Guo, Peibo

Naomi obtained her bachelors in Biochemistry at UCLA before pivoting to Environmental Engineering at Cornell University and DC Water. She now work...

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About Guo, Peibo

Naomi obtained her bachelors in Biochemistry at UCLA before pivoting to Environmental Engineering at Cornell University and DC Water. She now work with Brown and Caldwell as a solids and energy process engineer. She has a strong passion for sustainability and wildlife, which was especially influenced by her upbringing in rural suburban Pennslyvania. In her free time Naomi likes to go hiking, shopping, and most of all - trying out new food places!

Guo, Peibo

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

Evaluating the Potential of Recovering Vivianite for Phosphorus Removal and Improving Class A Biosolids Applications

Abstract

INTENDED OBJECTIVE: Biosolids from water resource recovery facilities (WRRFs ) are increasingly used for agricultural and recreational land purposes due to their sustainable means to replenish macronutrients. However, the relatively high phosphorous content of biosolids limits certain applications. This study aims to identify optimal locations for recovering vivianite and subsequently phosphorus, to allow class A biosolids reach ideal phosphorus levels. INTRODUCTION: Global consumption rates of synthetic fertilizers per unit of cropland have increased 3 to 8 times over the past half century (Lu et al. 2017). Class A biosolids are increasingly explored as an alternative to commercial fertilizers due to their effective means to replenish carbon and macronutrients (Gilmour et al. 2013). However, the N:P ratio of biosolids is typically lower than commercial fertilizers which can cause an accumulation of phosphorus when applied to soil, increasing risk for eutrophication (Penn et al. 2002). Therefore, it is critical to implement efficient phosphorus-removal technologies/techniques within the biosolids treatment train to improve the N:P ratio and limit the amount of phosphorus that result in the cake. Therefore, this study aims to analyze the P mass balance of the Blue Plains advanced wastewater treatment plant in Washington, DC as well as its vivianite characterization in full-scale. The process sampling, modelling and analysis led to identification of potential locations for vivianite recovery, and initial estimations on how much the P content in our class A biosolids might be reduced by recovering vivianite upfront. MATERIALS AND METHODS: Sampling campaign: Samples were collected in DC Water Blue Plains over a 3-month period (Mid-February to Mid-May 2022). Quantitative analysis: Phosphorus is measured by the EPA 365.1 method. Scanning Electron Microscopy with Energy Dispersive and Mossbauer Spectroscopy: Prepared by method in Prot et al. 2021. Modelling method: Visual Minteq version 3.3 with DOC SHM model RESULTS & DISCUSSION P mass balance at Blue Plains and P content in biosolids product Blue Plains advanced WWRF achieved a 98% incoming TP removal over its primary (enhanced-chemical phosphorus removal) and secondary systems through iron dosing. The removed P is diverted to the solids fraction and results in a Class A biosolids product (BLOOM) with 2.88% P (dry weight basis) and 28-32%TS (Fig.1A). The P:N ratio of our product is 1:1 and thus higher in P content than the target of 1:2 P:N for typical fertilizers. Decreasing P content in BLOOM by 50% or thus recovery 60% of vivianite would increase the value and applicability of BLOOM. Vivianite formation and formation potential along the Solids Treatment Train A total Fe/P molar ratio of 1.5 or greater allows for optimal vivianite precipitation (Cong et al. 2017) which is reflected in DC Water treatment flow diagram (Figu 1). Vivianite was detected in primary thickened sludge, blend of thickened primary (PS) and waste activated sludge (WAS), and digested sludge b ased on sequential extraction method in Wang et al. 2021. This was also further supported by the clear co-location of Fe and P in SEM images (Figure 2A and 2B). These locations are consistent with the vivianite scaling seen in primary sludge gravity thickening lines and centrifuge lines in the facility. Through quantitative analysis, the vivianite mass flow in thickened primary sludge, blended PS/WAS and digested solids accounted for 8%, 52%, and 49% of the incoming P to the plant (Fig. 1). These vivianite ranges are like those reported by iron-dosing plants in Prot et al. 2021 and Wilfert et al. 2016. Estimation of P recovery potential needed to impact Class A biosolids P content Based on the current vivianite-P levels in the three identified locations (Fig. 1), sludge after anaerobic digestion contained the highest level of vivianite-P. This is likely due to higher orthophosphorus levels after thermal hydrolysis treatment which allows for additional vivianite formation with Fe(II). This notion is supported by the low levels of Fe(II) concentrations after anaerobic digestion indicating that most of it is bound (Fig. 1). We estimated how much vivianite recovery efficiency we might need to decrease the P content in the BLOOM with an ideal target of ~0.014 kg P/kg TS and acceptable target of 0.022 kg P/kg TS. Given the highest vivianite levels in digested sludge, a recovery efficiency of at least 40% with ideally 70% is sufficient to meet our targets (Fig. 3). Utilizing vivianite recovery technologies such as magnetic separation (80% of vivianite recovery in digestates according to Wijdeveld et al. 2022), and other alternative options could provide the potential recovery target needed to improve BLOOM. CONCLUSIONS Based on current vivianite-removal technology efficiencies, removing vivianite will significantly impact the phosphorus levels in BLOOM. Results suggest that after anaerobic digestion is a preferred and feasible option to implement recovery technology due to its high vivianite content as well as the opportunity to recover vivianite in a fraction of the digestate to produce low P BLOOM rather than the whole biosolids treatment train. Future testing will explore recovery efficiencies of P and vivianite to confirm feasibility and setup a path towards pilot testing approaches.

Biosolids from water resource recovery facilities (WRRFs) are increasingly used for agricultural and recreational land purposes due to their sustainable means to replenish macronutrients. However, the relatively high phosphorous content of biosolids limits certain applications. This study aims to identify optimal locations for recovering vivianite to manage phosphorous levels in class A biosolids.

SpeakerGuo, Peibo

Presentation time

08:30:00

08:50:00

Session time

08:30:00

10:00:00

SessionEnhancing Digestion to Improve Operations and Resource Recovery: Capture of Control

Session number501

Session locationRoom 256

TopicBiosolids and Residuals, Energy Production, Conservation, and Management, Facility Operations and Maintenance, Intermediate Level

Author(s)

Guo, Peibo, Yan, Yuan, Ngo, Nam, Peot, Chris, Gu, April, Reid, Matthew, Bollmeyer, Melissa, De Clippeleir, Haydee

Author(s)P. Guo1, Y. Yan2, N.H. Ngo3, C.J. Peot4, A.A. Gu5, M. Reid2, M. Bollmeyer2, H. De Clippeleir6

Author affiliation(s)1Brown and Caldwell, VA, 2Cornell University, NY, 3, CA, 4DC Water & Sewer Authority, DC, 5, NY, 6DC Water & Sewer Authority, VA

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Oct 2024

DOI10.2175/193864718825159698

Volume / Issue

Content sourceWEFTEC

Word count16

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