Biofortification using bacteria containing an atrazine-degrading gene and its effects on reactor operating efficiency

Abstract

To investigate the effects of biofortification of activated sludge reactors using genetically engineered microbes containing a plasmid encoding atrazine chlorohydrolase, we compared biodegradation efficiency and sludge properties during three operating stages in a conventional activated sludge (CAS) reactor and a MBR. Our results show that with the addition of genetically engineered bacteria and the selection for indigenous biodegrading microbes, membrane fouling was reduced. Atrazine has a certain level of biotoxicity toward activated sludge and shows an inhibitory effect toward pollutant removal. After biofortification, atrazine degradation was superior in MBR than that in CAS reactors. The atrazine removal rate was 92.6% in the MBR, while it was 82.6% in the CAS reactor. Following biofortification, the sludge concentration in the MBR was maintained at 7.3 g/L, while the sludge concentration in the CAS reactor was 2.3 g/L.