The call for regional design code from the regional discrepancy of microbial communities in activated sludge

Discerning the differences in activated sludge (AS) microbial community due to geographic location and environmental and operational factors is of great significance for precise design and maintenance of wastewater treatment plants (WWTPs). Hence, in this study, 150 AS samples collected from WWTPs in South China and North China were analyzed by 16 S rRNA gene sequencing. In general, AS microbial community in North China had lower diversity, higher proportions of stochastic assembly (35.7% v.s. 15.8%) and more network keystone species (19 v.s. 5) compared with southern AS community. Conductivity and SRT had significant effects on AS community in both regions. Latitude, annual mean temperature, and influent BOD, COD, and ammonia influenced South China community significantly, while pH and influent total phosphorus affected North China community. To achieve stable performance, southern WWTPs should carefully monitor fluctuations in wastewater characteristics, while northern WWTPs should monitor AS communities for shifts in the dominant taxa from immigrant strains brought in through the influent. Additionally, WWTPs in North China should be aware of the need to proactively control sludge bulking because of the high abundance and occurrence of Haliscomenobacter in these AS communities. The call for regional design based on the regional discrepancy of microbial communities in activated sludge is uncovered and according suggestions were given. [Display omitted] •Higher diversity and more deterministic assemblages were observed in WWTPs in South China.•Distinctions of the AS core and microbial interactions were revealed between the two regions.•Special attention should be paid to sludge bulking and shift of main taxa in northern WWTPs.•Fluctuations in influent characteristics should be carefully monitored in southern WWTPs.