Pre-anoxic/Orbal Oxidation Ditch/Rotary Disc Filter Treatment of Mixed Sewage in Industrial Park

The design scale of a sewage treatment plant in the industrial center of a district in Changzhou is 2×10^(4) m^(3)/d. Data analysis, process selection and analysis and main structure design were carried out for the sewage treatment plant to ensure that the effluent quality meets the discharge standards. The operation results after the implementation of the project show that the project can effectively improve the effluent quality of the sewage treatment plant. The removal rates of COD, NH+4, TN and TP are 93.97%, 98.63%, 82.67% and 97.37% respectively, and the effluent quality can be discharged stably up to the standard. Using cost analysis to study the operation of the sewage treatment plant, the results show that the total investment of the sewage treatment plant is 40 million yuan, the electricity cost of this project is 0.426 yuan/m^(3), the pharmaceutical cost is 0.655 yuan/m^(3), and the material replacement fee is 0.323 yuan/m^(3). The direct operating cost is 1.404 yuan/m^(3). This method has good practical guiding significance for the optimization and operation transformation of the same type of sewage treatment plants.

Study on Piggery Anaerobic Fermentation Slurry Treated by Anoxic/Oxic Process

[Objective] The aim of this study was to provide a fast, stable and efficient piggery wastewater processing technology. [Method] The start-up process was studied through the experiment of piggery anaerobic fermentation slurry treated by Anoxic/Oxic （A/O） reactor. The process was divided into two stages： at the first stage, dominant micro flora were cultivated in Anoxic and Oxic reaction tanks respectively; at the second stage. Anoxic and Oxic reaction tanks were initiated jointly to gradually enhance water load and continued to cultivate and domesticate microorganisms, and finally the start-up process was completed. [ Result] The results showed that return mixture ratio and return sludge ratio was 2 and 1 respectively when the temperature reached 32 ±2 ℃. However. when aeration rate of Oxic reaction amounted to 0.5 m^3/h, the re- moval rate of COD and NH4^＋ -H were 89.87% and 89.31% respectively through practical operation within 50 days, which indicated that the start- up process through A/O reactor was successful. Conclusion This study can provide a scientific basis and reference for innocuous technique of piggery anaerobic fermentation slurry treatment.

Kinetics model of aerobic phase in hybrid anoxic-oxic process

Kinetics models of COD degradation,biomass growth of the anoxic-oxic ( A/O) system as well as NH3-N degradation in aerobic phase were presented according to the mass balance theory,reaction-diffusion theory and Fick law. Then these models were testified by comparson with experimental results. It is demonstrated that the variation trends of theoretical and experimental values for COD degradation and biomass growth are similar. The deviation rate between theoretical and experimental values is always under 20% even it increases along with the fluctuation of influent organic loading. In terms of NH3-N degradation,nitrification can also be well simulated by the model as the substrates of influent are sufficient. It indicates that the model can accurately reflect the reaction in hybrid A/O process. Models presented herein provide a theoretical basis for the design, operation and control of hybrid A/O process.

Enhanced Biological Nutrients Removal in Modified Step-feed Anaerobic/Anoxic/Oxic Process

In order to enhance phosphorus removal in traditional step-feed anoxic/oxic nitrogen removal process,a modified pilot-scale step-feed anaerobic/anoxic/oxic(SFA 2/O) system was developed,which combined a reactor similar to UCT-type configuration and two-stage anoxic/oxic process.The simultaneous nitrogen and phosphorus removal capacities and the potential of denitrifying phosphorus removal,in particular,were investigated with four different feeding patterns using real municipal wastewater.The results showed that the feeding ratios(Q1)in the first stage determined the nutrient removal performance in the SFA 2/O system.The average phosphorus removal efficiency increased from 19.17% to 96.25% as Q1 was gradually increased from run 1 to run 4,but the nitrogen removal efficiency exhibited a different tendency,which attained a maximum 73.61%in run 3 and then decreased to 59.62%in run 4.As a compromise between nitrogen and phosphorus removal,run 3 (Q1=0.45Qtotal) was identified as the optimal and stable case with the maximum anoxic phosphorus uptake rate of 1.58 mg·(g MLSS)-1 ·h-1.The results of batch tests showed that ratio of the anoxic phosphate uptake capacity to the aerobic phosphate uptake capacity increased from 11.96% to 36.85% with the optimal influent feeding ratio to the system in run 3,which demonstrated that the denitrifying polyP accumulating organisms could be accumulated and contributed more to the total phosphorus removal by optimizing the inflow ratio distribution.However,the nitrate recirculation to anoxic zone and influent feeding ratios should be carefully controlled for carbon source saving.

