The station undertook water conservation to reduce the amount of nutrients in our wastewater. Nutrients, nitrogen and phosphorus are harmful to receiving bodies of water as they cause algae blooms that reduce available oxygen for other organisms. Nutrient Total Maximum Daily Limits (TMDL’s) set by Maryland Department of Environment (MDE) and the Environmental Protection Agency (EPA) for Chesapeake Bay and major tributaries like the Potomac River – the Plant’s receiving body. Before merging with NRG, GenOn submitted a request to reopen the NPDES permit to Maryland Department of Environment (MDE) in August 2010, and had been working with MDE to resolve this issue since that time.Since the scrubber wastewater treatment system was brought on line in late 2009, we have continued to explore all options to increase the effectiveness of the system, including:•Lowering and equalizing the chlorides in the Sequential Batch Reactor (SBRs).•Enhanced use of Klaraid in the SBRs and the effluent tank•Improved clarifier performance•Improved temperature stabilization•Capturing ammonia rich plant demineralizer regeneration wastewater and routing it to the WWTP for nitrogen removal•Hiring a consultant with specific expertise in the operation of SBRs to improve operational results •In 2014 we completed the pilot study that showed lower, controlled solids retention times in the SBRs would help the station maintain nutrient levels in the 4 mg/l range. To be able to run at such a low SRT, filters that could capture, quantify and return solids to the SBRs would be necessary. NRG ran a membrane study to ensure that technology would be compatible with the scrubber wastewater. In addition, we are in the process of installing new instrumentation to the SBRs that could improve operations.

Project Results