For decades, the City of Lebanon Authority in Pennsylvania applied Class B biosolids to cropland in liquid or cake form. But in recent times, the authority found itself at the mercy of weather, community attitudes, storage constraints and other factors complicating the biosolids program.

So, in 2014, the district started up a drying process to yield Class A biosolids. It produces material at 94% to 95% solids, suitable for multiple uses including farm and landscape fertilizer and landfill soil reclamation. At present, an agricultural service company takes essentially all the material in bulk, ending the challenge of marketing and distribution.

It’s a clean, neat, efficient solution that put to rest a variety of issues related to Class B land application. “Hauling Class B material to farmers’ fields was very labor intensive,” says Frank DiScuillo Jr., wastewater systems director.

“During biosolids hauling season in spring and fall, we would have crews going 24 hours a day, six and sometimes seven days a week. It was a lot of manpower and a lot of tired people. Now we have much more control over when we run. We have storage. It takes one person on day shift and one on night shift to operate the building.”

The program’s quality has been noticed in the industry around the state: The authority received a 2018 Beneficial Use of Biosolids Award from the Pennsylvania Water Environment Association (category for plants larger than 5 mgd).

Major upgrade

Lebanon, in central Pennsylvania, is home to about 70,000 people and a modest amount of industry, largely dairy and food processors. The Lebanon Authority, separate from the city, handles water and wastewater services.

The wastewater treatment plant (8 mgd design, 5.3 mgd average) uses primary clarification and trickling filter BOD removal, followed by a modified Ludzack-Ettinger secondary process with nitrification and denitrification. After final clarification, the effluent receives denitrification filtration and UV disinfection before discharge to Quittapahilla Creek.

The Class A biosolids process was part of a $55 million comprehensive plant upgrade started in 2011 and finished three years later. The plant received a new SCADA system, new Ozonia UV disinfection system (SUEZ) and 2.5 MW diesel emergency generator (MTU Onsite Energy) with capacity to operate the entire plant.

The upgrade changed the process to include denitrification. “We had always nitrified, but we didn’t denitrify,” DiScuillo says. “We now use IFAS (integrated fixed-film activated sludge) media in our bioreactors. Without that, we would have had to build four additional aeration tanks to accomplish nitrification and denitrification in the same tanks.” The upgrade also included deep-bed sand denitrification filters.

The new biosolids building, including the structure, two centrifuges and the dryer (Komline-Sanderson) cost $11.7 million, of which a Pennsylvania Commonwealth Financing Authority grant covered $5.5 million.

Changing times

The biosolids program has evolved slowly. “In the 1970s we used an old oil tanker to land-apply biosolids,” says Tom Demler, biosolids and industrial pretreatment coordinator. “Then we moved up to an Ag-Gator vehicle with subsurface injection.” After the plant acquired a belt filter press, the authority shifted to liquid and dry manure spreaders for application.

As the community grew and biosolids production increased, the Class B program became burdensome. “We did everything ourselves — the trucking, the spreading, all the calculations and site permitting,” says Cora Shenk, compliance manager.

“We were at the mercy of weather. More neighbors were complaining. Once we got to talk to them, it was OK, but we anticipated more problems coming down the road. Biosolids haulers from other areas were coming into our area, and we had to contend with that, too.”

Storage of biosolids at the plant was problematic, as well. After installing the belt filter press, the authority built a cake storage facility on a concrete slab with a single side and a roof. At times, that facility became full to overflowing. Biosolids would spill onto the asphalt outside; if it rained, the staff had to place hay bales to keep runoff out of the stormwater system.

“We always anticipated going the next step to Class A, where there would be fewer restrictions on the use of the product,” Shenk says. “The question was how to get there.” Composting was rejected for the space and labor required and an uncertain supply of city yard and leaf waste. A small pilot test of lime stabilization proved unsatisfactory.

Making the choice

In 2007, aided by the Gannett Fleming engineering firm and engineer Fred Updegraff, the Lebanon team began visiting treatment facilities to evaluate biosolids dryer technologies. The search soon focused on an indirect drying system from Komline-Sanderson.

The team visited Derry Township and Pottstown, both in Pennsylvania and using the Komline-Sanderson dryer. “When we started to design our building, we flew to a Komline-Sanderson installation in Mason, Ohio,” Shenk says. “Our facility resembles theirs quite a bit.”

