Oil-Water Separation and Purification Technology at Oil Depots

In oil product storage depots such as petrochemical plants, aviation fuel reserves and vehicle filling stations, water draw-off is the key step in which water accumulated at the bottom of a tank is separated from the oil phase during production, transfer, storage and processing. The oily wastewater generated contains oil, suspended particles and other pollutants and must be properly treated before discharge to limit harm to the environment.

At present, water draw-off treatment at these depots typically faces the following challenges:

Limited separation performance: crude oil and water often form an intimate mixture inside the tank, and long-established methods such as gravity settling, cyclonic separation or membrane filtration rarely achieve complete separation. Poor operation leaves residual water and impurities that directly affect product quality.

Poor economics: conventional separation relies on large amounts of energy and chemical additives, driving up treatment cost. Some technologies also need large facilities such as settling ponds, further raising land use and operating costs.

High safety risk: if water in the tank is not separated promptly or completely, pressure and temperature inside the tank can fluctuate abnormally and even trigger a tank explosion. Such events not only threaten smooth depot operation but pose a major risk to the surrounding environment and personnel.

Environmental hazards: wastewater from the process may carry oil, heavy metals and other harmful components. Handled poorly, these pollutants cause significant damage to the local ecosystem, so water draw-off must follow strict environmental rules and ensure discharged water meets standards.

To meet these challenges, SINOKLE has developed a new treatment process built around CDFU cyclonic dissolved gas flotation system, coalescing de-oiling unit and CDOF ozone advanced oxidation flotation integrated equipment as its core. The process sharply reduces petroleum substances, suspended solids, chemical oxygen demand and other pollutants in the wastewater, helping depots achieve compliant discharge.

Process flow diagram

The process offers several clear advantages:

First, strong load tolerance and stable effluent. The system copes with wide variations in water quality and keeps treating efficiently, with effluent consistently meeting strict discharge standards, a systematic answer to the long-standing industry problem of depot wastewater discharge.

Second, a simple, largely physical and environmentally friendly flow. The core of the process is physical separation with almost no chemical dosing, cutting the risk of secondary pollution. Performance is stable and sludge yield low, making downstream disposal simple: a clean, green technology.

Third, fully automatic enclosed operation with a small footprint and simple handling. The system runs automatically and enclosed, shielding it from outside interference and ensuring continuous, stable operation. The unit is compact and needs little space, which suits sites with limited room. A high degree of automation reduces manual intervention and maintenance effort and improves operational management.

Water draw-off treatment project at an oil depot