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1.
Enhanced nutrient removal in three types of step feeding process from municipal wastewater 总被引:2,自引:0,他引:2
An anoxic/oxic step feeding process was improved to enhance nutrient removal by reconfiguring the process into (1) anaerobic/anoxic/oxic step feeding process or (2) modified University of Capetown (UCT) step feeding process. Enhanced nitrogen and phosphorus removal and optimized organics utilization were obtained simultaneously in the modified UCT type with both internal and sludge recycle ratios of 75% as well as anaerobic/anoxic/oxic volume ratio of 1:3:6. Specifically, the UCT configuration and optimized operational conditions lead to the enrichment of denitrifying phosphorus removal microorganisms and achieved improved anaerobic P-release and anoxic P-uptake activities, which were beneficial to the denitrifying phosphorus removal activities and removal efficiencies. Due to high mixed liquor suspended solid and uneven distributed dissolved oxygen, 35% of total nitrogen was eliminated through simultaneous nitrification and denitrification process in aerobic zones. Moreover, 62 ± 6% of influent chemical oxygen demands was involved in the denitrification or phosphorus release processes. 相似文献
2.
Atypical Polyphosphate Accumulation by the Denitrifying Bacterium Paracoccus denitrificans
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Polyphosphate accumulation by Paracoccus denitrificans was examined under aerobic, anoxic, and anaerobic conditions. Polyphosphate synthesis by this denitrifier took place with either oxygen or nitrate as the electron acceptor and in the presence of an external carbon source. Cells were capable of poly-β-hydroxybutyrate (PHB) synthesis, but no polyphosphate was produced when PHB-rich cells were incubated under anoxic conditions in the absence of an external carbon source. By comparison of these findings to those with polyphosphate-accumulating organisms thought to be responsible for phosphate removal in activated sludge systems, it is concluded that P. denitrificans is capable of combined phosphate and nitrate removal without the need for alternating anaerobic/aerobic or anaerobic/anoxic switches. Studies on additional denitrifying isolates from a denitrifying fluidized bed reactor suggested that polyphosphate accumulation is widespread among denitrifiers. 相似文献
3.
Enhanced biological nutrient removal using MUCT-MBR system 总被引:4,自引:0,他引:4
Biological nutrient removal was investigated in a combined modified University of Cape Town and membrane bioreactor system. When the influent nutrient mass ratio (COD/TN/TP) was 28.5/5.1/1 to 28.5/7.2/1, average removal efficiencies of COD, TN and TP were 90%, 81.6%, 75.2%. Obvious denitrifying phosphorus removal occurred with C/N ratio 3.98. When nitrite was the main electron acceptor, the ratio of denitrifying phosphate uptake to the total phosphate uptake were 99.8% and the sludge yield was 0.28kg VSS/kg COD; when nitrate was the main electron acceptor, the ratio was 92% and the yield was 0.32kg VSS/kg COD. In case of nitrite, the system not only kept TP and TN removal at 89.1% and 82.2%, but also ensured less sludge production. Batch tests showed that the proportion of denitrifying phosphorus-accumulating organisms in the total phosphorus-accumulating organisms in the system was higher than 80%. 相似文献
4.
Denitrifying granular sludge reactor holds better nitrogen removal efficiency than other kinds of denitrifying reactors, while this reactor commonly needs seeding anaerobic granular sludge and longer period for start-up in practice, which restricted the application of denitrifying granular sludge reactor. This study presented a rapid and stable start-up method for denitrifying granular sludge. An upflow sludge blanket (USB) reactor with packings was established with flocculent activated sludge for treatment of high concentration nitrite wastewater. Results showed mature denitrifying granular sludge appeared only after 15 days with highest nitrogen removal rate of 5.844 kg N/(m3 day), which was much higher than that of compared anoxic sequencing batch reactor (ASBR). No significant nitrite inhibition occurred in USB and denitrification performance was mainly influenced by hydraulic retention time, influent C/N ratio and internal reflux ratio. Hydraulic shear force created by upflow fluid, shearing of gaseous products and stable microorganisms adhesion on the packings might be the reasons for rapid achievement of granular sludge. Compared to inoculated sludge and ASBR, remarkable microbial communitiy variations were detected in USB. The dominance of Proteobacteria and Bacteroidetes and enrichment of species Pseudomonas_stutzeri should be responsible for the excellent denitrification performance, which further verified the feasibility of start-up method. 相似文献
5.
