Abstract
Abstract : In water scarce countries, the treatment and re-use of polluted mine water can be a solution to the water shortage problem. In this study, the possible use of pervious concrete to treat Acid Mine Drainage (AMD) for irrigation of agricultural crops, was investigated. Pervious concrete mixtures consisting of 6.7 mm granite aggregate and plain portland cement CEM I 52.5R (CEM I) with or without 30% fly ash (30%FA) were prepared and used to conduct column studies on AMD. The AMD types used in the study were obtained from abandoned coal (TDB) and gold (WZ) mines. Physico-chemical parameters of water including the pH, electrical conductivity (EC), Total Dissolved Solids (TDS), along with element concentrations were analysed. Also the Sodium Adsorption Ratio (SAR), Soluble Sodium Percentage (SSP), and Kelly’s ratio (KR) of the treated AMD were calculated and compared against the water quality criteria for irrigation use. Results showed that heavy metal concentrations in the treated TDB or WZ were generally reduced to satisfactory levels for crop irrigation. The treatment of AMD using pervious concrete had no significant influence on TDS, EC, SSP and KR values. Use of CEM I pervious concrete increased the Cr6+ concentrations to levels above the limits acceptable for irrigation water but use of 30% FA in the concrete reduced the Cr6+ levels to permissible limits. Pervious concrete was found to be more suited for treating AMD sources of low alkali concentrations such WZ, to produce treated water quality for irrigation use.