Progress in Multi-Soil-Layering Systems for Wastewater Treatment

The use of decentralized wastewater treatment technologies is a reasonable solution for rural areas. As a decentralized treatment technology, the multi-soil-layering (MSL) system has recently drawn an increasing amount of attention owing to its merits, such as a high hydraulic load rate, small land area occupation, low probability of clogging, low investment, and low operation cost. This review summarizes the progress in MSL systems in the past decade, focusing on the directions of efforts for system optimization, the latest applications of MSL systems to various wastewater treatments, and the integration of MSL with other technologies. The great application potential of MSL systems is illustrated, and future research directions regarding better application of MSL systems are provided.