A Review On Oil Water Separation Techniques
Abstract
Oil-water separation or demulsification has recently gained significant attention of the scientific community as it helps in resolving many industrial oil wastewater crises. Many industries such as mining industry, petroleum, food, textile and other mass production units continuously emit traces of oil in wastewater and pollutes the entire area where it is dumped. To understand the oil-water separation or demulsification,we first have to understand water-oil emulsion or emulsifictaion.
Water-oil emulsion forms when oil is mixed vigorously with water and made an immiscible mixture in presence of a stabilizing agent or vice-versa. Generally, there are two types of emulsion industries deal with. First is the water-in-oil emulsion (W/O emulsion) in which the water is dispersed phase or solute and oil is dispersion medium, while the second is the oil-in-water emulsion (O/W emulsion) where oil is dispersed phase or solute and water is dispersion medium. Water in oil or oil in water emulsion can be further divided into four types, namely stable water-oil emulsion, mesostable water-oil emulsion, entrained water-oil emulsion, and, unstable water-oil emulsion.
There are various demulsification techniques available, but for optimum result various parameters should be taken in to account such as salinity, temperature, pH value, emulsifier/demulsifier concentration and emulsion constituent (such as oil, surfactant, salt, alkali, polymer). Thus taking account of all these factors, demulsification techniques can be divided in to three categories, i.e. physical, chemical and biological treatment. In chemical treatment, chemically synthesized demulsifier agents are used to separate oil-water emulsion. On biological treatment, microbial is used as alternative for chemically synthesized demulsifiers. In physical demulsification process, various techniques such as gravitational techniques, skimming, thermal treatment, electrical and membrane demulsificationare used. All of these techniques have some specific advantages and limitations. There is very much scope of these techniques from future prospect. This paper have reviewed some contemporary demulsification techniques and discussed their advantages, limitations and application in various fields.