Simultaneous partial nitrification, anammox, and denitrification in an upflow microaerobic membrane bioreactor treating middle concentration of ammonia nitrogen wastewater with low COD/TN ratio.

The rapid start-up and operating characteristics of simultaneous partial nitrification, anammox, and denitrification (SNAD) process was investigated using synthetic wastewater with a low C/N ratio (COD: NH4+-N = 200 mg/L: 200 mg/L) in a novel upflow microaerobic membrane bioreactor (UMMBR). The average removal efficiencies of COD, NH4+-N, and TN in the stable phase were 89%, 96%, and 86%, respectively. Carmine granule, which coexisted with sludge floc, appeared on day 83. The high sludge concentration (12.9-17.2 g/L) and the upflow mode of the UMMBR could establish some anaerobicregions for anammox process. The anammox bacteria and short-cut denitrification (NO2-→N2) bacteria with activities of 4.46 mg NH4+-N/gVSS·h and 2.57 mg NO2--N/gVSS·h contributed TN removal of 39% and 61% on day 129, respectively. High-throughput sequencing analysis revealed that the ammonia-oxidizing archaea (AOA, 49.45% in granule and 17.05% in sludge floc) and ammonia-oxidizing bacterial (AOB, 1.30% in sludge floc) dominated the nitrifying microbial community. Candidatus Jettenia (47.14%) and Denitratisoma (10.92%) mainly existed in granule with positive correlations. Some heterotrophic bacteria (OLB13, SJA-15, 1-20, SBR1031, and SJA-28) in sludge floc benefited system stability and sludge activity and protected Candidatus Jettenia from adverse environments.

Effects of alkalinity addition with different strategies on CANON process: Start-up, performance, and microbial community.

The effects of alkalinity addition with different strategies on the start-up, performance, and microbial community of completely autotrophic nitrogen removal over nitrite (CANON) were investigated over 450 days. In phase I, the alkalinity was increased gradually from 300 to 2,000 mg/L to obtain the optimal range. In phase II, the reactor was restarted to verify the appropriate alkalinity value of 1,600 mg/L. The fact that it only took 90 days (phase I: 170 days) to complete the start-up of CANON in phase II demonstrated that an alkalinity value of 1,600 mg/L was suitable when the influent NH4 + -N concentration was 200 mg/L (alkalinity/NH4 + -N = 8:1). The slope (k = 2.00) of NH4 + -N concentration decrease in phase II during the start-up process was significantly higher than that in phase I (k = 1.50). High removal efficiencies of NH4 + -N (98%) and TN (80%) were attained in both phases. Specific anaerobic ammonium oxidation (anammox) activity tests showed that the anammox activity of the two phases reached 3.31 and 5.31 mg TN/(g VSS·h), respectively. High-throughput sequencing analysis revealed that appropriate alkalinity could promote the enrichment of Candidatus Brocadia, C. Jettenia, and C. Kuenenia (total abundance of 31.96%) while effectively inhibiting Nitrospira (abundance of less than 0.50%). PRACTITIONER POINTS: An alkalinity/NH4 + -N ratio of 8 promoted the rapid start-up and stable performance of CANON. NH4 + -N and TN removal efficiencies of 98% and 80%, respectively, were obtained. High alkalinity promoted the enrichment of Candidatus Brocadia, Candidatus Jettenia, Candidatus Kuenenia and inhibited Nitrospira.

The distribution of dissimilatory nitrate reduction to ammonium bacteria in multistage constructed wetland of Jining, Shandong, China.

Dissimilatory nitrate reduction to ammonium (DNRA) is an important process of nitrate reduction in the environment. The distribution of DNRA bacteria and the relationships with environmental factors in multistage constructed wetland were investigated in this study. The quantitative real-time polymerase chain reaction analysis showed that the abundance of DNRA bacteria at all sites ranged from 2.10 × 1010 to 1.10 × 1011 copies/g of dry sediments. The Anaeromyxobacter (belong to Deltaproteobacteria) was the most abundant DNRA bacteria at all sites. The Geobater known as DNRA bacteria was also identified in this study. The abundances of DNRA bacteria, denitrifying bacteria, and anammox bacteria were conspicuously negatively correlated with Eh and positively correlated with the NO3--N removal efficency by statistical analysis.

Survey of dissimilatory nitrate reduction to ammonium microbial community at national wetland of Shanghai, China.

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 NO2--N and NO3-N; the DNRA rates was positively correlated with sediment organic carbon (SOC), C/NO3- 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.

Nitritation-anammox process - A realizable and satisfactory way to remove nitrogen from high saline wastewater.

