A hybrid technology for wastewater treatment at dyeing and finishing facilities

Introduction. Nowadays people tend to follow fashion trends and wear clothes made of brightly coloured fabrics and furs. Their production requires a large set of chemical reagents, including dyes, tanning agents, surfactants, etc. Multicomponent wastewater with changeable composition is generated following the completion of the dyeing cycle and the treatment of materials. Their further processing requires advanced innovative approaches, most of which are integrative. Wastewater treatment technologies, used by dyeing and finishing facilities, are analyzed in the article. The authors present the results of the laboratory research into the development of an integrative technology for dye extraction from wastewater using a composite sorbent obtained by pelletizing dust wastes of the metallurgical industry and supplementary phytoextraction of dyes in bio-ponds. Materials and methods. The research was conducted in the laboratory environment. The technology entails the use of a composite porous material, made of man-made raw materials used in the production of silicon and aluminum. A pelleti­zing technique, proposed by the authors, is employed to make this composite material. The sorbent production technique, its characteristics and evaluation of sorption properties are presented. The phyto-sorption properties of aquatic plants were tested in the laboratory environment. Aquatic plants, growing in the Angara river, were used in the research. Plants were collected by trawl, freed from soil, washed, and grown in the laboratory aquariums filled with dechlorinated water in conditions of moderate lighting and at the temperature of 14–16 °С. They are Elodea canadensis, Myriophyllum spicatum, and Ceratophyllum demersum. The model wastewater was represented by dye solutions, such as C.I. Acid Yellow 11, C.I. Acid Blue 120, C.I. Acid Red 1, C.I. Basic Orange 21. Results. The newly developed technology of making a composite sorbent from waste is described; its treatment efficiency is analyzed. Experimental values of the phytoremediation potential of aquatic plants are obtained. A hybrid technology for local wastewater treatment, including sorption and phyto-treatment, involving gabions and biological ponds, is proposed. Wastewater is treated in gabions filled with composite sorbent and then poured into bio-ponds with aquatic plants. Conclusions. The findings enable researchers to outline areas of further research on optimization of integrated facilities, designated for the local treatment of wastewater, generated by dyeing and finishing facilities.