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1.
Well-formed denitrifying granular sludge with a biomass concentration of 24.8 gVSS L?1 and a specific nitrate removal rate of 0.19 gNO3-N gVSS?1 d?1 was obtained in an upflow sludge blanket (USB) reactor by cultivating seeded aerobic flocculent sludge for 6–8 weeks. Regularity phenomena exist in the granulation including flotation of flocculent sludge, formation of fine granules, occurrence of channelling, and formation of mature granular sludge. The granulation is similar to crystal growth, that the non-denitrifying bacteria evolve into the carriers (fine granules), on the surface of which denitrifying bacteria proliferate and develop into mature granular sludge.There are several key parameters that must be considered when developing a good denitrifying granular sludge. First, the proper seed sludge must be chosen (VSS/SS at 0.65–0.75, SRT over 25 days) to accelerate the granulation process. Secondly, any floating sludge should be stirred, and the sludge loading rate should be within the range of 0.05–0.15 gNO3-N gVSS?1 d?1 until fine granules emerge. Additionally, spontaneous gas agitation or interval air-blowing should be used to effectively eliminate channelling; Finally, the sludge loading rate should be less than 0.25 gNO3-N gVSS?1 d?1 until dense, mature granular sludge appears. This study could support and promote the full-scale application of denitrifying granular sludge. 相似文献
2.
Bacterial community dynamics in long‐term operation of a pilot plant using aerobic granular sludge to treat pig slurry
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A. Fra‐Vázquez N. Morales M. Figueroa A. Val del Río L. Regueiro J.L. Campos A. Mosquera‐Corral 《Biotechnology progress》2016,32(5):1212-1221
Aerobic granular sludge represents an interesting approach for simultaneous organic matter and nitrogen removal in wastewater treatment plants. However, the information about microbial communities in aerobic granular systems dealing with industrial wastewater like pig slurry is limited. Herein, bacterial diversity and dynamics were assessed in a pilot scale plant using aerobic granular sludge for organic matter and nitrogen elimination from swine slurry during more than 300 days. Results indicated that bacterial composition evolved throughout the operational period from flocculent activated sludge, used as inoculum, to mature aerobic granules. Bacterial diversity increased at the beginning of the granulation process and then declined due to the application of transient organic matter and nitrogen loads. The operational conditions of the pilot plant and the degree of granulation determined the microbial community of the aerobic granules. Brachymonas, Zoogloea and Thauera were attributed with structural function as they are able to produce extracellular polymeric substances to maintain the granular structure. Nitrogen removal was justified by partial nitrification (Nitrosomonas) and denitrification (Thauera and Zoogloea), while Comamonas was identified as the main organic matter oxidizing bacteria. Overall, clear links between bacterial dynamics and composition with process performance were found and will help to predict their biological functions in wastewater ecosystems improving the future control of the process. © 2016 American Institute of Chemical Engineers Biotechnol. Prog., 32:1212–1221, 2016 相似文献
3.
Bioaugmentation and enhanced formation of microbial granules used in aerobic wastewater treatment 总被引:7,自引:0,他引:7
Microbial aggregates of an aerobic granular sludge can be used for the treatment of industrial or municipal wastewater, but their formation from a microbial activated sludge requires several weeks. Therefore, the aim of this research was the selection of microbial cultures to shorten the granule-forming period from several weeks to a few days. An enrichment culture with the ability to accelerate granulation was obtained by repeating the selection and batch cultivation of fast-settling microbial aggregates isolated from the aerobic granular sludge. Bacterial cultures of Klebsiella pneumoniae strain B and Pseudomonas veronii strain F, with self-aggregation indexes of 65 and 51%, respectively, and a coaggregation index of 58%, were isolated from the enrichment culture. A mixture of these strains with the activated sludge was used as an inoculum in an experimental sequencing batch reactor to start up an aerobic granulation process. Aerobic granules with a mean diameter of 446±76 μm were formed in an experiment after 8 days of cultivation, but microbial granules were absent in controls. Considering biosafety issues, K. pneumoniae strain B was excluded from further studies, but P. veronii strain F was selected for larger-scale testing.Stephen Tiong-Lee Tay Passed away on 27 July 2005. 相似文献
4.
