Brower, William

Bill Brower, a licensed Professional Engineer and wastewater operator, specializes in the management and treatment of biosolids. He is a Senior Biosolids Engineer at Brown and Caldwell, focusing on biosolids master planning and design. Previously, he managed DC Water's Bloom biosolids program. He is the inaugural chair of the North East Biosolids and Residuals committee on carbon trading.

Titles from this speaker

Managing Biosolids in Maine: Challenges and Potential Solutions

Abstract

Background Portland Water District (PWD) has four wastewater treatment facilities (WWTFs) with a capacity of more than 25 million gallons per day. Two of the four facilities - East End and Westbrook - process most of the solids in the system and were the focus of PWD's comprehensive approach to assess the current solids system and develop a strategic plan that outlines the necessary upgrades, process modifications, and state-of-good-repair projects that PWD should undertake during the next 20-year planning period. PWD began contemplating this planning effort not only due to aging infrastructure, but rather due to increasing concern over lack of biosolids management options and rising public concern around per- and polyfluoroalkyl substances (PFAS) in biosolids. Throughout New England, decreased biosolids management capacity has been a rising concern. Much of the region relies upon landfills and regional incinerators, but beneficial use (land application) has served as a reliable, sustainable option for a number of utilities. In Maine, land application had been an accepted practice, with good market understanding of the benefits of biosolids, including biosolids based compost and thermally dried products. Concerns over PFAS in wastewater residuals, or solids, prompted legislative action to prohibit land application of treated wastewater solids (biosolids) and products containing biosolids in Maine (LD 1911 [An Act to Prohibit the Contamination of Clean Soils with So-Called Forever Chemicals]). The Governor signed this bill in April 2022, and it is currently in effect as Public Law 2021 Chapter 641. This law leaves Maine wastewater utilities with landfill as the only option for solids management within the state-and few, costly options outside the state. Instate wastewater solids landfilling became more challenging with the passing of solid waste bill, LD 1639 (An Act To Protect the Health and Welfare of Maine Communities and Reduce Harmful Solid Waste) in April 2022, and enacted February 1, 2023. This bill restricts the importation of out-of-state solid waste for processing in the state of Maine. Dewatered wastewater solids cake is considered a 'wet waste' by landfill operators and is typically mixed with bulking agents at landfills to avoid stability issues. Out-of-state solid waste (e.g., oversized bulky waste and construction and demolition debris) was one of the main sources of bulking agents for stabilizing wastewater solids. When the availability of these bulking agents decreased, the landfill operators handling most of the biosolids disposal in the state reported they needed to consequently reduce the amount of wastewater solids they accept. This left many utilities scrambling for alternatives, including costly long-distance hauling to Canada. Despite a two-year reprieve to LD 1639 (via LD 718, An Act to Facilitate the Management of Wastewater Treatment Plant Sludge at the State-owned Juniper Ridge Landfill), wastewater utilities in Maine, including Portland Water District (PWD), are still restricted to landfilling instate in the short-term, and following the two-year reprieve will face severe challenges in the long-term. Methodology This project was completed to define the technical, economic, and programmatic considerations for implementing a regional anaerobic digestion, drying, and thermal treatment biosolids processing facility. These technologies were selected for consideration for their following attributes: - Anaerobic Digestion. Anaerobic digestion biologically degrades solids, reducing their mass by 40-50 percent and generating energy-rich biogas. Anaerobic digestion can process a wide variety of liquid organic wastes, including food and beverage processing wastes and fats, oils, and grease waste. Anaerobic digestion and biogas utilization offer substantial opportunities for greenhouse gas reduction at a WWTF and for the region when processing imported organic waste. Anaerobic digestion can also treat solids to United States Environmental Protection