Organic Geochemistry of the Early Jurassic Oil Shale from the Shuanghu Area in Northern Tibet and the Early Toarcian Oceanic Anoxic Event

This paper presents new geological and geochemical data from the Shuanghu area in northern Tibet, which recorded the Early Toarcian Oceanic Anoxic Event. The stratigraphic succession in the Shuanghu area consists mostly of grey to dark-colored alternating oil shales, marls and mudstones. Ammonite beds are found at the top of the Shuanghu oil shale section, which are principally of early Toarcian age, roughly within the Harplocearas falciferrum Zone. Therefore, the oil shale strata at Shuanghu can be correlated with early Toarcian black shales distributing extensively in the European epicontinental seas that contain the records of an Oceanic Anoxic Event. Sedimentary organic matter of laminated shale anomalously rich in organic carbon across the Shuanghu area is characterized by high organic carbon contents, ranging from 1.8% to 26.1%. The carbon isotope curve displays the δ 13C values of the kerogen (δ 13Ckerogen) fluctuating from –26.22 to –23.53‰ PDB with a positive excursion close to 2.17‰, which, albeit significantly smaller, may also have been associated with other Early Toarcian Oceanic Anoxic Events (OAEs) in Europe. The organic atomic C/N ratios range between 6 and 43, and the curve of C/N ratios is consistent with that of the δ 13Ckerogen values. The biological assemblage, characterized by scarcity of benthic organisms and bloom of calcareous nannofossils (coccoliths), reveals high biological productivity in the surface water and an unfavorable environment for the benthic fauna in the bottom water during the Oceanic Anoxic Event. On the basis of organic geochemistry and characteristics of the biological assemblage, this study suggests that the carbon-isotope excursion is caused by the changes of sea level and productivity, and that the black shale deposition, especially oil shales, is related to the bloom and high productivity of coccoliths.

A Modified Oxidation Ditch with Additional Internal Anoxic Zones for Enhanced Biological Nutrient Removal

A novel modified pilot scale anaerobic oxidation ditch with additional internal anoxic zones was operated experimentally, aiming to study the improvement of biological nitrogen and phosphorus removal and the effect of enhanced denitrifying phosphorus removal in the process. Under all experimental conditions, the anaero- bic-oxidation ditch with additional internal anoxic zones and an internal recycle ratio of 200% had the highest nutrient removal efficiency. The effluent NH4 -N, total nitrogen （TN）, PO3 -P and total phosphorus （TP） contents were 1.2 mg.L-1, 13 mg.L 1, 0.3 mg.L -1 and 0.4 mg.L-1, respectively, all met the discharge standards in China. The TN and TP removal efficiencies were remarkably improved from 37% and 50% to 65% and 88% with the presence of additional internal anoxic zones and internal recycle ratio of 200%. The results indicated that additional internal anoxic zones can optimize the utilization of available carbon source from the anaerobic outflow for denitrification. It was also found that phosphorus removal via the denitrification process was stimulated in the additional internal anoxic zones, which was beneficial for biological nitrogen and phosphorus removal when treating wastewater with a limited carbon source. However, an excess internal recycle would cause nitrite to accumulate in the system. This seems to be harmful to biological phosphorus removal.

