| Paper industry is one of the industries with serious pollution and high egergy consumption. The pollution characteristic of papermaking wastewater is large amount of sewage discharge, including high concentration of COD and suspended solids (SS). Papermaking wastewater is one of the difficultly treated wastewater because of its high concentration of pollutants, complex composition and bad biodegradation. Scientists have studied the technology of papermaking wastewater treatment for a long time and obtained some achievement to certain degree, but a kind of high effect and low cost approach has not been found at home and abroad. Therefore, the research of papermaking wastewater treatment is an important and difficult point in the field of environmental protection.The preparation of modified montmorillonite was studied in the first part of this paper. The effects of the preparation of aluminum cross-linking agent, the concentration of montmorillonite suspension, the dosage of aluminum crosslinking agent (feed ratio), the temperature and time of cross linking reaction and other factors on the properties of flocculants.The optimum conditions of the preparation of modified montmorillonite in the laboratory were:(1) temperature:30℃. (2) Molar ratio of OH-:Al3+=2.4:1. (3) Concentration of montmorillonite suspension:3%. (4) Ratio of cross linker and montmorillonite:4.0 mmol:1 g.The application of the aluminum cross-linked montmorillonite, CF-PAC and PAM combined flocculant for papermaking wastewater was studied in the second part. The optimum formular and dosing order of the aluminum cross-linked montmorillonite, CF-PAC and PAM combined flocculant for papermaking wastewater treatments were determined. The effects of the pH value, temperature, stirring speed, stirring time and settling time on the flocculation properties were investigated, and then the optimum formulation and process parameters of the composite flocculant for papermaking wastewater treatment were determined. Results showed that, when 7 mL 3% modified montmorillonite lotion, 5 mL 5% CF-PAC and 4 mL 0.1% PAM were added in 1 litre wastewater, stirred at the speed of 120 r/min for 10 mins, and then settled for 10 mins, the CODcr removal rate was 45% and the cost was 0.48 yuan/t. Compared with the traditional complex formulation, the CODCr removal rate of the novel composite flocculant described in this paper was increased by 12.8%, while its cost was decreased by 9.1%. Therefore, the novel composite flocculant showed obviously economical benefits.
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