Treatment of Dairy Cooling Unit Washing Wastewater using Modified Sequencing Batch Reactor (MSBR) with various Media

Abstract

A bench scale modified sequencing batch reactor (MSBR) was employed for treatment of diary cooling unit wastewater. The reactor was constructed in cylindrical shape with outlet nozzle at the bottom using borosilicate glass with capacity of 10 L. The reactor was supplied with oxygen by bubble air diffuser at the aeration rate of 4 L/h. The aeration rate was optimized by doing series of trials for MSBR operation. The reactor was fed with dairy cooling unit wastewater under different operational conditions. For microbe feed, 10 g of cow dung was employed. For abundant growth of methanogenous bacteria present in cow dung, nutrients like phosphate buffer solution of 15 mL and 2 g of anhydrous glucose powder was supplied. As attached growth, media brickbats and wood chips were employed. The reactor was operated in continuous mode and maximum hydraulic retention time (HRT) of 6 h was given. The treatment efficiency was checked at every 1 h interval. At maximum HRT, the COD removal efficiency was found to be 70%, BOD removal was at 73%, pH was brought down to nearly neutral level (pH 6.79), transmittance was increased up to 81% and absorbance was reduced to 0.09. The other parameters of the wastewater were also reduced eventually which is clearly shown in this paper.