SEWAGE PLANT LEGISLATION

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Legislation preventing the discharge of untreated waste overboard has been in place for some time with a requirement that it should be retrofitted where not already in use. American legislation defines three types of sewage treatment units.

Type 1	A device capable of discharging effluent having no floating solids and a coliform count of less than 1000 per 100ml of effluent.
Type II	A device capable of discharging effluent with suspended solids not in excess of 150mg/litre and a coliform count of less than 200 per 100ml
Type III	A device to prevent the discharge overboard of treated or untreated waste.

Ventilation systems are to be kept independent of other vents A log is to be kept of any discharge overboard from a holding tank 1.     Subject to the provision that discharge is not required for the safety of the vessel, the discharge of sewage into the sea is prohibited, except when:

a.     the ship is discharging comminuted and disinfected sewage using a system approved by the Administration in accordance with regulation at a distance of more than four nautical miles from the nearest land, or sewage which is not comminuted or disinfected at a distance of more than 12 nautical miles from the nearest land, provided that in any case, the sewage that has been stored in holding tanks shall not be discharged instantaneously but at a moderate rate when the ship is en route and proceeding at not less than 4 knots; the rate of discharge shall be approved by the Administration based upon standards developed by the Organization; or

b.    the ship has in operation an approved sewage treatment plant which has been certified by the Administration to meet the operational requirements referred to in regulation of this Annex, and

                              i.        the test results of the plant are laid down in the ship's International Sewage Pollution Prevention Certificate (1973);

                             ii.        additionally, the effluent shall not produce visible floating solids in, nor cause discoloration of, the surrounding water; or

c.     the ship is situated in the waters under the jurisdiction of a State and is discharging sewage in accordance with such less stringent requirements as may be imposed by such State.

2.     When the sewage is mixed with wastes or waste water having different discharge requirements, the more stringent requirements shall apply.