INFLUENCE OF DISSOLVED OXYGEN ON THE PRETREATMENT OF MIXED WASTEWATER BY CATALYZED IRON INTERNAL ELECTROLYSIS PROCESS

Internal reflux, micro-aeration and macro-aeration catalyzed iron internal electrolysis (CIIE) processes were used for pretreatment of difficult-to-degrade mixed wastewater. The pilot-scale test results showedthat ratio of BOD5/CODcr increased respectively from 0.13 and 0.12 to 0.32 and 0.28 after the pretreatment of the mixed wastewater by the CIIE process under the conditions of anoxic (DO0.4mg/L) and micro-oxygen (DO≈1.2mg/L), and the average removal rate of TP came up to 29.3% and 36.1% respectively, moreover, the total Fe content in the effluent of CIIE process is in the range of 15~30mg/L, which enhanced the activated sludge concentration in the subsequent biological treatment process, improved the sludge stability and the separation effect of mixture. Under aerobic condition of DO4.5mg/L, the CIIE process could serve enhanced coagulation for the mixed wastewater, so that the average removal rate of COD and TP came up to 37.5% the Fe/cu fillings had greater consumption, and its strength got poor,moreover, the concentration of iron ions in the effluent was ashigh as 100mg/L, having adverse influence on biological treatment process.