A. Visser P. A. Alphenaar Y. Gao G. van Rossum G. Lettinga 《Applied microbiology and biotechnology》1993,40(4):575-581
The formation of anaerobic granular sludge on a sulfate-containing waste-water was studied in up-flow anaerobic sludge blanket reactors. Three systems were examined: a sulfidogenic system, a methanogenic system and a mixed sulfidogenic/methanogenic system. No significant granulation was observed in the sulfidogenic system. For the methanogenic and the mixed methanogenic/sulfidogenic system granulation proceeded well, and no significant difference in the granule diameter could be detected. In the three systems studied, different types of sludge developed. A (mainly) methanogenic granular sludge was developed in the methanogenic system, a (more) sulfate-reducing granular sludge was developed in the mixed methanogenic/sulfidogenic system, and a flocculant sulfate-reducing sludge was developed in the sulfidogenic system.
Correspondence to: A Visser 相似文献
5.
A gel-forming exopolysaccharide was previously shown to play an important structural role in aerobic granules treating nutrient-rich
industrial wastewater. To identify whether this exopolysaccharide performs a similar role in other granular biomass and if
conditions favouring its production can be more precisely elucidated, extracellular polymeric substances (EPS) were extracted
from granules grown under four different operating conditions. 1H nuclear magnetic resonance (NMR) spectroscopy of their EPS indicated that the gel-forming exopolysaccharide was expressed
in two granular sludges both enriched in Candidatus “Competibacter phosphatis”. In contrast, it was not expressed in granules performing denitrification with methanol as a carbon source and nitrate as
the electron acceptor or granules enriched in Candidatus “Accumulibacter phosphatis” performing enhanced biological phosphorus removal from synthetic wastewater. In one of the first two sludges, the exopolysaccharide
contained in the seeding granular sludge continued to be a major component of the granule EPS while Competibacter was being enriched. In the second sludge, a floccular sludge not containing the gel-forming exopolysaccharide initially was
also enriched for Competibacter. In this sludge, an increase in particle size was detected coinciding with a yield increase of EPS. NMR spectroscopy confirmed
its yield increase to be attributable to the production of this structural gel-forming exopolysaccharide. The results show
that (1) the particular gel-forming exopolysaccharide previously identified is not necessarily a key structural exopolysaccharide
for all granule types, and (2) synthesis of this exopolysaccharide is induced under conditions favouring the selective enrichment
of Competibacter. This indicates that Competibacter may be involved in its production. 相似文献
6.
Ting-Ting Chen Ping Zheng Li-Dong Shen Chong-Jian Tang Shuang Ding 《Biotechnology and Bioprocess Engineering》2012,17(5):1093-1102
This paper reports about the dispersal and control of anammox granular sludge at high substrate concentrations. The results demonstrate that anammox granular sludge would turn into flocculent sludge when the substrate concentrations exceed the inhibitory threshold concentrations, with an apparent drop in the settling velocity of anammox sludge from 73.73 to 16.49 m/h. Moreover, the sludge was washed out of the reactor and a decrease in the nitrogen removal rate from 23.82 to 16.97 kg N/(m3/day) was observed. The dominant anammox bacteria in the granular and flocculent sludge were Candidatus Kuenenia stuttgartiensis; however, the contents of heme c and extracellular polymeric substances in the flocculent sludge were much lower than in the granular sludge. Furthermore, the chemical composition of extracellular polymeric substances was different. The high nitrite concentrations more than the inhibitory threshold concentrations were regarded as the reason for the observed granular sludge dispersal and deterioration in reactor performance. The apparent dispersed granular sludge and malfunction of reactor performance could be recovered by means of washing out the residual substrate from the reactor and then re-running the reactor from low substrate concentrations. 相似文献
7.
