High solids anaerobic digestion system unveiled in Ohio

By City of Akron | November 08, 2013

Once again, Akron, Ohio, is at the forefront of “green” technology as it manages the biosolids generated from the Water Reclamation Facility. The Renewable Energy Facilityonce known as the Akron Compost Facility, now uses a state of the art high solids anaerobic digestion system (ADS). Biosolids once used to make compost is now transformed into biogas that produces renewable energy in the form of electricity. KB BioEnergy, formerly known as KB Compost Services, is now processing 100 percent of the biosolids through Akron’s new $32 million facility.

KB BioEnergy, a premier biosolids management company in Northeast Ohio, is dedicated to promoting new, environmentally responsible means and methods of creating usable byproducts from waste solids better known as biosolids. The city and KB BioEnergy have had a public-private partnership since 1989 to manage the biosolids through the city’s composting facility. In 2007, the city contracted with KB BioEnergy and constructed the ADS (Phase I) which processed one-third of the biosolids generated by the City while producing renewable energy. The success of that demonstration project resulted in a renewed contract with KB BioEnergy and the construction of the Phase II plant, which is three times the size of the original ADS and accommodates 100 percent of the city’s waste stream.

The Phase II plant incorporates the Bioferm/Schmack Biogas technology that was successfully demonstrated in Phase I. In addition, a new dryer by Komline-Sanderson was installed to dry the solids that remain after the digestion process has occurred. Approximately 15,000 cubic yards of “pellet-like” material will be generated through this process.

In the ADS process, the biosolids have a dual purpose. The biosolids contain microorganisms responsible for breaking down the wastes, and provide nutrients to sustain the microorganisms.  The biosolids are regularly added to the digestion tanks, which are maintained at 95 degrees Fahrenheit. The wastes are broken down and biogas is generated. This biogas is then used to fuel three 600 kilowatts (kW) combined-heat-and-power units. Expected renewable energy production will be 10,000 megawatt hours (MWh) annually, which is enough electricity to power 1,400 homes each year. In Phase II, the excess electricity will be used to offset the needs of the Water Reclamation Facility.

- With this new facility the City of Akron will recognize the following benefits:

- Generation of renewable energy available 24 hours a day, 7 days a week and 52 weeks a year

- Management of solid wastes or biosolids for future generations extending out 30 to 50 years.

- Reduction in greenhouse gas footprint

- Generation of sustainable products in the form of electricity and pelletized organics

“With the completion of Phase II, our Water Reclamation Facility will be ‘energy neutral,’ meaning all the electricity required for the facility is produced on site,” said Mayor Don Plusquellic.  “Not only is this a great technology that we’ve imported from Germany to help ‘green’ our city, but we are also a true business partner in this project -- for every community that constructs an ADS system based on Akron’s model, Akron receives a royalty.  And, Akron should have a good return on its investment as other cities around the country start using this money-saving, energy-producing, innovative process.”