Study On The Treatment Of Physicochemical-biochemical Combination Process Of BCTMP Effluent

The effluent of BCTMP of poplar in a paper mill of shandong was treated with the methods of physicochemical-biochemical combination process, took the solution of effluent reaching the national standard as a basis.In this paper, the wastewater treatment process was put forward based on the characteristics of the effluent: natural settlement, coagulation, micro-electrolysis method and anaerobic bio-treatment.The polyaluminium chloride (PAC) and polyacrylic amide (PAM) were used to be coagulating reagents after the natural sedimentation of effluent of BCTMP of poplar. The factors affecting on the removal of COD and color at room temperature were discussed which include the amount of the reagents, pH value, stirring intensity and standing time. It is noteworthy that a tentative research was made on which different concentrations of wastewater were treated with the PAC-PAM combined treatment while taking wastewater solid content as reference.Measurements were recorded methodically during the experiments.The factors affected on the micro-electrolysis method treatment were also studyed for comparison in this paper.As we can see from the conclusion, pH value was the most important factor to influence the reaction of micro-electrolysis,and other factors,such as Fe/C proportion, reaction time and the ratio of Fe/wastewater had also some effect on treatment efficiency. Under the optimum condition of 3～4 pH value, 0.5:1Fe/C weight proportion,15min reaction time and 0.1～0.125 ratio of Fe/wastewater, the decolorizing rate was 93%, and the CODcr removal rate was about 71%. What's more, BOD5/COD of wastewater increased to 0.35. All above proved that the micro-electrolysis method treatment was more suitable in this situation.The problems happened in anaerobic bio-treatment process were discussed and the effective corresponding measures are presented. It was observed that for wastewater with optimum concentration CODCr of 12000～14000 mg/L, the removal rate of COD was 78% and the decolorizing rate was 88% and the turbidity rate was 79% respectively when the following conditions were adhered to: pH range of wastewater 6.5～7.2 at 36℃while HRT is 24 hours. It would produce a suitable condition for subsequent treatment after all this processes.