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

April 2025 - MABA Biosolids Spotlight 

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

SPOTLIGHT on Two New York Plants – Watertown and Endicott

“Ingenuity, that is a good word for it,” agreed Angel French, Plant Manager of the Watertown Water Resource Recovery Facility. Unfazed by unconventional and innovative technologies, French encourages her operators and maintenance staff to apply ingenuity as a team to “make it all work” in the face of unexpected challenges. French explains, although Watertown’s WPCP is classified by NYS regulations as a large plant, with a design daily flow of 16 MGD, and an average daily flow of 10 MGD, compared to Buffalo, Syracuse and Rochester and those in metro New York, Watertown is on the small end of the spectrum.  At this size, French rotates operators across all processes, and the maintenance staff are licensed operators, fostering an ethic of teamwork that is able to apply ingenuity when new equipment stumbles on startup.

This Google Earth view of the Watertown Water Resource Recovery Facility, located in the northern reach of New York State, underscores the proximity of a major recreational facility to the south, and the cake storage area converted from a former lagoon rebuilt north of the digesters.

Ingenuity enabled Watertown to pivot in 2017 when new federal Sewage Sludge Incinerator regulations compelled the city to end incineration. Because sludge ash had been disposed of at solid waste landfills, Watertown was initially able to divert from incinerators to landfill disposal of cake for its management option. Dewatering equipment at Watertown is also unusual, representing one of a handful of plants in the MABA region with plate-and-frame presses. The discipline of maintaining good solids content, targeted at 20 percent solids, for incinerator feed was no less necessary for landfill disposal.  But tipping fees drove Watertown to pivot again from landfill disposal to land application.  This pivot required it to demonstrate that processes met the Class B standards through three anaerobic digesters, operating in series to achieve minimum hydraulic retention time.  

Land application is a challenge in this far reach of New York State, as the season for application is narrow, requiring the facility to develop capacity for on-site storage over the winter.  Storage is a particularly strong challenge for Watertown, as its plant adjoins actively used trails and playfields. Winter freeze and thaw cycles do not improve the quality of biosolids cake, and odors during pile disturbance is a risk factor.  Watertown’s biosolids are used typically for feed crops for dairy herds, and fertilization of field corn is the dominant use.  Last year, Watertown paved over its old ash lagoon, which had been shut down when incineration ceased, to increase the available space to store biosolids when cold weather makes storage necessary.

Two factors with land application have French considering management options.  First, against the capital cost for a future facility for cake storage is balanced the cost of installing a biosolids dryer. A dryer would have the obvious advantage of making winter storage easier, but it would also reduce risks from odors when biosolids are moved from storage.  Second is an arising concern with PFAS, both from state regulations and political responses to PFAS in New York State that include bans on land application.  Dried biosolids could be better handled than cake through a thermal conversion technology that destroys PFAS.  

Ingenuity at Watertown is highlighted by three features of the plant’s solids handling. The features are a low-head-loss headworks bar screen, second is a biogas fueled sludge pump system, and third is a dry polymer mix system that has been optimized for Watertown’s unique plate-and frame presses. 

Hydro-Dyne Engineering is the manufacturer of bar screens recently installed on Watertown’s principal influent line. Hydro-Dyne is represented in central New York by Siewert Equipment. Watertown has deployed the Great White Center Flow Screen which is special for a design that achieves “low head loss and zero carry over” with its ¼ inch  wide bars. The screen is deeply recessed in the influent well. At the outset of its operation at Watertown, the conveyor system at the discharge chute frequently tripped. While the discharge apparatus served to concentrate and dewater the screenings, the back pressure was too great for the equipment. With the ingenuity of the operators, the discharge chute was reduced in length, thereby reducing, too, the quantity of screening moved by the conveyor.  The ¼ inch screen has significantly reduced inert materials passing through the plant, improving the entire process train and biosolids quality. French anticipates a capital improvement to install a similar screen on the second major influent line, the one coming from a diverse number of other interceptor lines serving outlying communities.

The Hydro-Dyne Great White bar screen was a “game changer” for Watertown for improving treatment and biosolids quality, with images here of both downstairs influent equipment and upstairs screenings discharges.

Watertown has replaced two conventional sludge pumps with Kraft Energy Systems Model KB 130P equipment, using MAN direct drive biogas fueled engines, supplied by the Kraft Power Corporation in Syracuse, New York. Biogas from the digester complex is cleaned of siloxanes and is otherwise untreated. Sulfur is not a challenge at Watertown, as the use of ferric for phosphorus removal also captures sulfides.  During normal plant operations (i.e., not wet weather) one biogas fueled engine will pump 100% of plant influent flow.  The use of biogas in this part of the plant provides for consistent biogas demand across the year, in contrast to use of biogas to meet heat demand of boilers and digesters.