The formation of anaerobic granular sludge on wastewater from sugar-beet processing was examined in upflow anaerobic sludge blanket reactors. Two strategies were investigated: addition of high-energy substrate, i.e. sugars, and varying the reactor liquid surface tension. When there were insufficient amounts of sugars i.e. less than 7% of the chemical O2 demand of the influent, no granulation was observed; moreover lowering the reactor liquid surface tension below 48 mN/m was found to increase biomass wash-out. On the other hand, when there were sufficient sugars, granular sludge growth occurred; moreover operating the reactor at a low reactor liquid surface tension reduced biomass wash-out and increased granular yield. 相似文献
8.
Long-chain acylhomoserine lactones increase the anoxic ammonium oxidation rate in an OLAND biofilm 总被引:2,自引:0,他引:2
De Clippeleir H Defoirdt T Vanhaecke L Vlaeminck SE Carballa M Verstraete W Boon N 《Applied microbiology and biotechnology》2011,90(4):1511-1519
The oxygen-limited autotrophic nitrification/denitrification (OLAND) process comprises one-stage partial nitritation and anammox,
catalyzed by aerobic and anoxic ammonium-oxidizing bacteria (AerAOB and AnAOB), respectively. The goal of this study was to
investigate whether quorum sensing influences anoxic ammonium oxidation in an OLAND biofilm, with AnAOB colonizing 13% of
the biofilm, as determined with fluorescent in situ hybridization (FISH). At high biomass concentrations, the specific anoxic ammonium oxidation rate of the OLAND biofilm significantly
increased with a factor of 1.5 ± 0.2 compared to low biomass concentrations. Supernatant obtained from the biofilm showed
no ammonium-oxidizing activity on itself, but its addition to low OLAND biomass concentrations resulted in a significant activity
increase of the biomass. In the biofilm supernatant, the presence of long-chain acylhomoserine lactones (AHLs) was shown using
the reporter strain Chromobacterium violaceum CV026, and one specific AHL, N-dodecanoyl homoserine lactone (C12-HSL), was identified via LC-MS/MS. Furthermore, C12-HSL was detected in an AnAOB-enriched community, but not in an AerAOB-enriched community. Addition of C12-HSL to low OLAND biomass concentrations resulted in a significantly higher ammonium oxidation rate (p < 0.05). To our knowledge, this is the first report demonstrating that AHLs enhance the anoxic ammonium oxidation process.
Future work should confirm which species are responsible for the in situ production of C12-HSL in AnAOB-based applications. 相似文献
9.
M-K H. Winkler R. Kleerebezem M. Strous K. Chandran M. C. M. van Loosdrecht 《Applied microbiology and biotechnology》2013,97(16):7459-7468
In the present study, the factors influencing density of granular sludge particles were evaluated. Granules consist of microbes, precipitates and of extracellular polymeric substance. The volume fractions of the bacterial layers were experimentally estimated by fluorescent in situ hybridisation staining. The volume fraction occupied by precipitates was determined by computed tomography scanning. PHREEQC was used to estimate potential formation of precipitates to determine a density of the inorganic fraction. Densities of bacteria were investigated by Percoll density centrifugation. The volume fractions were then coupled with the corresponding densities and the total density of a granule was calculated. The sensitivity of the density of the entire granule on the corresponding settling velocity was evaluated by changing the volume fractions of precipitates or bacteria in a settling model. Results from granules originating from a Nereda reactor for simultaneous phosphate COD and nitrogen removal revealed that phosphate-accumulating organisms (PAOs) had a higher density than glycogen-accumulating organisms leading to significantly higher settling velocities for PAO-dominated granules explaining earlier observations of the segregation of the granular sludge bed inside reactors. The model showed that a small increase in the volume fraction of precipitates (1–5 %) strongly increased the granular density and thereby the settling velocity. For nitritation–anammox granular sludge, mainly granular diameter and not density differences are causing a segregation of the biomass in the bed. 相似文献
10.
