Partial nitrification in MBBRs for mainstream deammonification with thin biofilms and alternating feed supply

Abstract

A new principle for mainstream nitrogen removal through nitritation followed by anammox was studied in a two-stage moving bed biofilm reactor (MBBR) configuration. The first stage was optimized for nitritation by using thin biofilms and a feed alternating between synthetic mainstream wastewater at 15°C and, for shorter periods, synthetic reject water at 30 °C. The exposure of the biofilm to reject water conditions aimed to improve the growth conditions for ammonia oxidizing bacteria, while inhibiting nitrite oxidizing bacteria. The biofilm thickness was maintained below 200 μm to ensure high exposure of the total biomass to the bulk reactor conditions. Nitritation was successfully achieved in the configuration, with a nitrite accumulation ratio above 75% during the majority of the study, and ammonia removal rates between 0.25 and 0.50 g NH4-N/L,d. The anoxic second stage, optimized for anammox, was fed with the effluent from the nitritation reactor, reaching nitrogen removal rates above 0.20 g TN/L,d.

Thickness determines microbial community structure and function in nitrifying biofilms via deterministic assembly

“…The reactor contained a mixture of Z50 and Z400 carriers (Veolia Water Technologies AB – AnoxKaldnes, Lund, Sweden) at a total filling degree of approximately 30%. Thickness of the biofilm in Z-carriers is limited by a pre-defined grid wall height 35 . Samples for optical coherence tomography measurements were taken on day 272 and data showed a biofilm thickness of 45 ± 17 and 379 ± 47 (mean ± S.D.)…”

“…For the potential activity trials 3 L reactors, containing 400 carriers each, were used. The substrate consisted of NaHCO 3 − buffer, pH adjusted to 7.5 using H 2 SO 4 , with phosphorous and trace minerals added in excess 35 . Aerobic removal of NH 4 + (starting concentration 35.2 NH 4 + -N mg/l) and NO 2 − (starting concentration 32.5 NO 2 − -N mg/l) were measured separately in two different trials at 20 °C for 1 hour, with sampling every 10 minutes.…”

“…Recently, a biofilm carrier with a defined grid wall height that defines the biofilm thickness was designed (Z-carriers, Veolia Water Technologies AB – AnoxKaldnes, Lund, Sweden) 35–37 . These carriers allow stringent experiments with different biofilm thicknesses, which have shown that thickness can affect some biofilm functions 37,38 , evenness 38 , biofilm architecture 36 , abundance of key organisms 36,38 and functional stability after a disturbance 36 .…”

Enhanced nitrite accumulation under mainstream conditions by a combination of free ammonia-based sludge treatment and low dissolved oxygen: reactor performance and microbiome analysis

“…25,26 However, the average NLR of 0.22 AE 0.03 kg N per m per day in this study was much lower than that in similar studies, where NLR was in the range 0.63-0.80 kg N per m per day. [25][26][27][28] Thus, a higher NAR could be anticipated with the elevation of NLR. Besides, effluent ammonium concentration was lower in the control than that of the experimental reactor most of the time (Fig.…”

Systems Microbiology and Engineering of Aerobic-Anaerobic Ammonium Oxidation

“…At macro scale, impacts of process configurations (e.g., two-stage or single-stage), operational conditions, and environmental perturbations on PN/A remain far from being fully understood and solved 23,38,57,58 . Applied research is actively involved to optimize sidestream installations, while new applications are investigated to implement PN/A along with variations in wastewater composition, loads, and temperature at mainstream [59][60][61][62] .…”