Biodegradation of Propylene Glycol Wastewater Using Bacterial Consortia Isolated from Municipal Wastewater Treatment Sludge-Process Kinetics and Optimization

摘要

Propylene glycol (PG), commonly used in the food, cosmetics and pharmaceutical industries and considered non-PBT, is still an emerging contaminant of concern due to its widespread use. In this study, an isolate of a bacterial consortium obtained from an effluent treatment plant,MC1S, was used to degrade PG. The growth kinetics of the isolate was studied under aerated and non-aerated conditions. The isolate was able to effectively grow in saline water under aerated conditions using PG as the substrate. Using response surface methodology (RSM), the effect of pH, salinity, PG concentration, phosphate and nitrate concentration on cell growth and PG degradation was investigated. The isolated bacterium,MC1S, was capable of degrading PG with a maximum of 79% COD reduction observed and was able to withstand comparatively high salinity of the medium. Solution pH and salinity were the most important parameters affecting degradation. Salinity less than 0.1 M and pH close to 8 appeared to be the optimum conditions for PG degradation. HPLC analysis of the treated sample appeared to show the presence of three daughter products. Using RSM, a quadratic equation model between COD reduction and the process variables was developed. The results indicated that aerobic treatment of PG under specific conditions was the best approach for the specific isolate.