As the drying system moved toward completion, Komline-Sanderson trained the Lebanon plant operations team. Company technicians operated the building for the first two weeks, staying on site around the clock. “For any hiccups we had with the controls or equipment, Komline-Sanderson was quick to respond, either by telephone or by actually showing up here,” DiScuillo says.

Running the process

The biosolids production process starts in a two-stage, high-rate anaerobic digestion process. In the plant upgrade, floating domes on the 2-million-gallon primary and secondary digesters were replaced. The primary digester received a fixed-dome cover and a linear-motion mixer (Ovivo USA). The secondary digester received a Dystor double-membrane gas holding system (Evoqua Water Technologies) that holds about 240,000 cubic feet of biogas. The gas is used for building and digester heating and to heat the thermal oil used in the biosolids dryer.

From the secondary digester, material at 1.5% to 3% solids is delivered to the centrifuges, which raise the solids content to 21% to 22% and discharge cake into a live hopper where augers keep the material fluidized. A pair of variable-speed progressive cavity pumps (SEEPEX) then deliver the cake to the dryer at a rate manually controlled by a certified operator according to the solids concentration and temperature.

The paddle dryer can process 2.75 wet tons per hour. Thermal oil flows through two hollow counter-rotating paddles and the dryer shell at temperatures from 300 to 400 degrees F, boiling water out of the biosolids cake. The finished granular material is cooled and then delivered to a storage silo.

Keeping it running

The drying process is highly automated, requiring minimal operator interaction. The dryer operates seven to 10 days per month, running around the clock. Demler works in the biosolids building Monday through Friday from 7 a.m. to 3 p.m. The remaining hours are covered by plant operators on rotating 12-hour shifts.

Team members in addition to Demler who support the biosolids program are Gary Hammer, maintenance manager; his assistant Eric Shearer; certified operators Brian Sherman, Dustin Gingrich, Jason Schubert, John Schubert, Tim Long, Bill Rhine, Steve Miller, Chris Battistelli and Pat Mullen; mechanics Jim Lymaster, Andrew Seibert and Mike Behm; and Tom Lesher, electrician.

The end product, called CoLA-GRO and with an NPK analysis of 4-2-0, at first found quick acceptance among farmers. The authority delivered it at no charge, but after about a year, it discontinued that practice. At that point, farmers’ interest waned; many were not equipped to haul the material themselves.

“Then the local landfill contacted us,” DiScuillo recalls. “They were looking for nutrients to apply to their retired cells to help grow grass again. They were picking up 80% to 90% of the biosolids for soil reclamation.” Later, landscapers began taking some of the product. 

Finally, agricultural service provider Campbell Crops stepped in. The company had been using another community’s dried biosolids but preferred CoLA-GRO for its lower dust content and easier spreading. “They currently take all of our product,” DiScuillo says.

Looking back, the Lebanon team is pleased with the transition to drying technology. DiScuillo observes: “We are very grateful that our authority board allowed us to go with Class A biosolids.” There’s no feeling quite like being in control.

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CoLA-GRO’s customer

Campbell Crops has found an attractive fertilizer product in CoLA-GRO dried biosolids from the City of Lebanon (Pennsylvania) Authority.

The company provides agronomic sales and services in three Pennsylvania counties from its home base in Berrysburg. Its product offerings include seed, crop-protection chemicals, and liquid and dry fertilizers, delivered to farms. Services include crop consulting and scouting, soil sampling and nutrient management, along with custom planting, spraying, spreading, tillage and harvesting.

The company applies CoLA-GRO to corn and hay ground using a lime spreader that broadcasts the material about 25 feet to each side. Jonathan Campbell, company founder, says the product has appeal beyond its nutrient value and the fact that he receives it at no charge.

“My wife and I are dairy and steer farmers, so we view human manure the way we view animal manure. Why wouldn’t you want to put the nutrients back where they came from?

“We also want a product with some amount of handling characteristics that’s going to spread fairly uniformly. That’s something the system at Lebanon has done well. They have a really advanced setup. They’ve been able to make a product that’s nice and granular, handles well and has a reasonably high analysis.”

He notes that the state Department of Agriculture treats Class A biosolids such as CoLA-GRO as fertilizers, which unlike manures do not require farmers to create nutrient management plans. “In addition, you have a heat-treated product that’s 99.99% pathogen-free,” Campbell says. “That gives it a leg up above manure as well.”

Then there are farmers who prefer the product to manure because it eliminates odors.

Campbell concludes, “It’s really neat being a part of Lebanon’s program. Frank DiScuillo Jr. and his team are top-quality operators. I’m fortunate to have a relationship with them.”