Wastewater Treatment for Oil Industries

Wastewater generated from oil-based industries (such as palm oil and crude oil refinery) can be effectively handled with simple common treatment processes because mainly oil and water does not mix together. The treatment process only gets complicated when there is soap present, which naturally forms when there is caustic soda being added that acts as a surfactant that causes both oil and water to become emulsion and hard to separate. Generally the most important step towards oil removal is by using mechanical separation unit and later part, treatment at the DAF system should further bring down COD level before final biological process takes place at aeration tank.

Usually large buffer tanks play a major role to contain wastewater and provide a better control towards overall system setup because fluctuation in terms of incoming water quality will not cause drastic differences that will affect other processes. This can prevent automatic system such as pH adjustment device, which can sometimes unable to immediately or accurately respond to the new changes. The first step towards recovery of oils and lowering the COD load is by discharging the water to equalization tanks. These special-made tanks comprising two different compartments will have a built-in bottom baffle plate, which allows only water to pass through. Although this is a crude separation, it also offers a way to recover back waste oil which can be used for burner.

The next step will usually followed with acidulation process whereby the pH will be lowered down to about 3 to 4. This can be achieved by adding sulfuric acid (25 – 50% concentration) in order to break up the large oil particles that manage to escape from the equalization tank so that it become smaller particles. Lighter molecule will mostly float to the top and then scrapped off using a scrapper to further remove percentage of oils left in the wastewater. From here onwards, wastewater will then be sent for combination of chemical and physical treatment processes at the DAF and then finally to aeration tank. Read up about DAF system and function of aeration basin to get a better view of the whole system and learn about the best approaches.

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