Hanna, Amy

Amy is a Senior Associate in Hazens Raleigh, NC office. She specializes in biosolids, from planning and design through construction and commissioning. Amy serves as Hazens Mid-Atlantic Region Biosolids Lead. She graduated from Case Western Reserve University with Bachelors and Masters in Civil Engineering.

Titles from this speaker

Alternate: Getting it Started with Alternative Delivery Approaches to THP

Abstract

SUMMARY The cost and complexity of projects implementing thermal hydrolysis pretreatment (THP) at municipal water resource recovery facilities (WRRFs) has led many utilities to utilize alternative delivery approaches. Raleigh Water selected Construction Manager At Risk (CMAR) to deliver its Bioenergy Recovery Project at the Neuse River Resource Recover Facility (NRRRF). WSSC Water utilized Progressive Design Build (PDB) to deliver the Bio-Energy Project at the Piscataway WRRF. The benefits of THP-enhanced digestion are many, from increased volatile solids reduction and biogas production to higher digester loading and therefore less required digestion volume. Some of the considerations involved with implementing THP include sludge preconditioning and treatment of high-strength post-digestion recycle streams. The cost and constructability feedback made possible with alternative delivery helped the design teams for the Raleigh Water and WSSC Water projects identify the optimal solution for each project, with a collaborative approach to the site-specific benefits and challenges associated with THP implementation. This 'case study' provides a summary of these two projects from design, through construction, and commissioning. It will focus on the unique aspects of each project, highlighting the role that alternative delivery played in influencing the design and start-up of these projects. BACKGROUND & Raleigh Water's Bioenergy Recovery Project Raleigh Water is implementing a Bioenergy Recovery Project to produce green energy and a Class A biosolids product, demonstrating the City of Raleigh's commitment to sustainable local government operations. By transitioning to THP and anaerobic digestion, Raleigh Water can convert the methane generated in the process to renewable natural gas (RNG) to fuel the City's bus fleet. Using RNG for vehicle fuel will offset greenhouse gas (GHG) emissions, supporting the City's aggressive community-wide goal of an 80-percent reduction in GHG emissions by 2050. The Bioenergy Recovery Project will be net energy producing, qualifying Raleigh Water for a $50M zero percent interest loan under the Clean Water State Revolving Fund (CWSRF) Green Project Reserve. The project was recognized nationally as Exceptional under CWSRF's Performance and Innovation in the SRF Creating Environmental Success (PISCES) program. Raleigh Water manages residuals from all three of its wastewater treatment plants at the Neuse River Resource Recovery Facility (NRRRF), the largest permitted treatment works in North Carolina with a rated capacity of 75 mgd. Current biosolids management includes lime stabilization, aerobic digestion, and off-site composting. As the existing solids handling equipment neared the end of its useful life, the utility was motivated to explore alternative biosolids management strategies, specifically those that maximize the potential for resource recovery and minimize GHG production. The Bioenergy Recovery Project will use THP to maximize the efficiency of new anaerobic digesters, achieving a nearly 50-percent reduction in mass and generating enough RNG to fuel 50 City buses. €ƒ BACKGROUND & WSSC Water's Bio-Energy Project The WSSC Bio-Energy project centralizes biosolids processing from WSSC Water's five WRRFs at the 30 mgd Piscataway WRRF to produce a Class A biosolids product. In addition to the THP and anaerobic digestion processes, the overall project also includes cake receiving, solids screening, pre-dewatering, cake pumping, pre-THP cake storage, post-dewatering, cake conveyance, Class A cake storage, sidestream nitrogen removal, odor control, renewable natural gas production, gas storage, combined heat and power generation and steam boilers. The Bio-Energy project will fundamentally change how WSSC produces biosolids, allowing a focus on long-term sustainable end products with a Class A dewatered cake biosolids and renewable natural gas suitable for pipeline injection and vehicle fuel. The project will overall reduce the greenhouse gas emissions from WSSC by 15% and result in nearly $3 million per year in operation cost savings. COLLABORATIVE DELIVERY DURING DESIGN Some of the biggest benefits of alternative delivery include quick cost and constructability feedback during design. After the CMAR came onboard the Raleigh Water Bioenergy Recovery Project, cost estimates were provided at the 60-percent design level to inform value engineering for the project. Cost feedback continued throughout design, which progressed to 100-percent completion level for Guaranteed Maximum Price (GMP) development. At the beginning of the detailed design process of WSSC Water Bio-Energy Project, the PDB team considered how best to approach a series of critical decisions related to the digestion process to provide the best long-term solution for process performance, energy efficiency, and accommodation of potentially high volume expansion considerations while balancing capital costs. The critical decision areas that needed review and discussion included: digester construction method; digester mixing approach; digester volume/dimensions; rapid volume expansion containment approach; and digested sludge storage approach. These five decision areas were considered individually and collectively to understand the range of advantages and disadvantages that each would have on the overall project. SUCCESSFUL COMMISIONING Commissioning new equipment and processes can be challenging, especially when facilities must maintain operations and compliance with treatment standards. Discussions began during design to identify the optimal start-up and commissioning approach for each project. The different alternative delivery methods employed led to different roles, responsibilities, and contractual requirements for each project. This paper will review the start-up and commissioning plan for both projects.

