Removal of High Concentrations of Sulfate from Wastewater: Evaluating Different Methods and Proposing the Best Option

Background: Industrial wastewaters containing high amounts of compounds such as sulfate can cause serious risks to human health and environment. Therefore, proposing practical solutions with the lowest cost and the highest efficiency for pollutants removal is of special importance. The purpose of this study is to find a suitable method for treatment wastewater containing very high amounts of sulfate. Materials and Methods: This research is an experimental-research study in which four different practical methods have been investigated for treatment of sulfate containing wastewater including chemical precipitation with lime, electrocoagulation, biological degradation and thermal distillation. Results: After examining the performance of different methods and considering the special characteristics of wastewater, the results showed that the methods of chemical precipitation (removal efficiency of 5%) and electrocoagulation (removal efficiency of 7%) were less efficient. The distillation process also showed an acceptable performance in removing TDS and sulfate from this wastewater (removal efficiency of 98.7%) and the biological method could function well after wastewater dilution (the removal percentage of sulfate in the first 24 hours for wastewater with dilutions of 10, 25 and 50%, are about 55, 40 and 17%, respectively). Conclusions: According to the results obtained from this study, methods of chemical precipitation and electrocoagulation are proposed only as a pre-treatment method and biological treatment can be used as a supplementary treatment after pre-treatment. Distillation is also not recommended as a practical method due to high cost and energy consumption.