Polyphosphate accumulation by Paracoccus denitrificans was examined under aerobic, anoxic, and anaerobic conditions. Polyphosphate synthesis by this denitrifier took place with either oxygen or nitrate as the electron acceptor and in the presence of an external carbon source. Cells were capable of poly-beta-hydroxybutyrate (PHB) synthesis, but no polyphosphate was produced when PHB-rich cells were incubated under anoxic conditions in the absence of an external carbon source. By comparison of these findings to those with polyphosphate-accumulating organisms thought to be responsible for phosphate removal in activated sludge systems, it is concluded that P. denitrificans is capable of combined phosphate and nitrate removal without the need for alternating anaerobic/aerobic or anaerobic/anoxic switches. Studies on additional denitrifying isolates from a denitrifying fluidized bed reactor suggested that polyphosphate accumulation is widespread among denitrifiers. 相似文献
6.
水体富营养化是当前水环境保护工作的重点关注问题,微生物修复富营养化水体具有高效、低耗且不产生二次污染等特点,已经成为富营养化水体生态修复的一种重要方式。近年来,对反硝化聚磷菌的研究及其在污水处理工艺中的应用越来越广泛。不同于传统的反硝化细菌联合聚磷菌去除氮磷工艺,反硝化聚磷菌在交替厌氧、缺氧/好氧条件下能同时进行脱氮除磷而被广泛关注与研究。值得注意的是,近几年报道的部分微生物仅在好氧条件下就可进行同时脱氮除磷,但是其脱氮除磷机理仍未理清。基于此,文中总结了目前发现的反硝化聚磷菌和同时硝化反硝化聚磷微生物的种类及特点,并对其脱氮与除磷的关系及其机理进行了系统性分析,对目前反硝化除磷存在的问题进行了梳理,最后对今后的研究方向进行了展望,以期为完善反硝化聚磷菌的脱氮除磷机理及工艺改进提供参考。 相似文献
7.
8.
Effect of basic operating parameters on biological phosphorus removal in a continuous-flow anaerobic–anoxic activated sludge system 总被引:1,自引:0,他引:1
A continuous-flow anaerobic–anoxic (A2) activated sludge system was operated for efficient enhanced biological phosphorus
removal (EBPR). Because of the system configuration with no aeration zones, phosphorus (P) uptake takes place solely under
anoxic conditions with simultaneous denitrification. Basic operating conditions, namely biomass concentration, influent carbon
to phosphorus ratio and anaerobic retention time were chosen as variables in order to assess their impact on the system performance.
The experimental results indicated that maintenance of biomass concentration above 2,500 mg MLVSS/L resulted in the complete
phosphate removal from the influent (i.e. 15 mg PO4
3−-P/L) for a mean hydraulic residence time (HRT) of 15 h. Additionally, by increasing the influent COD/P ratio from 10 to 20 g/g,
the system P removal efficiency was improved although the experimental results indicated a possible enhancement of the competition
between phosphorus accumulating organisms (PAOs) and other microbial populations without phosphorus uptake ability. Moreover,
because of the use of acetate (i.e. easily biodegradable substrate) as the sole carbon source in the system feed, application
of anaerobic retention times greater than 2 h resulted in no significant release of additional P in the anaerobic zone and
no further amelioration of the system P removal efficiency. The application of anoxic P removal resulted in more than 50%
reduction of the organic carbon necessitated for nitrogen and phosphorus removal when compared to a conventional EBPR system
incorporating aerobic phosphorus removal. 相似文献
9.
Free nitrous acid (FNA) inhibition on denitrifying poly-phosphate accumulating organisms (DPAOs) 总被引:1,自引:0,他引:1
Yan Zhou Lily Ganda Melvin Lim Zhiguo Yuan Staffan Kjelleberg Wun Jern Ng 《Applied microbiology and biotechnology》2010,88(1):359-369
Free nitrous acid (FNA) has been identified to be a ubiquitous inhibitor of a wide range of microorganisms, including bacteria
involved in wastewater treatment. The FNA-induced inhibition on the anoxic (nitrite as electron acceptor) metabolism of denitrifying
poly-phosphate accumulating organisms (DPAOs) was investigated using sludge from a sequencing batch reactor performing carbon,
nitrogen, and phosphorus removal from synthetic wastewater. We found that FNA had a much stronger inhibitory effect on phosphorus
(P) uptake and glycogen production than on poly-β-hydroxyalkanoate degradation and nitrite reduction. The intracellular adenosine
triphosphate levels decreased sharply during the FNA incubation, and the decreasing rates were positively correlated with
increasing FNA concentrations. The electron transport activity of DPAOs when exposed to FNA displayed a similar trend. Further,
at FNA concentrations above 0.044 mg HNO2-N/L, the anaerobic metabolism of DPAOs was initiated despite of the presence of nitrite, as evidenced by the release of phosphorus
and the consumption of glycogen. DPAO metabolism did not recover completely from FNA inhibition in the subsequent FNA-free
environment. The recovery rate depended on the concentration of FNA applied in the previous anoxic period. These results suggest
that the inhibitory effects are diverse and may be attributable to different mechanisms operating simultaneously. 相似文献
10.
