Soils in some mining areas contain a high gypsum content, which can give adverse effects to the environment
and may cause many cultivation problems, such as a low water retention capacity and low fertility.
The quality of such mine soils can be improved by reducing the soil’s gypsum content. This study aims to
develop an appropriate in situ bioremediation technology for abbreviating the gypsum content of mine
soils by using sulfate reducing bacteria (SRB). The technology was applied to a mine soil from a gypsum
mine in the southern part of Thailand which contains a high sulfate content (150 g kg1
). Cheap organic
substrates with low or no cost, such as rice husk, pig farm wastewater treatment sludge and coconut husk
chips were mixed (60:20:20 by volume) and supplied to the soil as electron donors for the SRB. The highest
sulfate removal efficiency of 59% was achieved in the soil mixed with 40% organic mixture, corresponding
to a reduction of the soil gypsum content from 25% to 7.5%. For economic gains, this treated
soil can be further used for agriculture and the produced sulfide can be recovered as the fertilizer elemental
sulfur.