Natural Biodegradation for COD of Paper Mill Wastewater in Unsaturated Zone
包气带中造纸废水COD天然生物降解作用

In this paper distribution of natural biochemical layer and its biodegradation capability and mechanism in the unsaturated zone under the paper mill wastewater channel were studied through field tests and column experiments. The results indicated that the biochemical layer was composed of a oxidation zone and a reductive zone, thickness of biochemical layer was controlled by the thickness of the unsaturated zone. When thickness of unsaturated soil zone exceeds 10m, the biochemical layer developed well, the removal rate for COD was above 97%.