Agency (USEPA) requirements for Class B or A stabilization and improves downstream processing by improving and homogenizing solids quantities and quality. - Thermal Drying. Thermal drying removes nearly all the entrained water in dewatered solids, reducing solids mass by 4 to 5 times. This reduces the amount of solids needing to be hauled and can remedy capacity and structural limitations associated with landfilling of dewatered solids. Thermal drying can also meet USEPA Class A stabilization requirements, which provides nearly unrestricted beneficial reuse opportunities in other states. - High Temperature Thermal Processing. Thermal processing submits solids to high temperatures for further mass reduction and treatment of emerging contaminants such as PFAS. This has traditionally been performed by sewage sludge incineration (SSI), which oxidizes all solids to an ash. However, SSI air permitting regulations have become especially onerous and make SSI adoption in New England unlikely today. Pyrolysis and gasification are emerging, non-incineration thermal processes that employ high temperatures at oxygen free or starved conditions to generate a carbon-dense beneficial reuse product called biochar and a gas stream with an appreciable energy value. The technology is still in a developmental stage with one commercial biosolids pyrolysis facility in operation in the US at Silicon Valley, CA. In 2020, the USEPA found the Silicon Valley pyrolysis system removed PFAS from biochar to below reportable levels (Thoma et al., 2021). BC, with Silicon Valley Clean Water and the Water Environment Federation are scheduled to perform a PFAS air emissions test early 2024 to evaluate PFAS destruction in the gas phase. The Silicon Valley pyrolysis system uses a thermal oxidizer for emissions control and heat recovery and previous work by the USEPA demonstrated thermal oxidation as suitable for designation as a Best Available Control Technology for PFAS and capable of meeting permitted PFAS destruction criteria (Barr, 2022; Beahm, 2019; Focus Environmental Inc., 2020). While pyrolysis and gasification require solids be dewatered and dried for processing, a new class of thermal processes is also emerging called hydrothermal treatment, that treat solids in a liquid, slurry form at high temperatures. Super critical water oxidation is one example where all organics (including organoflourines such as PFAS) are intended for oxidation within a flow-through reactor. Hydrothermal carbonization and hydrothermal liquefaction use heat without an oxidant to refine the solids into solid and liquid biofuels, respectively. Conclusions The BC and PWD team completed the following outreach and assessment tasks to identify and compare current market offerings for the solids processing technologies mentioned above. The investigation included assessment of commercially available equipment and overall project delivery and operation under the following tasks. - Request for Information (RFI): BC developed and issued an RFI digestion, drying, and thermal processing system suppliers. The goal of issuing this RFI was to identify interested technology and/or solution providers and to compare current commercial offerings based on lifecycle cost and key non-economic criteria. - Technology Summit: Responders to the RFI could participate in a two-day in-person and virtual technology summit, in which each participant had 20 minutes to present information about their technology. These presentations were recorded and are available on the PWD website. - RFI Submission Review: Each submission was evaluated based upon set criteria, established in the RFI document. Table 1 summarizes the scores for the highest ranked submissions. - Alternative Evaluation: Based on the top three ranked system supplier offerings/technologies, facility concept level designs were developed for a business case evaluation (BCE). The Alternatives BCE evaluated three onsite and three regional technology alternatives. These alternatives are summarized along with their BCEs in Table 2. - Recommendations: The RFI submissions and BCEs enabled the PWD and BC team to identify a potential phased path forward for PWD. The purpose of this report is to summarize and describe the methodology BC employed, as well as the economic and noneconomic findings, from the evaluation of a regional, offsite biosolids processing facility. Ultimately, the goal is to characterize the economic viability and noneconomic attributes to assist PWD in determining a path forward to manage

