Biosolids SPOTLIGHT: A focus on the people of biosolids who work in our region

February 2024 - MABA Biosolids Spotlight 

Provided to MABA members by Bill Toffey, Effluential Synergies, LLC 


Transforming Quakertown


Dave “Butch” Erwin has big plans, very big plans! Erwin leads the Borough of Quakertown (PA) wastewater treatment plant, and he has seen his facility break ground early 2024 on implementing his “very big plans.”

Erwin’s vision takes in a wide view. He explains: “We stop landfill disposal of sludges, and we produce biosolids that we can recycle to local farms. We get green energy from the biogas which can run the plant. We can take in revenue from the trucked in food waste, which we hope one day will help us break even, or maybe even achieve reduced rates for the citizens of the borough.”

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Dave “Butch” Erwin, Superintendent, Borough of Quakertown Sanitation Department


Erwin is motivated by both his love of the job and his love of the borough. He was raised in Quakertown, and today serves as the chief of its volunteer fire company. He was a 14-year-old when he first volunteered for the fire company, joining his father, mother and sister in this vital community service. At Kutztown University, he studied biology and took a job right out of college at the Orwigsburg wastewater plant. He was grateful for work that had a new challenge every day, and happy he was not stuck behind a desk. Upon graduation, he married his college love, and they lived for a while in Schuylkill County, raising two daughters, and, of course, also volunteering in the local fire company. His next career stop was at the Lehigh County Authority Industrial Pretreatment facility, an operation unusual for its large inflow of high strength organic waste. Dave realized that there must be a better use for the methane gas produced by anaerobic digestion and for opportunities for use of biogas and cogeneration. Hired 7 years ago as the superintendent of the Borough of Quakertown Wastewater Treatment Facility, Erwin has now put together all his ideas for a sustainable wastewater system, and he looks ahead to the next decade, as an unfolding vision becomes a capstone to a career in wastewater treatment and public service.

The Quakertown plant is on the outer edge of the Philadelphia metropolitan area, a fast-growing area for which the Quakertown plant’s 4 MGD capacity today is too small to accommodate expected growth in sewage flows. Upgrades underway today will take the plant to a 5 MGD capacity, but the “vision” is a plant of ultimately 7 MGD. Engineering details for the facility upgrade has been led by Mike Filmyer of BCM Engineers/ATC Group Services, LLC, in Plymouth Meeting, PA. Scarcely any component will remain untouched over the next several years.

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 Borough of Quakertown Wastewater Treatment Facility sign


In working with ATC, Erwin drew on a series of scenarios for use of “trucked-in” high-energy content liquid wastes. This big opportunity arises from the thirty or more sources of high strength organic wastes within affordable reach of Quakertown. As Erwin saw during his days at Lehigh County, these waste sources are potential customers for the kind of service Quakertown could provide with a smartly installed processing system.

The Quakertown plant has a unique opportunity in the borough’s ownership of its own electrical grid. The Borough experienced serious financial charges for its occasional high electricity demand, charges that could be avoided with the right kind of in-plant electricity generation. The borough buys electricity wholesale from the open market of the Northeast Grid, and the treatment plant stood ready to be a generator, supplying “green” electricity for its wastewater operations and managing its demand. The biogas from anaerobic digesters could produce the electricity for meeting plant needs and offsetting demand charges.

Quakertown also had an opportunity to increase the proportion of sludge solids it was taking to farmlands at affordable prices. Existing solids stabilization is through aerobic digesters, but resultant biosolids fail in winter to meet vector attraction standards for farmland use. This means a premium price is paid for landfill disposal costs in winter. This could be fixed with anaerobic digesters.

If these factors were not sufficient, the firm Anaergia, with its robust offering of anaerobic digestion and combined heat and power, showed Quakertown a path to a partnership that made ownership of electricity generating equipment practicable. Anaergia has a successful operation in the Mid Atlantic region. The kind of digester it has supplied to Camden County Municipal Utilities Authority (CCMUA) was a local reference facility for Quakertown. The operational talent it employs at the CCMUA in operating the CHP system and its related biogas equipment can be shared with Quakertown. The stars are aligned for this vision to be eminently do-able.

quakertown 3Image showing the site where the Combined Heat and Power (CHP) will be located. The company removed an abandoned tank and is currently working to back fill the area with recycled concrete.

Erwin’s plan for enhancing the sustainability of his operations includes a focus on biosolids recycling. The Borough has an uncommon arrangement by which it uses its own tractor trailers and employees to deliver biosolids to local farmers. In 2023 Erwin delivered borough biosolids to three nearby farms. At present, Denali is contracted to provide field application services, though this service is in the process of being rebid as this article is in preparation.

