Abstract
The aerobic biodegradation of poly (3-hydroxybutyric acid) (PHB), a biodegradable plastic, through the action of sewage bacteria was followed by the production of CO2 at 510 mg carbon/L. The degradation started at after 23 d of lag phase and was 7179 % complete in 30 d. PHB is metabolized via acetoacetic acid, a potential precursor of trihalomethanes (THM). The biodegradation intermediates of PHB were thus chlorinated and THM production and the toxicity of other chlorinated products were examined. THM as volatile product could not be detected (less than 10 μg/L). Other non-volatile chlorinated products were not mutagenic (rec-assay) and no growth inhibitory (algae-assay) activity was noted. PHB at 510 mg carbon/L is thus shown to be extensively degraded by sewage bacteria and degradation intermediates are unlikely to produce toxic materials even following chlorination.
