Coal Pile Leachate Quality

Coal type, coal size and coal storage technique are three important factors which determine coal storage pile leachate quality. A factorial experimental design including all possible combinations of these three factors (each at two levels) was carried out under controlled laboratory conditions for a storage period of 119 days, including nine simulated rainfall events. Coal type was significant as it determines the amount of available pollutants which may be leached from the coal during each rainfall event. Coal particle size and storage technique were found to be of little importance during the first rainfall, but became increasingly important in influencing leachate quality as time and number of rainfall events increased. Some form of treatment is necessary if coal storage pile leachate is to meet the pH standards which currently exist for NPDES discharges from steam-electric power plants.