Denitrification and Dephosphatation by Anaerobic/Anoxic Sequencing Batch Reactor

Removal of denitrifying phosphorus was verified in a laboratory anaerobic/anoxic sequencing batch reactor (A/A SBR). The results obtained demonstrated that the anaerobic/anoxic strategy can enrich the growth of denitrifying phosphorus removing bacteria (DPB) and take up phosphate under anoxic condition by using nitrate as the electron acceptor. The phosphorus removal efficiency was higher than 90% and the effluent phosphate concentration was lower than 1 mg·L-1 after the A/A SBR was operated in a steady-state. When the chemical oxygen demand(COD) of influent was lower than 180mg· L-1, the more COD in the influent was, the higher efficiency of phosphorus removal could be attained under anoxic condition. However, simultaneous presence of carbon and nitrate would be detrimental to denitrifying phosphorus removal. Result of influence of sludge retention time (SRT) on denitrifying phosphorus removal suggested that the decrease of SRT caused a washout of DPB and consequently the enhanced biological phosphorus removal decreased with 8 days SRT. When the SRT was restored to 16 days, however, the efficiency of phosphorus removal was higher than 90%.

Denitrifying phosphorous removal in anaerobic/anoxic SBR system with different startup operation mode

To achieve stable and efficient nitrogen and phosphorus removal and to investigate the characteristics of the A/A SBR enriched with denitrifying phosphorus removal bacteria(DPB),the whole course of startup was studied with two reactors operated in different mode.The reactor I was operated under anaerobic/settling/anoxic/settling mode,and the reactor II was operated under anaerobic/anoxic/settling mode.Differences between the two reactors in removal efficiency of COD,nitrogen and phosphorus were examined.The results indicated that efficient performance could be achieved in both reactors with different startup operation mode,while the phosphorus removal efficiency was improved sooner in reactor I than in reactor II,which suggested that reactor I would supply a more favorable condition for DPB proliferation.Meanwhile,it was observed that the amount of organic substrates consumption had a linear correlation to that of phosphorus release in anaerobic phase when DPB was accumulated in the A/A SBR denitrifying phosphorus removal system.

Terrestrial records of the early Albian Ocean Anoxic Event:Evidence from the Fuxin lacustrine basin,NE China

The early Albian Oceanic Anoxic Event 1 b(OAE 1 b) is well documented in the Tethys, Pacific and North Atlantic, but few studies have evaluated whether or not terrestrial records of OAE 1 b exist. In order to identify terrestrial records of the early Albian OAE 1 b and to infer possible driving mechanisms, an integrated multi-proxy study from the late Aptian to Albian in the Fuxin lacustrine basin was conducted,including thick, organic-rich black mudstones, total organic carbon(TOC), organic carbon isotopes(d13 Corg), mercury concentration(Hg) and results from pyrolysis analyses(S2, Tmaxand HI). Results show three distinct short-term negative d13 Corgexcursions corresponding with relatively high TOC values,which could be counterparts of the Kilian, Paquier and Leenhardt sub-events of the early Albian OAE1 b. Atmospheric CO2 concentration(p CO2) recovered from C3 plant d13 Corgcompositions indicates an increasing trend in Unit C during the early Albian, and there are three short-term increases of p CO2 corresponding to the three sub-events of OAE 1 b at this time interval. We infer that a trend of increasing p CO2 during the Kilian sub-event in the study area is closely related to volcanism. Continental weathering calculated using chemical weathering indices(CIA, WIP and MIA(O)) show an increasing trend during the OAE 1 b interval, likely resulting from warmer and more humid conditions. Mixed sources of terrestrial plants and lacustrine plankton demonstrated by pyrolysis analyses(HI vs. Tmaxand S2 vs. TOC), indicate a terrestrial contribution to the organic-rich sediments of the Kilian, Paquier and Leenhardt sub-events of OAE 1 b. We suggest that a CO2-forced greenhouse effect during the early Albian might have triggered the relatively warm and humid palaeoclimatic conditions, and intensified chemical weathering that combined to create high nutrient and organic matter levels that were flushed into lakes contributing to eutrophication and anoxia in lacustrine and in contemporaneous oceanic systems.