In this study, an advanced wastewater treatment process, the denitrifying phosphorus/side stream phosphorus removal system (DPR-Phostrip), was developed for the purpose of enhancing denitrifying phosphorus removal. The enrichment of denitrifying phosphorus-accumulating organisms (DPAOs) and the microbial community structure of DPR-Phostrip were evaluated by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE), and the metabolic activity of seed sludge and activated sludge collected after 55 days of operation were evaluated by Biolog? analysis. This experimental study of DPR-Phostrip operation showed that nutrients were removed effectively, and denitrifying phosphorus removal was observed during the pre-anoxic period. PCR-DGGE analysis indicated that DPR-Phostrip supported DPAO growth while inhibiting PAOs and GAOs. The major dominant species in DPR-Phostrip were Bacteroidetes bacterium, Saprospiraceae bacterium, and Chloroflexi bacterium. Moreover, the functional diversity indices calculated on the basis of Biolog analysis indicated that DPR-Phostrip had almost no effect on microbial community diversity but was associated with a shift in the dominant species, which confirms the results of the PCR-DGGE analysis. The results for average well color development, calculated via Biolog analysis, showed that DPR-Phostrip had a little impact on the metabolic activity of sludge. Further principal component analysis suggested that the ability to utilize low-molecular-weight organic compounds was reduced in DPR-Phostrip. 相似文献
11.
Nitrogen removal and microbial communities in a three-stage system simulating a riparian environment
The riparian zone is an active interface for nitrogen removal, in which nitrogen transformations by microorganisms have not been valued. In this study, a three-stage system was constructed to simulate the riparian zone environments, and nitrogen removal as well as the microbial community was investigated in this ‘engineered riparian system’. The results demonstrated that stage 1 of this system accounted for 41–51 % of total nitrogen removal. Initial ammonium loading and redox potential significantly impacted the nitrogen removal performances. Stages 1 and 2 were both composed of an anoxic/oxic (A/O) zone and an anaerobic column. The A/O zone removed most of the ammonium load (6.8 g/m2/day), while the anaerobic column showed a significant nitrate removal rate (11.1 g/m2/day). Molecular biological analysis demonstrated that bacterial diversity was high in the A/O zones, where ammonium-oxidizing bacteria and nitrite-oxidizing bacteria accounted for 8.42 and 3.32 % of the bacterial population, respectively. The denitrifying bacteria Acidovorax sp. and the nitrifying bacteria Nitrosospira/Nitrosomonas were the predominant microorganisms in this engineered riparian system. This three-stage system was established to achieve favorable nitrogen removal and the microbial community in the system was also retained. This investigation should deepen our understanding of biological nitrogen removal in engineered riparian zones. 相似文献
12.
A bacterial strain (designated as YP1) was isolated from an aerobic granular sequence batch reactor (SBR) performing simultaneous nitrogen and phosphorus removal. Based on the morphological, biochemical characteristics, and phylogenetic analysis of 16S rRNA gene sequence, YP1 was identified as Pseudoxanthomonas sp. strain. Strain YP1 was confirmed to have the ability to conduct denitrifying phosphorus removal (DPR). The optimal conditions for YP1 were pH 8.0, phosphorus (PO43?-P) concentration of 8.0 mg/L, sodium citrate as carbon source, and nitrate nitrogen (NO3?-N) concentration of 30 mg/L. The functional genes including ppk and ppx, narG and narA, nirS and nirK were amplified for understanding the DPR pathways. The results provide more information about denitrifying polyphosphate-accumulating organisms (DPAOs) in aerobic granular sludge (AGS) and lay the foundations for full-scale DPR. 相似文献
13.
This study investigated the effects of internal recycling time mode and hydraulic retention time (HRT) on nutrient removal
in the sequencing anoxic/anaerobic membrane bioreactor process. Denitrification and phosphorus release were reciprocally dependent
on the anoxic/anaerobic time ratio (Ax/An). As Ax/An increased, nitrogen removal rate increased but phosphorus removal rate
decreased. The increasing Ax/An provided the longer denitrification period so that the organic substrate were consumed more
for denitrification rather than phosphorus release in the limited condition of readily biodegradable substrate. Decreasing
HRT increased both nitrogen and phosphorus removal efficiency because as HRT decreased, food-to-microorganism loading ratio
increased and thus enhanced the biological capacity and activity of denitrifying bacteria. This could be verified from the
observation mixed liquor suspended solids concentration and specific denitrification rate. The change of Ax/An and HRT affected
phosphorus removal more than nitrogen removal due to the limitation of favourable carbon source for phosphorus accumulating
organisms. 相似文献
14.
