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Treatment of Simulated Shipboard Gray Water in a Lab-Scale Membrane Bioreactor

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The Coast Guard is challenged to operate its fleet of ships in an environment of increasingly stringent shipboard wastewater discharge standards. Under the Uniform National Discharge Standards UNDS now in development, standards will be set for several non-sewage discharges from ships including gray water. Shipboard generated gray water contains high levels of typical wastewater pollutants including biochemical oxygen demand BOD, total suspended solids TSS, total nitrogen TN, and total phosphorous TP. Since gray water is typically produced at rates much greater than that for black water, ships will have very limited capacity to store untreated gray water when operating in regulated waters. The U.S. Coast Guard Academy has been involved in a multi-year project supported by Engineering Logistics Command to investigate the feasibility of treating shipboard black water and gray water in membrane bioreactors MBRs. MBRs with submerged membrane modules are considered a promising wastewater technology for use aboard ships since significant treatment can occur in a small space and the use of a filter for solids separation eliminates the need for gravity separation which would be infeasible on a ship. In past years, a lab-scale MBR system was designed, constructed, and used for three successive years to treat shipboard gray water and black water in various combinations. This report contains the results of an experiment conducted in Spring 2005 to treat simulated shipboard gray water in the lab-scale MBR for simultaneous removal of BOD and TN. Initially an experiment was performed to identify a recipe for shipboard gray water that most closely matches the composition of gray water from Coast Guard ships.

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  • Water Pollution and Control

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