Effects of loading rate and hydraulic residence time on anoxic sulfide biooxidation

The optimal operation conditions in an anoxic sulfide oxidizing (ASO) bioreactor were investigated. The maximal removal rates for sulfide and nitrate were found to be 4.18 kg/(m3·d) and 1.73 kg/(m3·d), respectively. The volumetrical volumetric loading rates (LRs) observed through decreasing hydraulic retention time (HRT) at fixed substrate concentration are higher than those by increasing substrate concentration at fixed HRT. The sulfide oxidation in ASO reactor was partially producing both sulfate and sulfur; but the amount of sulfate produced was approximately one third that of sulfur. The process was able to tolerate high sulfide concentration, as the sulfide removal percentage always remained near 99% when influent concentration was up to 580 mg/L. It tolerated relatively lower nitrate concentration because the removal percentage dropped to 85% when influent con- centration was increased above 110 mg/L. The process can tolerate shorter HRT but careful operation is needed. Nitrate conversion was more sensitive to HRT than sulfide conversion since the process performance deteriorated abruptly when HRT was decreased from 3.12 h to 2.88 h. In order to avoid nitrite accumulation in the reactor, the influent sulfide and nitrate concentrations should be kept at 280 mg/L and 67.5 mg/L respectively. Present biotechnology is useful for removing sulfides from sewers and crude oil.

Effects of Nitrate Concentration in Main Anoxic Zone on Denitrifying Dephosphatation

The effects of nitrate concentration in the main anoxic zone on denitrifying dephosphatation capability were conducted based on modified University of Cape Town （MUCT） process. Meanwhile the relation between optimal nitrate concentration （Nopt） and influent C/N ratio was evaluated, in which the influont chemical oxygen demand （COD） concentration was stabilized at （2905：10）mg/L, the influent total phosphorus （TP） concentration was stabilized at （7.0±0. 5）mg/L. The results indicated that： （1） the nitrate concentration in the main anoxic zone had an effect on denitrifying dephosphatation capability, and the average percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa） increased with nitrate cancentration increasing, i.e., increasing from 62.1% at2.0 mg/L to63.7%, 65.6%, 68.1%, and 72.3% at 2.2, 2.4, 2.6 and 2.8mg/L, respectively; （2） the Nopt as function of influent C/N ratio could be calculated by the equation： y = 0.67x^2-7.79x ＋ 22. 21; the maximum percentages of anoxic phosphorus uptake in total phosphorus uptake （ηa,max） as function of the Nopt could be calculated by the equation： y=0.77-0.33e^-（x/1.52）. The Nopt was the important control parameter that must be optimized for operation of conveational biological nutrieat removal activated sludge （BNRAS） system.

Nitrogen Removal Performance of Continuous Anoxic/Oxic System Using Activated Sludge and Sludge Biofilms

Nitrogen is the most important component for living beings while the excessive discharge of organic and inorganic nitrogen may create severe environmental problems.In this study,a continuous anoxic/oxic(A/O)reactor adopting activated sludge and sludge biofilms in the anoxic and oxic zones was applied for total nitrogen(TN)and chemical oxygen demand(COD)removal,and the efficiencies of nitrification and denitrification were compared as well.Results showed that when using activated sludge,the effluent concentrations of NH_(4)^(+)-N,NO_(3)^(-)-N,NO_(2)^(-)-N,TN and COD were inconsistent and fluctuated greatly,and the removal efficiencies of corresponding nitrification,denitrification and TN were also unstable;the obtained average COD removal efficiency was 85%.While using sludge biofilms,the acquired effluent concentrations of NH^(+)_(4)-N,NO^(-)_(3)-N,NO_(2)^(-)-N,TN and COD became stable and constant.The nitrification,denitrification,TN and COD removal efficiencies were 96%,84%and 65%and 94%,respectively.Bacterial community analysis of sludge biofilms indicated that the genus Arcobacter was the major denitrifiers in the anoxic zone with relative abundance of 76.1%,and in the oxic zone the abundances of Acinetobacter,Hydrogenophaga and Nitrospira responsible for complete nitrification were 20.05%,7.6%and 3.7%respectively.The high abundance of nitrifying bacteria and denitrifiers were related with the high and stable nitrogen and COD removal.

