Biological Sulphate Reduction

During construction, renovation and/or demolition activities, large amounts of construction and demolition debris are created. This debris contains high sulphate concentrations and toxic metals, which can create a lot of environmental problems, especially at landfill sites. The disposal of the debris can cause odour problems and possible health impacts to landfill staff and surrounding inhabitants due to hydrogen sulphide gas generation. In order to reuse this debris, sulphate and heavy metal have to be removed. This chapter reviews the technologies used for sulphate and heavy metal removal from the debris both by chemical and biological processes. Moreover, possible ways for sulphur recovery has been reviewed. A sulphate removal efficiency up to 99% can be achieved from the chemical sulphate removal process. However, for this high performance, toxic chemicals such as barium and lead compounds have to be used. The biological sulphate reduction process is an alternative method for sulphate removal and recovery of sulphur and heavy metals from debris. Sulphide which is the product of this bio-process can be easily precipitated together with dissolved metal as metallic sulphides. Moreover, sulphide produced in this process can also be recovered as elemental sulphur or sulphuric acid.