Treatment of slightly polluted river water by the combinedsystem of oxidation pond with constructed wetland using pumice as substrate in warm and cold seasons
An study on treatment of slightly polluted river water was carried out using the combined system of oxidation pond with constructed wetland using pumice as substrate in Kunming. The results shown that the system can purify polluted river water both in warm and cold seasons efficiently by regulating flow to a small extent. When the hydraulic loading rates of pond and wetland were held at 0.22 and 0.37 m3/(m2· d) respectively,adequate treatment could be got by the whole combined system and the mean removal efficiencies of CODCr, TP, TN and NH4[KG-*4/5]+-N in the system for warm season were 75%, 93%, 64%, 87% respectively, and for cold season were CODCr 72%, TP 89%, TN 53%, NH4[KG-*4/5]+-N 73% at the appropriate hydraulic loading rates of pond and wetland held at 0.17 and 0.29 m3/(m2· d) respectively. The treated water met the standard A of grade I discharge standard of pollutants for municipal waste water treatment plant, and can be used as urban general reuse water. Contaminant removal rate in the combined system in warm season was apparently higher than that in bcold season.