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

SpeakerBrower, William

Presentation time

14:00:00

14:30:00

Session time

13:30:00

15:00:00

SessionOutreach Updates: From State to Regional Solutions

Session number07

Session locationOklahoma City Convention Center, Oklahoma City, Oklahoma

TopicBiosolids Management Planning, business case evaluation, Regionalization

Author(s)

Firmin, Scott

Author(s)S. Firmin1, W. Brower2, T. Chouinard2, J. Ross2, N. Sierra2

Author affiliation(s)Portland Water District 1; Brown and Caldwell 2; Brown and Caldwell 2; Brown and Caldwell 2; Brown and Caldwell 2;

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date Jun 2024

DOI10.2175/193864718825159464

Volume / Issue

Content sourceResiduals and Biosolids Conference

Word count9

Description: Survey for the City of Raleigh of existing THP biosolids characteristics and...

Survey for the City of Raleigh of existing THP biosolids characteristics and end-use

Abstract

1) Introduction & Objectives The City of Raleigh, NC (Raleigh) is currently constructing new anaerobic digestion facilities including pre-digestion thermal hydrolysis process (THP) at its Neuse River Resource Recovery Facility. Raleigh has run a successful Class A limed cake program and land applied aerobically digested Class B liquid solids, but the new Class A THP biosolids cake will be a significantly different product. To inform their marketing plans, Raleigh wanted to gain insight from the four existing THP facilities in the U.S. The objectives of this paper are to: Determine the current status of marketing and product development efforts, and lessons learned, -Better understand the characteristics of their products, -Estimate heavy metal and nutrient concentrations for Raleigh THP cake. 2) Methods Details of the four water resource recovery facilities (WRRFs) in the U.S. with operating THP units are shown in Table 1. Telephone interviews were conducted with key staff from each utility covering a range of questions about biosolids treatment and end-use management before and after installing THP. Survey respondents were asked about changes in product characteristics that are attributed to THP, regulatory approvals, odors, additional cake processing, branding and marketing efforts. Utilities also submitted corresponding biosolids lab data. [Table 1. Existing THP Facilities] 3) Results A) Marketing efforts Raleigh is expecting the vast majority of its THP material to be distributed to agriculture initially. While Raleigh has experience marketing limed Class A material, THP cake will be a significantly new product in their region. Market familiarity exists with other Class A biosolids (e.g., compost, pellets) but Raleigh will need to educate former and potential future users on the benefits of applying Class A cake. To inform their marketing approach, Raleigh wanted to have a better understanding of the marketing efforts of facilities with similar material. These are summarized in Table 2. Of note, Medina does not plan to market its material due to the low cost of its land application program (~$15/wet ton), making it difficult to realize a return on investment through marketing. By contrast, DC Water has a well-established marketing program, currently consisting of 5-6 FTEs. [Table 2. Marketing Efforts of Existing THP Facilities] B) Product development efforts Raleigh is exploring options for post-dewatering processing to manufacture products with higher market value and a longer period of use than agricultural land application. The additional processing steps for Class A dewatered cake that have been presented previously are: 1) soil blending, 2) curing, 3) partial drying, 4) composting (Brower, 2018; Smoot, 2021). Blending and curing are generating the most interest among current and future THP facilities. In addition to blending performed on-site by staff, DC Water sells Bloom to soil blenders in the area, which incorporate the material into their blends. HRSD has on-going research looking at blending water treatment residuals with THP cake, with a particular aim to immobilize and/or dilute PFAS, and in the past completed market research pertaining to THP cake and soil blends. The curing process was developed at DC Water, with the assistance of R. Alexander Associates, Inc. (Brower, 2018). Dewatered cake is laid out in long piles and turned periodically, similar to windrow composting. Over the course of several weeks, if protected from precipitation, the less stable organic matter in the biosolids decomposes and the material dries out, creating a product that is easier to handle and is lower odor and more stable when incorporated in soil. HRSD has an on-going curing pilot and is looking to upgrade existing facilities to facilitate on-site curing. C) Heavy metals The heavy