Selection and dominance mechanisms of denitrifying phosphate-accumulating organisms in biological phosphate removal process 总被引:5,自引:0,他引:5
Johwan Ahn Tomotaka Daidou Satoshi Tsuneda Akira Hirata 《Biotechnology letters》2001,23(24):2005-2008
A sequencing batch reactor under different electron acceptor conditions was operated serially to investigate the selection and dominance mechanisms of denitrifying phosphate-accumulating organisms (DNPAOs) in a biological nutrient removal process. The presence of a small amount of NO–
3 at the start of the anaerobic phase stimulated the selection of DNPAOs in an anaerobic/aerobic system, and switching O2 to NO–
3 as an electron acceptor enhanced the activity of anoxic phosphate uptake. 相似文献
15.
Soejima K Oki K Terada A Tsuneda S Hirata A 《Bioprocess and biosystems engineering》2006,29(5-6):305-313
The effects of acetate and nitrite on the performance of sequencing batch reactors (SBRs) employing an anaerobic/aerobic/anoxic (AOA) process were investigated. Three types of SBR operations were used: sodium acetate addition at the start of anoxic condition for heterotrophic denitrification (Type 1); sodium acetate addition at the start of aerobic condition for anoxic phosphate removal by denitrifying phosphate-accumulating organisms (DNPAOs) (Type 2: conventional AOA process); and nitrite addition at the start of aerobic condition for inhibition of phosphate-accumulating organisms (PAOs) (Type 3). A track experiment shows that Type 2 led to the best performance of SBRs among the three types. An analysis by fluorescence in situ hybridization (FISH) revealed that nitrite addition decreased the ratio of PAOs with a decrease in phosphorus removal efficiency. The fraction of DNPAOs in Type 2 was the highest at 13%, indicating that Type 2 is suitable for the simultaneous nitrogen and phosphorus removal in the AOA process. 相似文献
16.
Anammox start-up in sequencing batch biofilm reactors using different inoculating sludge 总被引:1,自引:0,他引:1
In this study, anammox bacteria were rapidly enriched in sequencing batch biofilm reactors (SBBRs) with different inoculations. The activated sludge taken from a sequencing batch reactor was used and inoculated to SBBR1, while SBBR2 was seeded with stored anaerobic sludge from an upflow anaerobic fixed bed (2-year stored at 5–15 °C). Nitrogen removal performance, anammox activity, biofilm characteristics and variation of the microbial community were evaluated. The maximum total nitrogen loading rate (NLR) of SBBR1 gradually reached to 1.62 kg?N/(m3/day) with a removal efficiency higher than 88 % and the NLR of SBBR2 reached to 1.43 kg?N/(m3/day) with a removal efficiency of 86 %. SBBR2 was more stable compared to SBBR1. These results, combined with molecular techniques such as scanning electron microscope, fluorescence in situ hybridization, and terminal restriction fragment length polymorphism, indicated that different genera of anammox bacteria became dominant. This research also demonstrates that SBBR is a promising bioreactor for starting up and enriching anammox bacteria. 相似文献
17.
传统厌氧/好氧生物除磷与厌氧/缺氧反硝化除磷效能的比较 总被引:1,自引:0,他引:1
采用序批式反应器(SBR),对比厌氧/好氧(A/O)和厌氧/缺氧(A/A)2种运行模式对模拟生活和工业混合污水同时脱氮除磷的效能。结果表明:反硝化聚磷菌完全可以在厌氧/缺氧交替运行条件下得到富集,稳定运行的2种模式对有机物和P的去除率分别保持在90%和85%以上,且A/A SBR具有更强的释磷能力,其释磷量比A/O SBR高出1.2倍。进一步试验表明:磷的释放在有无硝酸盐的情况下效果是不同的。2个系统内污泥均有反硝化除磷能力,A/A SBR中所含反硝化聚磷菌(DPAO)的比例是A/O SBR的4.56倍。2种模式出水水质都能取得较好的效果,且能实现同步除磷脱氮,而反硝化除磷在生物除磷方面更具优势。 相似文献
18.
