Wastewater treatment for removal of dyes by coagulation and membrane processes

The development of effective wastewater treatment means and processes is one of the most important problems of textile dyeing-and-finishing plants. Textile dyeing wastewater contains large amounts of chemically different synthetic dyes, surfactants, and mineral substances, which are responsible for a serious chemical load on municipal wastewater treatment facilities. In this study using wastewater from direct and reactive dyeing processes at the Svitanak dye-works (Zhodino, Belarus) as an example, a comparative analysis has been performed of the efficiency of wastewater treatment by the following two processes: reagent coagulation with the use of aluminum hydroxychloride and anionic and cationic flocculants and ultrafiltration with the use of polyacrylonitrile, polysulfone, aromatic polyamide, and polysulfonamide membranes and experimental membrane samples with additionally modified surfaces.