Petrochemical and municipal wastewater treatment plants activated sludge each own distinct core bacteria driven by their specific incoming wastewater

Microorganisms in activated sludge from wastewater treatment plants (WWTPs) form complex networks to convert a wide variety of pollutants, thus ensuring water purification and environmental protection. In this study, activated sludge samples were collected from three full-scale WWTPs: a petrochemical WWTP (PWWTP), a municipal WWTP treating domestic wastewater (MWWTP_D), and a municipal WWTP treating a mixture of domestic wastewater and multiple industrial effluents (MWWTP_I+D). These samples were analyzed by high-throughput sequencing of 16S rRNA gene PCoA and CPCoA indicated that the samples from three WWTPs were separated, suggesting that each WWTP had unique microbiome characters (P < 0.05). This was also evidenced by the different predominant bacteria (PDB), biomarkers, and key nodes of co-occurrence network in the three WWTPs. Microorganisms with all three above mentioned characteristics were defined the core bacteria, specifically: Georgfuchsia, Thauera and GP4 in PWWTP, Phaeodactylibacter and Hyphomicrobiuml in MWWTP_D, and Otheakwangia, Terrimonas, Phenylobacterium, etc. in MWWTP_I + D. Furthermore, in accordance with the functional profile prediction, the functional groups in PWWTP metabolized aromatic compound, sulfur compounds and heavy metal typically present in petrochemical wastewater. In contrast, the microbiome in MWWTP_D was represented by the population breaking down macromolecular biodegradable organic matter and the nitrogen nutrients that constitute the vast majority of domestic wastewater pollutants. Both functional groups coexist in MWWTP_I + D. These results revealed that the specific composition of incoming wastewaters produced distinct ecological niches and modulated the ecological structure of activated sludge microbial communities in real-world WWTPs. However, the generalization of the results of this study will require further research.