Robust Nitritation of Anaerobic Digester Centrate Using Dual Stressors and Timed Alkali Additions

Abstract

Nitrogen is commonly removed from wastewater by nitrification to nitrate followed by nitrate reduction to N2. Shortcut N removal saves energy by limiting ammonia oxidation to nitrite, but nitrite accumulation can be unstable. We hypothesized that repeated short-term exposures of ammonia-oxidizing communities to free ammonia (FA) and free nitrous acid (FNA) would stabilize nitritation by selecting against nitrite-oxidizing bacteria (NOB). Accordingly, we evaluated ammonium oxidation of anaerobic digester centrate in two bench-scale sequencing batch reactors (SBRs), seeded with the same inoculum and operated identically but with differing pH-control strategies. A single stressor SBR (SS/SBR) using pH set-point control produced HNO3, while a dual stressor SBR (DS/SBR) using timed alkalinity addition (TAA) produced HNO2 (ammonium removal efficiency of 97 ± 2%; nitrite accumulation ratio of 98 ± 1%). The TAA protocol was developed during an adaptation period with continuous pH monitoring. After adaptation, automated TAA enabled stable nitritation without set-point control. In the SS/SBR, repeatedly exposing the community to FA (8–10 h/exposure, one exposure/cycle) selected for FA-tolerant ammonia-oxidizing bacteria (Nitrosomonas sp. NM107) and NOB (Nitrobacter sp.). In the DS/SBR, repeatedly exposing the community to FA (2–4 h/exposure, three exposures/cycle) and FNA (4–6 h/exposure, two exposures/cycle) selected for FA- and FNA-resistant AOB (Nitrosomonas IWT514) and against NOB, stabilizing nitritation.

Efficient Treatment and Simultaneous Energy Recovery from Cattle Wastewater by the Micro-Aerated UASB and SBR Coupled System

“…In SBR, the abundance of unclassified Xanthomonadaceae showed a positive correlation with ammonia. A possible explanation could be heterotrophic nitrification mediated by ammonia-oxidizing Xanthomonadaceae in SBRs operated with real cattle wastewater …”

“…https://doi.org/10.1021/acsestwater.3c00241ACS EST Water XXXX, XXX, XXX−XXX Xanthomonadaceae in SBRs operated with real cattle wastewater 66. …”

Dynamic Simulation of Nitrifying Microbial Communities for Establishing Acidic Partial Nitritation in Suspended Activated Sludge

“…Because of their advantages of operational simplicity, low cost, compact volume, and stable performance, SBRs have been widely used in wastewater treatment processes including the PN process. ,, Conventionally, SBR-based PN can be established in treating wastewater with a high NH 4 + concentration by maintaining high levels of FA at the beginning of the cycle and high levels of FNA at the end of the cycle. ,, Yet, difficulty is found in treating wastewater with a low NH 4 + concentration to produce such high levels of FA, so FNA-established PN becomes the key option, while it remains unknown whether PN can be established in SBRs if the process relies exclusively on FNA. Moreover, the implementation of an acidic PN in an SBR should be more complex than that in a continuous-flow reactor.…”

Achieving Partial Nitritation by Treating Sludge With Free Nitrous Acid: The Potential Role of Quorum Sensing

“…Under such process conditions, an insufficient carbon source in the influent will lead to insufficient denitrification, resulting in an excessively high concentration of total nitrogen (nitrate nitrogen) in the effluent ( Rahimi et al, 2020 ). In order to solve the problems of high energy consumption, carbon source shortage, and low nitrogen removal efficiency faced by traditional nitrogen removal processes, novel processes based on partial nitritation have gradually developed in recent years, such as the partial nitritation and denitrification process (PN/D) and the partial nitritation and anaerobic ammonia oxidation process (PN/A; Duan et al, 2020 ; Li et al, 2020 , 2021 ; Qiu et al, 2020 ; Yao et al, 2021 ). Different from the traditional nitrification and denitrification process, nitrogen removal processes based on partial nitritation only oxidizes ammonia to nitrite, and then directly enters the subsequent nitrogen removal stage, which greatly saves oxygen consumption and carbon source demand, while reducing excess sludge production and greenhouse gas emissions ( Sinha and Annachhatre, 2006 ).…”