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Research Article
Treatment of Oily Waste Water Emulsions from Metallurgical Industries Using Microwave Irradiation

N. Saifuddin and K.H. Chua

Biotechnology, 2006, 5(3), 308-314.


Emulsion waste water is one of the important industrial wastewaters, which results from the various manufacturing industries including the metal manufacturing and its processing. Wastewater treatment technologies utilizing flocculation and electrolysis have been used but these technologies have not been very helpful in resolving the problems in view of process consistency and economic merit. Aiming to mitigate the environmental hazard that these waste emulsions represent, a study was carried to investigate the microwave methods to destabilise water/oil emulsions without the addition of any destabilizing chemical agent. The experimental work consisted on breaking the simplest of the emulsions in terms of content, in order to obtain preliminary data that can help to extend the method to manage actual waste material. The samples consisted in water/oil emulsions waste (spent cutting oil), which was obtained from local metal industries. The sample emulsions underwent a domestic microwave radiating process at several exposure times. Certain factors, such as aromatic components and sodium hydroxide content and total heat exposure time proved to be the factors that more strongly affect the results. Within the category of paraffinic oils, light oils allow for quicker water separation than heavy oils. Also oils with higher aromatic content have higher viscosity, which makes the separation of water more difficult. It was observed in this study that emulsions added with acid up to a final concentration of 0.48 M, the separation efficiency and demulsification rate increased with increasing acid concentration. Hence microwave irradiation is an economical and rapid method for oil separation from oily waste water. Although this study was carried out on a lab scale basis, the process can scale up to a large industrial scale system. By using the microwave radiation, an aqueous phase recovery that ranged from 65 to 90% was obtained, which is a significant outcome that reveals the study of this technique needs to be taken further.

ASCI-ID: 11-215

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