Municipal wastewater treatment and utilization using vertical-flow constructed wetlands

Two pilot-scale plants (in the cities of Beijing and Chengdu) were studied using vertical-flow constructed wetlands (VFCW) to treat municipal wastewater over a 2,year period. The results show that VFCW treatment system had high and steady removal efficiency for municipal wastewater. The removal percentages for BOD5, total nitrogen, and fecal coliform were 96%, 47%, and 97%, respectively. Effluent concentrations of GOD, BOD5 and SS were less than 60 mg/L, 20 mg/L and 20 mg/L, respectively. The results also show that the hydraulic and organic loading rates of vertical-flow constructed wetlands were 208 similar to 288m/a and 14.9 similar to 26.6 kg BOD5/m(2).a, respectively. Treated effluent was then used as water source for agricultural irrigation and fish farms. It did not result in any secondary environmental pollution on plants, fish, or underground water. It also was found that constmcted.wetlands surface planted with some aquatic plants and terrestrial flowers had enhanced removal efficiencies of 22.5% and 27.6%, respectively, for total nitrogen and phosphorous.