AUTOMATIC CHANGEOVER DISCHARGE VALVES OF SEWAGE TREATMENT PLANT

Abstract

Water containing faeces, industrial waste, and debris such as rust and plastic made up of raw sewage. The effect of sewage on the marine environment is a source of concern. Pathogens, nutrients, detergents, pesticides, and heavy metals can all pollute seawater. As much as it could contaminate the sea, the environmental and health risks are also high for humans because the community shares the seawater for recreation, swimming, and food production. The sewage treatment system on most of the ships is designed to remove pollutants from sewage water before it is discharged into the sea. The basic principle of a sewage treatment plant on board is to treat and process raw sewage through a series of steps that include breaking, filtering, settling, controlled aerobic decomposition, and chemical treatment before it is discharged into the environment. The sewage water treatment system is one of the most important systems on board. According to MARPOL 73/78 of ANNEX 1V (Prevention of Pollution by Sewage from Ships), all ships 400 gross tonnage and above that carry more than 15 persons should have an approved sewage treatment plant. If the sewage is comminuted or disinfected, it can only be discharged overboard using a permitted sewage treatment plant 3 nautical miles from the nearest land. If the sewage is not comminuted or disinfected, the sewage may be discharged at 12 nautical miles from the nearest land when the ship is en route and proceeding in not less than 4 knots (Anish, 2021).