Ma, Persephone

Persephone Ma is a soil scientist and environmental engineer for Brown and Caldwell, doing wastewater treatment facility planning and design. Her PhD work included the study of sewage sludge incinerator ash, biosolids, and struvite as phosphorus fertilizers for corn and soybean in a three-year field study. She integrates that background into her current work in biosolids master planning, in which a comprehensive and broad perspective is applied to long-term capital planning for the solids handling process.

Titles from this speaker

Description: Developing a Regional Biosolids Master Plan for the North Shore Water Reclamation...

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. A process flow diagram of the preferred alternative is shown in Figure 7. The preferred alternative maximizes operational resiliency and resource recovery while reducing costs through consolidating solids processing and utilizing existing assets. After the selection of the preferred alternative, an implementation plan was developed for the biosolids program by dividing the BMP into sub-projects to distribute construction costs across the twenty-year planning time frame. During the BMP process, the NSWRD staff identified several concerns that could arise from regulatory changes, community impacts, and market conditions. The team prepared conditional projects in response to those concerns. They are not part of the core BMP, but were identified, discussed, modeled, and cost estimates were prepared. The intent was to give NSWRD some insight into what changes may need to occur to mitigate the risks of those future challenges. The preferred alternative and conditional projects for the BMP are summarized in Table 1. The NSWRD selected a new biosolids management program that addresses the drivers and issues as well as meets the stated goals by reducing solids, providing resiliency, adding redundancy, and creating renewable energy. Results and takeaways from throughout the planning process will be presented.

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

SpeakerMarino, Joe

Presentation time

09:00:00

09:30:00

Session time

08:30:00

11:15:00

SessionCase Studies & Lessons Learned

Session number27

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicAnaerobic Digestion, Biosolids Management Planning, Thermal Processes

Author(s)

Marino, Joe

Author(s)J. Marino1, P. Ma1, S. Waters2, N. Sierra1, T. Vodnik2, E. Silver2

Author affiliation(s)Brown and Caldwell 1; Brown and Caldwell 1; North Shore Water Reclamation District 2; Brown and Caldwell 1; North Shore Water Reclamation District 2; North Shore Water Reclamation District 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2024

DOI10.2175/193864718825159433

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count14

Sewage Sludge Incinerator Ash as a Phosphorus Fertilizer for Corn and Soybean

Abstract

The Metropolitan Council Environmental Services (MCES) operates the Metropolitan Wastewater Treatment Plant in downtown St. Paul, Minnesota, which treats an average of 172 million gallons of wastewater a day. Solids from this plant are incinerated to reduce sludge volume and produce energy, which offset energy needs within the plant. This process produces around 38 tons of sewage sludge incinerator ash (SSA) a day, which is currently landfilled. However, this ash contains significant amounts of phosphorus (P), an essential nutrient for healthy plant and animal development that is currently mined for in the US, China, and Sub-Saharan Africa. In this project, SSA from the Metro plant was applied to corn and soybean fields as a phosphorus source to assess its overall fertilizer viability and effects on agronomic response and soil chemical conditions. This research project is complete, and the findings could apply to any utility that incinerates their solids. Phosphorus is an integral part of every living thing, forming nucleic acids, metabolic energy transfer units (ATP/ADP), and cell membranes. In plants, P is responsible for healthy root growth and fruit development and is regularly applied as an annual fertilizer in agricultural systems. P-deficient soils can lead to 15% biomass losses in crop biomass and a 40% decrease in carbohydrate development in grain. The SSA produced in the Twin Cities is 11% total P (25.3% P2O5) and has been shown to be a viable source of P in past incubation and greenhouse studies. However, there are still several remaining questions regarding SSA applied as a P source in realistic conditions and its impacts on crops and the soil environment. We conducted a three-year corn and soybean field study at the University of Minnesota's Rosemount Research and Outreach Center. Our approach was threefold; We wanted to understand 1) whether SSA could be a source of P for agricultural crops, 2) how SSA compared to other P sources, including commercially-available residual products, and 3) the effect on metals concentrations and microbial communities in the SSA-amended soil and crops. While SSA is not a biosolid, the metals outlined in the 40 CFR Part 503 Biosolids Rule that regulates biosolids management in the US were used for comparison. The experiment was conducted on 1.4 hectares (3.5 acres) of Waukegan silt loam soil in Rosemount, Minnesota. Treatments were SSA, conventional P fertilizer (triple superphosphate), dried and pelletized biosolids from MCES' Blue Lake Wastewater Treatment Plant in Shakopee, MN, and commercial struvite. Each P source was applied and incorporated in the spring before planting corn at 20, 40, 60, and 80 kg P ha-1, with a zero-P control included for each P-source. Soil samples were taken throughout the season and were analyzed for available plant nutrients, pH, and total EPA 503 metal concentrations. Biomass samples (grain, when available, and stover) were also taken throughout the season, and analyzed for total P and 503 EPA metals. Corn yields in 2017 and 2018 were high for all treatments overall and only responded specifically to TSP amendment in 2017. In 2019, however, corn yields increased with increasing applications of all P sources, eventually plateauing at the highest rates of P application. These results indicate that in 2019, SSA performed similarly to the other P sources applied in the experiment. Though corn yield results were inconsistent in the first few years, many other measures of P uptake, including 2018 and 2019 soybean yields, P concentration and P uptake in corn grain and soybean among others, did show significant increases with increasing rates of SSA applied. At every sampling point following the initial pre-season sampling date, chemical analyses of the top 15 cm of soil demonstrated an increase in available P with increasing rates of any P source. Soil available zinc and copper increased with increasing applications of SSA and biosolids but not with the application of other P sources. Concentrations of copper in plant biomass did not respond to the application of any P source, whereas concentrations of zinc were higher in plants grown with SSA and biosolids. Total concentrations of soil mercury did statistically increase with SSA application, though the overall increase was low and was not reflected in the plant biomass concentrations. Otherwise, there were no detectable increases in soil or plant material of any metals of concern monitored by EPA 503 regulations. Results from this study indicate that SSA can be a viable source of P in an agricultural system with minimal short-term negative effects on soil or plant metal concentrations. Further investigation should include field studies with differing soil types, crops, and climates as well as a long-term study to monitor metal loading and slow-release P behavior. Available data from all three years (2017-2019) will be presented at the conference. If SSA is found to be an effective P fertilizer with minimal environmental impacts, MCES will have found an opportunity to beneficially reuse another wastewater residual product and recycle an invaluable natural resource.

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

SpeakerMa, Persephone

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionLand Application

Session number17

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicBiosolids, Circular Economy, incineration