Wastewater cogeneration projects
The Johnson County Wastewater department is implementing improvements at the Douglas L. Smith Wastewater Treatment Plant, which was recently expanded to process 14.5 million gallons of wastewater per day. The project will include the addition of a new anaerobic digester; a fats, oils, and grease (FOG) receiving station; a cogeneration system and gas storage and handling. The estimated cost of the project is $15.1 million, most of which will be funded through the American Recovery and Reinvestment Act.
The project is believed to be the largest of its kind in the history of the state of Kansas. The following benefits are anticipated:
Local power generation and carbon footprint reduction
Biogas from the digesters will be used to power two new cogeneration units that will generate power for the treatment plant. The cogeneration system is designed to generate 12,000 megawatt-hours annually – enough to supply all of the plant's power needs. The installation of the cogeneration system is estimated to reduce the county's utility costs by $540,000 per year and reduce the treatment plant's carbon footprint by 9,600 metric tons of CO2 equivalent (CO2e) annually.
Reduced travel from waste hauling
Currently waste grease and oils from restaurants and industrial facilities in Johnson County must be hauled to a location outside of the county. The FOG receiving station that will be constructed at the Smith Treatment Plant will reduce the average distance traveled by FOG waste haulers from 75,000 miles to 35,000 miles annually. This will result in 8,000 gallons of annual diesel fuel savings, which corresponds to a reduction of 80 metric tons of CO2e per year. The use of FOG is estimated to triple the biogas production capability of the treatment plant.
Reduced travel for sludge hauling
Upon completion of the improvements at the Smith Treatment Plant, sludge generated at the Blue River Treatment Plant in eastern Johnson County will no longer need to be hauled to a more distant facility. This will save approximately 25,000 miles annually in truck hauling, which equates to cost savings of over $62,000, fuel savings of 1950 gallons, and the elimination of 20 metric tons of CO2e annually.
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The wastewater project will turn biosolids produced in wastewater treatment and restaurant grease into enough electricity to power a wastewater treatment plant capable of treating the flows from almost 150,000 people. The work is part of the $15.6 million in improvements to the treatment plant complex funded by the American Recovery and Reinvestment Act. |
Additional beneficial reuse of biosolids
Blue River Plant sludge is currently sent to the landfill. Blue River sludge along with FOG received at the Smith Treatment Plant will now be added to the biosolids from Middle Basin where the current practice is land application. The reuse of Blue River biosolids and FOG will increase the overall reuse of biosolids in the Johnson County Wastewater system by nearly 30 percent. The annual reduction in CO2e gained by carbon sequestration through land application has not been calculated at this time.
Johnson County Wastewater is in the process of conducting a feasibility study to determine if its Myron K. Nelson and Mill Creek treatment plants would be good candidates for cogeneration projects. Preliminary results are expected in early 2010 and will be posted here.
Click here for information about the Johnson County Wastewater department.
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