existing biosolids management program at NSWRD and performed a regulatory and market assessment of the current biosolids land application landscape. In Phase II, the team performed a biosolids stabilization and biogas management technology pre-screening and an intensive three-round alternatives analysis, Each round of the analysis provided some clear trends. An outline of the number of alternatives, the objective of each round, and a summary of those takeaways are presented in Figures 2-5. The selection of the preferred alternative was made through a multi-criteria decision-making process in which the alternatives from round 3 were compared on cost and relative benefit. This process facilitates the selection of the program that provides the best value to the District by considering a variety of specific factors that the District's staff weigh in order of importance. A dashboard of these results is shown in Figure 6. The preferred alternative implements an advanced regionalized digestion and drying program that generates renewable energy and a high-quality Class A EQ product. It also consolidates solids management at the Gurnee WRF over the next 20 years. The regionalized thermophilic anaerobic digestion (TAD) and belt drying program will be located at the Gurnee WRF, with pipeline injection of the upgraded biogas or renewable natural gas (RNG). At full implementation, solids from Waukegan WRF and Clavey Road WRF would be conveyed via tanker or forcemain to Gurnee WRF for fully regionalized digestion, dewatering, and drying, with the option to convert to a Class A temperature-phased anaerobic digestion system in the future

In 2023, the North Shore Water Reclamation District in Illinois developed a Biosolids Master Plan (BMP) to layout the next twenty years of upgrades to their solids handling program. The BMP addressed operational and maintenance challenges, optimized resource recovery, and accommodated current and future regulations, all while incorporating stakeholder goals and values.

SpeakerMarino, Joe

Presentation time

16:00:00

16:30:00

Session time

15:30:00

17:00:00

SessionManaging Biosolids for Tomorrow: Infinite Resources, Finite Uses

Session number218

Session locationRoom 253

TopicBiosolids and Residuals, Circular Water Economy, Energy Production, Conservation, and Management, Intermediate Level, Public Communication and Outreach

Author(s)

Marino, Joe, Ma, Persephone, Sierra, Natalie, Waters, Steve, Vodnik, Travis, Prentice, Emily, Le, Trung

Author(s)J. Marino1, P. Ma1, N.V. Sierra2, S. Waters3, T. Vodnik3, E. Prentice3, T. Le4

Author affiliation(s)1Brown and Caldwell, IL, 2Brown and Caldwell, MA, 3North Shore Water Reclamation District, IL, 4Brown and Caldwell, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159644

Volume / Issue

Content sourceWEFTEC

Word count14

Description: Drone-Based Imaging and Sensing: Quantification of Fugitive Methane Emissions from...

Drone-Based Imaging and Sensing: Quantification of Fugitive Methane Emissions from Full-Scale Wastewater Treatment Facility