metal data obtained from the existing THP facilities before and after installing THP is shown in Table 3. The DC Water data is most illustrative of a change, similar to Raleigh, of a facility going from no anaerobic digestion to THP with anaerobic digestion with the same solids. [Table 3. Heavy metal concentration in biosolids before and after installing THP (mg/kg, dry)] Many of the metals in the DC Water cake increased around 150%, meaning a 2.5-times increase. Table 4 shows the average and maximum concentrations for Raleigh solids from a period in 2020-2021, and those values with a 150% increase. These values are compared to federal and state Exceptional Quality limits. Even the maximum heavy metal values when more than doubled are still no more than 51% of the EQ limit, so Raleigh should not be at risk of exceeding EQ standards. [Table 4. Raleigh Dewatered Cake Part 503 Heavy Metal Concentrations, Apr '20 - Mar '21 (mg/kg)] D) Nutrients Data from other THP plants were used to estimate likely nutrient values in Raleigh cake. Table 5 summarizes previously published nutrient data from WWRFs in Europe, along with data gathered from the existing U.S. installations. [Table 5. Typical properties of thermally hydrolyzed digested biosolids cake from municipal water resource recovery facilities] Based on these data, a range of likely characteristics were estimated for the Raleigh cake (last line of Table 5). HRSD and Oakland County were used to estimate TKN and ammonia as these plants have the most similar treatment to Raleigh. 4) Lessons Learned Marketing Based on the experience of the four existing THP facilities, markets exist for THP biosolids, particularly in agriculture. While cost savings and revenue are possible, resources must be dedicated to marketing efforts and related market conditions must be considered. DC Water is saving well over $1M per year (compared with contracted land application) but estimates 5-6 FTEs support this effort. Medina County is seeing competition for their THP solids, but since they contract their biosolids management they are not able to obtain value reflecting that demand. Product Development Class A designation opens up opportunities for THP solids, including soil blending. DC Water has expanded its blending facility and HRSD is conducting research on blends. DC Water has also found a market for Bloom as a feedstock for external soil blenders. Curing, which Raleigh is exploring, produces a product with the highest market value. Most outlets for Cured Bloom are in bulk, but it is a testament to the quality of the material that it is able to be bagged and has a retail price higher than other bagged amendments. Heavy Metals While the effect of THP on heavy metals through digestion is unclear, the experience of the existing facilities show that heavy metals will not typically concentrate more than would be expected from the conversion of solid organic matter to biogas. Nutrients Existing THP facilities, in the U.S. and Europe, provide a useful guide for typical nutrient levels in THP biosolids; however, each facility is different and nutrient interactions are complex so the true levels will not be known until the digesters reach steady state. Raleigh's cake is estimated to have an NPK of 1.5-2-0 on a wet-weight basis. 5) Conclusions The uncertainty in nutrient levels (a range of +/- 0.5% for nitrogen on a wet-weight basis) can have a dramatic impact in the field. A dewatered cake with a nitrogen concentration of 1% would be applied at a significantly higher application rate than a cake with a nitrogen concentration of 2%. These values are not absolute even for existing facilities. For instance, for Medina cake in 2021 the total Kjeldahl nitrogen and ammonia concentrations varied 40% and 230%, respectively. From a preliminary analysis, it does not appear Raleigh will have an issue meeting Exceptional Quality requirements. The Water Environment Federation (WEF) has a Research and Innovation Committee (RIC) focus group on Improving Pre-digestion Hydrolysis with a sub-group on End-Product Considerations. In initial discussions, this group has expressed interest in exploring the effect of THP on product characteristics, nutrients and heavy metals in more detail. The preliminary results in this abstract could be the starting point for a more detailed analysis of more extensive data from these utilities before and after installing THP to refine these results. Based on the experience of the four existing THP facilities, markets exist for THP biosolids, particularly in agriculture. While cost savings and revenue are possible, resources must be dedicated to marketing efforts. Additional processing, such as curing, can increase market value and open up additional outlets to support broader diversification of end uses.

