Marine vessels are presently required by Federal Regulations to have certified sanitation devices installed to hold or treat sewage. There are four general types of such sanitation devices categorized as “flow-through and discharge” devices and “non-flow-through” devices. The “flow-through and discharge” devices receive and treat sewage, producing an effluent that meets specified fecal coliform (FC) population and total suspended solids (TSS) limits. The “non-flow-through” devices are designed to collect and hold either sewage only, or a combination of graywater and sewage, depending on the system design, to enable the ship to transit restricted navigable waters. Graywater is defined as wastewater from showers, sinks, laundry, galley and scullery sources. No wastewater treatment is performed in the “non-flow-through” type of systems.
Both commercial and military vessels frequently travel to foreign ports which have discharge regulations that are so restrictive as to establish limits not only for TSS and FC, but also for biochemical oxygen demand (BOD). A reduction of BOD to specified limits can only be achieved through selected methods of treatment. It is therefore an important object of the present invention to provide a system for marine vessels including U.S. Navy ships that will collect and treat both graywater and sewage, producing a clean effluent that satisfies current and anticipated limits for BOD, TSS, and FC.