[Influencing factors on start-up period in a bioaugmented membrane bioreactor using genetically engineered...

High and stable atrazine removal could be obtained after a start-up period in a membrane bioreactor (MBR) bioaugmented with genetically engineered microorganism (GEM) and the removal efficiency was above 90% . The shortest start-up period was 2 d and the longest one was 12 d under different conditions. Initial influent atrazine loading, operation temperature and initial population size of GEM affected the start-up period greatly. High initial influent atrazine loading, high operation temperature and large initial population size of GEM were favorable to shorten the start-up period. The characteristics of the influent had little effect on the start-up period. When other conditions were identical, two kinds of influents, synthetic wastewater and real domestic wastewater, had the same start-up periods. Moreover, after the start-up period, atrazine removal had also no difference with these two influents in the following stable period. Then it could be concluded that the characteristics of the influent influenced atrazine removal little not only in the start-up period but also in the stable period.