Biological treatment of refractory organic compounds in coal gasification wastewater: A review

Coal gasification wastewater (CGW) has a complex composition, containing common refractory organics, the majority of which have been shown to be mutative and carcinogenic. CGW is extremely hazardous to the environment and poses a risk to human health as well. The CGW treatment has grown to be a significant challenge for the coal industry's sustainable development with the growth of the global coal industry. The great effectiveness of physical and chemical approaches in the wastewater treatment has attracted considerable interest. Secondary pollution and high operating expenses are issues with physical and chemical approaches. The biological method utilizes microorganisms to degrade COD and organic pollutants. It is also more economical and environmentally benign. The biological approach has taken over as the primary means of treating wastewater from coal gasification. This study reviews the biological treatment of coal gasification wastewater, including anaerobic, aerobic, and combined biological treatment technologies. Introduces the enhanced treatment of coal gasification wastewater through external reinforcement methods such as co-metabolism, conductive media, biological reinforcement technology, and adsorption materials in response to the inhibitory effect of toxic substances in coal gasification wastewater on microorganisms. By summarizing the biological treatment technology and enhancement strategies, it is expected to serve as a technical guide for promoting the effective use of biological methods in the treatment of wastewater from coal gasification.