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Because ammonium (NH 4 + -N) coexists with organic matter in some wastewaters, the possible adverse influences of organic matter become a major concern in the applications of anaerobic ammonium oxidation (anammox). In this study, the effects of acetate, as a representative of micro-molecule organic matter, on anammox were investigated. Efficient nitrogen removal was realized because denitrifying bacteria and anammox bacteria (AnAOB) had a better synergistic effect under the condition of chemical oxygen demand (COD) concentrations lower than 251 ± 7 mg L −1 . Furthermore, the nitrogen removal efficiency (NRE) decreased to 82.02 ± 3.14% when COD was increased to 730 ± 9 mg L −1 , and effluent free ammonia (FA) reached 21.93 ± 4.71 mg L −1 might be one of factors leading to inhibition. However, the nitrogen-removal contribution rate of anammox remained steady at 61.97 ± 2.84% at COD of 730 ± 9 mg L −1 , which indicated that anammox was still dominant in the system. AnAOB, such as Ca. Kuenenia and Ca. Jettenia, and denitrifying bacteria, such as Denitratisoma and Thauera, were found to coexist in the reactor. Interestingly, Ca. Kuenenia presented in the trend of first decreased then increased with the increasing of organic matter concentration, which might be one of reasons that anammox played an important role in nitrogen removal at high COD concentration. [ABSTRACT FROM AUTHOR]

An anaerobic membrane bioreactor was configured for methanogenic degradation of cellulose-containing sewage. The degradation performance and microbial changes were evaluated under five hydraulic retention times (HRTs). The results indicated the methane production was largely enhanced with 92.6% efficiency of chemical oxygen demand (COD) converting to methane and 80% proportion of methane in produced biogas, meanwhile the biomass yield presented the fewest at the shortest HRT 8 h. Enhanced methane production with decreased biomass yield was attributed to an association between fungi and methanogens. Microbial analysis showed fungi Basidiomycota and methanogen Methanoregula apparently established the association, especially Basidiomycota reaching 93% relative abundance at HRT 8 h. Specific methanogenic activity (SMA) and biochemical methane potential (BMP) tests suggested the association was derived from H 2 production by fungi and H 2 consumption by methanogens, during the process of cellulose degradation. The methanogenic degradation of cellulose-containing sewage was markedly promoted via the fungi-methanogens syntrophic association. [ABSTRACT FROM AUTHOR]

A novel single-stage partial nitritation–anammox process equipped with porous functional suspended carriers was developed at 25 °C in a CSTR by controlling dissolved oxygen <0.3 mg/L. The nitrogen removal performance was almost unchanged over a nitrogen loading rate ranging from 0.5 to 2.5 kg NH 4 + -N/m 3 /d with a high nitrogen removal efficiency of 81.1%. The specific activity of AOB and anammox bacteria was of 3.00 g-N/g-MLVSS/d (the suspended sludge), 3.56 g-N/g-MLVSS/d (the biofilm sludge), respectively. The results of pyrosequencing revealed that Nitrosomonas (5.66%) and Candidatus_Kuenenia (4.95%) were symbiotic in carriers while Nitrosomonas (40.70%) was predominant in the suspended flocs. Besides, two specific types of heterotrophic filamentous bacteria in the suspended flocs ( Haliscomenobacter ) and the functional carrier biofilm ( Longilinea ) were shown to confer structural integrity to the aggregates. The novel single-stage partial nitritation–anammox process equipped with functional suspended carriers was shown to have good potential for the nitrogen-rich wastewater treatment. [ABSTRACT FROM AUTHOR]

In this study, amino acid waste liquid was employed as a functional supplement (designated as amino acid-rich FS) in the up-flow anaerobic sludge blanket (UASB) treatment of methanolic wastewater. The effect of amino acid-rich FS was evaluated through repeated batch tests, showing that a 0.5% and 1% dosage increased the maximum methane production rate by 93.60% and 123.04%, respectively, by promoting faster methanol degradation. Additionally, long-term operation of the UASB reactor was conducted with increased dosages of amino acid-rich FS, resulting in improved performance. Microbial community analysis demonstrated that the addition of amino acid-rich FS enhanced microbial diversity, with the abundance of Sporomusa increasing by 47.5 times. Beyond the original cooperative relationships, an additional synergy between Sporomusa and Methanosarcina was observed. These findings could address the key challenge of limited microbial diversity in the anaerobic treatment of methanolic wastewater., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2024. Published by Elsevier Ltd.)