The Treatment Of Cotton Pulping Black Liquor

Alkaline cotton pulping black liquor has special properties: high OC, deep color, strong odor, a mass of organic contamination, high pH, and the content of lignin and the quantity of heat is very small, it isn't fit for alkali recycle and is very difficult to treat. If the black liquor is discharged without any treatment, will populate environment. At the same time, slag and pyrite cinder both are solid waste materials. But there are also many useful components in them, if we don't make use of them, not only waste resource, but also destroy ecology balance.In this paper, firstly, microbial acification was used to reduce the pH of cotton pulping black liquor, and then anaerobic treatment and aerobic treatment were used to continue to deal with the black liquor. At last, in order to reach the standard of discharge, flocculation treatment was used. The flocculant was prepared from waste residue by ourselves. Thus we can reach the goal of dealing with waste by waste and saving resources.In the first part of this paper, microbial acification of cotton pulping black liquor was studied, including microbial acification under high temperature and medium temperature. The changes of pH, CODcr, BOD5, VFA and r with the HRT were studied, and discussed the mechanism of microbial acification. Through experiment, the best acification conditions of different cotton pulping black liquor were decided.In the second part, the anaerobic and aerobic treatment of cotton pulping black liquor, which had been treated by microbial acification, were studied. The removes of CODcr and BODs and the change of pH with the HRT were discussed in this paper. It was discovered that microbial acification treatment could greatly improve the properties of cotton pulping black liquor and increase the effect of succedent anaerobic and aerobic treatment to a great extent. In this part of experiment, the CODcr and BOD5 can be removed about 93% and 98%, reached about 1000-1500mg-l-1 and 70-120 mg-l-1 respectively.In the third part, the preparation of flocculant from slag and pyrite cinder and its application in the treatment of cotton pulping black liquor were studied. Firstly, searched for main factors that greatly influence the reaction of preparation. Then, the conditions were optimized: HC1 dosage, 12mg.l-1; reaction temperature, 35 C; reaction time, 10h; catalyzer dosage, 11.32 mg.l-1. Finally, the flocculant was applied in the treatment of cotton pulping black liquor. The result shows: the cotton pulping black liquor treated by the flocculation, which had been treated by acification treatment, anaerobic and aerobic treatment, can reach the demand of GB3544-2001.