Biological Sulfate Reduction for Treatment of Gypsum Contaminated Soils, Sediments, and Solid Wastes

Abstract

Solid wastes containing sulfate are an important source of pollution, which can create a lot of environmental problems, especially during disposal management at landfill sites. These solid wastes, such as construction and demolition (C&D) debris and phosphogypsum, cause odor problems and possible health impacts to landfill employees and surrounding residents. These wastes do not only contain high sulfate concentrations, but also contain toxic metals and radioactive compounds. Although these wastes can be reused as soil amendment or to make building materials, a concern has been raised by regulators regarding to the chemical characteristics of the material and the potential risks to human health and the environment. Therefore, use of these solid wastes has been banned in most countries. In addition, soils containing solid sulfate (gypsum), namely gypsiferous soils, have several problems during agricultural development. Reduction of the sulfate content of these solid wastes, soils and sediments by biological sulfate reduction is an option to overcome the previously mentioned problems. The authors review the topics necessary for developing biological sulfate removal technologies from these sulfate rich solid wastes as well as soils and sediment types (i.e., their contamination by sulfate minerals, solid sulfate as an electron acceptor for sulfate reducing bacteria, and sulfate reduction processes both in natural and in bioengineered reactor systems).