Potential of hybrid constructed wetland system in treating milking parlor wastewater under cold climatic conditions in northern Hokkaido, Japan

摘要

A real scale hybrid constructed wetland (CW) system (656 m2), with a configuration of VFA-VFB-HF bedsnconstructed in series is operating since November 2006 in northern Hokkaido, Japan. The system wasnexperimented to assess its capability in purifying 4.5 m3d-1 of high strength milking parlor wastewater underncolder climate. Annual mean air temperature at site was recorded as 6.4 oC (extremes vary as -22.8 oC atnlowest and 30.6 oC at highest). From the monthly sampling from November 2006 to January 2010, averagenloading and removal rates of TSS, CODcr, BOD5, TN and TP were 5.4 g m-2 d-1 (98%), 30.3 g m-2 d-1 (88%),n11.5 g m 2 d-1 (89%), 1.2 g m-2 d-1 (76.4%) and 0.2 g m-2 d-1 (76%). System did not stop for a single day, efficientlynworked even during snow covered periods and was tolerant to the load fluctuations.