Mitigation of Rainfall Erosion in Coal Mine Overburden Via Microbial Calcification

In spite of renewable sources, many countries still mostly depend on coal for electricity generation. It accompanies massive dumping of coal mine overburden further accumulated and formed large heap during open cast coal mining. These coal mine overburden occupy not only huge land but also create many environmental challenges. Water and soil pollution due to leachate during rainfall and air pollution due to dust during erosion are two major environmental challenges confronted in daily basis. The present study focuses to evaluate the feasibility of enzyme-induced calcite precipitation to mitigate water/rainfall-induced erosion of coal mine overburden. For this, the jack bean urease was augmented with two different concentration ratios of urea and calcium chloride dihydrate, viz. 1:1 and 1:1.25 by spraying method. After 10 days of curing, the rainfall erosion test concluded that the erosion rate decreased significantly in the biotreated sample due to precipitation of calcium carbonate biomineral. Also, an increase in the strength was observed in the biotreated sample via pocket penetrometer. Further, the microscopic characterization proves the carbonate biomineral precipitation and its linkage formation inside the sample pore which is the reason of erosion resistance and strength gain.