This paper was presented at the WEF Residuals and Biosolids Conference in Columbus, Ohio, May 24-27, 2022.

SpeakerHanna, Amy

Presentation time

13:30:00

16:45:00

Session time

13:30:00

16:45:00

Session number12

Session locationGreater Columbus Convention Center, Columbus, Ohio

TopicAlternative Delivery, Startup and Commissioning, THP

Author(s)

A. Hanna

Author(s)A. Hanna1; E. Stempien2; C. Bullard3; R. Wierzbicki4; J. Uglevich5

Author affiliation(s)Hazen; 1City of Raleigh; 2Hazen and Sawyer; 3PC Construction; 4Residuals and Biosolids Speaker; 5

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2022

DOI10.2175/193864718825158421

Volume / Issue

Content sourceResiduals and Biosolids

Word count11

Alternate: Thinking 'Outside the Box' to Implement Advanced Biosolids Technologies

Abstract

Solids handling has become an increasingly important aspect of the wastewater recovery industry as we deal with new pressures on hauling costs, limitations on historical outlets, drivers for improved energy recovery, and emerging regulatory pressures. The industry is being asked to reduce the total mass of biosolids products while also considering implementation of high temperature and/or pressure processes to comply with potential regulations of emerging contaminants. These new processes require additional handling within the facility. This presentation will focus on the elements of solids handling 'outside the box' to incorporate a wide range of advanced solids technologies including thermal hydrolysis, thermal drying, pyrolysis, gasification and supercritical water oxidation. The conversation around each element will include how it relates to upstream and downstream processes, the impact on O&M efforts and some practical implementation considerations for each. Elements that will be discussed include solids screens, low pressure cake conveyance, high(er) pressure cake pumping, high temperature elements, and final product management. A primary challenge facing WRRFs in the implementation of advanced solids treatment is how to best incorporate these processes into their existing plant and also ensure that the solids feed to these processes meet the often-specific requirements of these treatment approaches. The primary elements and impacts that will be discussed are: 1. Solids Screens -- how does the removal of stringy or fibrous materials either benefit or negatively impact dewatering, drying or processes with reduced flow path areas. 2. Low Pressure Cake Conveyance -- how can WRRFs best balance containment, agitation, energy consumption, cake consistency and downstream process integration while ensuring a consistent and reliable solids feed to advanced solids treatment processes. 3. High(er) Pressure Cake Pumping -- how can higher pressure feed requirements be safely and reliably implemented through intentional design incorporating online monitoring and passive safety features, operational controls, and standard operating procedures that ensure long term performance. 4. High Temperature Elements -- how can WRRFs maintain safe and reliable operation with systems that require skills sets that are vastly different than those traditionally required in the wastewater industry while achieving energy efficiency and operational high performance. 5. Final Product Management -- how can realistic reliability be achieved while transporting and handling solids with increasingly abrasive properties while also ensuring safe atmospheres, high levels of pipe integrity and consistency in transport to final beneficial use destinations. As the wastewater recovery industry moves into the future, a detailed understanding of how to integrate these elements into the existing treatment process is critical to long-term success. At the heart of the discussion is how to best 'manage the interfaces' to bring the whole facility together. This requires careful consideration during the design phase as well as careful thinking during implementation to ensure that operations and maintenance staff are educated on these new elements and are equipped with the tools needed to effectively use these new facilities to achieve new goals.