In this study, acclimation of freshwater nitritation-anammox sludge to remove nitrogen in high saline and hypersaline wastewater was evaluated, during which the microbes activity and microbial community revolution were revealed to understand the fate of a nitritation-anammox process (SNAP) in response to increasing salt stress. By enhanced aeration, the SNAP system can treat saline (3%) ammonium-rich (185 mg/L) wastewater after gradual adaption. Hypersalinity (5%) caused final deterioration of the SNAP system due to a severe inhibition on anammox activity. Genera Kuenenia (anammox), Nitrosomonas (AOB) and Nitrosovibrio (AOB) bacteria were salt adaptable microbes, while genus Nitrospira (NOB) bacteria were sensitive to salinity. Under the enhanced aeration, AOB bacteria could bear 3% salinity with possible enriched ammonia monooxygenase to stimulate the conversion of ammonium to nitrite by producing more intermediate-hydroxylamine, which could alleviate the negative effect of insufficient hydroxylamine oxidase members in AOB bacteria.

In situ remediation of ortho-nitrochlorobenzene in soil by dual oxidants (hydrogen peroxide/persulfate).

The efficacies of catalyzed H2O2, activated persulfate, and catalyzed H2O2-persulfate processes for the degradation of ortho-nitrochlorobenzene (o-NCB) in soil were investigated. The application of catalyzed H2O2-persulfate process was promising, and after a careful adjustment of oxidants and activator doses, it demonstrated a considerable improvement in o-NCB degradation compared with activated persulfate process and catalyzed H2O2 process. The degradation of o-NCB in catalyzed H2O2-persulfate process was obviously influenced by the concentration of persulfate and H2O2, the molar ratio between persulfate and H2O2, the concentration of o-NCB, and initial pH. Degradation of o-NCB was obviously inhibited by the addition of tert-butyl alcohol, methanol, and phenol, suggesting that nitrobenzene was dominantly oxidized by HO· and SO4 (-)· generated in the catalyzed H2O2-persulfate process. The results from these studies demonstrated that the natural iron species present in soil could effectively facilitate the degradation of organic pollutants in the presence of H2O2 and persulfate.

Effect of COD/N ratio on cultivation of aerobic granular sludge in a pilot-scale sequencing batch reactor.

Aerobic granular sludge was successfully cultivated with the effluent of internal circulation reactor in a pilot-scale sequencing batch reactor (SBR). Soy protein wastewater was used as an external carbon source for altering the influent chemical oxygen demand/nitrogen (COD/N) ratios of SBR. Initially, the phenomenon of partial nitrification was observed and depressed by increasing the influent COD/N ratios from 3.32 to 7.24 mg/mg. After 90 days of aerobic granulation, the mixed liquor suspended solids concentration of the reactor increased from 2.80 to 7.02 g/L, while the sludge volumetric index decreased from 105.51 to 42.99 mL/g. The diameters of mature aerobic granules vary in the range of 1.2 to 2.0 mm. The reactor showed excellent removal performances for COD and N4⁺--N after aerobic granulation, and average removal efficiencies were over 93% and 98%, respectively. The result of this study could provide further information on the development of aerobic granule-based system for full-scale applications.

Aerobic granulation and nitrogen removal with the effluent of internal circulation reactor in start-up of a pilot-scale sequencing batch reactor.

Aerobic granular sludge was successfully cultivated with the effluent of internal circulation (IC) reactor in a pilot-scale sequencing batch reactor (SBR) using activated sludge as seeding sludge. N removal was investigated in the start-up of aerobic granulation process. Initially, the phenomenon of partial nitrification was observed and nitrite accumulation rates (NO(2) (-)-N/NO (x) (-) -N) were between 84.6 and 99.1 %. It was potentially caused by ammonium oxidizing bacteria (AOB) in the seeding activated sludge, high external environmental temperature (~32 °C) and free ammonia (FA) concentration. After 50 days' running, the aerobic granules-based bioreactor demonstrated perfect performance in simultaneous removal of organic matter and ammonia nitrogen, and average removal efficiencies were maintained above 93 and 96 %, respectively. The maximum nitrogen removal efficiency of 83.1 % was achieved after the formation of aerobic granules. The average diameter of mature aerobic granular sludge mostly ranged from 0.5 to 1.0 mm. Furthermore, one typical cyclic test indicated that pH and DO profiles could be used as effective parameters for biological reactions occurring in the aerobic/anoxic process. The obtained results could provide further information on the cultivation of aerobic granular sludge with practical wastewater, especially with regard to nitrogen-rich industrial wastewater.