Study On The Advanced Treatment And Reuse For The Effluent From Chemical Biological Flocculation Wastewater Treatment Process

The chemical-biological flocculation is a new wastewater treatment process. The advanced treatment process using the effluent of chemical biological flocculation wastewater process as influent was studied in this paper.The advanced treatment process is made up of suspended packing bed, flowing sand micro-filtration process and chlorine dioxide synergetic disinfection process. Suspended packing bed is a high efficient process which assimilates the benefits both traditional fluidized bed and biological contact oxidation process. The carriers in the suspended packing bed are fluidized by liquid velocity and gas velocity. The microorganism attached on the packing material paly an important role to biodegrade the COD_Cr and NH_3-N in wastewater. Flowing sand micro-filtration takes advantage of the theory of the micro-coagulant filtration and the technique of continuous backwashing. This working procedure can be operated continuously and has high removal efficiencies for total phosphorus (TP) and turbidity. The chlorine dioxide synergetic generator uses NaClO₃ and hydrochloric acid to produce ClO₂ and Cl₂ which can improve the removal efficiency of total coliform and algae in water distribution networks. Some polltants in the advanced treatment process are mainly studied based on the removal efficiency of different processes.Based on the 100t/d pilot scale study, the results showed that the optimal operation parameters of the suspended packed bed are determined as air/water ratio of 2.0:1 and hydraulic retention time (HRT) of 2.7h. Under these conditions, the removal rates of NH3-N, COD_Cr and TP are better than designed. Suspended packed bed process achieved good nitrification results, satisfactory results can be achieved even under low temperature condition. Air volume of backwashing for flowing sand micro-filtration is 2m³/h, water backwashing rate is less than 10%. The flocculants should be used and the suggested dose of PAFC should be more than 3.1mg/L when the influent turbidity is more than 10.0NTU or influent TP is more than 0.60mg/L, otherwise, the flocculants can not be used. When chlorine dioxide synergeticdisinfection was used to treat the effluent of flowing sand micro-filtration and when the residual chorine concentration is more than 0.20mg/L, the contact time should be more than 30 minutes;when the residual chorine concentration is more than 0.40mg/L, the contact time should be more than 15 minutes. Under above conditions, the best running state was achieved and the effluent quality can reach the requirement of the water reuse.