Research progress on the characteristics of biochar material and its application in greywater treatment

Biochar has the advantages of large specific surface area, high porosity and abundant surface functional groups, and has large potential for application in greywater treatment. The water quality and quantity characteristics of greywater and common treatment technologies were introduced, the properties of biochar, modification methods and the progress of domestic and international applications of biochar substrates in greywater treatment were mainly reviewed, and the regeneration performance of biochar was analyzed. The results showed that most of the biochar currently applied in greywater treatment was wood-derived biochar which has an alkaline range of pH and the advantages of large specific surface area and high porosity, and its specific surface area and porosity were mostly in the range of 0-520 m²/g and 48%-83%. Among numerous modification methods, there were many studies on the modification of metal salt biochar. This method could improve the adsorption capacity of biochar and make it magnetized, making it convenient for later separation and recovery. The biochar matrix was mostly used in constructed wetlands, green walls and other ecological treatment systems for greywater treatment, and the removal rate of organic matter and nutrients in greywater could reach 90% under optimal operating conditions, which had good application prospects. Finally, the problems in the application of biochar in greywater treatment were summarized, and an outlook on three aspects of the research was provided, including strengthening the removal of new pollutants, the regeneration of biochar and the energy saving and consumption reduction.