Denali’s local land manager for the past several years, Ryan Cherwinski, counts Quakertown among Denali’s best partners. Cherwinski explains that the agency’s aerobically-digested cake product is consistently low in odors and easily stored and spread, and the plant staff is super at communications and coordination. Cherwinski believes that the future for Quakertown could well be year-round recycling, if the opportunity for on-farm storage is developed. With the buildout of the new facility, Quakertown foresees production of 30 tons per day of cake, at 25 percent total solids.

Erwin already has the firm Material Matters drafting paperwork for the future biosolids production. Natalie Switala, senior wastewater specialist, is handling solid waste permits for disposal and use of the new biosolids products. Over the past several years, Pennsylvania DEP has floated the proposal to require those municipal plants accepting trucked-in high strength organics to obtain their own utilization permits, outside the current General Permit 08 for Non-Exceptional Quality Biosolids. Switala has these permit applications underway.

Ground has broken for the new biosolids facility. Stormwater basins are being relocated, and the site of the new generators has been cleared for pouring the building foundation. The public private partnership with Anaergia calls for two anaerobic digesters, each about one-half million gallons, using the Anaergia Omnivore design that handles “high solids” liquid sludge feed, meaning it accepts a liquid feed of 12 percent solids. Existing aerobic digester tanks will be repurposed as equalization tanks for digester feed. These tanks will accept about 14k gallons of thickened sludges from the primary and secondary tanks at the plant itself, but also will take in deliveries of 35k gallons of food waste, of fats, oils and grease (FOG) and of sludges from nearby small wastewater plants. These tanks will be kept well blended and will provide for consistent thickened liquid feed to the digesters. Half of the organic loading to the digesters is expected to be from these outside sources.

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Image is of Quakertown 1920 sludge holding tanks. These will be reconditioned and updated to be sludge holding tanks. 


The Quakertown plant has a state-certified lab on site. This lab will be used to check each load delivered for conformance to the characteristics approved in advance by Quakertown. All sources will require pre-authorization and chemical characterization.

The Quakertown plant is in a sweet spot when it comes to its electricity supply and generation. Quakertown owns the electrical grid within the borough limits. Two internal combustion engines, each 800 kW in size, will be fueled with the digester gas, after gas clean up to remove water, sulfur, and siloxanes. The ICE will work as combined heat and power (CHP) energy generators to provide 800 kWe of heat for the digesters and building and deliver a steady 1.0 mWe of baseload electricity for plant operations, with occasional surplus electricity fed to the borough’s grid. The engines will be fueled only with digester gas, as the premium cost of developing peak shaving using larger dual fuel generators did not show a return on investment.

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Two new digestors will be installed in this location. The current digestors hold 800,000 gallons and the new ones will be able to hold 600,000 gallon each, almost doubling our capacity. 

Anaergia has been important for driving the Quakertown project. Its staff conducted a survey of the market in this part of southeastern Pennsylvania for the processing of high strength organic waste. This included grease trap haulers, food processors, and WWTPs, and checking on current tipping prices with facilities elsewhere in the metropolitan area. Avi Dalfen is Anaergia’s process engineer, arranging the digester, biogas and CHP systems, which will include a double membrane gas storage roof to allow for steady biogas feed to the generators. Anaergia has supplied the digesters and CHP units for Quakertown’s purchase and ensures integration of the several units. After installation, Anaergia will provide maintenance services.

Subsequent to the installation of the digesters and the CHP, Quakertown will rebuild its dewatering facility. The existing centrifuges will be replaced, and new systems will include conveyance of biosolids cake to waiting trucks. This will replace the current attention operators need to give to cake loading to the trucks. The centrifuges will be operated two shifts daily, seven days a week, which may require the Borough to add one trailer to its current fleet of three that provide cake storage through the weekend.

Patience is what our entire biosolids community needs today. A transformation is underway at Quakertown, and Erwin believes that in two years the major components of his vision will be operational. Perhaps the Mid-Atlantic Biosolids Association can get dibs in for a conference with a plant tour in Quakertown the Summer of 2026, just ahead of the United States Semiquincentennial. Now, that is a vision worth having!

For more information, contact Mary Firestone at [email protected] or 845-901-7905.

