Effect of Carbon to Nitrogen Ratio on Water Quality and Community Structure Evolution in Suspended Growth Bioreactors through Biofloc Technology

Abstract

Application of biofloc technology could effectively treat wastewater. However, the effect of influent carbon to nitrogen ratio (C/N ratio) on water quality and microbial community structure evolution in suspended growth bioreactors (SGBRs) through biofloc technology is still unclear. Here, we show that the total ammonia nitrogen (TAN) and nitrite nitrogen in the effluent of the C/N 10 treatment was significantly higher than that in the C/N 15, C/N 20 and C/N 25 treatments (p < 0.05). Higher TAN removal efficiency was obtained in treatments of C/N 15, C/N 20 and C/N 25, and there was no accumulation of nitrite nitrogen and nitrate nitrogen. Increasing the C/N ratio strengthened the elimination ability of total phosphorus and chemical oxygen demand (COD). The concentrations of TAN and COD first dropped to the lowest level and then increased slightly within one cycle in all treatments. The accumulation of biomass in the reactors increased with the increasing C/N ratio, indicating that a higher C/N ratio was conducive to microbial proliferation. The 16S rRNA sequencing revealed that the microbial community diversity in SGBRs was significantly higher than that in the natural wastewater (P0). The predominant phylum were Proteobacteria, Bacteroidetes and Verrucomicrobia, but Saccharibacteria occupied a dominant position in the late period of the experiment. Pathogens, such as Aeromonas, Acidovorax, Flavobacterium, and Malikia were significantly decreased after high C/N ratio simulative wastewater treating natural wastewater in the reactors. In summary, the water quality and biomass concentrations in SGBRs can be improved under the conditions of influent C/N ratio, equal to or greater than 15.

Heterotrophic aerobic denitrification by novel bacterium Georgenia daeguensis ARB2 for treatment of nitrate contaminated waters

“…Strain Georgenia daeguensis ARB2 gave the best growth and nitrate reduction at a molar C/N ratio of 34. Gou et al (2019) also suggested that higher C/N ratios are conducive for microbial growth. However, in this study, lower or higher C/N ratios than 34 resulted in restricted growth and nutrient removal which can be attributed to limited availability of carbon required for growth of heterotrophs at lower C/N ratios and possibly the reduced denitrification enzyme activity at higher C/N ratios.…”

Nitrate Water Contamination from Industrial Activities and Complete Denitrification as a Remediation Option

“…In O 2 -limited environments, the ratio of carbon source to nitrogen (C:N) is mostly three or lower, with lower carbon source demand for bacterial metabolism of ethanol and nitrates [160]. The balance between the C and N sources is vital in remediation systems, as higher consumption of N by bacteria requires greater accumulation of biomass, which in turn requires a sufficient C-source to proliferate [186]. The effectiveness of a bacterial system in removing N from water depends mostly on the preference bacteria has for the supplied C-source, which is needed to accumulate enough biomass to remove the NO 3 − in the system.…”

Pengaruh Sistem Aerasi Intermittent terhadap Removal Organik dan Nitrogen pada Pengolahan Air Limbah Domestik Kamar Mandi Umum

“…Berdasarkan grafik hubungan rasio C/N dan efisiensi removal diatas, semakin tinggi rasio C/N maka efisiensi removal COD, efisiensi removal fosfat dan efisiensi nitrifikasi juga semakin meningkat. Hal serupa terjadi pada penelitian (Gou et al, 2019) dengan menggunakan teknologi bioflok. Efisiensi removal amonia nitrogen (NH3-N) pada rasio C/N 10, C/N 15, C/N 20 dan C/N 25 berturutturut sebesar 88,67%, 94,98%, 100% dan 100%.…”