Microbial Degradation Of Polyurethane

ABSTRACT

Polyurethane is a non-easily degradable synthetic polymer used as packaging material. Its presence and durability in the environment pose global disposal and degradation problem. Polyurethane releases toxic substances with carcinogenic or mutagenic potential during burning in dumpsites. An alternative to burning of waste materials is the use of microorganisms to degrade them. However, little is known about microbial degradation of polyurethane. Therefore, microbial degradation of polyurethane was investigated as an alternative treatment and management method. Polyurethane samples were collected from a dumpsite in the University of Ibadan and rubbish-bins of two fast foods outlets within Ibadan metropolis. The packs were buried at depths ranging from 15-70 cm in the garden soil of Microbiology Department, University of Ibadan. They were exhumed at predetermined intervals between the dry and rainy seasons of June 2010-June 2012 for isolation of microorganisms. The microbial isolates were screened for ability to utilise polyurethane as nitrogen and/or carbon source using mineral salts medium. Selected polyurethane-utilising microorganisms as carbon and nitrogen sources were characterised and identified using standard microbiological procedures and the advanced bacterial identification software database. Biodegradation study was carried out on sterilised soil in the laboratory and garden soil in the field with the best six polyurethane-utilising bacteria. This was done using complete randomised block design with 4x3x2 factorial experiment for isolates combinations (A: Pseudomonas alcaligenes E14+ Providencia pseudomallei D25, B: Enterobacter amnigenus D12+ Vibrio sp. C32, C: Pseudomonas aeruginosa E32 + Providencia pseudomallei D21 and D: Consortium of the six bacteria) and biostimulation treatments (cassava peels, potato peels, no peels) at 1 and 3 month periods. Changes in the functional groups of degraded polyurethane samples were determined using Fourier transform infrared spectroscopy. Weight loss of polyurethane samples was monitored by measurement. Data were analysed using ANOVA at p = 0.05.