Microturbine to burn digester gas from wastewater facility

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As one of the first wastewater treatment facilities in the state to become energy-neutral, the Eastern Ohio Regional Wastewater Authority (EORWA) celebrated the grand opening of their recently upgraded Resource Recovery plant in Bellaire, Ohio with a ribbon cutting ceremony, hosted tours, and luncheon. The $5.3 million upgrade project, led by quasar energy group, constituted design-build services of an anaerobic digestion system that was retrofit into the plant's existing assets. Fully powered by a Flex 


which converts gases from the digesters into electricity, the system also includes flexible membrane roofs, heat exchangers, feedstock receiving, mixing system, and a pre-digestion Class A system.

In addition to enabling the facility to go off the grid, the upgrades have given EORWA the ability to harvest additional renewable energy from residual organic waste. Raw materials generated in the Ohio Valley such as agricultural and municipal waste, manure, plant material, sewage, food waste, etc. would otherwise be sent to landfills and buried. But the new anaerobic digesters installed by quasar energy group divert this waste and turn it into biogas for the microturbine.

"Upgrading to the anaerobic digesters was the most effective way to address infrastructure improvements without passing the costs on to ratepayers. Anaerobic bacteria break down the volatile solids in the digester, releasing biogas, which is then combusted by the Flex 


 to generate electricity. The electricity generated then helps power the system, further enabling energy neutrality," explained Renato Contipelli, Municipal Manager for quasar energy group.

The industrial Flex 


GT333S (333 kW) that powers the system is the most advanced in the industry with up to 85% Combined Heat and Power (CHP) efficiency and variable inlet guide vanes. With less than 9 ppmv of NOx the Flex



 readily meets even the strictest air quality standards and environmental regulations. The 


 has proven reliability (99+% uptime) and runs continuously off grid using the site's digester biogas. This provides both clean air and renewable energy for the plant 24 hours per day, seven days per week.

"In looking at ways we could stabilize our rate structure, we wanted to think outside of the box and utilize new technologies. This project allowed us to go off the grid and be independent from the utility," said EORWA's Executive Director, Valerie Moore. The resulting biosolids generated at the EORWA facility are designated as Class A/EQ Quality, which meets U.S. EPA guidelines for land application with no restrictions. Thus, the resulting class A biosolids will be used as a replacement for commercial fertilizer in the region. Primarily used on area farms for wheat, corn, and soybean crops, the commercial fertilizer offsets the use of chemical fertilizers that are derived in part from mining minerals and/or burning fossil fuels.

Devised from the microturbine manufacturer FlexEnergy, a manufacturer of natural


powered microturbines and custom-fit heat exchangers, Flex Energy Solutions expedites commercial accessibility of localized service for the Flex