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Thiocyanate (SCN−) exists in various industries and is detrimental to the ecosystem, necessitating cost-effective and environmentally benign treatment. In response to alleviate the bacterial toxicity of SCN−, this study developed a two-stage coupled system by tandem of anammox in reactor 1 (R1) and SCN−-driven autotrophic denitrification in reactor 2 (R2), achieving simultaneous removal of SCN− and nitrogen. The total nitrogen removal efficiency of the coupled system was 92.42 ± 1.98%, with nearly 100% of SCN− elimination. Thiobacillus was responsible for SCN− degradation. The deduced degradation pathway of SCN− was via the cyanate pathway before coupling, followed by the co-action of cyanate pathway and carbonyl sulfide pathway after coupling. Although scaling-up study is needed to validate its applicability in real-world applications, this study contributes to the advancement of sustainable and cost-effective wastewater treatment technologies, being an attractive path for low-carbon nitrogen removal and greenhouse gas emission-free technology. [ABSTRACT FROM AUTHOR]

Divalent cations were known to alleviate salinity stress on anammox bacteria. Understanding the mechanism of reducing the salinity stress on anammox granules is essential for the application of the anammox process for saline wastewater treatment. In this study, the effect of Ca2+ and Mg2+ augmentation on the recovery of the activity of freshwater anammox granules affected by salinity stress was evaluated. At the condition of a salinity stress of 5 g NaCl/L, the specific anammox activity (SAA) of the granule decreased to 50% of that of the SAA without NaCl treatment. Augmentation of Ca2+ at the optimum concentration of 200 mg/L increased the SAA up to 78% of the original activity, while the augmentation of Mg2+ at the optimum concentration of 70 mg/L increased the SAA up to 71%. EPS production in the granules was increased by the augmentation of divalent cations compared with the granules affected by salinity stress. In the soluble EPS, the ratio of protein to polysaccharides was higher in the granules augmented by Ca2+ than with Mg2+, and the functional groups of the EPS differed from each other. The amount of Na+ sequestered in the soluble EPS was increased by the augmentation of divalent cations, which seems to contribute to the alleviation of salinity stress. Ca. Kuenenia-like anammox bacteria, which were known to be salinity stress-tolerant, were predominant in the granules and there was no significant difference in the microbial community of the granules by the salinity stress treatment. Our results suggest that the alleviation effect of the divalent cations on the salinity stress on the anammox granules might be associated with the increased production of different EPS rather than in changes to the anammox bacteria. [ABSTRACT FROM AUTHOR]

Samples collected in summer and winter were analyzed by high-throughput sequencing technology to reveal differences in the microbial community diversity of activated sludge at different temperatures in a municipal wastewater treatment plant of Northern China. A total of 36,438 validated reads were obtained from the samples, and the bacteria belonged to 25 phyla and 139 genera. The Shannon diversity index decreased from 5.367 in summer to 5.168 in winter. During summer, the dominant phylum wasProteobacteria(50.5%), while it wasBacteroidetesduring winter (40.5%). At the genus level,Chitinophagawas most abundant during summer (8.7%), whileHaliscomenobacter(2.8%) had the greatest abundance in winter. Almost all nitrogen and phosphorus removal-related functional microbes, includingThiobacillus(denitrifying bacteria),Rhodocyclus(phosphorus-accumulating bacteria), andNitrosomonadaceae(ammonia-oxidizing bacteria), showed significantly higher abundance in summer than winter. Conversely, cryophilic microbial abundance was significantly higher in winter than summer. [ABSTRACT FROM PUBLISHER]

Dissimilatory nitrate reduction to ammonia (DNRA) process is an important nitrate reduction pathway in the environment. Numerous studies focused on the DNRA, especially in various natural habitats. However, little is known about the envrionmental parameters driving the DNRA process in anthropogenic ecosystem. Human activities put forward significant influence on nitrogen cycle and bacterial communities of sediment. This study aimed to assess the DNRA potential rates, nrfA gene abundance, DNRA bacterial community's diversity and influencing factors in a national wetland park near the Yangtze River estuary, Shanghai. The results of 15N isotope tracer experiments showed that DNRA potential rates from 0.13 to 0.44 μmol N/kg/h and contribution of nitrate reduction varied from 1.56% to 7.47%. The quantitative real-time PCR results showed that DNRA functional gene nrfA abundances ranged from 9.87E+10 to 1.98E+11 copies/g dry weight. The results of nrfA gene pyrosequencing analysis showed that Lacunisphaera (10.4–13.4%), Sorangium (7.1–10.7%), Aeromonas (4.2–6.8%), Corallococcus (1.8–6.9%), and Geobacter (3.3–6.6%) showed higher relative abundances in their genus levels. Combined with environmental parameters of sediments, redundancy analysis indicated that the nrfA functional gene was positively correlated with moisture content, the concentration of NO 2 −-N and NO 3 −N; the DNRA rates was positively correlated with sediment organic carbon (SOC), C/NO 3 − ratio and salinity (ranked by explains %). This study is the first simultaneous determination of nitrate reduction pathways including denitrification, anammox and DNRA rates to assess the role of DNRA in a national wetland park and revealed the community abundance, diversity of DNRA bacteria and its relationship with environmental factors. Image 1 • Denitrification was the dominant nitrate reduction pathway in the wetland park. • The contribution of DNRA to nitrate reduction varied from 1.56% to 7.47%. • SOC and C/NO 3 − were the key factors driving the distinction of DNRA potentials rates. • Lacunisphaera , Sorangium , Aeromonas , Corallococcus and Geobacter were dominant DNRA. [ABSTRACT FROM AUTHOR]