Abstract

Tannery wastewater contains a high concentration of total nitrogen, and its direct discharge will lead to eutrophication of water bodies, thus the treatment of total nitrogen in tannery wastewater has become the focus of environmental protection. In this paper, total nitrogen removal rate in tannery wastewater was investigated as an index, and sm-A3 cationic starch was used as an initiator to optimise the modification process of flocculant produced by Bacillus cereus CZ1001. In the modification optimisation process, single-factor optimisation experiments and orthogonal optimisation experiments were conducted on the dosage of cationic starch, bioflocculant, initiator, reaction time, reaction temperature, pH and rotational speed of the reaction system. The results showed that with cationic starch (2mL) 0.3 g/L, bioflocculant (25mL) 4.5g/L, initiator (0.02mol/L) dosage 2mL, reaction time in the first stage 7.5min, reaction temperature 55°C and the reaction system pH7.0, the highest total nitrogen removal rate of 89.22% was achieved for the tannery wastewater, and finally, we produced a cationic starch modified bioflocculant with high nitrogen removal rate. This research result reduced the environmental impact of tannery wastewater and broadened the treatment pathway of tannery wastewater.