Comparison between two anammox fiber fillers under load impact and the effect of HCO3− concentration

Based on the establishment of a stable anaerobic ammonia oxidation treatment system in 100 days, the impact resistances of two different anammox fiber fillers (the curtain filler: R1 and the bundle filler: BR) were compared.

Integration of anammox into the MBR process for main stream sewage treatment

The integration of Anaerobic ammonia oxidation (anammox) into the membrane bioreactor (MBR) process (AX-MBR) is proposed in this study to reduce operating costs. The temperature was not controlled during the study. Anammox, denitrification, and nitrification were studied in the AX-MBR for 210 days. The reactor was fed with mainstream sewage from Guilin City, China. The results showed that AX-MBR could run with reduced dissolved oxygen (DO) concentration, and COD, NH4+-N, and total nitrogen removal were maintained or improved. The microbial analysis results demonstrated that the added anammox sludge could survive in the AX-MBR, but the sludge microbial diversity decreased. Nitrospira, Candidatus Kuenenia, and Nitrosomonas dominated the anammox sludge. In a word, the AX-MBR developed in this study could treat mainstream sewage with the appropriate management, and the operation costs are expected to reduce by decreasing the amount of aeration.

Rapid Start-Up of Anammox by Immobilization and Its Response to Low Temperature Stress

In view of the problems of slow start, easy loss and sensitive to low temperature environment in the suspension culture of anaerobic ammonia oxidation bacteria (AnAOB) suspension culture, polyvinyl alcohol (PVA) was used to prepare the anaerobic ammonia oxidation (anammox) immobilized filler, so as to realize the rapid start-up and activity improvement of anammox. Meanwhile, the response of nitrogen removal performance of encapsulated biomass to temperature reduction was determine by batch experiment. In addition, changes in the internal structure, flora composition and diversity of the filler were analyzed by scanning electron microscopy (SEM) and high-throughput sequencing. The results showed that the nitrogen removal capacity of the immobilized filler (E1) was significantly higher than that of the suspended sludge contrast system (S1) after 100d enrichment culture. The final nitrogen removal rate reached 1.168kg·(m3·d-1) -1, and the total nitrogen removal efficiency was 92%. The immobilization improved the resistance of AnAOB to low temperature. At 15°C, the effluent ammonia and nitrite of S1 were seriously accumulated, and E1 could maintain a stable nitrogen removal effect under the regulation of HRT. The population diversity was maintained in the immobilized filler, and the functional bacteria of anammox Candidatus Kuenenia was effectively enriched, accounting for 32.55% in E1. The results of this study provide valuable information for the application and popularization of anammox immobilized filler.

Effects of Recirculating Aquaculture System Wastewater on Anammox Performance and Community Structure

Recirculating aquaculture systems (RAS) are good candidates for the sustainable development of the aquaculture sector. A current limitation of RAS is the production and accumulation of nitrogenous waste, which could affect fish health. We investigated the potential of the anaerobic ammonia oxidation (anammox) process to treat marine wastewater from a cold-water RAS. We show that the marine anammox bacteria Candidatus Scalindua is a promising candidate. However, its activity was affected by unknown compounds in the RAS wastewater and/or the sub-optimum of essential trace elements (TEs). Anammox activity dropped to 2% and 13% in NH4+ and NO2- removal, respectively, when nitrate-rich RAS wastewater was used as a medium in the absence of TE supplementation. A TE supplementation was added to the RAS wastewater in a subsequent phase, and a recovery in anammox activity was shown (25% and 24% in NH4+ and NO2- removal, respectively). Future studies need to identify the unknown factor and determine the specific needs regarding TE for optimal RAS wastewater treatment by Candidatus Scalindua.

Nitrate- and Nitrite-Sensing Histidine Kinases: Function, Structure, and Natural Diversity

Under anaerobic conditions, bacteria may utilize nitrates and nitrites as electron acceptors. Sensitivity to nitrous compounds is achieved via several mechanisms, some of which rely on sensor histidine kinases (HKs). The best studied nitrate- and nitrite-sensing HKs (NSHKs) are NarQ and NarX from Escherichia coli. Here, we review the function of NSHKs, analyze their natural diversity, and describe the available structural information. In particular, we show that around 6000 different NSHK sequences forming several distinct clusters may now be found in genomic databases, comprising mostly the genes from Beta- and Gammaproteobacteria as well as from Bacteroidetes and Chloroflexi, including those from anaerobic ammonia oxidation (annamox) communities. We show that the architecture of NSHKs is mostly conserved, although proteins from Bacteroidetes lack the HAMP and GAF-like domains yet sometimes have PAS. We reconcile the variation of NSHK sequences with atomistic models and pinpoint the structural elements important for signal transduction from the sensor domain to the catalytic module over the transmembrane and cytoplasmic regions spanning more than 200 Å.

Development of Strategies for AOB and NOB Competition Supported by Mathematical Modeling in Terms of Successful Deammonification Implementation for Energy-Efficient WWTPs

Novel technologies such as partial nitritation (PN) and partial denitritation (PDN) could be combined with the anammox-based process in order to alleviate energy input. The former combination, also noted as deammonification, has been intensively studied in a frame of lab and full-scale wastewater treatment in order to optimize operational costs and process efficiency. For the deammonification process, key functional microbes include ammonia-oxidizing bacteria (AOB) and anaerobic ammonia oxidation bacteria (AnAOB), which coexisting and interact with heterotrophs and nitrite oxidizing bacteria (NOB). The aim of the presented review was to summarize current knowledge about deammonification process principles, related to microbial interactions responsible for the process maintenance under varying operational conditions. Particular attention was paid to the factors influencing the targeted selection of AOB/AnAOB over the NOB and application of the mathematical modeling as a powerful tool enabling accelerated process optimization and characterization. Another reviewed aspect was the potential energetic and resources savings connected with deammonification application in relation to the technologies based on the conventional nitrification/denitrification processes.

Research of landfill leachate treatment based on anammox

Landfill leachate has the characteristics of high ammonia nitrogen content, high concentration of organic matter and low carbon nitrogen ratio. Traditional biological treatment technology is difficult to meet the increasingly stringent emission standards. Ammonia nitrogen is the main pollutant in landfill leachate. The ammonia-nitrogen-rich leachate not only poses a threat to the surrounding environment, but also has adverse effects on the subsequent biological treatment of leachate. Anaerobic ammonium oxidation (Anammox) is a new biological denitrification technology, which has the advantages of high denitrification capacity and low energy consumption, and is suitable for the treatment of landfill leachate. This article from the process type, inhibiting factors and microbiology at home and abroad are reviewed in three aspects: the anaerobic ammonia oxidation treatment, the research progress of landfill leachate by analyzing the national environmental protection agency of leachate quality related data in the database, and combining previous research results, reveals the infiltration drain liquid ammonia nitrogen in the different conditions of concentration variation characteristics, for anaerobic ammonia oxidation treatment of landfill leachate to provide the reference for engineering applications.