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1.
A comparative study of methanol as a supplementary carbon source for enhancing denitrification in primary and secondary anoxic zones 总被引:1,自引:0,他引:1
A comparative study on the use of methanol as a supplementary carbon source to enhance denitrification in primary and secondary anoxic zones is reported. Three lab-scale sequencing batch reactors (SBR) were operated to achieve nitrogen and carbon removal from domestic wastewater. Methanol was added to the primary anoxic period of the first SBR, and to the secondary anoxic period of the second SBR. No methanol was added to the third SBR, which served as a control. The extent of improvement on the denitrification performance was found to be dependent on the reactor configuration. Addition to the secondary anoxic period is more effective when very low effluent nitrate levels are to be achieved and hence requires a relatively large amount of methanol. Adding a small amount of methanol to the secondary anoxic period may cause nitrite accumulation, which does not improve overall nitrogen removal. In the latter case, methanol should be added to the primary anoxic period. The addition of methanol can also improve biological phosphorus removal by creating anaerobic conditions and increasing the availability of organic carbon in wastewater for polyphosphate accumulating organisms. This potentially provides a cost-effective approach to phosphorus removal from wastewater with a low carbon content. New fluorescence in situ hybridisation (FISH) probes targeting methanol-utilising denitrifiers were designed using stable isotope probing. Microbial structure analysis of the sludges using the new and existing FISH probes clearly showed that the addition of methanol stimulated the growth of specific methanol-utilizing denitrifiers, which improved the capability of sludge to use methanol and ethanol for denitrification, but reduced its capability to use wastewater COD for denitrification. Unlike acetate, long-term application of methanol has no negative impact on the settling properties of the sludge. 相似文献
2.
Hoi-Ping Shi Chi-Mei Lee Wei-Hsien Ma 《World journal of microbiology & biotechnology》2007,23(5):625-632
Polyhydroxyalkanoates (PHAs), intracellular carbon and energy reserve compounds in many bacteria, have been used extensively
in biodegradable plastics. PHA formation is influenced by nutrient limitations and growth conditions. To characterize the
PHA accumulation in a new denitrifying phosphorus-removing bacterium Brachymonas sp. P12, batch experiments were conducted in which the electron acceptor (oxygen or nitrate) was varied and different concentrations
of carbon (acetate), nitrogen (NH4Cl), and phosphorus (KH2PO4) were used. Polyhydroxybutyrate (PHB) was the dominant product during PHA formation when acetate was the sole carbon source.
The PHB content of aerobically growing cells increased from 431 to 636 mg PHB g−1 biomass, but the PHB concentration of an anoxic culture decreased (−218 mg PHB g−1 biomass), when PHB was utilized simultaneously with acetate as an electron donor for anoxic denitrification. The specific
PHB production rate of the carbon-limited batch, 158.2 mg PHB g−1 biomass h−1, was much greater than that of batches with normal or excess carbon. The effects of phosphorus and nitrogen concentrations
on PHB accumulation were clearly less than the effect of carbon concentration. According to the correlation between the specific
PHB production rate and the specific cell growth rate, PHB accumulation by Brachymonas sp. P12 is enhanced by nutrient limitation, is growth-associated, and provides additional energy for the biosynthesis of
non-PHB cell constituents to increase the cell growth rate beyond the usual level. 相似文献
3.
