Study on the characteristics of fillings in soil trench system

Soil trench system is an important way to phosphorus and nitrogen removal by the combination of physical, chemical and biological degradation processes. The specific surface, osmosis, saturation water holdup, cost , adsorption and desorption capacity of four fillings (red soil, sand, coal fly-ash and carbonized rice hull) in soil trench system were analyzed. Taking the removal effect, useful time, construction cost and clogging problem into consideration, the mode of the quantity of four fillings in soil trench system should follow "red soil>;coal fly-ash>;carbonized rice hull>;sand".