Treatment of the domestic sewage by the lab-scale sub-surface horizontal-flow wetland

The constructed wetland is a new kind of wastewater treatment developing in recent years, which is very suitable for the regional characteristics of Shaanxi province. The design of the constructed wetlands is developed from the traditional sub-surface horizontal-flow wetlands (SSHFW). Two groups of wetlands were designed in parallel, and each single wetland can also became the vertical-flow wetland system. Aerating in front of the constructed wetlands is to study the removal efficiency of the organics. Test indicators contained SS, COD, Nitrogen, Phosphor and the strength of nitrification and de-nitrification. According to the experiments of the self-designed SSHFW, the removal efficiency of the SS, COD, NH4+-N, TN and TP were 92%, 82%, 40%, 46.2% and 70% respectively. The strength of nitrification and de-nitrification of the packing reached to 0.35mg/(kg.h) and 3.32mg/(kg.h). On the basis of the Langmuir adsorption isotherm equation, the adsorption quantity of coarse sand and gravel were 405.2mg/kg and 498.6mg/kg. The quality of the effluent met the primary standard of B-standard in the discharge standards of pollutants for municipal wastewater treatment plant (GB18918-2002).