Differences of bacterial communities in two full-scale A2/O municipal wastewater treatment plants and their effects on effluent total nitrogen removal

Bacterial communities and functional bacteria played a vital role in the biological removal of nitrogen in wastewater. Bacterial communities, nitrogen removal and their correlationship were compared and analyzed in two full-scale anaerobic/anoxic/aerobic (A(2)/O) municipal wastewater treatment plants (WWTPs) (assigned as D and X plants). Illumina high-throughput sequencing results showed remarkable differences in the bacterial communities' diversity were found between these two WWTPs. Significant differences in species diversity existed in anaerobic, anoxic, and aerobic tanks in X plant, while no significant differences were found among the D plant's tanks. In the aerobic tanks of X and D plants, nitrifying bacteria genera accounted for 5.29% and 1.57%, respectively, while aerobic denitrifying bacteria accounted for 0.64% and 0.47%. In the two plants' anoxic tanks, denitrifying bacteria accounted for 1.14% and 1.64%, respectively. During the two months of monitoring, average effluent total nitrogen (TN) concentrations of X and D plants were 14.85 +/- 1.85 and 17.66 +/- 0.92 mg/L, respectively, and the former was satisfied with the stringent discharge standard. Effluent TN was significantly negatively correlated with Nitrospira, Denitrobacter, Thauera, Comamonas and Dechloromonas (P<0.05) and positively correlated with Paracoccus and Dokdonella (P<0.05). Overall, species diversity in each functional tank of X plant was remarkably different, and functional genera were more abundant in X plant than that in the D plant, which might be one reason for the lower effluent TN concentrations in the two WWTPs. (C) 2020 Elsevier B.V. All rights reserved.

Automated summary

The study found that the bacterial community diversity was higher and the functional bacterial genera were more abundant in X plant compared to D plant, resulting in lower effluent total nitrogen concentrations.