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

SpeakerHanna, Amy

Presentation time

10:15:00

11:45:00

Session time

10:15:00

11:45:00

SessionAdvanced Thermal Processes for Sustainable Biosolids Management: Case Studies and Innovations

Session number25

Session locationBaltimore Convention Center, Baltimore, Maryland, USA

TopicBiosolids treatment, business case evaluation, Hydrothermal Liquefaction, Innovative Technology, PFAS/Emerging Contaminants, Sludge treatment

Author(s)

Hanna, Amy, Van Horne, Matt, Van Horne, Matt

Author(s)A. Hanna1, M. Van Horne1, M. Van Horne1

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

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2025

DOI10.2175/193864718825159808

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count11

Description: Growing Up Together Lessons Learned During Startup: Commissioning Sidestream...

Growing Up Together Lessons Learned During Startup: Commissioning Sidestream Deammonification Concurrent with THP Digestion to Meet Strict Recycle Limits

Abstract

WSSC WATER will commission the Bio-Energy project in Q1 2024. The Bio-Energy project will centralize WSSC Water's biosolids processing at the Piscataway WRRF, including thermal hydrolysis pretreatment (THP) and mesophilic anaerobic digestion to provide the necessary stabilization to meet regulatory requirements for a Class A biosolids product as well as produce valuable digester gas, which is converted to renewable natural gas (RNG) suitable for pipeline injection. See Figure 1 for an overall process schematic. The Bio-Energy project has fundamentally changed how WSSC WATER manages biosolids, allowing a focus on long-term sustainable end products with a Class A dewatered cake biosolids, and RNG suitable for pipeline injection and use as vehicle fuel. The project will reduce greenhouse gas emissions and result in significant operational cost savings. But with these benefits comes one of the biggest challenges of the Bio-Energy Project - to treat the additional nutrient recycle loads that will be generated from sludge imported from the other WRFs and increased even more by THP and anaerobic digestion. Total nitrogen recycle loads from the Bio-Energy Project must be limited to ensure the Piscataway WRRF can maintain compliance with effluent discharge limits. Two ANITA Mox (TM) sidestream treatment reactors are undergoing startup concurrent with the digestion process to treat high ammonia filtrate from the Bio-Energy dewatering process. Managing nutrient recycle from filtrate generation in coordination with startup of both the Digester and Sidestream processes is essential to maintaining permit compliance at the Piscataway WRRF. Figures 2 and 3 present digester and sidestream treatment startup graphs. This presentation discusses the early challenges, successes, and lessons learned during concurrent biological startups of the anaerobic digestion and sidestream deammonification processes, as well as a reflective assessment of integrated startup plan assumptions and approaches presented during the 2023 WEF RBC. Phase 1 -Preparation and Seeding Commissioning begins with preparation and biological seeding of one digester and one sidestream reactor. Preparation of Digester 1 for liquid seed sludge import from the DC Water Blue Plains Advanced Wastewater Treatment Plant (AWWTP)(thermally hydrolyzed Class A). Lessons learned include: o Planning for and executing successful delivery of seed sludge during winter conditions. o Pre-heating digester to mesophilic temperature range. o Maintaining a Class A digester in preparation for seed sludge. Preparation of Sidestream Reactor 1 for seeded media from an operating ANITATM Mox process. Lessons learned include: o Delivery of annamox seeded media sludge during winter conditions o Conditioning of virgin media o Pre-heating reactor to annamox temperature range Phase 2 - Digester Ramp Up to Piscataway Load During initial digester ramp up, only Piscataway sludge is processed through the Bio-Energy process. Indigenous sludge from the Piscataway WRRF is thickened, screened and dewatered prior to THP. THP throughput is increased from 4 dry tons/day (dtpd) up to the full Piscataway load, approximately 16 dtpd, over 30 days. Lessons learned include: - Managing indigenous sludge management between THP and current pathway, while limiting increase in