Effect of coagulation on bio-treatment of textile wastewater: Quantitative evaluation and application

Abstract

Abstract To address the challenge of high water consumption, massive wastewater discharge and high pollution risk in textile industries, different countries have chosen various treatment method for textile wastewater according to the location and management of textile enterprises. It is not economical purposely to build separate wastewater treatment plants (WWTPs) for each small-scale enterprise, hence, it is common to treat the wastewater for a group of factories and then complete the treatment via a municipal wastewater treatment plant. However, the complex characteristics of textile wastewater brings some new problems for WWTPs: Textile wastewater contains over 300\xa0mg/L COD, 100\xa0μg/L antimony, 1000\xa0μg/L aniline, some of which are toxic to microbes or non-biodegradable. Coagulation plays an important role in the pretreatment of textile wastewater for removing hydrophobic dyes, decreasing the SS and COD. In this paper, Poly Ferric Sulfate (PFS), Poly Aluminum Chloride (PAC) and Poly Aluminum Ferric Chloride (PAFC) were chosen to improve the biodegradability of the textile wastewater. And then, quantitatively evaluate the biodegradability of wastewater before and after coagulation treatment by analyzing the proportion of different organic pollution, which could be divided into four parts including rapid bio-treated, easy bio-treated, normal bio-treated and non-biological treatment. Results showed that the biodegradability of textile wastewater could be improved by coagulation process, and the contents of organic matter of rapid bio-treated and easy bio-treated could be maximizing when the control condition of coagulation process was optimized. Moreover, because of its characteristics of simple, easy to use, and rapidly online implement, this approach holds a great promise for applications such as investigate wastewater feature deeply, treatment technology optimization, risk control and management.