Abstract

Introduction Greenhouse gas (GHG), such as methane (CH4), nitrous oxide (N2O) and hydrofluorocarbons (HFCs), emissions are considered a major contributor to global climate change which has a substantial impact on the public and environmental health (Hopwood et al., 2008; Gautam et al., 2021). Multiple sources, including the Intergovernmental Panel on Climate Change (IPCC), highlighted that global temperatures have increased between 0.3 - 0.74 degrees Celsius in the past century due to the natural and anthropogenic sources including the GHG emissions (Solomon et al, 2010; Liu et al., 2019). Methane as a GHG has been reported to have 27-29 times higher global warming potential compared to carbon dioxide. According to EPA's 2022 report, the wastewater sector is the fifth largest methane source. For example, the methane emissions from domestic sewage in WWTPs can reach up to 25 Tg-CH4/yr (Wallington et al. 2019). Such estimations were developed based on top-down approaches where average emission factor is used to estimate such emissions. However, a major contributor to such emissions is direct process and fugitive methane emissions such as anaerobic digesters and waste gas burners. Such emissions may vary significantly according to operational conditions and infrastructure integrity. Moreover, there might be additional unexpected sources of GHG emissions that may contribute to the overall emissions from WWTPs. Therefore, the application of sensing technologies can aid in accurate quantification of the methane emissions from the WWTPs where these emissions can be correlated to specific treatment processes. Objectives In the current study, the main objectives are to: (1) utilize a multi-platform sensor approach to detect and quantify the fugitive methane emissions from a WWTP using drone and Optical Gas Imaging (OGI) sensing; (2) identify the hotspots of methane emissions within the wastewater treatment facility based on these different sensing technologies; and (3) determine the overall methane emissions from the treatment facility. Methods and Materials A drone and OGI sensing campaigns were carried out in a local WWTP in Ontario, Canada during the Summer of 2024. The WWTP contains the typical treatment processes including the primary treatment, secondary treatment, anaerobic digesters, biosolids loading facilities, and sludge settling tanks. Worth noting, this WWTP receives high organic loading rates which can significantly increase the methane emissions from the WWTP. During the campaign, the drone was flown to isolate each treatment process through creating flight paths upwind and downwind each process and building. These flight paths are known as the wind curtains where they are selected to be perpendicular on the wind direction at different altitudes around the potential process sources. To effectively capture the methane plumes from emission sources, the wind curtains were flown between 30 to 150 ft upwind and downwind the potential sources and treatment processes. The drone sensing approach generally features a quantification sensor (i.e., open-path laser spectrometer (OPLS)) that can detect methane levels as low as 10 parts per billion (ppb). In general, the flight conditions of the drone require a wind speed range of 4 and 20 mph while maintaining a consistent drone speed approximately 3.0 to 4.0 mph for optimal performance. In addition, an OGI camera was mounted on the drone for detecting the potential leakage within the treatment processes. A hand-held OGI camera comprising a cooled infrared sensor was used to access the areas that cannot be assessed using the drone including the indoor spaces and chambers. The OGI camera detects the methane using three factors: the infrared absorption of the gas aligning with the camera's spectral response, the temperature difference between the gas and background, and the gas concentration meeting the camera's sensitivity threshold. The OGI camera is connected with a gimbal which enables the OGI camera to rotate freely without restrictions. Results According to the outcomes of the drone and OGI campaigns, it was found that there are multiple hotspots for methane emissions within the WWTP. For example, the primary treatment process emitted approximately 8.0 kg-CH4/hr. This can be referred to the high organic loads received in such a treatment plant and mixing primary sludge with thickened waste activated sludge. In addition, the anaerobic digesters, gas burner facility, and sludge handling facilities yielded high emissions that ranged from 2.0 to 19.8 kg-CH4/hr. based on the sludge treatment stages and wind characteristics. For example, the anaerobic digesters had an emission rate of approximately 8.9 kg-CH4/hr. (Fig. 1a). Interestingly, considerable methane emissions were observed around the aeration tanks where the methane emission rate was approximately 3.8 kg-CH4/hr. (Fig. 1b). The activated sludge process in this plant does not entail any anoxic or anaerobic zones. Hence, the high emissions from the aeration basins can be attributed to unideal aeration and mixing conditions (coarse bubble aeration used for mixing and aeration), and/or the circulation of the centrate which is anticipated to be saturated with dissolved methane. A major methane emission spot was found to be the sludge holding tanks. Methane concentrations from such tanks reached more than 60 ppm, highlighting a major fugitive methane emission in the facility. However, there were some challenges in estimating the actual methane emission rates due to low wind speed at this area which ranged between 0.7 to 2.0 m/s that were lower than the recommended values of wind speed for accurate quantification of methane emissions using drone-based sensing techniques. In general, these hotspots were also surveilled using either the drone-based or hand-held OGI camera where the methane plumes were detected and recognized (Fig. 2). Conclusions and summary The current study aimed to accurately quantify the methane emissions from a WWTP using drone-based sensing approach to assist in calculating the methane emissions rates from various treatment processes. The methane emission quantification campaign at the WWTP demonstrated the efficacy of drone-based sensing combined with OGI cameras for detecting and measuring fugitive methane emissions where it provided important insights into the interplay between the treatment processes and methane emissions. The results showed significant methane hotspots near the primary tanks, aeration basins, sludge processing and anaerobic digestion units. This encompasses both anticipated and unexpected emissions sources which can enhance our understanding about the sources of fugitive methane emissions in WWTPs. The advantages of the aerial drone, coupled with the OGI camera, allowed for rapid and comprehensive coverage of the facility, providing accurate spatial emission data. Overall, the campaign underscored the potential of drone and OGI technology as a powerful tool for enhancing fugitive methane monitoring and supporting emission reduction strategies in wastewater operations.

