Major pollution sources in opencast coal mining are pumping of mine effluents; run off from coal stock yards, overburden dumps and haul roads; effluents from workshop and washing of heavy earth moving machinery and coal handling plant; disposal sites of sludge from oil and grease trap; domestic effluents from colony.

Sequential batch reactor (SBR) process is basically a fill-and-draw activated sludge process. Being a very popular technology, SBR was not being frequently used for the treatment of wastewater like activated sludge process (ASP). This paper reviews two case studies, where SBR was used for capacity expansion of existing and ASP was converted to SBR.