An anaerobic, propionate-producing, mesophilic, Gram-negative, non-spore forming, non-motile, coccoid-shaped bacterium (strain S119) was isolated from methanogenic granular sludge of an upflow anaerobic sludge blanket reactor. Based on morphology and cytological and physiological properties the isolate was assigned to the genus Veillonella. Strain S119 forms spherical monospecies biofilms (granules), 1.0–3.0 mm in diameter, when grown in continuously mixed medium with sodium lactate as the sole carbon source and powdered activated carbon as biofilm support particles. The granules attained concentrations of volatile suspended solids up to 38 mg/cm3. Veillonella sp. strain S119 has a highly hydrophobic cell surface and produces extracellular slime, which contains polysaccharide fractions. Growth characteristics and adhesion properties of the isolated microorganisms suggest its participation in the formation of granular sludge.
Correspondence to: W. Verstraete 相似文献
11.
Dexiang Liao Xiaoming Li Qi Yang Zhihong Zhao Guangming Zeng 《World journal of microbiology & biotechnology》2007,23(7):1015-1020
A sequencing batch reactor (SBR) seeded with methanogenic granular sludge was started up to enrich Anammox (Anaerobic Ammonium
Oxidation) bacteria and to investigate the feasibility of granulation of Anammox biomass. Research results showed that hydraulic
retention time (HRT) was an important factor to enrich Anammox bacteria. When the HRT was controlled at 30 days during the
initial cultivation, the SBR reactor presented Anammox activity at t = 58 days. Simultaneously, the methanogenic granular sludge changed gradually from dust black to brown colour and its diameter
became smaller. At t = 90 days, the Anammox activity was further improved. NH4+-N and NO2−N were removed simultaneously with higher speed and the maximum removal rates reached 14.6 g NH4+-N /(m3
reactor·day) and 6.67 g NO2−-N /(m3
reactor·day), respectively. Between t = 110 days and t = 161 days, the nitrogen load was increased to a HRT of 5 days (70 mg/l NH4+ and 70 mg/l NO2), the removal rates of ammonium and nitrite were 60.6% and 62.5% respectively. The sludge changed to red and formed Anammox
granulation with high nitrogen removal activity. 相似文献
12.
The microbial community and extracellular polymeric substances composition of anaerobic granular sludge exposed to selenate (~10 mg/L), cadmium (Cd) and zinc (Zn) (~2 and 5 mg/L) were investigated by high-throughput sequencing and fluorescence excitation emission matrix (FEEM) spectra, respectively. As a response to selenate, Cd and/or Zn exposure, significant fluorescence quenching of fulvic-like acids and humic-like substances was observed. With selenate, Cd and/or Zn in the influent with respective concentrations of 10, 5 and 5 mg/L, the abundance of the phyla Proteobacteria, Firmicutes, Spirochaetae, Cloacimonetes and Synergistetes increased significantly, and the dominant taxa in the anaerobic granular sludge exposed to Se, Cd and/or Zn were Halothiobacillaceae (10.2%), Pseudomonas (8.8%), Synergistaceae (7.7%), Spirochaetaceae (7.2%), Blvii28 wastewater sludge group (6.7%), Telmatospirillum (4.6%), Veillonellaceae (4.3%), Geobacter (4.0%) and Enterobacteriaceae (3.0%). Compared with the inoculum, the abundance of the archaea Methanobacterium and Methanosaeta decreased to below detection limit in the UASB reactor after 116 days exposure to Se, Cd and Zn. 相似文献
13.
Shuo Wang Wenxin Shi Tang Tang Yuying Wang Liling Zhi Jinze Lv Ji Li 《Reviews in Environmental Science and Biotechnology》2017,16(1):1-13
Aerobic granular sludge (AGS) has recently attracted attention because of its excellent settling ability and treatment efficiency compared with traditional activated sludge. This review provides recent advances on the formation process of AGS and mainly analyzes the function of quorum sensing (QS) and cell signaling during AGS formation. QS and cell signaling play important roles in the formation of AGS. QS can accelerate the synthesis of extracellular polymeric substance (EPS) and increase microbial adhesion to the surface of AGS. Cell signaling can also promote the secretion of EPS and influence biofilm formation. Cyclic diguanylate (c-di-GMP), as a second messenger, acts an important role in granulation. C-di-GMP causes bacteria to adhere to each other and form a biofilm. Adding Ca2+ benefits bacterial growth and promotes c-di-GMP secretion. Adding Mn2+ reduces c-di-GMP content and triggers AGS disintegration. Finally, the review discusses the possible trends of AGS: QS and cell signaling can lay a theoretical foundation for the formation mechanism of AGS and would be of practical significance for its application in the future. 相似文献
14.
