Review of Sulfate Removal in Low Concentration Brine Solutions

Abstract

Sulfate is a common ion present in natural water bodies at low concentrations and as effluent in different metallurgical processes. The discharge of sulfate in rivers and waterbodies can cause direct and indirect damage to the environment. Regulatory agencies have been increasing the constraints in sulfate content limit for discharge focused on human equity and environmental protection. A common practice is the precipitation of sulfate with lime, but the remaining solution still has ca. 1,500 mg L-1 of sulfate, which is not acceptable for disposal or reuse. This work describes the main routes for sulfate removal such as chemical precipitation, biological degradation, ion exchange, and separation through membranes and discusses the main advantages and issues of each approach. One of the main challenges is to scale up the tests and show the performances at the industrial level. The subject must be the focus of constant study to obtain relevant results so that usual technologies are replaced by more innovative, cheap and efficient methods.