Biodegradation of polyvinyl alcohol adsorbed on granular activated carbon

Abstract

Polyvinyl alcohol (PVA) is a water soluble polymer used as emulsifier for suspension polymerization. PVA discharged from industrial effluents poses a threat to the environment through bio accumulation. It also has the potential to mobilize heavy metals from sediments in water streams and lakes and thus increase their bioavailability to the food chain. Adsorption of PVA onto carbon is a versatile treatment but cost prohibitive unless regenerated. This study aims at restoring the adsorptive capacity of PVA adsorbed granular activated carbon (GAC) by biodegradation catalyzed by oxidases and/or hydrolases. The biodegradation of PVA adsorbed on GAC by acclimatized microbial cultures, was carried out using specified media along with controls (without cultures). Biodegradation of aqueous solutions of PVA was studied under similar conditions using the mixed cultures. Results indicate a steady decrease in PVA concentration upto 96 hrs. Biodegradation of PVA on GAC was almost 2-3 fold higher that of controls. The surface characterization of PVA adsorbed GAC before and after biodegradation that of an and GAC fresh sample was also carried out. Re-adsorption of PVA on bio-regenerated GAC was studied alongwith control. The study indicates biodegradation can be used for regaining the adsorption capacity of PVA on GAC.