Amenta, Julianne

Julianne Amenta is a professional engineer licensed in Virginia and received her Bachelors in environmental engineering from Tufts University and her...

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About Amenta, Julianne

Julianne Amenta is a professional engineer licensed in Virginia and received her Bachelors in environmental engineering from Tufts University and her Master of Engineering in environmental engineering from the University of Cincinnati. As a Principal Engineer at Hazen and Sawyer, Julianne has served on several key wastewater projects spanning wastewater integrated planning, design, and construction.

Amenta, Julianne

Titles from this speaker

Biosolids Solutions Tailored to Fit Small Facilities

Abstract

Introduction Rising disposal costs, flexibility in biosolids beneficial reuse end use, the desire to optimize bioenergy use, and the uncertainty around future regulations require utilities to balance proactivity with their inevitably constrained capital budgets. This presentation will review two customized planning solutions developed for smaller utilities (2 million gallons per day (mgd) and 12.6 mgd), helping them prepare for future changes without committing to large-scale capital expenditures prematurely. Case Study 1: Opequon Biosolids and Bioenergy Planning The Opequon Water Reclamation Facility (OWRF), located in Winchester, VA, is permitted to treat 12.6 mgd. The OWRF uses mesophilic anaerobic digestion (MAD) and dewatering to produce Class B cake for beneficial use. The OWRF accepts fats, oils, and grease (FOG) and high strength waste (HSW) from industrial customers for co-digestion. The OWRF generates electricity using digester gas in a combined heat and power (CHP) system. While co-digestion increases digester gas production available for beneficial use, it is believed to also reduce dryness of final cake product, increasing hauling and management costs. A biosolids and bioenergy evaluation was conducted for Frederick-Winchester Service Authority (FWSA), the owner/operator, and included the following considerations: 1.Digester gas production in excess of what can be beneficially used in the current CHP, 2.Existing CHP reaching the end of its expected useful life, 3.Significant increases in biosolids hauling and management costs from the third party contractor, exacerbated by the low percent total solids in the final cake product due to industrial flows 4.Potential for future regulations on emerging constituents of concern in biosolids, including PFAS and microplastics Approach Alternatives Development A world-of-options list of biosolids management and digester gas beneficial use technologies was developed. The list was narrowed down through a multi-criteria, non-cost evaluation that scored the technologies against the OWRF's weighted objectives: market sensitivity, future flexibility, ease of operations and maintenance, environmental impact, and community impacts. A short list of alternatives was identified for evaluation in the next phase, which included development of an energy balance and financial analysis evaluation. The alternatives to be considered were combinations of the following: - Baseline solids management: continue MAD and production of Class B cake - Baseline gas management: replacement in kind of the CHP system - Advanced thermal processing (drying with pyrolysis or gasification) - Supercritical water oxidation - Upsizing the CHP system Vendor outreach was conducted to understand the sizing options commercially available as well as estimated capital and O&M costs and site-specific implementation considerations. Operating, maintenance and plant design data was used to conduct preliminary sizing of potential alternatives and in completing a 20-year net present value lifecycle cost evaluation. Energy Balance and Financial Analysis Using the Power BI-based Energy Balance Analysis Tool (EBAT), a framework was developed to provide a sensitivity analysis of the short-listed alternatives against the input parameters. Mass and energy balances were completed to determine the likely energy use/generation potential. Comprehensive 20-year lifecycle costs of each combination of biosolids and bioenergy alternatives were calculated including O&M costs, financing costs for demolition and construction, biosolids disposal costs, and any bioenergy-recovery benefits, such as energy savings and/or revenues. FWSA benefits from analysis using EBAT because they can adjust inputs and variables to simulate how future conditions may evolve. For example, by reducing the capital costs (anticipated as technology matures) or increasing Class B hauling costs (as regulations evolve), the most cost-effective alternative changes. Results Figure 1 shows part of the EBAT dashboard, illustrating the user functionality and visualizations. The tool makes it very easy to prepare projections and conduct justifiable decision-making for stakeholders. Figure 2 shows the 20-year net present value of each combination of alternatives. Two different sizing options for advanced thermal processing were considered to explore if a piloting approach would make financial sense for the OWRF. Nominal decrease in 20-year net present cost was predicted with a pilot demonstration of an advanced thermal process over a full-scale; this approach could be considered to further explore viability of the technology. The results of the evaluation suggest that at current market and regulatory conditions, the most cost-effective option is to continue digestion and replace the CHP in kind, due to the marginal estimated benefit of upsizing the CHP. The OWRF plans to continue PFAS sampling and monitoring regulations. The development of this dashboard provided a path for FWSA to understand the cost of implementing improvements to reduce hauling costs and justification to continue with the status quo. As conditions evolve, FWSA can continue to use the EBAT to evaluate changing conditions. Case Study 2: Dorsey Run Drying Technology Evaluation The Dorsey Run Advanced Wastewater Treatment Plant (AWWTP), located in Jessup, MD, is permitted to treat 2 mgd. The AWWTP uses lime stabilization and dewatering to produce a Class B biosolids product for land application. Maryland Environmental Service (MES), who owns and operates the AWWTP was interested in conducting an evaluation to explore implementation of thermal drying, to explore the following: 1.Long-term feasibility and cost of implementing a thermal drying system, 2.Consideration for producing a Class A product in lieu of current Class B product to expand options for beneficial use, and 3.Preparation for future implementation of gasification or pyrolysis if required due to possible future PFAS regulations, which requires dried material as the feedstock. Approach Historical data and plant capacity, and operational strategies were used to develop design loads and flows for a thermal drying system. Inquiries were put out to thermal drying manufacturers of three different technologies: belt, screw/paddle, and tray dryers. Manufacturer information from the vendor and from references was used to present advantages, challenges, and site-specific implementation considerations of each to MES. The evaluation suggested that paddle and screw dryers are most feasible for a facility of 2 mgd. A short list of three drying systems was established for further evaluation: Paddle #1, Screw, and Paddle #2. The next phase of evaluation included development of full capital and lifecycle costs. Comprehensive 20-year lifecycle costs for each drying system included: demolition and construction costs and O&M costs; including but not limited to manpower, utilities, and maintenance. Conceptual layouts were developed for each of the three drying systems, and the most conservative (largest) is shown in Figure 3. For all three alternatives the existing lime stabilization system would be demolished and an elevated platform for the drying system installed. Finally, a multi-criteria evaluation was completed using cost and non-cost criteria to determine the most favorable alternative. Results The 20-year lifecycle costs were one factor in the multi-criteria evaluation shown in Figure 4. The criteria and weightings were developed with input from MES to ensure the appropriate priority was given to each consideration. This desktop evaluation allowed MES to prepare for the next level in biosolids processing and understand the current vendor and technology landscape to make an informed decision in design. MES plans to wait to design the drying system due to budgeting constraints. It is anticipated that funding will be secured if and when regulations require it. At that time, they plan to install a thermal drying and PFAS destruction process.

