A method for determining VOC biotransformation rates

A method was developed for determining biotransformation rate coefficients for volatile organic compounds in activated sludge systems. It consisted of a sealed batch reactor containing primary substrate, VOCs and biomass. A bubbleless oxygenation system was used to supply oxygen. Two types of substrate were studied to determine method reliability; domestic wastewater and synthetic wastewater, as were various conditions; abiotic, biotic, anaerobic, anoxic denitrifying and aerobic. The anaerobic and anoxic denitrifying conditions revealed minimal VOC biotransformation, while under aerobic conditions, the method successfully measured mixed second-order biotransformation rate coefficients for the ten VOCs studied. The proposed method will be useful to designers and operators of wastewater treatment plants, who need reliable kinetic parameters to predict the fate of contaminants in wastewater treatment plants.