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Polycyclic aromatic hydrocarbons (PAHs) as polar organic pollutants, their potential harm to the environment has caused widespread concern. This study describes a simple method to prepare modified aerobic granular sludge (AGS) by hydroxypropyl-β-cyclodextrin (HP-β-CD). Using HP-β-CD modified AGS as the adsorbent, the removal of specific PAHs: Fluoranthene (Fla) reached 95% comparing to 80% of the unmodified AGS. The removal of Fla was related to initial concentration, temperature and ion concentration (Na+, Mg2+). The removal efficiency of Fla reached 96.27%, 94.26% and 93.69%, when initial concentration of Fla was 10, 15 and 20 μmol/L. At temperatures of 15°C, 30°C and 45°C, the removal efficiency of Fla (15 μmol/L) gradually improved from 87.20% to 94.84% and 95.73%. The presence of Na+ and Mg2+ ions led to the deterioration of PAHs removal. With the increase of Na+ and Mg2+ concentrations, the removal efficiency of modified AGS on PAHs decreased by 3.9% and 6.5%, respectively. These findings indicate the potential application of cyclodextrins as the active sites of a complex modified polymer network for PAHs wastewater treatment. [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]

The long start-up time of anaerobic ammonium oxidation (anammox) process hinders the widespread application of anammox technology in practical wastewater treatment when anammox seed sludge is not available. Meanwhile, the production of nitrate cannot meet the increasingly more strict discharge standards. To combine the chemical nitrate reduction to ammonium with biological nitrogen removal, two anammox upflow anaerobic sludge blanket reactors packed with different types of zero-valent iron (ZVI), microscale ZVI (mZVI) and nanoscale ZVI (nZVI), were developed to accelerate the start-up of anammox process. The results revealed that anammox start-up time shortened from 126 to 105 and 84 days with the addition of mZVI and nZVI. The nitrogen removal performance was also improved remarkably by adding ZVI, especially in the start-up stage. The value of dissolved oxygen showed that ZVI could be regarded as a useful deoxidant to create anaerobic condition for the proliferation of anammox bacteria. ZVI was favorable for the secretion of EPS, which would represent the activity of anammox bacteria. The result of real-time quantitative PCR (qPCR) further confirmed that the proliferation of anammox bacteria was enhanced by ZVI. [ABSTRACT FROM AUTHOR]

Membrane bioreactor with non-woven fabric membranes (NWMBR) is developing into a suitable method for anaerobic ammonium oxidation (anammox). As a carrier, non-woven fabric membrane divided total biomass into biofilm and suspended flocs gradually. Total nitrogen removal efficiency was maintained around 82.6% under nitrogen loading rate of 567.4 mg N/L/d after 260 days operation. Second-order substrate removal and Stover-Kincannon models were successfully used to simulate the nitrogen removal performance in NWMBR. High-throughput sequence was employed to elucidate the underlying microbial community dynamics. Candidatus Brocadia , Kuenenia , Jettenia were detected to affirm the dominant status of anammox microorganisms and 98.2% of anammox microorganisms distributed in biofilm. In addition, abundances of functional genes ( hzs , nirK ) in biofilm and suspended flocs were assessed by quantitative PCR to further investigate the coexistence of anammox and other microorganisms. Potential nitrogen removal pathways were established according to relevant nitrogen removal performance and microbial community. [ABSTRACT FROM AUTHOR]

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]

In this study, greenhouse gas emissions and microbial community succession during the realization of the partial nitrification (PN) process were studied. The results show that N 2 O emission mainly occurred in the aerobic stage and the PN reactor released about 20 mg of N 2 O gas each cycle. There is a positive correlation between the dissolved N 2 O concentration and the temperature of a typical cycle. High-throughput sequencing was used to illustrate succession in the microbial community structure. The most significant microfloral change during the PN startup process was that some aerobic bacteria were relatively enriched and some anaerobic bacteria were weeded out. The ammonia oxidizing bacteria (AOB) like Nitrosomonadaceae were enriched on account of the suitable external environment. Pseudomonas whose main function is denitrification declined and Planctomyces (anammox) showed the same tendency. This study comprehensively demonstrates the fluctuations of dissolved and emitted N 2 O while researching the succession of the microbial community in the culture of the PN process., Competing Interests: There are no conflicts to declare., (This journal is © The Royal Society of Chemistry.)