Effects of side-stream ratio on sludge reduction and microbial structures of anaerobic side-stream reactor coupled membrane bioreactors

Simultaneous sludge minimization, biological phosphorous removal and membrane fouling mitigation in a novel plant layout for MBR

“…The above results were in good agreement with previous literature, indicating that the released COD in the anaerobic reactor increased with the HRT (Cheng et al, 2017). Although previous studies reported that the implementation of the anaerobic reactor improved the COD removal efficiency (Saby et al, 2003;Semblante et al, 2014), the findings of the present study demonstrated that the COD removal efficiency decreased with HRT higher than 8 h, in good agreement with what reported by Ye et al (2008).…”

The role of microbial diversity and composition in minimizing sludge production in the oxic-settling-anoxic process

“…Chloroflexi has been associated with anaerobic degradation of carbohydrates and cellular materials (Weissbrodt et al, 2014), and has been detected as one of the dominant bacteria in an external anaerobic reactor attached to an aerobic MBR (Cheng et al, 2017). Furthermore, fermentative bacteria such as OP8, Firmicutes, WS3, and Spirochaetae were only found in significant abundance in the external anoxic reactor (2.2 ± 1.2, 1.0 ± 0.1, 1.0 ± 0.5 and 1.0 ± 0.3%, n = 3, respectively) (Supplementary Figure S6).…”

“…Application of pyrosequencing analysis showed that an aerobic/anoxic system with external anaerobic reactor has greater microbial diversity than a control aerobic/anoxic system (Ning et al, 2014;Zhou et al, 2015) probably because slow-growing fermentative (Azospira, Propionivibrio and Sulfuritalea) (Zhou et al, 2015) and hydrolyzing (Sphingobacteria) (Ning et al, 2014) bacteria were enriched under anaerobic conditions. Meanwhile, Illumina sequencing analysis in the study by Cheng et al (2017) showed enrichment of different types of bacteria in an aerobic membrane bioreactor (MBR), e.g., Nitrospirae, and the attached external anaerobic reactor, e.g., Chloroflexi and Armatimonadetes. It was further observed that microbial groups that facilitate sludge autolysis, such as those that perform degradation of extracellular polymeric substances (EPS), sulphate reduction, and fermentation, survive in the external anaerobic reactor attached to an anoxic/aerobic sequencing batch reactor (SBR) (Cheng et al, 2017;Ferrentino et al, 2016).…”

“…Meanwhile, Illumina sequencing analysis in the study by Cheng et al (2017) showed enrichment of different types of bacteria in an aerobic membrane bioreactor (MBR), e.g., Nitrospirae, and the attached external anaerobic reactor, e.g., Chloroflexi and Armatimonadetes. It was further observed that microbial groups that facilitate sludge autolysis, such as those that perform degradation of extracellular polymeric substances (EPS), sulphate reduction, and fermentation, survive in the external anaerobic reactor attached to an anoxic/aerobic sequencing batch reactor (SBR) (Cheng et al, 2017;Ferrentino et al, 2016).…”

“…These studies imply that aerobic-anaerobic interchange enriched sludge biomass and that microbial composition yielded useful information regarding potential biological reactions relevant to sludge reduction (Cheng et al, 2017;Ferrentino et al, 2016;Ning et al, 2014;Zhou et al, 2015). Therefore, it is necessary to characterize the microbial community structure of OSA, which is expected to differ from that of other configurations available in literature due to the sensitivity of bacteria to redox and other operating conditions, to understand its effects on sludge reduction.…”