How Oily Water Separator (OWS) operates?

Bilge water supplied into the separator by the positive displacement pump (usually piston-type). The pump is located either on the inlet or outlet of the separator. Last arrangement allows prevention the formation of an emulsion. As the oily bilge water enters the OWS, it flows upward through the mesh pack. The oil separates due to the reduced flow velocity and the difference in specific gravity between oil and water. Oil droplets impinge on the surface of the matrix plate pack and begin the coalescing process. The oil droplets coalesce until they become large enough to detach from the corrugated plates and gravitate to the top of the separator. Smaller oil droplets that escape the mesh pack are removed by the polishing pack. After the separated oil accumulates to a predetermined level, the oil sensor initiates the oil discharge and cleaning cycle by stopping the pump, closing the water discharge valve and opening the clean water inlet valve. This allows clean sea or fresh water to cleanse the mesh pack and flow upward in the reverse direction washing the polishing pack displacing the accumulated oil.
The outlet of the Oily Water Separator directed by 3-way valve either to overboard or to the storage tank. The valve controlled by 15ppm monitor which allows overboard discharge if oil content below 15 ppm and stops discharge if oil content is exceeded.