ABSTRACT

Barapukuria Coal Mine (BCM), the country's first mine is in production since early 2005. Since implementation, the mine is facing groundwater inrush problem and the authority is dewatering it at a rate of 1594 m3/h (normal water flow) up to 2636 m3/h continuously to keep it fit for production. The mine drainage is treated primarily to settle the suspended solids, mainly fine coal particles or sludge, before releasing into canal outlet which local farmers use for irrigation purpose and as a result groundwater level in the area went down since mining started. The study was taken to investigate the environmental pollution by mine drainage and its sustainability for irrigation. Eight mine drainage samples were analyzed for major cations (Na, K, Ca and Mg), anions (SO4, Cl, HCO3, CO3 and NO3 -) and minor and trace elements (Fe, Mn, Β, Cu, Zn, Pb, Cd, Hg, Co and Mo). Twenty paddy field soil samples collected at three different depth intervals from mine water irrigated and non-irrigated zones surrounding the mine and a mine sludge sample were analyzed for organic matter content, pH, nutrients (N, P, K, S, Ca, Mg, Fe, Μn, Β, Zn, Cu and Mo) and toxic heavy metal (As, Pb, Hg and Cd). Nutrient contents (P, K, S, Ca, Mg, Fe, Mn, Zn and Cu) and non-essential heavy metal (As, Pb, Cd and Cr) of two composite samples of root, stem, leaf and grain of rice plant from two respective zones were also determined. The mine drainage is classified as normal chloride, normal sulfate, normal carbonate and very hard types showing calcium-sodium and bicarbonate and bicarbonate-chloride-sulfate cation and anion facies. No deleterious effects are found on soil chemistry and rice plant tissue in both mine water and non-mine water irrigation area, and therefore rice grains are safe for human consumption. So coal mine drainage has suitability, and hence sustainable for irrigation uses keeping the mine drainage quality at present level.