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

SpeakerBrower, William

Presentation time

10:45:00

11:15:00

Session time

8:30:00

11:15:00

SessionSession 18: Managing Biosolids in the Carolinas

Session number18

Session locationCharlotte Convention Center, Charlotte, North Carolina, USA

TopicManaging Biosolids in the Carolinas

Author(s)

W. Brower

Author(s)W. Brower1, R. Alexander2, M. Dalton3,

Author affiliation(s)Brown and Caldwell1; R. Alexander Associates, Inc.2; City of Raleigh3

SourceProceedings of the Water Environment Federation

Document typeConference Paper

PublisherWater Environment Federation

Print publication date May 2023

DOI10.2175/193864718825158807

Volume / Issue

Content sourceResiduals and Biosolids

Word count14

Working Towards a Sustainable Outlet for Maine Biosolids through a Regional Solution

Abstract

Background Throughout New England, decreased biosolids management capacity has been a rising concern. Much of the region relies upon landfills and incinerators, but beneficial use has served as a reliable option for a number of utilities, including in Maine. Concerns over PFAS prompted legislative action to prohibit land application in Maine. This law leaves wastewater utilities with landfill as the only option for solids management in the state. Landfilling has gotten more challenging with limited capacity and adoption of additional laws impacting the availability of bulking agents. A company has been working with the regulators in Maine and individual utilities, including the Portland Water District (PWD), to explore approaches to alleviating some of these challenges. The Maine Department of Environmental Protection (DEP) contracted to evaluate the current situation for biosolids management in the state and make concrete recommendations for change. PWD and the company worked together to determine the feasibility of onsite and offsite processing technologies. The technology evaluation for Maine DEP and PWD focused on digestion, drying, and thermal treatment technologies. These technologies were selected for consideration for their following attributes, among others: (1) Anaerobic Digestion. Biologically degrades solids, reducing their mass and generating energy-rich biogas. (2) Thermal Drying. Removes nearly all the entrained water in dewatered solids. This reduces the amount of solids to manage and can remedy capacity and structural limitations at landfills. (3) High Temperature Thermal Processing. Submits solids to high temperatures for further mass reduction and treatment of emerging contaminants such as PFAS. Pyrolysis and gasification are emerging, non-incineration thermal processes that employ high temperatures to generate a carbon-dense beneficial reuse product or an ash and a gas stream with an appreciable energy value. Hydrothermal treatment technologies were also considered-including super critical water oxidation and hydrothermal carbonization/liquefaction. Objectives This paper will detail the specific challenges facing biosolids management in the state (which echo the situation in many other parts of the country) and proposed 'levers' for the state government to address concerns. The situation will be further elucidated by looking in detail at the realities facing PWD and options available to the utility. Status The study for Maine DEP recently has been completed so final results will be presented. The company continues to work on refinements with PWD, but the main analysis has been completed. Methodology The company evaluated public data sources and DEP records to determine the amount of biosolids generated and the amount going to different end use locations. A questionnaire was sent to landfill operators to estimate future capacity for biosolids and barriers to landfills accepting biosolids. Questionnaires were also sent to organizations with interest in developing regional solutions and to providers of technology purported to reduce PFAS. To provide a guide for utilities throughout Maine, lifecycle cost analysis was performed on promising technology approaches at different scales using representative costs for the state. For PWD's specific situation, the team completed the following outreach and assessment tasks to identify and compare current market offerings.

*Request for Information (RFI): BC developed and issued an RFI for technology suppliers. The goal was to identify interested providers and to compare commercial offerings based on lifecycle cost and non-economic criteria.

*Technology Summit: Responders to the RFI could participate in a two-day in-person and virtual technology summit, in which each participant could present information about their technology.

*RFI Submission Review: Each submission was evaluated based upon set criteria.

*Alternative Evaluation: Based on the top three ranked onsite and offsite system supplier offerings, concept level designs were developed for a business case evaluation (BCE). Findings The company projected capacity within the state to manage biosolids; under certain scenarios capacity would be greatly exceeded by the amount of biosolids generated in as little as five years (see Figure 1). The company developed a range of recommendations for Maine government, including addressing limits on bulking agent availability at landfills, pushing for landfill expansions, funding pilots of PFAS treatment technologies, providing grants for volume reduction and dryer projects, and making changes to state regulations. The results of the BCE for PWD are shown in Figure 2, with the twenty-year net-present cost broken out by capital and operations and maintenance costs. The RFI submissions and BCEs enabled the team to identify a potential phased path forward for PWD that will address near term solids needs at the plant while continuing to explore regional processing options. Significance The challenges facing Maine are not unique to the state. The recommendations for Maine are transferable to other parts of the country. And many utilities around the country are looking at the same technologies-digestion, drying, thermal treatment-as approaches that reduce exposure to these challenges, so the results of the BCE for PWD will be of interest to many around the country

This paper details the specific challenges facing biosolids management in Maine (which echo the situation in many other parts of the country) and proposed 'levers' for the state government to address concerns. The situation is further elucidated by looking in detail at the realities facing the Portland Water District and options available to the utility.

SpeakerBrower, William

Presentation time

15:30:00

16:00:00

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)