[Study on subsurface wastewater infiltration system covered by different turfgrass for domestic sewage treatment]

Domestic sewage was treated with subsurface wastewater infiltration system covered by two different turfgrass, namely, Festuca arundinacea Schres. and Zoysia japonica Steud.. The result shows that all the different systems have good removal rates to COD. The concentration of COD decreased to less than 48 mg x L(-1) from 97-357 mg x L(-1) which achieve the second class criteria specified in Integrated Wastewater Discharge Standard, and there are no prominent difference among different systems. The concentration of NH4(+) -N decreased to less than 0.5 mg x L(-1) from 76.3-125.8 mg x L(-1) which achieve the IV criteria (< or = 0.5 mg x L(-1)) specified in Groundwater Quality Standard, the effluent concentration of NH4(+) -N in naked system are prominently higher than that in system covered by Festuca arundinacea Schres., and there are no prominent difference compared with system covered by Zoysia japonica Steud.. The concentration of TP in different systems decreased to less than 0.05 mg x L(-1) from 3.70-18.42 mg x L(-1) which achieve the II criteria (< or = 0.1 mg x L(-1)) specified in Surfacewater Quality Standard, and there are no prominent difference among different systems. The removal rates of TN and nitrate were all not good enough, the probability which achieve the III criteria (< or = 20 mg x L(-1)) specified in Groundwater Quality Standard are less than one third, and the effluent concentration of TN and nitrate in naked system are prominently higher than that in systems covered by Festuca arundinacea Schres. and Zoysia japonica Steud..