Transformation of phthalic acid diesters in an anaerobic/anoxic/oxic leachate treatment process

Transformations of di-n-butyl phthalate(DBP) and di(2-ethylhexyl) phthalate(DEHP) have been investigated in anaerobic/anoxic/oxic(A/A/O) leachate treatment processes. Although the DBP removal processes are different when the DBP initial concentration is different, the overall system DBP removal efficiencies are high(N 94%).DEHP is much more difficult to remove than DBP. The removal efficiency of DEHP is approximately 75%–78%.The results of mass balance calculations indicate that approximately 33.7%–50.7% of the DBP is degraded by the activated sludge, 48.9%–64.9% accumulates in the system, and 0.4%–1.4% is contained in the final effluent. Approximately 15.0%–19.0% of the DEHP is degraded by activated microcosms, 75.8%–79.0% accumulates in the system, and 5.2%–6.0% is contained in the final effluent. Biodegradation and adsorption to the activated sludge are the main mechanisms for DBP removal and adsorption to the activated sludge is the main mechanism for DEHP removal. The different removal mechanisms of the two PAEs may be related to their different molecular structures. However, PAEs are not really removed when they adsorb onto the sludge. Therefore, methods for decreasing PAEs adsorption and increasing the biodegradation efficiencies of the leachate treatment processes should be further investigated.

QTL Analysis of Anoxic Tolerance at Seedling Stage in Rice

Coleoptile lengths of 7-day-old seedlings under anoxic stress and normal conditions were investigated in two permanently segregated populations and their parents in rice （Oryza sativa L.）. Using anoxic response index, a ratio of coleoptile length under anoxic stress to coleoptile length under normal conditions, as an indicator of seedling anoxic tolerance （SAT）, QTLs for SAT were detected. Two loci controlling SAT, designated as qSAT-2-R and qSAT-7-R, were detected in a recombinant inbred line （RIL） population （247 lines） derived from a cross between Xiushui 79 （japonica variety） and C Bao （japonica restorer line）. qSAT-2-R, explaining 8.7% of the phenotype variation, was tightly linked with the SSR marker RM525. qSAT-7-R, explaining 9.8% of the phenotype variation, was tightly linked with the marker RM418. The positive alleles of the two loci came from C Bao. Six loci controlling SAT, designated as qSAT-2-B, qSAT-3-B, qSAT-5-B, qSAT-8-B, qSAT-9-B and qSAT-12-B, were detected in a backcross inbred line （BIL） population （98 lines） derived from a backcross of Nipponbare （japonica）/Kasalath （indica）//Nipponbare （japonica）. The positive alleles of qSAT-2-B, qSAT-3-B and qSAT-9-B, which explained 16.2%, 11.4% and 9.5% of the phenotype variation, respectively, came from Nipponbare. Besides, the positive alleles of qSAT-5-B, qSAT-8-B and qSAT-12-B, which explained 7.3%, 5.8% and 14.0% of the phenotype variation, respectively, were from Kasalath.

Real-time control of aerobic/anoxic digestion for waste activated sludge

Experiments were conducted to study the performance characters of aerobic/anoxic （A/ A） digestion of sludge at 30± 1 ℃, while the sludge retention time （SRT） was kept 16 d. The varia tions of oxidation reduction potential （Eh ） and pH were continuously monitored during the A/A di gestion and the conversions of ammonium and nitrate were investigated. Important features on both Eh and pH profiles were identified to develop process control strategy. Since the feature point on Eh profile where d2 Eh/dt^2 =0 is very stable during anoxic cycle, it can be used to determine the end of denitrification. The end of nitrification can be identified according to dpH/dt = 0. A real-time control strategy of A/A digestion of sludge was developed and tested with pH and Eh as control parameters. It is shown that the performance of the real-time control strategy is better than that of a fixed time control strategy. While the real time controlled A/A digestion system can achieve a similar volatile suspended solids （VSS） destruction efficiency of 35.2 % as a continuously aerated system, it im proves the supernatant quality in a shorter aeration time（7. 75 d for a 20 d period）.

