MSc Thesis Title: Treatment of simulated textile wastewater by chemical and biological degradation in a Moving Bed Biofilm Reactor (MBBR)

Wednesday 3 April 2019, at:13:30, Venue: Hall K2.I1

Examination Committee

• Professor Nicolas Kalogerakis (advisor)
• Associate Professor Danae Venieri
• Associate Professor Petros Gikas

Abstract:

Most of the textile industries generate large amount of wastewaters, which come from the synthetic dyes used. During the dyeing process of textile products, about 50% of the dyes remain within the spent dye bath effluent, in their hydrolyzed form, which loses its affinity towards the fabric and hence, it cannot be re-used in the dyeing process. The direct discharge of such effluent to water streams such as lakes, rivers, etc., pollutes the water and affects flora and fauna. Typical treatment of such effluents includes remediation methods such as, precipitation, flocculation, photocatalysis, flotation, chemical oxidation and adsorption and biological methods. However, the variability in physicochemical characteristics of these wastewaters, due to the different types of dyes and chemicals used during the production processes of textile fibers, renders the application of a single treatment method practically impossible. In order to achieve a sufficient level of color removal, usually two or three different methods have to be combined.

The present study investigated the decolorization potential of a simulated textile wastewater, using a combined process of chemical (coagulation-flocculation and adsorption) and biological techniques. The treatment began with coagulation-flocculation process using chemical compounds for the removal of dyes used in wastewater. This was followed by biological treatment of wastewater using a microbial community isolated from sewage disposal tank of a textile factory. The biodegradation process was carried out in a Moving Bed Biofilm reactor under aerobic conditions. A further step with adsorbent resins was added for the isolation of residual dyes in the effluent due to the limited impact of biological treatment to wastewater decolorization.

The coagulation process using polyaluminum chloride resulted in high levels of dye removals in the simulated wastewater. The reduction of dyes and organic load of wastewater during biological treatment was less satisfactory, however the subsequent application of adsorption resins to the biologically pre-treated wastewater maximized decolorization efficiency.