MAN direct drive biogas engines, supplied and installed by Kraft Power in Syracuse, are close to overcoming start up challenges, and promise soon to fully meet pumping requirements on biogas during normal flows.

Now over four decades old, Watertown’s plate-and-frame presses operate well when given special attention to polymer dosage and annual replacement of filters.

As French and her staff look for new ideas and new ways of solids handling, they are taking cues from other agencies, and one such agency is the treatment plant serving Village of Endicott, New York, led by a similarly ingenious plant manager, Philip Grayson. The Mid Atlantic Biosolids Association held its Summer Technical Symposium in Endicott in 2023, and Grayson’s plant was the destination for the tour on the second morning.

Endicott Water Pollution Control Plant, in the southern tier of New York, has enjoyed loyal compost customers in the past, and is building a market for its new biosolids product.

At the time of the Symposium, Grayson was already winding down the plant’s composting operation.  The Village began in 1985 the composting of biosolids with a Taulman-Weiss in-vessel system and after 20 years of operations, it had added windrow composting to ensure complete stabilization.  To reduce costs while still producing a Class A EQ product, the Village moved to biosolids drying, selecting a Gryphon Environmental’s single-pass belt dryer.  As an early adopter of this technology in the MABA region, Grayson relied on the collaborative culture at Gryphon to be a team that together could meet challenges with ingenuity. One notable area were changes to the method of conditioning the feed material to the dryer belt. Gryphon previously only handled aerobically digested and not anaerobically digested material. The differences between how those two dewatered cakes are significant and created operational challenges. In addition, occasionally Endicott had issues with blinding of the inlet screens with human hair and other fibers. These two issues led to Endicott installing a Gryphon system that uses blades to shred the feed.

Endicott is an “early adopter” of Gryphon Environmental’s single pass belt dryer and has already fitted a new 10 foot module to expand processing capacity by 25 percent. 

Hair and fiber are seldom a focus of attention at biosolids conferences, giving rise to the kind of challenge Gryphon has had with its dryer feeding system, one that requires ingenuity in a solution.  Josh DeArmond, Gryphon’s Director of Engineering, says that a frequently invoked motto at Gryphon is: “This is NOT our fault, but it IS our problem.” In the brainstorming of solutions to a blinding by fibers of the dryer feed system, the term “harrow” was borrowed from the agricultural industry to describe a system of star-like blades for cutting through the fibers in the dryer feed. The company has this as a patent pending solution. 

The second area was ensuring adequate drying time by extending the belt with an additional ten-foot module. During the early stages of dryer operation, Grayson determined that having flexibility in managing solids flows and in ensuring steady compliance with time/temperature standards warranted an additional dryer module, a fifth 10 foot drying section and a new longer belt, adding 25% to processing capacity. The challenge was fitting the new unit into a building with narrow aisles and limited dimensions. Endicott’s staff was able to shift the location of the belt filter press and conveyor, and Gryphon modified its modules construction to allow the staff to squeeze the unit in place.  Ingenuity and collaboration enabled Endicott and Gryphon to together accomplish results that met the unexpected challenges of the moment. 

Endicott shares several key features with French’s Watertown facility in size (Endicott serves 50,000 customers), in its anaerobic digesters and in having process equipment that utilizes the biogas. But a key common concern is the vulnerability of its planned, long-term recycling program to changes in state regulations of land application, largely a consequence of the global issue of PFAS.  Gryphon Environmental’s motto applies here: PFAS is not our fault, but it is our problem.  While neither agency sees a problem with results of biosolids testing for PFAS undertaken at NYS DEC’s direction, both are concerned with the potential endpoint of current political and regulatory reaction to PFAS, which may yet throw the entire recycling pathway for biosolids into question. One area of concern is that, even with a final resolution of PFAS standards in their favor, both agencies rely on willing farm customers to take their biosolids. Farmers may become wary of accepting biosolids even when their sources are better than regulatory limits, and companies servicing the farmers face emerging acceptance obstacles and challenges from local officials.  This situation underscores Endicott’s interest in diversifying its outlets for dried biosolids, and in Watertown’s interest in embarking on a search for a suited dryer technology. Both French and Grayson anticipate a need to have flexible outlets for biosolids, a need that requires the ingenuity that has guided investments in each agency’s processes over the past decade.  And both will have the teams within their facilities and with their equipment suppliers to meet future challenges. 

Watertown and Endicott exemplify the power of teamwork to meet challenges with ingenuity.

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