IACS Approved IMO MEPC227(64) Standard Marine Sewage Treatment Plant For Ships

1. Marine Sewage Treatment Plant Preface 

    The Marine Sewage Treatment Plant belongs to the key device for prevention of pollution form ships in seas and oceans according to the revised Annex IV of the International Convention of the Prevention of Pollution (MARPOL 73/78).
    This device is according to the MEPC.227(64) resolution enacted on 5th, October, 2012. Which only used to the "black water" from toilet fecal sewage. In the treating process, to add any dilution water, gray water (from washing room), and sea water are forbidden. This device is also not suit for the passenger vessles which on the Baltic Sea. This device is regardless of the total nitrogen and total phosphorus performance index requirements.
    This device is apply to install on the below vessels later 1st, January, 2016:
    (1) All areas of the vessel (except passenger vessle),
    (2) The passenger vessel beyond of the Annex IV of the International Convention of the Prevention of Pollution (MARPOL 73/78).

    The SWCM(I) type marine sewage treatment plant uses activated sludge, contact oxidizing and principle of biologic membrane (MBR) to digest the organic pollutant, which can treat sewage effectively and reach at the IMO new effluent standard or other stricter requirements. The device is patent product, provided with independent innovation intellectual property.

2. Process Principle 

   The device adopts activated sludge, contact oxidizing and principle of biologic membrane to digest the organic pollutant, which can treat sewage effectively and meet the IMO new effluent standard or other stricter requirements.
    In the 1st stage aeration tank, the activated sludge mainly consisting of aerobic bacteria form sticky flock is used to absorb and digest the organic substance to carbon dioxide and water under the condition of aeration, and produce new activated sludge in the meantime. The bacteria will die owing to the decreasing of organic pollution substance. The death bacteria are digested by the protozoa and the metazoan, which attached in the active sludge. The 95% of the sewage is easy-digested organic substance, they are oxidized entirely.
    The soft bio film stuffing is hung in the 2nd stage contact oxidizing compartment. The bio film, which can digest organic substance, is floated in water. Most of the protozoa and the metazoan live in the fiber film. The organic substance is further digested by the protozoa on film. If restarting plant after stopped for some while, the restarting time is much quicker than that of conventional aeration starting time, because of the bacteria existing in the spore on the membrane. Meanwhile, the soft stuffing, similar as "cotton boll", is able to expand as over nutrition and absorb superfluous activated sludge, or digest themselves as lack of nutrition, which is also called "endogenous respiration". The "cotton boll" will be shrunk and wait for the future nutrition.
    Then the sewage enters into setting tank and the sludge will settle as no aeration and with help of solid filter material. The activated sludge sediment accumulated in the setting tank is to be returned to the 1st stage aeration tank by the method of air lifting for reproducing of aerobe medium.
    The clear supernatant liquid then flows into membrane tank, and creates good operational conditions for membrane module. The membrane module placed in membrane tank is an immerged type and can create biochemical reaction, which is also called membrane bio-reactor (MBR). The membrane is made of hollow fiber ultra filtration material, through which the permeated clean water is sucked by self primingpump, then disinfected by ultraviolet ray (or ozone), it can meet effluent standard, and discharge overboard or to clean holding tank on ships.
    It is designed automatic lifting procedure for the sludge sediment in membrane tank. When the self priming pump is working, the solenoid valve opens once every 30min to lift the sludge in membrane tank to the 1st stage coalscer. SV2 is closed after it is opened for 5min. Then the solenoid valve SV3 in settling tank opens for 5min to lift the sludge in settling tank to the 1st stage coalescer. And that cycle repeats. Note: only when the self priming pump is working, the device can lift the sludge in membrane tank.

3. Main Technical Parameters