The activated sludge obtained from wastewater coke oven plant was immobilized by entrapment with polyethylene glycol (PEG). The effects of several factors on the biodegradation of CN- from synthetic wastewater were investigated using batch and continuous reactors. The degradation rate of CN- increased with increasing of the immobilized bead volume in the reactor. Approximately 7.65 mg/L of NH4-N was produced upon the degradation of 35 mg/L of CN-. When high concentrations of the toxic cyanide complex were used in the testing of cyanide degradation, the free activated sludge could be inhibited more than that of the immobilized activated sludge. When the phenol concentration was higher than 400 mg/L in the synthetic wastewater, approximately 98.4% of CN- was removed within 42 hours by the immobilized activated sludge. However, the cyanide was not completely degraded by the free activated sludge. This indicates that high phenol concentrations can act as a toxic factor for the free activated sludge. A CN- concentration of less than 1 mg/L was achieved by the immobilized sludge at the loading rate of 0.025 kg CN-/m3-d. Moreover, it was found that the HRT should be kept for 48 hours in order to obtain stable treatment conditions.

A laboratory experiment was performed to investigate nitrogen removal by the soil column. The addition of 20% waste oyster shell to the soil accelerated nitrification in soil column. The NO3--N concentration in the effluent decreased with the decrease of HRT(Hydraulic Retention Time). When methanol and glucose added as carbon sources, the average removal rates of T-N(Total Nitrogen) were 82% and 77.9%, respectively. The NO3--N removal by methanol supplementation in soil column can likely be attributed to denitrification. In continuous removal of nitrogen using the soil column, the COD(Chemical Oxygen Demand) and NH4+-N removed simultaneously in organic matter decomposing column. The greater part of NH4+-N was nitrified by the percolated through nitrification column, and the little NH4+-N was found in the effluent. The T-N of 87.4% removed at HRT of 36 hrs in denitrfication column. Because of nitrified effluents from nitrification column are low in carbonaceous matter, an external source of carbon is required.