LAUSR

Conventional onsite wastewater treatment systems (OWTSs) provide only primary treatment of domestic wastewater, while a limited level of nutrients (N, P), pathogens, pharmaceuticals, and personal care products (PPCPs) removal could be achieved in such a treatment process. Biochar has the capacity to remove various contaminants and has been widely used as an ideal soil amendment in agriculture, due to its persistence, superior nutrient-retention properties, low-cost and ready availability. However, few applications on the use of biochar in onsite wastewater treatment have been explored. In this review, we systematically reviewed the applications of biochar in filtration based OWTSs for nutrients (N, P) removal and recovery, pathogens and PPCP removal. While adsorption was the main mechanism for phosphorus, pathogen and PPCPs removal, biochar can also serve as the growth media for enhanced biological degradation, a good supplement of alkalinity, and can increase water holding capacity in the OWTSs. The biochar source, surface modification methods and preparation procedures (e.g., pyrolysis temperature change) have significant impacts on contaminants removal performance in the biochar amended OWTSs. Specifically, contradictory results have been reported on the pyrolysis temperature change impact on biochar removal performance (i.e., increased, decreased, or no change) of nitrogen, phosphorus and PPCPs. The wastewater composition and environmental pH also play important roles in the removal of nutrients, pathogens and PPCPs. Overall, biochar holds great potential to serve as an alternative filtration material or be amended to the current OWTS to improve the system performance in removing a variety of contaminants at low cost. This article is protected by copyright. All rights reserved.