Reliant Energy has selected Siemens Water Technologies to provide a system to treat wastewater from a flue gas desulfurization (FGD) scrubber being constructed at the Keystone Generating Station. The plant is located about 40 miles northwest of Johnstown, Pa., in Plumcreek Township, Armstrong and Indiana counties.
Keystone is jointly owned by seven electric companies, including Reliant Energy, which also maintains and operates the station on behalf of all owners. The wastewater treatment system will de-saturate the wastewater and remove suspended solids and heavy metals from the scrubber waste stream so the water can be safely discharged. The project is scheduled to begin operation in 2009.
The wastewater system will include storage tanks, reaction tanks, chemical feed systems, a clarifier, gravity sand filters and belt filter presses. An equalization tank receives the waste stream and equalizes the flow to eliminate spikes in flow rates and concentration. Next, two reaction tanks in series continue the treatment process to de-saturate the wastewater, reduce heavy metals and prepare the wastewater for clarification. The treated wastewater then enters the clarifier process, where suspended solids are coagulated and settled. Solids from the clarifier are dewatered in the filter presses. The remaining treated water from the clarifier is sent to a gravity sand filter for final treatment before discharge. The system flow rate is 450 gal per minute.
The Keystone Generating Station consists of two coal-fired, steam-electric generation units with a generating capacity of 1700 megawatts.
Source: Siemens
