SULFATE REMOVAL FROM WASTEWATER BY CHEMICAL PRECIPITATION METHOD

In the study, removal of sulfate, which is one of the polluting parameters in wastewaters by chemical precipitation method was investigated. Chemical precipitation is based on formation of scarcely soluble salt by combining an anion and a cation. Metal sulfate salts are CaSO4, SrSO4, PbSO4 and BaSO4, with respect to reducing solubility. Although metal salts except calcium sulfate are scarcely soluble they are expensive and harmful for the environment. Due to the low cost and non polluting characteristic, calcium compounds are widespread used for sulfate removal. However, calcium sulfate has relatively high solubility in comparison with the others. Many thermodynamic and kinetic factors affect chemical precipitation like species of solid precipitate, ionic strength, presence of other ions (salting in-out effects), temperature and precipitation rate. In this study, these factors have been investigated comprehensively.