The essence of the oil is a viscous liquid, often with a characteristic odor lighter than water and often insoluble in water. They oxidize very slowly, can survive up to 50 years.

In fact, oil exists in water in many different states and it is difficult to accurately identify these components by experiment. Common oil exists in water in the following 4 states:

Free form: In this form, the oil will float into oil film, oil exists in the form of free oil particles or mixed with a little water, free oil will float on the surface due to the specific gravity of the oil is lower than the weight. own water.

Mechanical emulsion form: There are two types of mechanical emulsions depending on the diameter of the oil drop:

  • A few dozen micrometers: low stability.
  • Smaller type: high stability, similar to glue.

Chemical emulsion form: A form formed by chemical agents (soap, caustic soda, detergents) or asphalten chemicals that alter surface tension and stabilize dispersed oil chemistry.

Soluble form: Molecules dissolve as aromatics.

In addition, insoluble oils form a thin film that wraps around suspended solids, which can affect the ability to settle or float of suspended solids when forming combined non-settling compounds.

Proposed technology diagram


The production wastewater containing grease and oil generated during the operation of the Western Petroleum Depot is collected along pipelines and ditches and then brought to a centralized treatment station.

Waste water receiving and conditioning tank is the first oil receiving wastewater treatment plant of the treatment plant. This work is responsible for receiving and regulating the flow and quality of wastewater. Oil contaminated wastewater is transported by 02 pumps that transport wastewater from the receiving tank and regulate the wastewater to the DAF flotation treatment device. Pump operates according to signal of float level indicator.

DAF flotation device is an oil treatment unit that is completely imported and synchronized from abroad. Flotation device consists of 3 processing tanks placed in succession. The waste water from the regulating tank is pumped into the mixing tank, where flocculation chemicals are added to the water, thanks to the high speed agitator that the flocculant chemicals are mixed with the waste water. The waste water is then transferred to the reactor tank, where the colloidal chemical aid, PAA, is mixed with wastewater by a low-speed agitator before flowing to the DAF flotation tank.

DAF flotation device system diagram

At the DAF flotation tank. Thanks to the operation of the device including high pressure pumps, compressors and pressure vessels. Micro-sized air bubbles are generated in the treatment tank. These bubbles have gravity attached to the particulate matter in sewage, grease and tiny floating on the surface of the tank to form bubbles or scum floating on the tank surface. After that, the foaming system will clear this scum and lead the pipes to the waste oil container. Sludge in flotation tank will be periodically discharged to the sludge drying yard by the operation of electric valve. Clean water after the treatment tank is usually drawn from the end of the flotation tank, which is piped into the receiving water

+ The waste sludge stored in the waste mud drying yard, the waste oil stored in the conditioning tank and receiving the waste oil will be vacuumed and periodically removed and treated according to regulations. Waste oil tanks after flotation equipment are also closed and transported to handle as prescribed.