Removal performance of nitrogen and endocrine-disrupting pesticides simultaneously in the enhanced biofilm system for polluted source water pretreatment

• No significant change of EDPs removal with increase of NH4+–N and NO3−–N transfer.
• Simultaneous denitrification and EDPs removal in anoxic niches via reed addition.
• Many species related to the nitrogen and EDPs removal enhanced with reed addition.

The removal performances of nitrogen and trace levels of endocrine-disrupting pesticides (cypermethrin and chlorpyrifos) were studied in the enhanced biofilm pretreatment system at various substrates concentrations and dissolve oxygen (DO) niches. No significant change of EDPs removal occurred with the increased feed of ammonia nitrogen in aerobic batch tests or nitrate in anaerobic batch reactors, but significantly enhanced via reed addition both in aerobic and anaerobic conditions. Simultaneously enhanced denitrification and EDPs removal were achieved in the anoxic niche with reed addition. The results of denaturing gradient gel electrophoresis (DGGE) indicated that new bands appeared, and some bands became more intense with the reed addition. Sequences analysis showed that the dominant species belonged to Methylophilaceae, Hyphomicrobium, Bacillus and Thauera, which were related to the nitrogen or EDPs removals. In addition, the growth of functional heterotrophic microbes may be promoted via reed addition.