Biomass Fraction of Phosphate-Accumulating Organisms Grown in Anoxic and Aerobic Stages under Optimum Nitrate Concentration

The effects of nitrate concentration on the capability of phosphorus uptake in the main anoxic stage were investigated.Meanwhile, the biomass fractions — heterotrophs, phosphateaccumulating organisms( PAOs),and nitrifying organisms in a pilot-scale enhanced biological phosphorus removal( EBPR) system— were both experimentally and theoretically evaluated( from the mass balance calculations of organic matter, nitrogen and phosphorus),under optimum nitrate concentration in the main anoxic stage,in which the influent chemical oxygen demand( COD)concentration was stabilized at( 290 ± 10) mg·L- 1and the influent total phosphorus( TP) concentration was stabilized at( 7. 0 ± 0. 5)mg · L- 1. In long term operations,the process exhibited high performance in removing organic matter, nitrogen, and phosphorus. Approximately 46. 41% of organic matter,57. 21% of nitrogen,and 48. 14% of phosphorus were removed from the influent in the form of carbon dioxide,nitrogen gas,and polyphosphate,respectively. XH( heterotrophs),XPAO( PAOs),and XAUT( autotrophs) were regarded as the major organisms responsible for biomass production. The yield fractions of XHgrowth in the first anoxic,the second anoxic,and the aerobic stages were 10. 24%,19. 11%,and 19. 71%,respectively; the yield fractions of XPAO growth in the second anoxic and the aerobic stages were 24. 34% and19. 86%,respectively; the yield fraction of XAUTgrowth in the aerobic stage was 6. 74%. These results showed that XHand XPAOformed the major community. Moreover,a higher amount of XPAOgrowth on stored poly-hydroxyalkanoates( PHAs) under the anoxic condition was seen in this EBPR system for municipal wastewater treatment.

Adsorption Characteristics of Remazol Black B on Anoxic Sludge

The adsorption characteristics of Remazol Black B on anoxic sludge were investigated.The parameters,such as initial pH,sulphate concentration,and temperature,affecting the dye adsorption were studied.The adsorption data were analyzed with three adsorption isotherm models,namely Langmuir,Freudlich,and linear partition.The results showed that adsorption of Remazol Black B on the sterilized sludge reached equilibrium in 4 h.It also indicated that pH had significant effect on anoxic sludge adsorption behavior.The adsorption capacity of anoxic sludge decreased with the increase of pH value and the maximum adsorption capacity of dyes occurred at pH=3.The adsorptive capacities increased with the decrease of temperature and increase of sulphate concentration.Results also indicated that the adsorption equilibrium of Remazol Black B on anoxic sludge could be well fitted by Freundlich model.

The influence of ganglioside on the blood gas analysis and serum inflammatory cytokines in newborns with anoxic ischemic encephalopathy

Objective:To observe the influence of ganglioside on the blood gas analysis and serum levels of inflammatory cytokines in newborns with anoxic ischemic encephalopathy.Method: A total of 100 newborns with anoxic ischemic encephalopathy in our hospital were selected and randomly divided into 2 groups: the control group and the observation group. Conventional oxygen inhalation, reducing intracranial pressure, controlling eclampsia and neurotrophic drug treatment were given to the observation group. Treatment of ganglioside was given to the control group on the basis of observation group. Blood gas analysis and serum levels of inflammatory cytokines were detected before treatment (T0), 3 d after treatment (T1), and 7 d after treatment (T2).Result: (1) The comparison of pH, PaO2, PaCO2, SaO2 in the two groups in T0 was not statistically significant. The comparison of pH, PaO2, PaCO2, SaO2 in T0, T1, T2 was considered to be statistically significant. Among these, the result of comparision of pH, PaO2, SaO2: T0<T1<T2. comparision of PaCO2: T0>T1>T2. The pH, PaO2, SaO2 in observation group were higher, PaCO2 in observation group was lower compared with that in control group in T1 and T2. The difference was considered to be statistically significant. (2) The comparision of IL-2, IL-6, hs-CRP, TNF-α in the two groups in T0 was not statistically significant. IL-2 in the observation in T1 and T2 was higher than that in the control group, IL-6, hs-CRP, TNF-α in the observation in T1 and T2 was lower than that in the control group. The difference was considered to be statistically significant.Conclusion: Ganglioside can improve blood gas analysis indexes, decrease the serum inflammatory cytokines in newborns with anoxic ischemic encephalopathy.