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

SpeakerAmenta, Julianne

Presentation time

09:30:00

10:00:00

Session time

08:30:00

11:15:00

SessionProgram Drivers: Economics, Regulatory, and Market Considerations

Session number24

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicBiogas Utilization, Supercritical water oxidation, Thermal drying

Author(s)

Amenta, Julianne

Author(s)J. Amenta1, M. Blate1,

Author affiliation(s)Hazen and Sawyer 1; Hazen and Sawyer 1;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2024

DOI10.2175/193864718825159436

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count8

Dry Another Day

Abstract

Introduction As markets and regulations change, so must our approach to biosolids resource recovery. Loudoun Water's Broad Run Water Reclamation Facility (BRWRF), located in Ashburn, VA was first constructed in 2008 and has a total current capacity of 11 million gallons per day. Loudoun Water is currently constructing an expansion of the liquids treatment process to a design flow of 16.5 mgd. The BRWRF sets a new world-wide technology standard for environmental protection and water reclamation. Waste activated sludge is centrifuge thickened, combined with primary sludge for stabilization in anaerobic digesters, and centrifuge dewatered prior to land application as a Class B biosolid product. To anticipate future growth, regulatory changes regarding PFAS, and a shift in appetite from Class B to Class A products, the BRWRF has undertaken planning efforts to expand several treatment processes. As part of the evaluation, Loudoun Water determined that a thermal rotary drum drying system will best prepare the BRWRF for flexibility in future expansion and upgrades as well as provide short-term solids treatment capacity. The approach for identifying and evaluating treatment processes and technologies for the BRWRF involved: -Defining the near-term and long-term boundary conditions -Exploring the world of options relevant to biosolids treatment processes -Evaluating integrated technology solutions that can serve Loudoun Water's near- and long-term needs -Converging on a selected path forward As illustrated in Figure 1, the overall approach is analogous to a sieve analysis whereby each step facilitates convergence towards integrated alternatives that are most applicable to the BRWRF. Boundary Conditions Hazen established boundary conditions to ensure project decisions meet the near-term and long-term needs of the BRWRF for the following criteria: -Environmental discharge -Flexibility for future end use -Biosolids -Energy -Reliability -Resource recovery -Treatment capacity Hazen developed the near-term (up to 2040) and long-term (2040 to 2070) boundary conditions with input from Loudoun Water to ensure that decisions align with the BRWRF-specific vision, and position Loudoun Water for a flexible future. Figure 2 is a graphical depiction of the near-term boundary conditions, and Figure 3 is a graphical depiction of the long-term boundary conditions that the BRWRF will maintain flexibility for in the future. Viability Screening Hazen developed a world-of-options of innovative to established biosolids treatment technologies. The list was narrowed down to technologies viable for BRWRF through a multi-criteria evaluation that scored the technologies on six overarching themes. The biosolids treatment overarching themes included: appetite for innovation, product marketability, sidestream impacts, biosolids/energy co-management approach, long term applicability, and reliability/redundancy. Figure 4 and Figure 5 show the results of the multi-criteria evaluation at this screening stage. Applicability Screening Following the viability screening phase, Hazen evaluated the technologies further for applicability to the BRWRF using the criteria shown in Table 1. Among the screened stabilization technologies, thermal hydrolysis (THP) was initially recommended for sludge pretreatment. THP increases the production of digester gas, reduces the final mass of biosolids for disposal, reduce digester volume and footprint, increase the dewaterability of biosolids, produce a Class A biosolids, and will support the long-term vision for resource recovery and movement towards energy neutrality. During piloting, it was found that the biosolids pretreatment process released high concentrations of nitrogen, phosphorus and COD to the return stream in forms that were not bioavailable for removal in the liquid treatment train, increasing final recalcitrant nutrient concentrations in the effluent. At that time, the project team came to the consensus that THP was not a technology to be evaluated further due to the stringent effluent limits imposed on BRWRF. The screened advanced biosolids treatment technologies were evaluated based on anticipated regulatory requirements regarding emerging contaminants and final product management. Loudoun Water required biosolids treatment to produce Class B biosolids at a minimum; however, flexibility for PFAS destruction in the future was an important consideration. As PFAS is a concern that is