Effect of different carbon sources on the enhanced biological phosphorus removal in a sequencing batch reactor 总被引:1,自引:0,他引:1
Hollender Juliane van der Krol Doris Kornberger Liane Gierden Edith Dott Wolfgang 《World journal of microbiology & biotechnology》2002,18(4):359-364
The effect of the different carbon sources acetate, acetate/glucose or glucose on the enhanced biological phosphorus removal
(EBPR) process was studied by experiments under alternating anaerobic–aerobic conditions in one sequencing batch reactor for
each carbon source. The glucose was consumed completely within the first 30 min of the anaerobic phase whereas acetate degradation
was slow and incomplete. Phosphate was released independently of the carbon source during the whole anaerobic phase. The highest
phosphate release (27 mg P l−1) and polyhydroxyalkanoate (PHA) storage (20 mg C g−1 dry matter (DM)) during the anaerobic phase as well as the highest polyphosphate (poly-P) (8 mg P g−1 DM) and glycogen storage (17 mg C g−1 DM) during the aerobic phase were observed with acetate. In contrast to other investigations, glycogen storage did not increase
with glucose as substrate but was significantly smaller than with acetate. The PHA composition was also influenced strongly
by the carbon source. The polyhydroxyvalerate (PHV) portion of the PHA was maximal 17% for acetate and 82% for glucose. Due
to the strong influence of the carbon source on the PHA concentration and composition, PHA storage seems to regulate mainly
the phosphate release and uptake.
This revised version was published online in July 2006 with corrections to the Cover Date. 相似文献
4.
Nitrite accumulates during biological denitrification processes when carbon sources are insufficient. Acetate, methanol, and
ethanol were investigated as supplementary carbon sources in the nitrite denitrification process using biogranules. Without
supplementary external electron donors (control), the biogranules degraded 200 mg l−1 nitrite at a rate of 0.27 mg NO2–N g−1 VSS h−1. Notably, 1,500 mg l−1 acetate and 700 mg l−1 methanol or ethanol enhanced denitrification rates for 200 mg l−1 nitrite at 2.07, 1.20, and 1.60 mg NO2–N g−1 VSS h−1, respectively; these rates were significantly higher than that of the control. The sodium dodecyl sulfate polyacrylamide
gel electrophoresis of the nitrite reductase (NiR) enzyme identified three prominent bands with molecular weights of 37–41 kDa.
A linear correlation existed between incremental denitrification rates and incremental activity of the NiR enzyme. The NiR
enzyme activity was enhanced by the supplementary carbon sources, thereby increasing the nitrite denitrification rate. The
capacity of supplementary carbon source on enhancing NiR enzyme activity follows: methanol > acetate > ethanol on molar basis
or acetate > ethanol > methanol on an added weight basis. 相似文献
5.
Potential use of the municipal sludge ozonolysate as a carbon source was examined for phosphorus removal from low strength wastewater in a modified intermittently decanted extended aeration (IDEA) process. At ozone dosage of 0.2 g O3/g solids, readily biodegradable COD accounted for about 36% of COD from sludge ozonolysate. The denitrification potential of ozonolysate as a carbon source was comparable to that of acetate. Although, the first order constant for phosphorus release with the ozonolysate was half that of acetate, it was much higher than that of wastewater. Continuous operation of the modified IDEA process showed that the removals of nitrogen and phosphorus were simultaneously enhanced by addition of the ozonolysate. Phosphorus release was significantly induced after complete denitrification indicating that phosphorus release was strongly depended on nitrate concentration. Effectiveness of the ozonolysate as a carbon source for EBPR was also confirmed in a track study of the modified IDEA. 相似文献
6.
Comparison of biological removal via nitrite with real-time control using aerobic granular sludge and flocculent activated sludge 总被引:2,自引:0,他引:2
The process of nitrification–denitrification via nitrite for nitrogen removal under real-time control mode was tested in two
laboratory-scale sequencing batch reactors (SBRs) with flocculent activated sludge (R1) and aerobic granular sludge (R2) to
compare operational performance and real-time control strategies. The results showed that the average ammonia nitrogen, total
inorganic nitrogen (TIN), and chemical oxygen demand (COD) removal during aeration phase were 97.6%, 57.0%, and 90.1% in R2
compared with 98.6%, 48.7%, and 88.1% in R1. The TIN removed in both SBRs was partially due to the presence of simultaneous
nitrification–denitrification via nitrite, especially in R2. The specific nitrification and denitrification rates in R2 were
0.0416 mgNH4+–N/gSS-min and 0.1889 mgNOX−–N/gSS-min, which were 1.48 times and 1.35 times that of R1. The higher rates for COD removal, nitrification, and denitrification
were achieved in R2 than R1 with similar influent quality. Dissolved oxygen (DO), pH, and oxidization reduction potential,
corresponding to nutrient variations, were used as diagnostic parameters to control the organic carbon degradation and nitrification–denitrification
via nitrite processes in both SBRs. The online control strategy of granular SBR was similar to that of the SBR with flocculent
activated sludge. However, a unique U-type pattern on the DO curve in granular SBR was different from SBR with flocculent
activated sludge in aerobic phase. 相似文献
7.
