(1) Oily ballast water

After the oil tanker has unloaded its oil, in order to ensure safe navigation and improve the efficiency of the propeller, a certain amount of water must be installed in the cargo oil tank or ballast. The mixed water and the viscous oil attached to the bulkhead become the pressure. Carry dirty oil and water. Generally, ballast water occupies about 25 of the load of the wheel, and the oil content is about 3000 mg/liter. The average oil content of the ballast water middle layer is generally 12 ~ 15 mg/L. Since the discharge of ballast water has a certain time limit, the source is extremely uneven. Obviously, clean ballast water and dedicated ballast water do not contain dirty oil.

(2) Oily tank washing water

The cargo oil tank must be cleaned when the oil tanker enters the factory to repair or change the oil product. The slop water produced by using high-pressure water to clean the cabin is called the slop water. The amount of washing water is generally about 20% of the ship's load. The oil content of the washing water is generally about 15,000 mg/L. The concentration of layer oil in the washing water is 30-130 mg/L. Obviously, the use of crude oil washing technology to wash tanks does not produce the above-mentioned large amount of slop water.

(3) Engine room water

Ship engine room water is due to the slop water leaked from various valves and pipelines in the engine room mixed with the lubricating oil, combustion oil, etc., which are recited during the operation of the turbine. The annual water volume of the engine room is generally about 10 of the ship's gross tonnage. The water quality is more complicated. It is a mixture of various oils and the oil content is generally around 5000 mg/L. The average oil content in the water layer of the cabin is about 250 mg/liter.