Kinston, N.C.’s, City Council approved at the beginning of the year an ordinance to begin utilizing a biosolids dryer in the city’s wastewater treatment process.
Typically, the end result of a city’s wastewater treatment process is an environmentally safe byproduct that is irrigated into the land. Using a biosolids dryer, however, this can be dried, formed into pellets and sold commercially or disposed of in a landfill.
“The overwhelming majority of wastewater is land applied after treatment,” City Manager Tony Sears said. “This works well, unless we have an unseasonably wet season and the byproduct can’t be land applied, or we start producing more wastewater than there is land. We’re always looking for how to better control getting rid of this waste.”
While land application is popular, only certain areas are allowed to be utilized. Since there is bacteria in the liquid byproduct, any farmland that produces anything a human may consume is out. The use of a biosolids dryer eliminates those hazardous restrictions and opens the door for many more uses.
“This will enable us to change our biosolids from a Class B material, which is heavily regulated and requires state permits and restrictions on what we can do with it, to a Class A product that could be commercially sold,” Steve Miller, assistant public services director of Kinston Public Services, said in an interview with blueridgenow.com.
The shift from Class B material to Class A product is significant, largely due to the removal of hazardous substances that may be left behind in a typical wastewater treatment system.
“The dryer has a belt press that we run the wastewater through to draw out the liquid, leaving a solid material. Th en, that goes into a high-powered dryer where it makes the solid non-hazardous. We can then sell it to a customer or dispose of it in a landfill,” Sears said.
The end result is thousands of tiny black pellets that serve multiple uses.
“The pellets can be used in landscaping and really almost anything you would use fertilizer for,” Public Services Director Rhonda Barwick said. “Some companies have even mentioned burning it for biofuel. Citizens could come pick up a truckload, too, if they had a use for it.”
While the process itself is cutting edge, the real perk is the convenience of the dryer and ease of transporting the waste material to a landfill. The pellets collect in a large bin that is stored on site, allowing the city to control when they dispose of them.
“The dryer is so important because it makes the disposable solid lighter and, therefore, cheaper to dispose of in a landfill,” Sears said. “Eliminating all of the water allows us to avoid paying for the disposal of liquids, rather just a solid product.”
Barwick anticipates the implementation of the dryer leading to a less complicated process overall.
“Currently with the land application, all of us in the area are contracted with the same company for disposal,” she said. “We were getting boxed in by weather and availability. The dryer grants us more regulation. This is the solution to be able to get rid of waste in an environmentally friendly way when we need to.”
Biosolids dryers are largely popular in Europe, although a few regions of the United States have started exploring the option. As the recipients of a zero-interest $2.5 million loan as part of the Clean Water State Revolving Loan Fund, Kinston’s biosolids dryer will serve as a pilot program with the hope that other North Carolina cities will follow suit in the future.
While the dryer has not been permanently installed yet, a demo product was used in the city for six months and exceeded expectations.
“It’s unbelievable that this process even exists,” Sears said. “We were completely happy with the product and how it operated. We’re looking forward to implementation.”
During that demo time, Sears said, the water treatment facility staff had a chance to master maintenance and repair of the machine and to get comfortable with the way it operates. All repair parts are locally sourced, which is another appeal of the dryer.
Ease of process, convenience and innovation aren’t the only perks of the new technology — the city will save money in the long run, too.
“We calculate in the first 10 years, the expenses for the biosolids dryer will be within $20,000 of what we currently pay. After that period, we could see an annual savings of almost $200,000 per year,” Barwick said.
According to Barwick, implementation is pending some legal documents. Once those are complete, she expects to begin use of the biosolids dryer by late 2017.