Treatment of Commercial Laundry Wastewater Using Extracellular Polymeric Substances (EPS)

Abstract

Abstract The problem of management and treatment of wastewater from commercial laundries is a matter of concern. The present study provides an effective and eco-friendly solution to the treatment of wastewater from commercial laundries in Quebec (Canada) by using extracellular polymeric substance (EPS) as bio-flocculant. EPS was produced from valorization of crude glycerol and paper mill sludge by a bacterial strain (BS-04). Two different types of EPS: Slime EPS (S-EPS) and Broth EPS (B-EPS) were used for treatment of commercial laundry wastewater (CLWW). This is the first study for treatment of CLWW using bio-flocculant EPS. A comparison between the conventional treatment of laundry wastewater (LWW) by chemical coagulants (FeSO4, CaCl2, Alum) and enhanced treatment by bio-flocculant EPS has been drawn in the study. Moreover, LWW treatment by combination of EPS and chemical coagulants was also investigated. It was observed that S-EPS (0.6 g/L) gave better flocculation activity (FA) than B-EPS. S-EPS alone can remove 83.20% of turbidity, 77.69% suspended solids (SS) and 76.37% chemical oxygen demand (COD). The best results were obtained by combining S-EPS (0.6 g/L) together with alum (300 mg/L) at pH 7 for treatment time of 30 min. This combination was able to remove 98% of turbidity, 95.42 % of SS and 83.08% of COD from LWW. When treatment time has been increased to 4 h at pH 7, it resulted in more than 88% COD removal from CLWW.