The denitrification performance of a lab-scale anoxic rotating biological contactor (RBC) using landfill leachate with high
nitrate concentration was evaluated. Under a carbon to nitrogen ratio (C/N) of 2, the reactor achieved N-NO3
− removal efficiencies above 95% for concentrations up to 100 mg N-NO3
− l−1. The highest observed denitrification rate was 55 mg N-NO3
− l−1 h−1 (15 g N-NO3
− m−2 d−1) at a nitrate concentration of 560 mg N-NO3
− l−1. Although the reactor has revealed a very good performance in terms of denitrification, effluent chemical oxygen demand (COD)
concentrations were still high for direct discharge. The results obtained in a subsequent experiment at constant nitrate concentration
(220 mg N-NO3
− l−1) and lower C/N ratios (1.2 and 1.5) evidenced that the organic matter present in the leachate was non-biodegradable. A phosphorus
concentration of 10 mg P-PO4
3− l−1 promoted autotrophic denitrification, revealing the importance of phosphorus concentration on biological denitrification
processes. 相似文献
8.
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
9.
Effect of anaerobic reaction time on denitrifying phosphorus removal and N2O production 总被引:3,自引:0,他引:3
Nitrous oxide (N2O) is a highly potent greenhouse gas; however, the characteristics of N2O production during denitrification using poly-β-hydroxyalkanoates (PHA) as a carbon source are not well understood. In this study, effects of anaerobic reaction time (AnRT) on PHA formation, denitrifying phosphorus removal and N2O production were investigated using a laboratory-scale anaerobic/anoxic/oxic sequencing batch reactor (An/A/O SBR). The results showed that operation of the An/A/O SBR for 0.78 SRT (47 cycles) after the AnRT was shortened from 90 min to 60 min resulted in anaerobically synthesized PHA improving by 1.8 times. This improvement was accompanied by increased phosphorus removal efficiency and denitrification. Accordingly, the N2O-N production was reduced by 6.7 times. Parallel batch experiments were also conducted with AnRTs of 60, 90 and 120 min. All results indicated that in addition to the amount of anaerobically synthesized PHA, the kinetics of PHA degradation also regulated denitrifying phosphorus removal and N2O production. 相似文献
10.
Biological nutrient removal by a sequencing batch reactor (SBR) using an internal organic carbon source in digested piggery wastewater 总被引:14,自引:0,他引:14
Experiments in a lab-scale SBR were conducted to demonstrate the feasibility of using an internal carbon source (non-digested pig manure) for biological nitrogen and phosphorus removal in digested piggery wastewater. The internal C-source used for denitrification had similar effects to acetate. 99.8% of nitrogen and 97.8% of phosphate were removed in the SBR, from an initial content in the feed of 900 mg/l ammonia and 90 mg/l phosphate. 相似文献
11.
