Experimental study on follow-up treatment of anaerobically digested effluent of cassava alcohol wastewater

The mass concentration of CODCr and NH3-N in the effluent of cassava alcohol wastewater after two-stage anaerobic fermentation were 1 300-1 500 and 400-500 mg/L respectively,the value of m(BOD5)/ m(CODCr) was relatively low.A combined process of iron-carbon microelectrolysis-immobilized microorganism technology-coagulation sedimentation-Fenton reagent was used to treat the said effluent.The results of the test showed that,under the optimal condition: the mass ratio of iron to carbon was 2,the pH value was 2.0,the reaction time of microelectrolysis was 9 h,the time of aerobic biochemical reaction was 24 h,the pH value and reaction time of coagulation sedimentation unit was 9.0 and 0.5 h respectively,the time and pH value of Fenton reaction were 1.0 h and 3.0 respectively,the dosage of H2O2(30%) and FeSO4.7H2O were 1.8 mL/L and 0.91 g/L respectively,the removal rates of CODCr and NH3-N by the said combined process reached 98.8% and 98.1% respectively,the mass concentration of CODCr in the effluent water was about 20 mg/L,and the mass concentration of NH3-N was lower than 10 mg/L,which indicated that,through the treatment,the effluent water quality could meet the specification for grade 1 in GB 8978—1996 Integrated wastewater discharge standard.