Research Of Flocculation-Anaerobic-Aerobic Biological Treatment In The Treatment Of Straw Pulp Gray Water

Straw pulp gray water is one of the main sources of fresh water pollution. Research of treatment technology on pulp and paper industry wastewater has emerged as an issue appealing to heavy attention from workers specialized in environment protection both at home and abroad.Characteristics of bleaching liquor and present research and treatment techniques over the world were given in the paper. This paper discussed the start-up process and influence factors in the running of the treatment system after a long time bench-scale research, and effective treatment system and running parameters were decided at last.Experimental conditions of coagulation pretreatment were studied in the paper. Effect of PAFC was better than PAM as coagulant. The optimum condition was that the dosage was 1.0g/L, the scale of pH value floated from 6 to 8, agitating intensity was 120r/min and agitating time was 4 minutes.This paper researched on the start-up process of the ABR-biological contact oxidation filter process by keeping low organic load rate. The process could finish in only 50 days.After researching the generally running process of each treatment reactors, changing the influence parameters, optimum running parameters were confirmed. The optimum running condition of ABR was that the HRT was 12 hours, the organic load rate was below 2.5 kgCOD/ (m³Â·d). Meanwhile the biodegradability (BOD₅/COD) value rose from 0.23～0.30 to 0.34～0.43 which was good to sequent aerobic treatment. The optimum running condition of biological contact oxidation filter was that the HRT was 8 hours, the organic load rate was 0.75～1.2 kgCOD/ (m³Â·d) and the gas/water rate was 20:1.Once the water quality of effluent was beyond water standard, the effluent must be further treated by coagulation. The removal rates of COD and color is considered to decide the quantity of PAFC. The optimum dosage was 1.0g/L with other parameters as coagulation pretreatment, and the effluent could reach the standard finally.The united system could run well when the HRT was 20 hours, the inflow COD was between 2300 mg/L and 2500 mg/L, gas/water rate of biological contact oxidation filter was 20:1, dosage of PAFC was 1.0 g/L. Then the COD removal rate can reach 94.7%～95.5%, the color removal rate can reach 94.3%～95.1 %, the effluent basically reached Shandong province regional standard Discharge Standard of Water Pollutants for Paper Industry (DB37/336-2003).The effective combined system of ABR reactor and biological contact oxidation filter could not only show the advantages of the anaerobic technology with low energy and high efficiency as well, but also could develop the advantages of contact oxidation filter that has high anti-shock loading ability and stabilization. The research offered a good reference to straw pulp gray water treatment technology, which was worth spreading.