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerAbdelrahman, Omar

Presentation time

08:50:00

09:10:00

Session time

08:30:00

10:00:00

SessionDrones, Satelites, Sensors, Oh My!: Advances in Fugitive Methane Monitoring

Session number11

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicBiosolids To Energy, Climate Change Mitigation, Energy and Carbon Neutrality, Greenhouse Gases, Odor/Air Emissions, Regulatory Requirements, Sensors, wastewater

Author(s)

Abdelrahman, Omar, Elsayed, Ahmed, Alsayed, Ahmed, Khalil, Mostafa, Zaghloul, Mohamed, Kakar, Farokh, Bell, Katherine, Le, Trung, Willis, John, Elbeshbishy, Elsayed

Author(s)O. Abdelrahman1, A. Elsayed1, A. Alsayed 2, M. Khalil1, M. Zaghloul3, F. Kakar4, K. Bell4, T. Le4, J. Willis4, E. Elbeshbishy1

Author affiliation(s)Toronto Metropolitan University, 1Northwestern University, 2United Arab Emirates University, 3Brown and Caldwell, 4

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159804

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count15

How Columbus Used Fugitive Methane Quantification to Implement Fugitive Methane Abatement Solutions as Part of a Major Bioenergy Program

Abstract

Methane is a major contributor to climate change, accounting for 45 percent of current net warming. As a potent greenhouse gas (GHG), it is 84 times more effective at trapping heat in the atmosphere compared to carbon dioxide over a 20-year timeframe. A global effort to reduce methane emissions was inaugurated by the Global Methane Pledge (GMP) with 150 countries committing to reduce methane emissions by at least 30 percent from 2020 levels by 2030. Its reduction is crucial to mitigate near-term warming and to avoid the worst effects of climate change. Municipal water resource recovery facilities (WRRFs) have been estimated to contribute around 5-8% of global anthropogenic methane emissions (Ocko, 2021) which are largely attributable to fugitive, or unintended, releases. These emissions are associated primarily with anaerobic digestion and associated solids handling. The significance of methane and its impacts on the climate, coupled with burgeoning interest and attention to WRRFs as a source, creates considerable opportunities within the wastewater sector to address both local and global climate action goals by reducing these emissions. Recently, new measurement technologies developed in other sectors (oil, gas, and landfill) have provided WRRFs with the ability to more accurately quantify and identify sources of emissions. In addition, new abatement technologies and knowledge to reduce fugitive methane has emerged that allows solutions to be implemented. This abstract covers one of the first efforts to reduce fugitive methane as part of a major bioenergy program based on new technology quantification and represents the second part of a two part presentation. As part of the Bioenergy Project at Southerly Wastewater Treatment Plant (SWWTP), the City of Columbus embarked on a field campaign to quantify fugitive methane emissions. The field campaign was the first US multi-technology effort to quantify fugitive methane at a WWTP using commercial services and products. This included drone flux measurement (DFM), an optical gas imaging (OGI) camera and discrete sampling with a flame ionization detector (FID). The field investigation spanned several days and included an evaluation of the solids handling facilities, waste gas burner (WGB), digestion facilities, and the BLAF. The OGI camera was used as a qualitative method for source identification. The DFM is an ISO 17025-accredited top-down method and was used as the primary method for quantification. The DFM was used to collect area emissions from various parts of the plant and a representative DFM. The total amount of fugitive methane measured via drone at SWWTP at the time of the investigation was approximately equal to 15 percent of the total biogas production or 70 kg/hr as seen in Figure 1. The outcomes of the campaign lead to an alternatives evaluation looking at a comprehensive list of abatement options. A fugitive methane model was developed to estimate fugitive methane emissions based on the quantification campaign results and future flows and loads for years 2028 and 2048 see Figure 2 and Figure 3. In the no-action scenario, the total FM would increase 87 percent. Due to the severity of the FM issue, the City decided to take initial actions to reduce fugitive methane emissions by developing a beneficial biogas program, implementing digestion system improvements, and replacing the methane phase digester floating covers with concrete fixed covers. These actions would result in a fugitive methane reduction of 74 percent based on 2048 flows and loads see Figure 4. The remaining FM needed to be mitigated were from the solids handling facilities and the BLAF (see Figure 1). Solutions that were evaluated included augmented biofiltration, vapor combustion units (VCUs), regenerative thermal oxidizers (RTOs), an Elovac system, and replacing the BLAF cover to capture the gas. A cost-benefit analysis based on cost per metric ton (MT) CO2e reduced was used to evaluate the alternatives. RTOs were selected for the BLAF and VCUs for the solids handling facilities as shown in the costs in Table 1 and 2. The end solution resulted in a 96 percent decrease in FM emissions from the solids handling and treatment processes at SWWTP see Table 3.