Aerobic granulation may play an important role in the field of wastewater treatment due to the advantages of aerobic granules compared to the conventional sludge flocs, such as denser structure, better settleability and ensured solid-effluent separation, higher biomass concentration, and greater ability to withstand shock loadings, which is promising for a full-scale implementation. As an aid for this implementation, mathematical modeling would be an invaluable tool. In this paper, the existing mathematical models available in literature concerning aerobic granule systems are reviewed, including the modeling of the dynamic facets of the aerobic granulation process, the mass transfer and detachment in aerobic granules, the granule-based sequencing batch reactor, the fate of microbial products in granules, and the multi-scale modeling of aerobic granular sludge. An overview of the parameters used in the aerobic granular modeling approaches is also presented. Our growing knowledge on mathematical modeling of aerobic granule might facilitate the engineering and optimization of aerobic granular sludge technology as one of the most promising techniques in the biological wastewater treatment. 相似文献
15.
酰基高丝氨酸内酯(AHLs)介导群感效应在好氧颗粒污泥中的研究进展 总被引:1,自引:1,他引:0
虽然好氧颗粒污泥(Aerobic Granular Sludge,AGS)具有沉降性能好、高效脱氮除磷以及抗冲击负荷等优点,但是该技术仍然存在颗粒化进程缓慢及容易解体等技术瓶颈.因此,如何克服上述瓶颈是实现好氧颗粒污泥技术在实际污水处理推广的关键.近年来,酰基高丝氨酸内酯(Acyl Homoserine Lactone... 相似文献
16.
The anaerobic biodegradation of carbon tetrachloride (CT) was investigated during the granulation process by reducing the hydraulic retention time, increasing the chemical oxygen demand (COD) and CT loadings in a 2l laboratory-scale upflow anaerobic sludge blanket (UASB) reactor. Anaerobic unacclimated sludge and glucose were used as seed and primary substrate, respectively. Granules were developed 4 weeks after start-up, which grew at an accelerated rate for 8 months, and then became fully grown. The effect of operational parameters such as influent CT concentrations, COD, CT loading, food to biomass ratio and specific methanogenic activity (SMA) were also considered during granulation. The granular sludge cultivated had a maximum diameter of 2.1 mm and SMA of 1.6 g COD/g total suspended solid (TSS) day. COD and CT removal efficiencies of 92 and 88% were achieved when the reactor was firstly operating at CT and COD loading rates of 17.5 mg/l day and 12.5 g/l day, respectively. This corresponds to hydraulic retention time of 0.28 day and food to biomass ratio of 0.5 g COD/g TSS day. Kinetic coefficients of maximum specific substrate utilization rate, half velocity coefficient, growth yield coefficient and decay coefficient were determined to be 2.4 × 10–3 mg CT/TSS day–1, 1.37 mg CT/l, 0.69 mg TSS/mg CT and 0.046 day–1, respectively for CT biotransformation during granulation. 相似文献
17.
This work investigated the modification of aggregate properties during the formation of granular sludge in a sequencing batch airlift reactor (SBAR). The cohesion of biological aggregates was quantified by subjecting sludge samples to two different controlled shear stresses in a stirred reactor. For reference sludge (without granules), flocs broke and reformed easily, indicating that floc size was controlled by the turbulence micro-scale (Kolmogorov scale, here from 17 μm to 62 μm). In contrast, granules showed high strength which enabled them to resist turbulence and their size was no longer imposed by the Kolmogorov micro-scale. Different steps were observed during the granulation process: a first increase of aggregate cohesion associated with a decrease in sludge volume index (SVI), a growth of aggregates with detachment of fragile particles from the surface and, finally, an increase in the sizes of small and large granules to reach a pseudo-stable size distribution. Results suggest that small particles could have formed the seeds for new granules, as they were maintained in the bioreactor. Here, granular sludge was formed in an SBAR with a conventional settling time (30 min), i.e. without particle washout, and with a low superficial air velocity (SAV = 0.6 cm s−1): it is thus demonstrated that high SAV and low settling time are not necessary to produce granules, but probably only accelerate the accumulation of granules. It is shown that the increase of cohesion is the initial phenomenon explaining the granule formation concomitantly with bacterial aggregates densification. It seems important, in the future, to investigate the reasons for this cohesion increase, which is possibly explained either by bacterial bounding interactions or the excretion of extracellular polymeric substances (EPS). 相似文献
18.
