Abstract:
Plastics have a vital role in our lives. Many items of everyday life come from
different types of plastic, from films to packaging, including blankets, containers and
bags to building materials, electronic applications and electrical equipment. Lack of
biodegradability of these products draws public awareness to increase in environmental
pollution problem. In the current study, low molecular weight polyvinyl chloride is
biodegraded using bacterial strains isolated from open dumping site situated on the upper
bank of Korang River, Islamabad Expressway. Four bacterial strains were screened and
used as consortium to degrade PVC under varying physical and chemical experimental
conditions in minimal salt medium for 15 days at 30°C. Effect of different cometabolites, light, Ultra-violet radiations and pH was evaluated to assess biodegradation
of PVC pieces. Maximum bacterial growth in terms of CFU/ml, 665/ml, was observed
when Glycerol as co-metabolite was added in the medium. Non UV pre-treated sample
showed more growth, 591/ml, as compared to UV pretreated samples. 9 pH showed
maximum stability and growth in terms of CFU/ml that is, 212/ml by the end of the
experiment. Chemical changes were observed using Fourier Transform Infrared
Spectroscopy (FTIR) and physical changes were observed using Scanning Electron
Microscopy (SEM). FTIR showed breakdown and formation of many compounds as
evident by new peaks formation in microbial treated PVC samples in comparison with
the control (untreated). SEM showed structural and surface changes in PVC in the form
of depression, pits, erosions, discoloration and small holes. Clear image of biofilm on the
surface of treated PVC samples in the form of rod shaped bacteria was observed. In SEM
images it can be concluded that bacterial consortium was able to bring about chemical
and physical changes in PVC pieces which gives positive indication of occurrence of
biodegradation processes taking place.
