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

March 2024 - MABA Biosolids Spotlight 

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

Sailing the Sludge Boat to Newark

The job opening was posted recently for this job with New York City Department of Environmental Protection (NYC DEP) : Sludge Boat Captain. The minimum requirements for this public sector biosolids job are unusual in the biosolids business – the requirements include a “valid U.S. Coast License as Master of Coastwise steam or motor vessels.” Sludge boats?

“Sludge boats” for which NYC is seeking a captain serve as the equivalent of pipelines for moving liquid digested sludge between New York’s Water Recovery REcovery Facilities (WRRFs) and its non-dewatering WRRFs and the WRRF facility in Newark operated by the Passaic Valley Sewerage Commission (PVSC). The “boats,” as they have been known for many decades, are not barges, but self-powered marine vessels. The era of ocean dispersal of sludges began in 1938 and ended in 1992 when this method of sludge management was banned. “Boats” were deployed to collect liquid sludge from each plant and discharge just 12 miles from the coast, followed by a period of discharge at mile 104, at the edge of the continental shelf. Then entered the period of dewatering and land based biosolids recycling, when the sludge boats became the “pipeline” for liquid digested sludge movement between WRRFs, to make optimal use of dewatering equipment and cake hauling. Thus, sludge boats have been a consistent part of the NYC marine and “sludge” experience.

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NYC DEP’s five marine vessels are staffed by 5 operators and one sludge boat captain. Each vessel is named after one of the agency’s WRRFs, which is appropriate for their role in transporting liquid digested sludge from eight WRRFs not served by onsite dewatering facilities to those six that are equipped with dewatering centrifuges. The North River (commissioned in 1974) is the last remaining vessel originally built for ocean disposal of liquid sludges. The Red Hook (2008) can transport over one million gallons of sludge and is the largest boat in the fleet at 352 feet. The three newer vessels, each with the capacity to carry 1 million gallons of liquid sludge, were commissioned in 2014 and are named the Hunts Point, the Port Richmond and the Rockaway. At a total construction cost of $106 million, these three are equipped with the latest marine technology, have a greater cargo capacity and more versatility than the older models, including a shallower draft, which allows them to have no bridge height restrictions in serving the treatment plants. Operations of the vessels are 24/7, 365 days a year, and their movements stretch out to all five boroughs, including the bays, rivers and creeks that make up greater New York Harbor. All told, the “boats” move about 75 million gallons monthly, or 900 million gallons of liquid digested sludge annually. 

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Arguably, no job in the entire Mid-Atlantic region is more critical to the environmentally sound management of biosolids than that of the sludge boat captain. The sludge boat captain has an intriguing set of job requirements. The captain acts as the pilot navigating the vessel throughout the NY Harbor and duties include “responsibility for the safe operation of the vessel at all times,” “inspect the ship at frequent intervals; and maintain proper upkeep of the vessel.”.

The draw of being a sludge boat captain may be in the local fandom of sludge boat operations. NYC DEP’s chief of Residuals Operations Kevin Byrnes, a 40-year employee of NYC DEP, has the Marine Section under his command. The story of the Maritime Division operations and its history is told in 80 Years of Maritime Excellence, and mirrors the evolution of biosolids management in the United States. The sludge boats have been a consistent part of the maritime scene around NYC. On the occasion of its “retirement” after 47 years of service, the M/v Newtown Creek was recognized by Byrnes in an article he wrote: From the First Splash to the Last: a Ship that Keeps on Giving.  The fascinating program, Open House New York (OHNY), has offered a virtual sludge boat tour (April 2022) on Zoom, DEP Sludge Boat Tour. Only a few select ticket holders could enjoy the nine-hour tour on 16 August 2023, DEP Experience Tour: Sludge Boat, but all folks can sign up with OHNY for the next marine tour, even if it is only a virtual tour. The news media is also a fan of the sludge boats (Sailing Round Manhattan on the Sludge Boat and Sludge Boats: Out of Sight, but Never Out of Mind). 

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One of the unique ports of call for the NYC DEP marine vessels is Newark, New Jersey. For two decades, the PVSC in Newark has been receiving deliveries of liquid digested sludge from various WRRFs. PVSC is one of the largest WRRFs on the East Coast US, with a designed capacity of 330 million gallons per day (MGD), and it is the nation’s largest facility for regional acceptance of trucked in liquid wastes. Its Liquid Waste Acceptance Program (LWAP) was initiated in 1996, after PVSC had lost the influent of several major industrial customers within its waste watershed. NYC joined PVSC LWAP program in 2004, with just a few barge loads monthly. 

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By the time the most recent 5-year intergovernmental agreement had been signed between NYC and PVSC in 2023, NYC was delivering about 200 million gallons yearly, ensuring NY’s outlet in Newark will remain a component of New York’s evolving biosolids program for the foreseeable future.

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The PVSC biosolids treatment system is itself unique in the nation. First, it has the nation’s only Zimpro Wet Air Oxidation (WAO) system which accomplishes extraordinary volatile solids destruction and pathogen reduction under high temperature and pressure. The injection of oxygen into the Zimpro reactors distinguishes this thermal process from the array of other related processes, such as hydrothermal liquefaction, gasification, pyrolysis and supercritical water oxidation, which have attracted renewed interest in the field of wastewater engineering. Unlike these newcomers, PVSC’s Zimpro equipment has been in operation for over 40 years and its operational, maintenance and in-house fabrication capabilities have played a large part in the longevity of the Wet-Air Oxidation process equipment. Post WAO stabilization, solids are dewatered by a set of recessed plate and frame chamber filter presses, also one of two installations of this class of dewatering presses remaining in the United States, but one well suited to the unique qualities of WAO residuals. PVSC’s robust preventive and maintenance program on its Zimpro equipment and the on-going rehabilitation of the Decant and Filter Press Facility will continue to give PVSC the ability to accept and process NYC DEP liquid digested sludge.

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Sludge “boats” arrive at PVSC 5 to 7 times a week. This comes to about 200 million gallons of liquid sludge annually. PVSC’s sludge thickening, thermal sludge conditioning (Zimpro) and dewatering sludge process greatly reduces NYC DEP’s liquid digested sludge, in effect reducing by 70% the mass of residuals attributable to NYC. The PVSC process results in a residual that is qualified by New Jersey Department of Environmental Protection (NJDEP) for use as alternative daily cover at municipal solid waste landfills, which New Jersey credits to in-state beneficial use. 

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NYC DEP is only one of PVSC’s customers for liquid digested sludge deliveries, and it is also not the only customer that delivers by the water route. Bergen County Utilities Authority is the second largest source of imported solids to PVSC via barge. Just over 100 other customers from industrial and municipal wastewater sources in New Jersey deliver upwards of 200 truckloads daily under PVSC’s LWAP.

The star of this biosolids SPOTLIGHT is the amazing collaboration of two utilities that has implemented the national biosolids policies of the Clean Water Act. The NYC DEP’s Marine Section enjoys its rich tradition and current reputation, with its staff of 80 hailing from 11 different countries. Kevin Byrnes points to the unique specialization of the crews, their great flexibility in adjusting to unexpected treatment plant requirements and their nearly unblemished track record of responding to turbulent weather, navigation hazards and operational constraints. The PVSC, having recovered from Superstorm Sandy in 2012, has rebuilt its solids handling equipment to provide for another several decades of reliable service. These two agencies have made their maritime-dependent intergovernmental agreement into a long-term successful and sustainable program, unique to the biosolids profession.

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

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.
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