【背景】投加微生物菌剂是强化生物处理效能的重要手段,反硝化是污水脱氮除磷的关键步骤,但目前对于反硝化微生物菌剂相关的研究报道较少。【目的】驯化高效反硝化聚磷菌菌剂,并对系统进行生物强化。【方法】采用两阶段法快速富集反硝化聚磷菌,筛选高效脱氮除磷功能菌株NC1-1并进行鉴定,以NC1-1为菌种来源制备干粉菌剂,研究菌剂强化A2SBR系统污水处理效果。【结果】历经36 d后反硝化聚磷菌富集成功,菌株NC1-1经鉴定属于戈登氏菌属,其脱氮除磷率分别为89.46%和91.68%。麦麸、玉米粉配比为85%:15%、NC1-1投菌量为20 mL、发酵液用量20 mL的条件下成功制得干粉菌剂,干粉菌剂最佳投加量为10%的A2SBR系统总磷(total phosphorus,TP)和NO3--N去除率比未投加菌剂的A2SBR系统提高12.06%和11.52%。【结论】菌剂NC1-1的投加使A2SBR系统的污染物去除效能进一步提高,研究结果为进一步研究反硝化聚磷菌菌剂提供了... 相似文献
12.
Biological breakdown of denitrifying sulfide removal process in high-rate expanded granular bed reactor 总被引:1,自引:0,他引:1
This work conducted a denitrifying sulfide removal (DSR) test in an expanded granular sludge bed (EGSB) reactor at sustainable
loadings of 6.09 kg m−3 day−1 for sulfide, 3.11 kg m−3 day−1 for nitrate–nitrogen, and 3.27 kg m−1 day−1 for acetate–carbon with >93% efficiency, which is significantly higher than those reported in literature. Strains Pseudomonas sp., Nitrincola sp., and Azoarcus sp. very likely yield heterotrophs. Strains Thermothrix sp. and Sulfurovum sp. are the autotrophs required for the proposed high-rate EGSB-DSR system. The EGSB-DSR reactor experienced two biological
breakdowns, one at loadings of 4.87, 2.13, and 1.82 kg m−3 day−1; reactor function was restored by increasing nitrate and acetate loadings. Another breakdown occurred at loadings of up to
8.00, 4.08, and 4.50 kg m−1 day−1; the heterotrophic denitrification pathway declined faster than the autotrophic pathway. The mechanism of DSR breakdown is
as follows. High sulfide concentration inhibits heterotrophic denitrifiers, and the system therefore accumulates nitrite.
Autotrophic denitrifiers are then inhibited by the accumulated nitrite, thereby leading to breakdown of the DSR process. 相似文献
13.
Control of carbon and ammonium ratio for simultaneous nitrification and denitrification in a sequencing batch bioreactor 总被引:1,自引:0,他引:1
《International biodeterioration & biodegradation》2007,59(1):1-7
This study shows how the carbon and nitrogen (C/N) ratio controls the simultaneous occurrence of nitrification and denitrification in a sequencing batch reactor (SBR). Data demonstrated that a low C/N ratio resulted in a rapid carbon deficit, causing an unbalanced simultaneous nitrification–denitrification (SND) process in SBR. When the initial COD/NH4+-N ratio was adjusted to 11.1, the SND-based SBR achieved complete removal of NH4-N and COD without leaving any NO2−-N in the effluent. The nitrogen removal efficiency decreases gradually with increasing ammonium-loading rate to the SND–SBR system. Altogether, data showed that appropriate controls of carbon and nitrogen input are required to achieve an efficient SND–SBR. An established SND technology can save operation time and energy, and might replace the traditional two-stage biological nitrification and denitrification process. 相似文献
14.
A Pseudomonas sp. strain, which can utilize quinoline as its sole carbon, nitrogen and energy source, was isolated from activated sludge
in a coking wastewater treatment plant. Quinoline can be degraded via the 8-hydroxycoumarin pathway. We quantified the first
two organic intermediates of the biodegradation, 2-hydroxyquinoline and 2,8-dihydroxyquinoline. We tracked the transformation
of the nitrogen in quinoline in two media containing different C/N ratios. At least 40.4% of the nitrogen was finally transformed
into ammonium when quinoline was the sole C and N source. But addition of an external carbon source like glucose promoted
the transformation of N from NH3 into NO3
−, NO2
−, and then to N2. The product analysis and gene characteristics indicated that the isolate accomplished heterotrophic nitrification and aerobic
denitrification simultaneously. The study also demonstrated that quinoline and its metabolic products can be eliminated if
the C/N ratio is properly controlled in the treatment of quinoline-containing wastewater. 相似文献
15.
