Oily wastewater treatment is generally divided into primary treatment and secondary treatment. The primary treatment is to separate free oil, dispersed oil and sludge from water and emulsified sake koji. The secondary treatment is to destroy the oil-water emulsion and separate the remaining oil.

The process of removing oil from oily sewage to make the water quality meet the discharge standard. Oily sewage in power plants mainly includes drainage from oil storage tanks, tanker trucks, flushing water from oil unloading platforms, drainage from oil pump houses, purging drainage from oil pipelines, drainage from bearing oil systems of steam turbines and rotating machinery in main buildings, rainwater drainage from oil storage tanks and ground flushing water.

The oil content is about 600 ~10000 mg/L. When oily sewage is discharged into rivers, lakes or bays, it will pollute water bodies and affect the survival of aquatic organisms. If it is used for agricultural irrigation, it will block soil gaps and hinder crop growth. Therefore, oily sewage must be treated before it can be discharged.

Oily sewage sources include petroleum, chemical industry and other industrial sectors. Flocculation, flotation, filtration and other methods are often used. According to the characteristics of oily sewage and the requirements of effluent quality, biological treatment should be adopted in sewage treatment process to achieve the expected purpose.

Features:

1. Only oil, some solid impurities and suspended solids in the oily sewage of ships exceed the national sewage discharge standard, and other toxic and harmful substances are not exceeded.

2. The dispersion state of oil in oily water from ships is mainly floating oil and dispersed oil, and emulsified oil without surfactant.

3. The measurement results of the particle size distribution of dispersed oil droplets in oily water of ships show that the oil with the particle size less than 10 micron accounts for about 15 of the oil concentration.