MCPA biodegradation in an anoxic sequencing batch reactor (SBR)
This research investigated the potential for industrial strength 2 methyl 4 chlorophenoxyacetic acid (MCPA) degradation by activated sludge microorganisms in a sequencing batch reactor (SBR) under nitrate reducing conditions. The research was divided into four phases consisting of Phase I (a "proof of concept" phase) Phase II (an initial "tolerance" exploration phase) Phase III (an "effect of hydraulic retention time" phase) and Phase IV (a "limits" phase) The SBR successfully and simultaneously removed the nitrates completely and around 98 of the MCPA up to an initial concentration of 50 mg/L MCPA in the dimethylamine salt form (DMCPA) (Phases I, II and III) however, it took approximately 28 days to observe a steady, high level of MCPA removal. When the concentration of DMCPA was increased to 75 mg/L (Phase IV) the MCPA removal efficiency dropped to 85 but removal was observed only for a relatively short period of time since the biomass appeared to eventually become saturated with the herbicide, stopping conversion of DMCPA to its acid form and halting biodegradation.
International Journal of Environmental Science and Technology