Nitrogen removal in a wastewater treatment plant through biofilters: nitrous oxide emissions during nitrification and denitrification 总被引:1,自引:0,他引:1
In order to estimate N2O emissions from immersed biofilters during nitrogen removal in tertiary treatments at urban wastewater treatment plants (WWTPs), a fixed culture from the WWTP of “Seine Centre” (Paris conurbation) was subjected to lab-scale batch experiments under various conditions of oxygenation and a gradient of methanol addition. The results show that during nitrification, N2O emissions are positively related to oxygenation (R
2 = 0.99). However, compared to the rates of ammonium oxidation, the percentage of emitted N2O is greater when oxygenation is low (0.5–1 mgO2 L−1), representing up to 1% of the oxidized ammonium (0.4% on average). During denitrification, the N2O emission reaches a significant peak when the quantity of methanol allows denitrification of between 66% and 88%. When methanol concentrations lead to a denitrification of close to 100%, the flows of N2O are much lower and represent on average 0.2% of the reduced nitrate. By considering these results, we can estimate, the emissions of N2O during nitrogen removal, at the “Seine Centre” WWTP, to approximately 38 kgN-N2O day−1. 相似文献
16.
Macrophyte presence is an indicator of enhanced denitrification and nitrification in sediments of a temperate restored agricultural stream 总被引:1,自引:0,他引:1
Stream macrophytes are often removed with their sediments to deepen stream channels, stabilize channel banks, or provide habitat
for target species. These sediments may support enhanced nitrogen processing. To evaluate sediment nitrogen processing, identify
seasonal patterns, and assess sediment processes relative to stream load, we measured denitrification and nitrification rates
in a restored third- to fourth-order agricultural stream, Black Earth Creek, Wisconsin, and estimated processing over a 10 km
reach. Our results show that sediments with submerged and emergent macrophytes (e.g., Potomageton spp. and Phalaris arudinacea) support greater denitrification rates than bare sediments (1.12 μmol N g−1 h−1 vs. 0.29). Sediments with macrophytes were not carbon limited and organic matter fraction was weakly correlated to denitrification.
The highest denitrification potential occurred in macrophyte beds (5.19 μmol N g−1 h−1). Nitrification rates were greater in emergent beds than bare sediments (1.07 μg N ml−1day−1 vs. 0.35) with the greatest nitrification rates during the summer. Total denitrification removal in sediments with macrophytes
was equivalent to 43% of the nitrate stream load (463.7 kg N day−1) during spring and nitrification in sediments with macrophytes was equivalent to 247% of summer ammonium load (3.5 kg N day−1). Although the in-channel connectivity to nitrogen rich water was limited, actual stream nitrogen loads could increase with
removal of macrophytes. Macrophyte beds and supporting fringing wetted areas are important if nitrogen management is a concern
for riparian stream restoration efforts. 相似文献
17.
ImGyu Byun JeungJin Park SoRa Park TaeHo Lee TaeJoo Park 《Biotechnology and Bioprocess Engineering》2008,13(1):96-101
Spent sulfidic caustic was applied to sulfur utilizing autotrophic denitrification as the simultaneous source of electron
donor and alkalinity. The two experiment set-up of upflow anoxic hybrid growth reactor (UAHGR) and upflow anoxic suspended
growth reactor (UASGR) was adopted and nitrate removals were similar in both reactors. Approximately 90% of the initial nitrate
was denitrified at nitrate loading rate of 0.15∼0.40 kgNO3
−/m3·d. The experimental stoichiometric ratio of sulfate production to nitrate removal was ranged from 1.5 to 2.1 mgSO4
2−/mgNO3
−. During the operation period, denaturing gradient gel electrophoresis (DGGE) analysis of polymerase chain reaction (PCR)-amplified
16S rDNA fragments for the sludge sample of both reactors showed the change of microbial communities. Thiobacillus denitrificans-like microorganism occupied 28.5% (18 clones) of the 63 clones by cloning the PCR products from the sludge sample of UAHGR.