January 2024 - MABA Biosolids Spotlight 

Provided to MABA members by Bill Toffey, Effluential Synergies, LLC 


Restoring the Solids Flow in Baltimore


“Solids are flowing as they should, at both plants.”  This is a recent assessment of one contractor working for the Baltimore Department of Public Works at both Back River Wastewater Treatment Plant and Patapsco Wastewater Treatment Plant.  Aging infrastructure, retiring public operators, and COVID had contributed to a crisis in solids flows, resulting  in such headlines in mid-2022 as “New report outlines failures across 'nearly every level' of Back River Wastewater Plant.” Two years of focused effort by agencies, environmental consultants, and contractors, under watchful eyes of environmental groups and the media, have made good things happen for biosolids in Baltimore, and so the solids are flowing. 

The journey from “failures” to “flows” has been a great challenge for Baltimore, and Patapsco WWTP is a case example.  Daily solids production had stopped completely in 2021. Lack of dewatering and drying operations caused Patapsco to become overwhelmed with solids, and plant effluent water quality was severely impacted. Under an emergency authorization, Baltimore contracted with the firm Hazen and Sawyer (Hazen) to provide daily on-site operational support, technical process control support, plant modeling, and other operations related tasks. Together with subcontractor Williams Environmental Services, Hazen assigned a small team of certified operators and engineers to get to work.

An aerial view of the Patapsco Wastewater Treatment Plant

An aerial view of the Patapsco Wastewater Treatment Plant


Restoring the sludge dryer (aSwiss-Combi direct drum dryer) was top priority. The dryer owner, Synagro, devised and permitted a temporary solids disposal outlet. Hazen and the City addressed issues of feed sludge quality and transfer. Solids production resumed with an agreement between Synagro and the City on a temporary processing plan.  With implementation, the solids backlog eased. Hazen conducted a “root cause investigation,” leading to changes in sludge storage ahead of dewatering and drying. The recommended changes were successful, and Synagro was able to move away from the temporary plan. Dryers were fired back up in April 2023. Clearing out the excess solids inventory, maintaining daily solids production goals, and a renewed focus on communication and transparency between the City and Synagro have paid huge dividends.  Patapsco WWTP was NPDES permit compliant for 2023, and all parties -- employees, consultants, and contractors, can be proud of Baltimore’s accomplishments.

Swiss Combi direct dryer drums at Patapsco

 Swiss Combi direct dryer drums at Patapsco


Baltimore DPW is a new member of the Mid Atlantic Biosolids Association, and Mahmudal Hasan, Ph.D., one of the agency’s new senior managers, has just begun his service on MABA’s Board of Trustees. But Baltimore’s leadership among the region’s biosolids programs is not new.  Its iconic egg-shaped digesters at the Back River plant were among the earliest such installations in the country. Its adoption of public-private partnerships for production of Class A EQ biosolids products was also groundbreaking among large municipally owned utilities. Long term contracts in the early 1990s resulted in composting and pelletizing facilities, cutting edge at the time, and still in operation today.

The Egg Shaped Digesters at Back River WTPThe Egg Shaped Digesters at Back River WTP

Even as the imminent crises of 2021 to 2023 have subsided, significant projects are moving forward at the opening of 2024 to continue the solids handling improvements.  Very significant is the major repair and upgrade of anaerobic digestion at the Back River plant.  In addition to the visible egg digesters, solids are processed through in-ground pancake style anaerobic digesters, in an acid-gas sequence configuration, and the system has “wide spot” storage tanks to balance flows and for short term dewatered solids storage. These digesters and tanks are being cleaned and repaired, and pumps and gas collection systems replaced.  Solids feed to digesters will be upgraded with new sludge thickeners. The cost of this large digester upgrade program is pegged at nearly $90 million.

DPW has elected, as well, to keep in place its contractor-operated Class A EQ production capabilities.  Veolia Water North America operates the Baltimore City Composting Facility, a hybrid system using an enclosed tunnel reactor and aerated curing piles. It receives approximately 35,000 tons of biosolids cake from Back River annually from which it produces about 50,000 cubic yards of OrGro biosolids compost.  A stable commercial market for this compost has been developed by Veolia over the past three decades.

Veolia’s Baltimore City Composting Facility

Veolia’s Baltimore City Composting Facility


MABA member Synagro, the owner of the Patapsco dryer described above, is also owner and operator of the dryer at Baltimore’s Back River WWTP.  Originally selected and installed over 30 years ago, Synagro has managed to continue operating these unique, one-of-a-kind systems, in bundled full-service contracts that include dewatering, drying and marketing under the brand name Granulite. The Back River dryer, a Pelletech vertical multiple pan hot air dryer, is being repaired by Synagro, after an explosion in March 2023 put it out of service, but through it all Synagro has maintained drying and biosolids disposal services to the city. Feedstock to the Patapsco dryer is unstabilized sludge, a factor which contributes to vulnerabilities in operations, odor risks and product marketing, and a factor that will be addressed in future capital investments is solids processing. 