This study was conducted to obtain a better insight into the metabolic behavior of denitrifying phosphate-accumulating organisms relative to the transformations of relevant intracellular compounds as well as phosphorus and nitrate for enhanced biological phosphorus removal under different combinations of electron acceptor (oxygen or nitrate) and electron donor (acetate). Under anoxic conditions, the amount of polyhydroxybutyrate (PHB) produced per acetate taken up considerably increased with the increasing amount of nitrate reduced whereas the amounts of nitrate reduced and phosphorus released per acetate taken up remained almost constant. However, glycogen utilization occurred during PHB production and then was again observed in response to the initial supplementation of acetate after glycogen accumulation was transiently observed during anoxic phosphorus uptake using nitrate as an electron acceptor. On the other hand, under subsequent aerobic conditions, the additional supplementation of acetate again caused aerobic phosphorus release and PHB production, which showed that PHB production was associated with polyphosphate cleavage regardless of electron acceptor conditions. In contrast to anoxic conditions, glycogen accumulation was observed during PHB production. Based on these observations, the preliminary model for the metabolic behavior of denitrifying phosphate-accumulating organisms was proposed and could well account for the complex transformations of PHB and glycogen together with phosphorus release in the presence of acetate under different electron acceptors. 相似文献
19.
Wei Zeng Boxiao Li Yingying Yang Xiangdong Wang Lei Li Yongzhen Peng 《Bioprocess and biosystems engineering》2014,37(2):277-287
Impact of nitrite on aerobic phosphorus (P) uptake of poly-phosphate accumulating organisms (PAOs) in three different enhanced biological phosphorus removal (EBPR) systems was investigated, i.e., the enriched PAOs culture fed with synthetic wastewater, the two lab-scale sequencing batch reactors (SBRs) treating domestic wastewater for nutrient removal through nitrite-pathway nitritation and nitrate-pathway nitrification, respectively. Fluorescence in situ hybridization results showed that PAOs in the three sludges accounted for 72, 7.6 and 6.5 % of bacteria, respectively. In the enriched PAOs culture, at free nitrous acid (FNA) concentration of 0.47 × 10?3 mg HNO2-N/L, aerobic P-uptake and oxidation of intercellular poly-β-hydroxyalkanoates were both inhibited. Denitrifying phosphorus removal under the aerobic conditions was observed, indicating the existence of PAOs using nitrite as electron acceptor in this culture. When the FNA concentration reached 2.25 × 10?3 mg HNO2-N/L, denitrifying phosphorus removal was also inhibited. And the inhibition ceased once nitrite was exhausted. Corresponding to both SBRs treating domestic wastewater with nitritation and nitrification pathway, nitrite inhibition on aerobic P-uptake by PAOs did not occur even though FNA concentration reached 3 × 10?3 and 2.13 × 10?3 mg HNO2-N/L, respectively. Therefore, PAOs taken from different EBPR activated sludges had different tolerance to nitrite. 相似文献
20.
A sequencing batch reactor system for high-level biological nitrogen and phosphorus removal from abattoir wastewater 总被引:2,自引:0,他引:2
A sequencing batch reactor (SBR) system is demonstrated to biologically remove nitrogen, phosphorus and chemical oxygen demand
(COD) to very low levels from abattoir wastewater. Each 6 h cycle contained three anoxic/anaerobic and aerobic sub-cycles
with wastewater fed at the beginning of each anoxic/anaerobic period. The step-feed strategy was applied to avoid high-level
build-up of nitrate or nitrite during nitrification, and therefore to facilitate the creation of anaerobic conditions required
for biological phosphorus removal. A high degree removal of total phosphorus (>98%), total nitrogen (>97%) and total COD (>95%)
was consistently and reliably achieved after a 3-month start-up period. The concentrations of total phosphate and inorganic
nitrogen in the effluent were consistently lower than 0.2 mg P l−1 and 8 mg N l−1, respectively. Fluorescence in situ hybridization revealed that the sludge was enriched in Accumulibacter spp. (20–40%), a known polyphosphate accumulating organism, whereas the known glycogen accumulating organisms were almost
absent. The SBR received two streams of abattoir wastewater, namely the effluent from a full-scale anaerobic pond (75%) and
the effluent from a lab-scale high-rate pre-fermentor (25%), both receiving raw abattoir wastewater as feed. The pond effluent
contained approximately 250 mg N l−1 total nitrogen and 40 mg P l−1 of total phosphorus, but relatively low levels of soluble COD (around 500 mg l−1). The high-rate lab-scale pre-fermentor, operated at 37°C and with a sludge retention time of 1 day, proved to be a cheap
and effective method for providing supplementary volatile fatty acids allowing for high-degree of biological nutrient removal
from abattoir wastewater. 相似文献