Methane is a major contributor to climate change and a major source of GHG emissions for WRRFs. As part of the Bioenergy Project, the City of Columbus embarked on a field campaign to quantify FM emissions. The campaign measured FM via drone at Southerly WWTP that was equal to 15 percent of the total biogas production or 70 kg/hr. An alternatives evaluation was conducted on FM abatement solutions and integrated into the bioenergy to reduce fugitive methane up to 95 percent.

SpeakerLe, Trung

Presentation time

14:30:00

14:50:00

Session time

13:30:00

15:00:00

SessionGreenhouse Gas Strategies in Action: Measure to Mitigate

Session number402

Session locationRoom 344

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Intermediate Level

Author(s)

Le, Trung, Schaad, Katie, Weidman, Emily, Andrews, Nancy, Willis, John, Bronstad, Embrey, Schweinfurth, Geoffrey

Author(s)T. Le1, K. Schaad2, E. Weidman3, N. Andrews4, J.L. Willis5, E. Bronstad6, G.T. Schweinfurth7, D. Fiorino3

Author affiliation(s)1Brown and Caldwell, VA, 2, OH, 3Brown and Caldwell, OH, 4, MN, 5Brown and Caldwell, GA, 6Brown and Caldwell, WA, 7City of Columbus Department of Public Utilities, OH