Pelletech dryer at Back River
Pelletech dryer at Back River

Improved operations at both Back River and Patapsco have restored treatment levels and solids flows to levels of regulatory compliance.  DPW has rebuilt its workforce capabilities, with appointments of Dr. Hasan, biosolids manager and now Chief Technology Officer, and Mike Hallmen, manager of wastewater facilities, as examples of strong staffing.  For the difficult period over the past two years, the state government had called upon Maryland Environmental Services  along with Hazen, to assist DPW in expediting repair activity. Going forward, Jacobs, an engineering firm operating the Wilmington WRRF, has been contracted by Baltimore to handle solids treatment operations at Back River over the near term.  A long-range master plan is under consideration, with a scope of capital reinvestment in solids handling of about $400 million, envisioned largely through public-private partnerships.  An overarching initiative is a proposal to create a Baltimore Regional Water Authority, which would put drinking water and wastewater treatment for the entire County and some adjacent governments under one organizational and financial management umbrella.  

Just as it is true that it “takes a community to raise a child,” it takes a community of professionals with varied skills to manage biosolids, and Baltimore is one of the very strong examples. 

For more information, contact Mary Firestone at [email protected] or 845-901-7905.

July 2023 - MABA Biosolids Spotlight

featuring Village of Endicott


Join us for a tour of the Village of Endicott plant Thursday, July 20 at the 2023 Summer Symposium!
For more information, contact Mary Firestone at [email protected] or 845-901-7905.



Working Forward in Biosolids Management
From In-Vessel to Windrows to a Dryer at the Endicott WPCP


For almost 40 years the Village of Endicott Water Pollution Control Plant (WPCP) located in the Southern Tier of NYS has recycled biosolids. The WPCP has a 10 MGD design flow and serves about 50,000 people from the V. Endicott, T. Union and T. Vestal. The recycling of biosolids began in 1984 with a Taulman-Weiss In-Vessel system and shifted to the traditional windrow method in 2004 due to mechanical issues with the In-Vessel system. In an effort to reduce process time and costs while also continuing to recycle and produce Class A material, the WPCP added a Thermal Dryer.

The thermal dryer reduces costs and time in the production of Class A material.

The thermal dryer reduces costs and time in the production of Class A material.


“The dryer allows the facility to eliminate the need for a carbon source,” said Philip Grayson, chief operator at Endicott, “Which is a significant cost in our compost operations.”'

In addition, the Village had employed a full-time compost operator. Upon that employee’s retirement the position was eliminated through attrition, another significant cost savings benefit. Furthermore, the dryer process produces a Class A material in less than an hour versus the weeks and months needed for windrow composting.

 Endicott Belt Press Operation with dryer behind it

 Endicott Belt Press Operation with dryer behind it


The Endicott WPCP is continuing to work with NYSDEC for the dried product to be an approved Class A material. The Village is exploring the traditional Thermal Drying Class A parameters, such as more than 90 percent solids requirement versus 75 percent solids if all material is stabilized municipal sludge. The Village recognizes time, energy and cost savings if a Class A product can be achieved at less than 90 percent solids.

The Endicott WPCP is completing a Solids Handling Upgrade project that includes new anaerobic digestion membrane covers, mixing system, gas train, flare, septic receiving station, process water system and a thermal biosolids dryer.

Another view of Endicott dryer with Belt PressAnother view of Endicott dryer with Belt Press

The new equipment provides for increased reliability and access to repair and replacement parts. Grayson explained that the digester is performing better due to increased mixing, the gas train’s new safety devices and flare relocation bring the building into current building codes, the septic receiving station allows for the material to travel to one of two locations for treatment, a new process water pump and distribution lines, and the thermal dryer was the final piece to the Solids Handling Upgrade providing for a new way to treat and produce a beneficial product. 


Endicott Plant drone image

Endicott Plant drone image


“The upgrades give our system more flexibility, safety and reliability,” said Grayson, “This is achieved through providing options and redundancy within the system. There is now more than one path for our septic material (headworks or digester), multiple water sources on-campus (potable and non-potable) water and more than one way to achieve Class A material (windrow and thermal dryer). These upgrades together increase our ability to operate and achieve recyclable water and biosolids.”

For additional information, contact Philip Grayson, Chief Operator, Wastewater, Village of Endicott at [email protected].

Join us for a tour of the Village of Endicott plant on Thursday, July 20 at the MABA 2023 Summer Symposium!
For more information, contact Mary Firestone at [email protected] or 845-901-7905.


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