Effect of influent COD/N ratio on performance and N₂O emission of partial nitrification treating high-strength nitrogen wastewater

Abstract

The effect of influent chemical oxygen demand/nitrogen (COD/N) ratio on nitrogen removal and nitrous oxide (N 2 O) emission during partial nitrification treating high-strength nitrogen wastewater was investigated. Three laboratory scale anoxic/aerobic sequencing batch reactors (SBRs) were operated under different influent COD/N ratios (0.5, 1.0, and 2.5, respectively). Stable and high nitrite accumulation ratios around 90% were obtained at COD/N ratios of 0.5 and 1.0. A temporary high nitrite accumulation ratio (89.9 AE 1.04%) was observed at a COD/N of 2.5 (days 20-65), however, the main nitrogen species in the effluents changed from nitrite to nitrate afterwards. Despite the many benefits of the partial nitrification process, the significant generation of N 2 O, a potent greenhouse gas, remains a problem for this innovative and promising process. Attempts to minimize N 2 O emissions during the partial nitrification process by increasing the anoxic/aerobic phase fraction were conducted, and it was found that the N 2 O emission quantity was reduced by 50.6% and 46.2% in SBR with influent COD/N of 0.5 and 1.0, respectively. This was because a longer anoxic phase benefited nosZ gene expression and resulted in higher abundance of heterotrophic microorganisms.

Numerical assessment of a soil moisture controlled wastewater SDI disposal system in Alabama Black Belt Prairie

“…Furthermore, the stimulated soil microbial growth zone is dominated by heterotrophs, and autotrophic nitrifiers (AOB and NOB) thrive outside the heterotrophs dominant zone. This outcome conforms to the rival growth of heterotrophs and autotrophic nitrifiers observed in reality that autotrophic nitrifiers thrive only when organic substrates are insufficient for heterotrophs ( Zhang et al., 2015 ). Since heterotrophs are the major force for organic removal and biofilm formation ( Ahmad and Husain, 2017 ), enhanced soil microbial growth indicates stimulated biofilm growth around drip emitters.…”

Effect of free ammonia inhibition on NOB activity in high nitrifying performance of sludge

“…They belonged to the phyla Acidobacteria, Bacteroidetes and Proteobacteria, respectively, which were the main components of the activated sludge in the wastewater treatment system. 34,35 Nitrosomonas (affiliated to b-Proteobacteria phylum, called ammonia-oxidizing bacteria) and Nitrospira (a distinct phylum, called nitrite-oxidizing bacteria) were detected at 0.43% and 2.14%, respectively, in municipal wastewater treatment. 36,37 These implied that the abundance of the specic functional species (Nitrospira) was very low.…”

Dosage-Dependent Toxicity of Universal Solvent Dimethyl Sulfoxide to the Partial Nitrification Wastewater Treatment Process

“…To further characterize the activity of AOB and NOB, the SOUR of each SBR reactor was measured and calculated. The oxidation rates of NH 4 + –N and NO 2 – can be obtained by subsequent addition of 200 mM NaClO 3 and 50 mg/L allyl thiourea, selective inhibitors of AOB and NOB, respectively . The ammonia removal efficiency (ARE) and nitrite accumulation rate (NAR) were calculated.…”