AKRON, OHIO- THE CITY INCORPORATES AN ANAEROBIC DIGESTION PROCESS INTO THEIR BIOSOLIDS MANAGEMENT PROGRAM

The City of Akron has been managing their wastewater solids over the last 20 years by composting. While the operations of the facility and the marketing of the end product have been a success, it has not come without its trials. Odors still are present and the cost of operations is steadily increasing. With oil prices rising at a record pace, amendment materials such as sawdust, once thought to be a waste, are now an alternative fuel source and demand higher prices. In addition, the transportation of various amenities (polymer, chemicals) inclusive of the sawdust coupled with a lower net return for the sale of compost have all contributed to an overall increase in operational costs. Likewise, the ever increasing costs associated with labor highlighted mainly by uncontrollable rising health care costs have also contributed to increased costs. In a continual effort to minimize odors and find a way to stabilize the costs associated with handling the wastewater solids, the City has turned to an anaerobic digestion process whereby fewer amenities are necessary for it to operate and labor is minimal.The anaerobic digestion process being used in Akron comes from a US firm, Schmack BioEnergy. Schmack BioEnergy, along with its parent company Schmack Biogas AG from Germany, has been maximizing the generation of biogas while anaerobically digesting feed stocks high in solids (whether they are an organic waste or specifically grown for use in the digester) over the last ten years. Phase I of the anaerobic digestion process in Akron is designed to handle up to 5,000 dry tons. This is approximately one third of the solids presently being composted.This paper will provide a closer look into how the anaerobic digestion process is being phased into the Akron composting operation and how the present infrastructure is being used for the anaerobic system. A review of present composting operational data will also be presented and the impact anaerobic digestion will have on the operational and maintenance costs of the operations. Likewise, a look at the anticipated costs for just the anaerobic digestion system will be explored. Finally, this paper will include an analysis of how the present composting facility could accommodate a 100% anaerobic digestion process.