Karger, Naqibullah creator Annachhatre, Ajit P. Chairperson Visvanathan, C. Examination Committee Shipin, Oleg V. Examination Committee Ministry of Higher Education (MoHE) / Kandahar University, Afghanistan Scholarship Donor Asian Institute of Technology Fellowship Scholarship Donor text series technical report th Pathum Thani, Thailand Asian Institute of Technology 2015 continuing eng 73 leaves : ill. + 1 online resource High gypsum content in soils of some mining areas gives adverse effects to the environment such as acid mine drainage, leachate to groundwater and may cause numerous cultivation problems in the soil, such as low fertility, high erodibility, pedon hardening, structural instability, crust formation, high runoff generation potential and low water retention capacity . The quality of such mine soils can be improved by reducing the soil gypsum content. The objective of this study is to develop a suitable in-situ bioremediation technology by using sulfate reducing bacteria (SRB) for reducing the gypsum content in the mine soils. This technology can be applied in the south western part of Afghanistan, including Kandahar, where mine soil contains high gypsum content (more than 100 g kg-1). Low or no cost organic substrates, such as; rice husk (RH), coconut husk chips (CHC) and municipal wastewater treatment sludge (MWTS)indifferent percentages (10%,20%,30% & 40% by weight) was mixed with the soil as electron donors for the SRB. The highest sulfate removal efficiency (57%) was attained in the soil mixed of 40% CHC of mixture, followed by 30% CHC (54.76%), 40% MWTS (52.07%), corresponding to a reduction of the soil gypsum contents from 15% to 6.46%, 6.79%, 7.19%, respectively. The optimum residence time for the treatment of 40% CHC mixture was 11 weeks (77days). For economic achievements, this treated soil can be further used in agriculture as a soil amendment and the liberated sulfide can be recovered as the fertilizer elemental sulfur. A thesis submitted in partial fulfillment of the requirements for the degree of Master Science in Environmental Engineering and Management Thesis (M.Sc.) - Asian Institute of Technology, 2015 Soils Gypsum content Asian Institute of Technology. http://203.159.5.9/ait-thesis/detail.php?q=B02608 http://203.159.5.9/ait-thesis/detail.php?q=B02608 170519 20260819085209.0