Search

Anaerobic ammonium oxidation (anammox) is a promising biological nitrogen removal process, due to its advantages of high efficiency and low cost. However, problems remain in the application, such as long startup period and susceptibility to environmental variations. Quorum sensing (QS), as a means of bacterial communication, attracts more attentions in regulating aggregation behavior and microbial density. Many physiological characteristics of anammox bacteria have been confirmed to be associated with QS, including specific anammox activity, growth rate and the production of extracellular polymeric substances (EPS), which directly affect the performance of anammox process. Therefore, a comprehensive understanding of the QS in anammox process is prerequisite. This work systematically reviewed the role and application of QS in the anammox process with the focus on mechanism. Additionally, current challenges and research needs were proposed. [ABSTRACT FROM AUTHOR]

While the application of mesophilic anammox process is currently the state of the art, the feasibility of a thermophilic anammox bioprocess is still unclear. In this study, we investigate whether glycine betaine (GB) addition can enhance the thermotolerance of mesophilic anammox biomass in the upflow anaerobic sludge blanket (UASB) reactors fed with synthetic wastewater at a nitrogen loading of approximately 4 kg N m–3 d−1. The results showed that during a long-term operation at 45°C with GB (0, 0.1, 1, 2 mM) addition, anammox performance became worse with the final effluent concentrations of NO2–N of 145 ± 11.6 mg L−1 and nitrogen removal efficiency decreased from 92.3–6.9%. Specific anammox activity decreased from 392.1 ± 12.1–6.0 ± 0.8 mg N g−1 VSS d−1, which were not significantly higher than those in the control reactor. The content of heme c showed a stronger downward trend in T1 (with GB addition) than in the control reactor T0. The qPCR results showed that the relative abundance of Candidatus Kuenenia decreased in both the experimental (from 53.5–28.8%) and control reactors (from 54.1–35.1%). Overall, continuous addition of exogenous GB did not improve the thermotolerance of mesophilic anammox consortia at 45°C. [ABSTRACT FROM AUTHOR]