Biotreatment of high-salinity wastewater: current methods and future directions

Saline wastewaters are usually generated by various industries, including the chemical, pharmaceutical, agricultural, and aquacultural industries. The discharge of untreated high-salinity wastewater may cause serious environmental pollution and damage the aquatic, terrestrial, and wetland ecosystems. For many countries, the treatment of saline wastewater has become an important task. Generally, saline wastewaters are treated through physical and chemical methods. However, these traditional techniques are associated with higher treatment costs and the generation of byproducts. In contrast, biotreatment techniques are environmentally friendly and inexpensive. This review highlights the sources and environmental concerns of high-salinity wastewater and illustrates the latest problems and solutions to the use of biological approaches for treating saline wastewater. Although high salinity may inhibit the effectiveness of aerobic and anaerobic biological wastewater treatment methods, such strategies as selecting salt-adapted microorganisms capable of degrading pollutants with tolerance to high salinity and optimizing operating conditions can be effective. This mini-review may serve as a reference for future efforts to treat high-salinity wastewater.