Empirical Investigation of Treatment Process of Outlet Waste Water from Petroleum Industries

Published researches about the pretreatment of exit wastewater from desalination units are rare. Nowadays, lake of potable water, development of industries and population growth, extend desalination units. Although desalination units have been grown up, but exit brine stream is usually drained into the sea ecosystem [1-4]. Moreover, annually a large quantity of concentrated brine is discharged into the sea [5,6]. By treatment of this saline wastewater, it is possible to eliminate the hazardous effects of salinity on sea ecosystem. Additionally two valuable matters, salt and sweet water can be produced. Total hardness and turbidity of wastewater must be reduced during pretreatment process of wastewater to produce Sodium Chloride salt [7,8]. Coagulants are the matters used to decrease total hardness of wastewater. The pretreatment process includes 3 steps: coagulation, flocculation and sedimentation. Improving the efficiency of pretreatment process depends on water specifications and also the operating parameters [9-11]. The optimum mixing rate of first pretreatment reactor, type of coagulant, ratio of sodium carbonate to coagulant and sodium hydroxide to coagulant are some of the important factors in operating conditions. Polyelectrolytes or mixture of coagulants can be used to improve the efficiency of total hardness removal [12,8]. In this research various binary mixtures of three mineral coagulants were investigated quantitatively and qualitatively. The optimum amounts of Sodium Carbonate to coagulant and Sodium Hydroxide to coagulant were studied for each coagulant individually. This shows that the best ratio for Sodium Carbonate to coagulant is three and for Sodium Hydroxide to coagulant is four. Materials and Methods