developing globally, technologies for PFAS destruction are still undergoing research, and Loudoun Water had a preference to implement technologies that are established in the industry. SCWO was eliminated due to the lack of case studies in which the technology has been implemented successfully. Advanced thermal processing has been implemented in several locations for the purpose of reducing biosolids volume; however, the success of each technology in PFAS destruction is still undergoing R&D. Current results show several data points where PFAS is non-detect in the biochar product. Research is on-going to validate destruction of PFAS in the gas emissions following the thermal oxidation of the produced syngas. Nutrient reclamation was a consideration that was driven by end product marketability. Biosolids fertilizer pellets was considered because it is an enhancement to BRWRF efforts in increased resource recovery. Ultimately, this processing approach was eliminated as the end product did not appear to provide significant economic benefits as compared to the cost required to implement the technology. The two technologies that scored the highest the applicability screening phase include conventional mesophilic digestion and thermal drying. As shown in Table 1, conventional mesophilic digestion is a technology with which the staff are familiar with operation and maintenance. It can be used in conjunction with downstream advanced biosolids treatment technologies to produce a higher than Class B quality end product. Thermal drying was determined to be the most reliable technology that exceeds the near-term minimum boundary condition (production of Class B biosolids) and has potential for expanded beneficial reuse alternatives. Thermal drying can also serve as a prerequisite step to advanced thermal processing. Advanced thermal processing is an enhancement that was determined to be non-critical for implementation as part of the near-term planning. However, it may be considered in the future as a viable long-term technology. Benefit to Cost Ratio Evaluation Hazen performed a benefit-to-cost ratio evaluation on the final two alternatives that were being considered for implementation. The first alternative, in which the entire solids load is digested, is described schematically in Figure 6. The second alternative, including thermal drying, is described schematically in Figure 7. Loudoun Water assigned a level of importance to each criterion shown in Table 2. The most important criteria were ease of operations and maintenance, future flexibility, and regulatory compliance. Figure 8 shows the weighted scoring for the two alternatives evaluated. Although the baseline alternative scores highest in ease of operations and maintenance, the PS only digestion + thermal drying alternative offers greater regulatory compliance and future flexibility than the baseline alternative, which ultimately gives the PS only digestion + thermal drying alternative the highest weighted MCE score. After determining the weighted scores, Hazen calculated the benefit-to-cost ratio for the two alternatives. The benefit-to-cost ratio is the total weighted MCE score (shown in Figure 8) divided by the 20-year net present value. A higher benefit-to-cost ratio reflects a better alternative because more value will be provided for a lower cost. The PS only digestion + thermal drying option was found to have a higher benefit-to-cost ratio compared to the baseline option. Converge The evaluation of technologies converged on a near-term solution that addresses the issue of insufficient capacity, satisfies the near-term (and many of the long term) boundary conditions for BRWRF, and allows for future implementation of long-term solutions. Detailed design will proceed with the near-term solution of digesting only primary solids at a 12-day SRT (minimum), including an excess primary solids bypass only to be used under peak conditions, and constructing a thermal drying system. Because Class A biosolids are achieved in the proposed design, Loudoun Water can defer the decision of how to manage primary sludge digestion beyond the capacity of the existing digesters to a future stage of improvements. Consideration of long-term solutions will advance when regulations and R&D for emerging contaminants develop further.

This paper was presented at the WEF/IWA Residuals and Biosolids Conference, May 16-19, 2023.

SpeakerAmenta, Julianne

Presentation time

10:45:00

11:15:00

Session time

8:30:00

11:15:00

SessionSession 21: Advances and Innovations in Thermal Processes II

Session number21

Session locationCharlotte Convention Center, Charlotte, North Carolina, USA

TopicThermal Processes and Biochar

Author(s)

J. Amenta

Author(s)J. Amenta1, K. Sveum2, M. Vanhorne3, 4,

Author affiliation(s)Hazen and Sawyer1; Loudoun Water2

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2023

DOI10.2175/193864718825158811

Volume / Issue

Content sourceResiduals and Biosolids

Word count4

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Amenta, Julianne

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