The oily sewage treatment system is a system used to collect, store, treat and discharge the bilge water of the machinery spaces of ships. The sewage discharged from the machinery spaces shall meet the requirements of the regulations, that is, the ships are not in the special requirements area; ②The oil content of the undiluted discharge does not exceed 15×10; ③The oil discharge monitoring and oil-water separation equipment is being transferred.

Oily sewage treatment is to remove oil from water, and the separation method is mainly used to remove oil on ships. Oily sewage is a mixture of oil and water in a dispersed or emulsified state. Due to the different density and viscosity of water and oil, oily wastewater has a tendency to separate naturally. The floating speed of oil particles in water is directly proportional to the oil-water density difference and inversely proportional to the viscosity of water. The lower the water flow rate, the higher the water temperature, and the larger the size of oil particles, the more advantageous it is for oil-water separation. Due to the stirring of the pump and the mixing of various emulsifiers in the oily sewage on ships, the particle diameter of the oil is less than 250 μm, and gravity separation alone cannot meet the discharge requirement of 15×10. Generally, multiple plates or tube bundles and blocking are used to promote the polymerization of oil particles, so that the treated water meets the discharge requirements.

On the premise of complying with the requirements of the Convention, we have also noticed that although the slop tank does not have the function of prohibiting its loading, it does not mean that the slop tank can be used at will. It is necessary for the crew to make judgments on the following aspects:

1. During the operation of this voyage in the future, there is no need to collect "cabin discharge, tank washing water and other oily mixtures";

2. When the slop tank is used for cargo, the loading conditions can meet the requirements of the loading manual and other documents;

3. If there are tank discharges, washing water and other oils previously collected in the slop tank

When mixing sexual mixtures, mixing should be avoided, especially for product oil tankers.

4. The quantity and whereabouts of dirty oil and water collected during operation should be accurately recorded in the oil record book, and corresponding evidence should be provided