Molecular characterization of organic matter transformation mediated by microorganisms under anoxic/hypoxic conditions

Dissolved organic matter(DOM) in the ocean is one of the largest carbon pools on Earth. Microbial metabolism is an important process that shapes the marine DOM pool. Current studies on the interactions between microorganisms and DOM focus mainly on oxic environments. Few studies have addressed the molecular characteristics of DOM in microbial-mediated transformation under anoxic/hypoxic conditions. As a result of deteriorating water quality due to eutrophication and global warming, anoxia occurs frequently in coastal waters. In this study, we performed an experiment to investigate changes in microbial community responses and the molecular characteristics of DOM in microbial-mediated transformation under hypoxic conditions. We compared microbial-mediated DOM transformation at different dissolved oxygen levels(7, 5, and 2 mg L^(-1)) and in different media(natural and artificial seawater with and without laminarin). We also investigated differences in DOM composition between groups using spectroscopic analysis and ultrahigh-resolution Fourier transform ion cyclotron resonance mass spectrometry. The results showed decreased microbial metabolic activity and delayed community succession at low oxygen(≤2 mg L^(-1)) in natural seawater supplemented with laminarin. The growth of strictly aerobic bacteria such as Pseudomonadaceae and Sphingomonadaceae was inhibited and the total organic carbon utilization rate was reduced by 36.9–46.7% from 4 to 32days. Moreover, tyrosine-like and tryptophan-like components were preserved, while DOM humification and modified aromaticity indices were significantly reduced under low oxygen conditions. This experiment provides justification for further study of the processes and mechanisms of improved labile DOM preservation in anoxic estuarine and coastal waters.

A novel multistage anoxic/aerobic process with sludge regeneration zone (R-MAO) for advanced nitrogen removal from domestic sewage

To achieve advanced nitrogen removal from actual municipal sewage,a novel multistage anoxic/aerobic process with sludge regeneration zone(R-MAO)was developed.The reactor was used to treat actual domestic sewage and the nitrogen removal capacity of the sludge regeneration zone(R zone)was investigated during the long-term operation.The best performance was obtained at the R zone’s Oxidation-Reduction Potential(ORP)of-50±30 mV and hydraulic residence times(HRT)of 1.2 hr.The average effluent COD,TN,NH_(4)^(+)-N and NO_(3)^(−)-N of the R-MAO process were 18.0±2.3,7.5±0.6,1.0±0.5 and 4.6±0.4 mg/L,respectively,with the corresponding removal efficiency of COD,TN and NH_(4)^(+)-N were 92.9%±1.0%,84.1%±1.5% and 97.5%±1.1%.Compared to the sole MAO system,the TN removal efficiency of the R-MAO increased by 10.1%.Besides,under the optimal conditions,the contribution of the R zone in the R-MAO that removal COD,TN,NH_(4)^(+)-N and NO_(3)^(−)-N were 0.36,0.15,0.032 and 0.82 g/day.High-throughput sequencing results showed that uncultured_bacterium_f_Burkholderiaceae(5.20%),OLB8(1.04%)and Ottowia(1.03%)played an important role in denitrification in the R zone.This study provided effective guidance for the design and operation of the R-MAO process in domestic sewage treatment.