design: For DNA extractions, 50 - 60 mL of influent and 100 - 400 mL of effluent were filtered in triplicate through sterile membrane filters with a pore size of 0.2 m. The filters were cut into smaller pieces and placed in tubes for DNA extraction using the Qiagen PowerSoil Kit DNA. PCR amplification of the V3-V4 region was performed with primers 341F1-4 and 785R1-4 containing Illumina TruSeq adapter sequences at the 5 ends using Phusion Hot Start Polymerase with GC buffer.