feed and overall organic loading. - Building volume in Digester 1 while maintaining conditions conducive to THP mesophilic community. Phase 3 - Sidestream Reactor 1 Startup and Initial Acclimation During Phase 3, THP throughput and digester feed is constant at the Piscataway WRRF load (16 dtpd). This period is used to build the volume under digestion, establish robust microbial communities in both digesters, and fine-tune operations prior to introduction of imported sludges. Digester withdrawal also begins during Phase 3 to generate filtrate to be used in the sidestream deammonification reactors biological startup. Lessons learned include: - Splitting contents between Digester 1 and Digester 2. -Dewatering optimization for thermally hydrolyzed digestate - Balancing digester filtrate generation with sidestream reactor capacity - Sidestream acclimation of annamox community in moving bed biofilm reactor (MBBR) mode Phase 4 - Sidestream Reactor 1 Acclimation and Reactor 2 Preparation Digester 1 and 2 continue building the volume under digestion, digester microbial communities, and fine-tuning operations during the 16 dtpd hold period. Sidestream reactor 1 influent ammonia concentration and load gradually increased, RAS recycle is initiated, and process is converted from MBBR to integrated fixed-film activated sludge (IFAS) mode. Sidestream Reactor 2 prepared for startup. Lessons learned include: - Managing Filtrate EQ Basin for nutrient load equalization and solids capture prior to introduction to sidestream reactors. - Sampling campaign to target biological startup concentrations and mass loading conditions. - Dilution water adjustments to meet competing biological needs. - Maintaining bypass flexibility and nitrogen recycle limitations to plant headworks. Phase 5 - Increased Digester Loadings, Sidestream Reactor 1 Fast Acclimation and Reactor 2 Initial Acclimation After the digester 16 dtpd hold period, sludge import from the four remote WSSC Water WRRFs was initiated to increase sludge to the Bio-Energy process. Both digesters reach normal operating level, and digester withdrawal is carefully managed to ensure filtrate does not overwhelm the sidestream reactor treatment capacity or exceed total allowable Bio-Energy recycle limits. Lessons learned include: - Growing sidestream treatment capacity to meet full load from digesters. - Impacts to filtrate quality and sidestream treatment during digester upsets or dewatering issues. Phase 6 Steady State Digestion and Sidestream Deammonification Phase 6 begins as the Bio-Energy process reaches full loading, with all indigenous and remote sludge being treated through THP and digestion. Both digesters will be in steady state operation. As Sidestream Reactors 1 and 2 complete ramp up to full treatment capacity; startup will be complete, sidestream will be in steady state, and final operation and performance testing will commence. Lessons learned and a high level assessment of integrated startup plan assumptions and approaches presented during the 2023 WEF RBC include: o Digester in-tank characteristics o Volatile Solids Loading Rate vs. Hydraulic Loading Rate for feed control o Volatile Solids Reduction o Nitrogen recycle o Biogas production o Sidestream removal efficiency o What went right and what would we do differently next time? o Recommendations moving forward. Conclusion Sidestream deammonification is critical to the successful implementation of WSSC Water's Bio-Energy Project, mitigating the impacts of increased nutrient recycle from THP and digestion and imported sludge from WSSC Water's remote WRRFs. The stability of the concurrent biological startups of sidestream treatment and digestion are critical to meeting nutrient recycle targets and ultimately effluent discharge limits, all while maintaining an advantageous startup and commissioning schedule. This presentation will share practical 'how to' lessons learned from the startup as well as a review of theoretical assumptions made during the planning phase vs. observed results to help inform future work.

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

SpeakerLe Bel, Paul

Presentation time

09:30:00

10:00:00

Session time

08:30:00

10:00:00

SessionThermal Hydrolysis Process

Session number13

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicAerobic Digestion, Sidestream Treatment, Thermal Hydrolysis