Volodymyr Ivanov Xiao-Hui Wang Olena Stabnikova 《World journal of microbiology & biotechnology》2008,24(4):533-539
Aggregation of bacterial cells is used in formation of microbial granules. Aerobically grown microbial granules can be used
as the bio-agents in the treatment of wastewater. However, there are problems with start up of microbial granulation and biosafety
of this process. Aim of this research was selection and testing of safe microbial strain with high cell aggregation ability
to shorten period of microbial granules formation. Five bacterial strains with cell aggregation index higher than 50% have
been isolated from the granules. Strain of Pseudomonas veronii species was considered as most probably safe starter culture for granulation because other strains belonged to the species
known as human pathogens. The microbial granules were formed after 3 days of cultivation in case when P. veronii strain B was applied to start-up aerobic granulation process using model wastewater. The granules were produced from activated
sludge after 9 days of cultivation. Microbial aggregates produced from starter culture of P. veronii strain B were more compact (sludge volume index was 70 ml/g) than those produced from activated sludge (sludge volume index
was 106 ml/g). It is a first proof that application of selected safe starter pure culture with high cell aggregation ability
can accelerate and enhance formation of microbial granules. 相似文献
19.
László Morvai Pál Miháltz Lajos Czakó Miklós Péterfy János Holló 《Applied microbiology and biotechnology》1990,33(4):463-468
Summary The development of granular sludge in laboratory-scale upflow anaerobic sludge-blanket reactors was studied. Acetate was supplied as sole carbon source in order to select the acetotrophs Methanosarcina and Methanothrix. These microorganisms are dominant in methanogenic ecosystems and their ratio seems to control the speed of granulation. Changing the ratio of the above species was followed on the basis of their different F
420-coenzyme content. Five reactors were operated at the same hydraulic retention time but at different feed substrate concentrations. We found that granulation takes place only in acetate-fed systems but this process was slower and the resultant granules looser and less stable than those developed on sugar-starch substrate. In the range of feed acetate levels examined (0.5–0.3 g/1) higher concentrations of feed caused faster granulation of the sludge bed and, presumably, of the microbial population, and resulted in larger granules containing sludge that settled more readily. We found no evidence for selection pressure at substrate concentrations below 0.5 g/1 acetate in the reactor.
Offprint requests to: J. Holló 相似文献
20.
Aerobic granulation is a promising technology for wastewater treatment, but problems regarding its formation and stability need to be solved. Divalent metal ions, especially Ca2+, Mg2+ and Mn2+, have been demonstrated to play an important role in the process of aerobic granulation. Here, we studied whether iron ions can affect aerobic granulation. Granular sludge formed without iron ion addition (<0.02 mg Fe2+ L?1) was fluffy and had a finger-type structure and filamentous out-growth. The addition of iron ions to concentrations of 1 and 10 mg Fe2+ L?1 repressed the finger-type structure and filamentous out-growth. The results show that chemical precipitation in the granules with iron ion addition was higher than that in the granules without ferrous addition. The amount of precipitates was higher inside the granules than outside. This study demonstrates that iron ions (Fe2+/Fe3+) increase the size and stability of aerobic granular sludge but do not affect the granulation time, which is the time that the first granular sludge is observed. The study shows that aerobic granular sludge technology can be confidently applied to actual wastewater containing a high concentration of iron compounds. 相似文献