One Rotary Sludge Dryer Benefits Many WWTPs

The Clearwater Cogeneration Wastewater Treatment Plant (WWTP) in Corona, Calif., is using a Sernagiotto directly heated sludge dryer from the Water Technology division of the Siemens Industrial Solutions and Services Group (I) to process 8 mgd of combined municipal and industrial hydraulic influent, as well as sludge, from the city's three other WWTPs. Since coming online four months ago, the dryer system has saved the Clearwater plant considerable wet cake hauling costs and helped it meet U.S. EPA's strict 40 CFR Part 503 regulation. The Sernagiotto dryer system is part of a combined system that produces electricity and dry, dewatered biosolids by using the hot exhaust gas to recover energy from the combined-cycle cogeneration turbine. This is the first Sernagiotto dryer installation in the U.S.

According to Frank Garza, plant supervisor, the dryer will reduce the normal wet cake handling to 20% of the present production volume and thus save the city money. It will also prevent odors that could have been a major problem because of the plant's location within city limits.

The Clearwater plant will ultimately sell all of the effluent water produced and beneficially reuse the Class A biosolids for land applications. In turn, the community will use the produced electricity, and the city of Corona will sell any excess to the electrical grid.

The dryer system is designed to evaporate 8,800 lbs of water per hour from the wet cake produced by the belt filter press dewatering system. It includes a belt conveyor system that will either direct cake to the dryer wet feed silo or to a truck loading station for disposal. The dryer contains the latest safety sub-systems based on years of experience with Siemens' European engineering and manufacturing partner, Sernagiotto. The dryer uses a regenerative thermal oxidizer that reduces the potential odor problem to harmless carbon dioxide and water.

Source: Siemens Water Technologies