Acidovorax avenae, which can reduce nitrate to nitrogen gas while oxidizing phenol (heterotrophic denitrifier), was also found in 7 clones
(11.1%). Although an organic carbon source was not added to the medium, a microorganism (Kaistella koreensis) capable of oxidizing organic compounds was found in 7 clones (11.1%). Therefore, the microbial community of spent sulfidic
caustic applied autotrophic denitrification process well corresponds to the substrate components of spent sulfidic caustic.
Through the batch cultivation of microorganisms in UAHGR, the microbial kinetic coefficients of spent sulfidic caustic applied
autotrophic denitrification were estimated to be μ
max
= 0.097 h−1, k
d
= 0.0021 h−1, K
s
= 200 mgNO3
−/L, and Y = 0.31 mgMLVSS/mgNO3
−. 相似文献
18.
Enhanced biological denitrification of high concentration of nitrite with supplementary carbon source 总被引:3,自引:0,他引:3
Nitrite accumulates during biological denitrification processes when carbon sources are insufficient. Acetate, methanol, and ethanol were investigated as supplementary carbon sources in the nitrite denitrification process using biogranules. Without supplementary external electron donors (control), the biogranules degraded 200 mg l?1 nitrite at a rate of 0.27 mg NO2–N g?1?VSS h?1. Notably, 1,500 mg l?1 acetate and 700 mg l?1 methanol or ethanol enhanced denitrification rates for 200 mg l?1 nitrite at 2.07, 1.20, and 1.60 mg NO2–N g?1?VSS h?1, respectively; these rates were significantly higher than that of the control. The sodium dodecyl sulfate polyacrylamide gel electrophoresis of the nitrite reductase (NiR) enzyme identified three prominent bands with molecular weights of 37–41 kDa. A linear correlation existed between incremental denitrification rates and incremental activity of the NiR enzyme. The NiR enzyme activity was enhanced by the supplementary carbon sources, thereby increasing the nitrite denitrification rate. The capacity of supplementary carbon source on enhancing NiR enzyme activity follows: methanol?>?acetate?>?ethanol on molar basis or acetate?>?ethanol?>?methanol on an added weight basis. 相似文献
19.
Membrane-aerated biofilms (MABs) are an effective means to achieve nitrification and denitrification of wastewater. In this
research, microsensors, fluorescence in situ hybridization (FISH), and modeling were used to assess the impact of bulk liquid
biological oxygen demand (BOD) concentrations on the activity and microbial community structure of nitrifying MABs. With 1 g
m−3 BOD in the bulk liquid, the nitrification rate was 1.3 g N m−2 day−1, slightly lower than the 1.5 g N m−2 day−1 reported for no bulk liquid BOD. With bulk liquid BOD concentrations of 3 and 10 g m−3, the rates decreased to 1 and 0.4 g N m−2 day−1, respectively. The percent denitrification increased from 20% to 100% when the BOD increased from 1 to 10 g m−3 BOD. FISH results indicated increasing abundance of heterotrophs with increasing bulk liquid BOD, consistent with the increased
denitrification rates. Modeling was used to assess the effect of BOD on nitrification rates and to compare an MAB to a conventional
biofilm. The model-predicted nitrification rates were consistent with the experimental results. Also, nitrification in the
MAB was much less sensitive to BOD inhibition than the conventional biofilm. The MAB achieved concurrent nitrification and
denitrification, whereas little denitrification occurred in the conventional biofilm. 相似文献
20.
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