Comamonadaceae, Thiotrichaceae, and Rhodocyclaceae denitrifying bacteria dominated the bacterial community and accelerated the performance of the MRBR. Microbial analysis was performed on samples taken from the surface and inside the mesh carrier.

While NO3−-N remained after 2 h, adding methanol to enhance denitrification resulted in 93% removal after 8 h. A batch test showed that soluble chemical and biological oxygen demand removal efficiencies were 87% and 93%, respectively, after 2 h of operation. The total nitrogen removal was 190 ± 130 g N m⁻³ d⁻¹, compared to 860 ± 310 g N m⁻³ d⁻¹ with added nitrate at ≥20 ✬ and 100 ± 47 g N m⁻³d⁻¹ compared to 830 ± 220 g-N m⁻³d⁻¹ with added nitrate at ≤15 ✬. Influent NO3−-N concentration was decreased from 27.8 ± 6.0 mg-N L⁻¹ to an effluent value of 8.4 ± 4.8 mg-N L⁻¹ at ≥20 ✬ under 2 h of hydraulic retention time. A laboratory-scale MRBR was continuously operated for approximately 550 days under ambient conditions, fed with actual sewage. This study evaluated the denitrification performance of an MRBR during municipal wastewater treatment. MRBRs have a high specific surface area for biomass in order to achieve efficient nutrient removal performance. The mesh rotating biological reactor (MRBR) is one of the advanced modifications of the rotating biological contactor. The predominant denitrifying genera were different between the PS-RBC and JO-RBC, as well as in the cross-sectional layers of the PS-RBC, suggesting the functional diversity of denitrifying bacterial genera inhabiting the RBC. The relative abundance of total denitrifying bacteria in the PS-RBC was twice as much as that in JO-RBC, while nitrifying bacterial phylotypes had a similar relative abundance. The microbial community of activated sludge likely affected that of RBC. The microbial community composition of RBC (an attached growth process) was similar to that of the activated sludge (a suspended growth process). Here, we observed that the microbial community compositions at the phylum and class levels were similar between the PS-RBC and JO-RBC, whereas the relative abundances of several phyla (Euryarchaeota, Acidobacteria, Chloroflexi, Firmicutes, Patescibacteria, and Betaproteobacteria) significantly differed between them.

We investigated the microbial community of the rotating biological contactor (RBC) units treating PS and JO, in which the RBC was submerged in the mixed liquor of activated sludge. The public sewage (PS) and night soil mixed with johkasou sludge (JO) have similar chemical compositions however, the concentrations of organic matter and nitrogen compounds were different.

Aoi tsukasaqun ly