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159710

Volume / Issue

Content sourceWEFTEC

Word count20

I Spy Fugitive Methane: A Look at 3-years of Leak Detection Surveys

Abstract

Bioenergy programs at municipal water resource recovery facilities (WRRF) are centered around anaerobic digestion, beneficial use of biogas, and opportunities for co-digestion. These programs can help to can provide avenue for climate positive action and cost offsets or revenue generation. Although bioenergy programs provide major benefits, they can also be an unsuspecting major source of greenhouse gas (GHG) emissions. Fugitive methane is the unintended release of methane typically from anaerobic digestion and solids handling systems but can also come from upstream processes as well. Fugitive emissions are often one of the sources of GHG emissions from WRRFs along with energy use and nitrous oxide emissions. Methane is a major contributor to climate change, accounting for 45 percent of current net warming. As a potent GHG, methane is 84 times more effective at trapping heat in the atmosphere compared to carbon dioxide over a 20-year timeframe. WRRFs are estimated to contribute 5-8% of global anthropogenic methane emissions (Ocko, 2021). The significance of methane and its impacts on the climate, coupled with burgeoning interest and attention of WRRFs as a source, creates considerable opportunities within the wastewater sector to address both local and global climate action goals by reducing these emissions. The adoption of leak detection and repair (LDAR) programs can provide a means to substantially reduce emissions while addressing odors, safety, asset renewal, and other drivers. This presentation will provide an overview of LDAR programs and summarize data collected from optical gas imaging (OGI) fugitive methane surveys from 15 WRRFs over the course of two and a half years. To date, most of the fugitive emissions detection and quantification efforts have been focused on the oil and gas (O&G), landfill, and mining sectors. Additionally, only the O&G sector have mandates for LDAR programs. A vast majority of WRRFs do not deploy regular leak detection efforts as part of route maintenance or are reliant on rudimentary leak detection methods. New detection technologies and methods developed in O&G provides the significant opportunities to implement effective LDAR programs. Leak detection methods include audio, visual, and olfactory (AVO) inspections, portable monitoring instruments, or OGI cameras. Many of these methods are established as part of the Environmental Protection Agency (EPA) Reference Method 21 (40 CFR Part 60, Appendix A). The direct appropriation of some of these methods by the wastewater sector may present challenges due to the unique nature of emissions from WRRFs. WRRF emissions have high variability, broad range of quantities, and types of leaks that can deviate from O&G calibration and detection settings. However, OGI technology has translated well to its use at WRRFs where it has been effective at detecting biogas leaks and could potentially be a key component of LDAR programs. OGI relies on thermal imaging spectrometry to isolate gases that are invisible to the human eye by detecting the infrared radiation that passes through the gases. As infrared radiation travels through certain gases, energy is absorbed at specific wavelengths and changes the infrared radiation transmittance. The OGI camera is equipped with a spectral filter that limits the type of infrared radiation that can pass into the detector. This spectral filter is designed to uniquely match the gases' infrared fingerprint. A cryogenically cooled detector then translates the signal into a thermographic image of the gas. Many OGI cameras are also capable of quantification or QOGI which allows the camera to compute mass and volumetric flow rates of gases. A Konica Minolta GMP02 OGI camera was used to identify and record methane emissions at solids and liquid treatment processes. Figure 1 depicts the Konica Minolta GMP02 OGI camera and illustrates the process through which OGI detects gases. The fugitive emissions surveys took place between 2022 and 2024 at 15 WRRFs to capture unintended leaks from equipment, structures, piping, and other assets. The following locations were typical of most surveys: - Headworks, preliminary treatment - Aeration tanks and primary clarifiers - Solids thickening - Biogas/natural piping and appurtenances - Biogas system (boilers, condensate traps, co-generation, gas conditioning/upgrading) - Digesters (walls, covers, appurtenances) - Dewatering equipment, building, and cake storage - Odor control Over two hundred emissions leaks were classified in three broad arbitrary categories of small (1 - 200 g CH4/hr), moderate (201 - 1000 g CH4/hr), and large (>1000 g CH4/hr). Quantifications of methane emissions occurred at most locations, but some emissions were qualitatively classified. Photos and video were documented at all leak locations. Example sources of leaks are shown in the following figures. Additional data summaries will be provided in the presentation and the final proceedings. The outcomes of the survey found that the most common sources of leaks included pressure vacuum release valves (PVRV), floating covers, digester cover safety appurtenances, biogas compressors, biogas condensate and drip traps. One of the more common leak points were from PVRVs which were attributed to lack of maintenance, manufacturing quality control issues, and system operating pressure. PVRV are designed to be leak tight up to 75% of the setpoint and less 1 scfm at 90% of the setpoint. However, many of the PVRV leaks reflected greater than 1 scfm of biogas even when below the setpoint. Several plants had significant leaks due to corrosion and failure of the PVRVs while others were venting per normal operation where system pressures exceeded the set point. During the course of the survey, several leaks were corrected by plant staff and resurveyed to verify mitigation of the leaks. When considering methane emissions, they can be classified as either venting and fugitive methane leaks. Venting is the intentional operational and maintenance actions that leads to emissions of methane typically for system operation, safety, and performance. Fugitive methane is the unintended emissions of methane due to damage, wear, corrosion, and human error. Both fugitive leaks and venting can potentially be addressed with design improvements and innovations. Some elements include redesigning digesters for higher pressures allowing for greater buffer between PVRV setpoint and operating pressure. This study indicated that voluntary LDAR programs may be effective at identifying and reducing fugitive emissions. They also play a vital role in ensuring the safety and health of plant staff and reduction of nuisances to the surrounding communities. LDAR programs can lead to considerable cost savings by preventing the loss of biogas. Additional studies are needed to develop the framework of LDAR program included recommended technologies, frequency of inspections (annual, quarterly, monthly), documentation and workflow, and other key factors.

This paper was presented at the WEF Residuals & Biosolids and Innovations in Treatment Technology Joint Conference, May 6-9, 2025.

SpeakerLe, Trung

Presentation time

16:25:00

16:45:00

Session time

13:30:00

16:45:00

SessionCase Studies for Optimizing THP, Dewatering, and Digestion

Session number7

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicAnaerobic Digestion, Biosolids, Dewatering Optimization, Energy and Carbon Neutrality, fugitive methane emission, Full-scale Optimization, Greenhouse Gases, Mesophilic Anaerobic Digestion, Odor/Air Emissions, Operations And Maintenance, Process modeling, Reliability, Sludge Digestion, THP, THP, CAMBI

Author(s)

Le, Trung, Cavanaugh, Shannon, Nangle, Tom, Fiorino, Dante

Author(s)T. Le1, S. Cavanaugh1, T. Nangle1, D. Fiorino1

Author affiliation(s)Brown and Caldwell, 1

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159811

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count13

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