Effect of Shear Stress on Granulation in Oxygen Aerobic Upflow Sludge Bed Reactors

1992 ◽  
Vol 26 (3-4) ◽  
pp. 601-605 ◽  
Author(s):  
H.-S. Shin ◽  
K.-H. Lim ◽  
H.-S. Park
Keyword(s):  
Shear Stress ◽  
Morphological Study ◽  
Loading Rate ◽  
Granular Sludge ◽  
Treatment Method ◽  
The Self ◽  
High Rate ◽  
Synthetic Wastewater ◽  
Filamentous Bacteria ◽  
Start Up

Aerobic upflow sludge blanket(AUSB) process is a new biological wastewater treatment method applying the concept of the self-immobilization to activated sludge. Two sets of AUSB system with different mixing velocities of 3 rpm(R1) and 6 rpm(R2) were operated for high-rate treatment of synthetic wastewater. The COD removal efficiency in R2 was higher than R1 at the same loading rate up to 7 kg/m3·day. However, in R1, the sludge bulking was observed at the end of the experiment. The chocolate colored granules were formed about 5 days after the start-up. The morphological study on the granular sludge consortia was made with both scanning electron and optical microscopes. The granules were 0.5-2.5 mm in diameter and mainly consisted of bacteria with pili-like appendages and filamentous bacteria, which were thought to be Sphaerotilus natans and Beggiatoa. In R1, the long multicellular filaments causing bulking were prevalent in the granule, while in R2 overgrowth of filamentous bacteria was prevented with appropriate shear stress resulting in higher MLSS density. Experimental results indicated that granulation could be controlled by physical stress on granular sludge.

Evaluation of UASB Reactor Performance During Start-Up Operation Using Glucose Bearing Synthetic Wastewater

2020 ◽  
Vol 9 (1) ◽  
pp. 32-51
Author(s):  
Revanuru Subramanyam
Keyword(s):  
Removal Efficiency ◽  
Loading Rate ◽  
Granular Sludge ◽  
Cod Removal ◽  
Synthetic Wastewater ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Cod Removal Efficiency ◽  
Start Up ◽  
Seed Sludge

This research article describes start-up performance of an UASB (Upflow Anaerobic Sludge Blanket) reactor in terms of chemical oxygen demand (COD) removal efficiency, biogas production, sludge loading rate (SLR), volatile fatty acids (VFA), pH, alkalinity, total solids (TS) and volatile suspended solids (VSS), fed with synthetic wastewater with increased concentrations of glucose. The reactor was loaded up to an OLR (Organic Loading Rate) of 15 kg COD m-3 d-1 and achieved a COD removal efficiency of 82 ±3%. The results showed that digested seed sludge was successfully acclimatized and transformed finally into granular sludge within a period of 120 days. An increase in the accumulation of VFA at high OLRs showed that methanogenesis could be the rate-limiting step in the reactor operation. The SLR and VSS/TS ratio were increased with an increase in OLR. During the initial stages, uniform distribution of VSS concentration and later on maximum VSS concentration were found at port number two at a height of 350 mm. The carbon balance depicts that the maximum percentage of influent COD converted to methane COD. An increase in specific methanogenic activity values with the age of sludge confirmed the transformation of the seed sludge in to a granular sludge.

High-Rate Anaerobic Treatment of Industrial Wastewaters

1991 ◽  
Vol 24 (1) ◽  
pp. 69-74 ◽  
Author(s):  
J. Rintala
Keyword(s):  
Granular Sludge ◽  
Anaerobic Treatment ◽  
High Rate ◽  
Upflow Anaerobic Sludge Blanket ◽  
Synthetic Wastewater ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Industrial Wastewaters ◽  
Start Up ◽  
Uasb Reactors

Anaerobic mesophilic treatment of synthetic (a mixture of acetate and methanol) and thermomechanical pulping (TMP) wastewater was studied in laboratory-scale upflow anaerobic sludge blanket (UASB) reactors and filters with emphasis on the process start-up. The reactors were inoculated with nongranular sludge. The start-up of mesophilic and thermophilic processes inoculated with mesophilic granular sludge was investigated in UASB reactors fed with diluted vinasse. The start-up proceeded faster in the filters than in the UASB reactors with TMP and synthetic wastewater. Loading rates of over 15 kgCODm−3d−1 with 50-60 % COD removal efficiencies were achieved in 10 days in the mesophilic and in 50 days in the thermophilic UASB reactor treating vinasse. The results show that high-rate anaerobic treatment can be applied to different types of industrial wastewaters under varying conditions.

Granular biofilm-based anaerobic digestion: molecular biomonitoring and high-rate psychrophilic treatment of phenolic wastewater

2007 ◽  
Vol 55 (1-2) ◽  
pp. 43-49 ◽  
Author(s):  
C. Scully ◽  
G. Collins ◽  
V. O'Flaherty
Keyword(s):  
Community Dynamics ◽  
Phenol Degradation ◽  
Granular Sludge ◽  
Cod Removal ◽  
High Rate ◽  
Synthetic Wastewater ◽  
Polymorphism Analysis ◽  
Applied Loading ◽  
Microbial Community Dynamics ◽  
Start Up

Two pairs of expanded granular sludge bed (EGSB) bioreactors, R1/R2 and R3/R4, were designed. R1/R2 were used for mesophilic (37 °C) treatment of synthetic wastewater over a 100-day trial. A successful start-up was achieved by R1 and R2, with COD removal over 90%. Both reactors were operated under identical parameters; however, increased organic loading induced a reduction in COD removal by R1, while R2 maintained satisfactory performance throughout the experiment. R3/R4 were operated at 15 °C throughout a 422-day trial and were used for the stabilisation of volatile fatty acid-based wastewater. Phenol was introduced to R4 at an applied loading rate of 1 kg phenol m−3 d−1, which was increased to 2 kg phenol m−3 d−1. No phenol was supplied to R3. Efficient COD conversion was recorded in both R3 and R4, thus demonstrating the feasibility of high-rate phenol degradation under psychrophilic conditions. Terminal restriction fragment length polymorphism analysis was applied to the characterisation of microbial community dynamics within each of the reactors. The results indicated a microbiological basis for the deviation, in terms of operational performance, of R1 and R2. TRFLP analyses indicated stable microbial communities in R3 and R4, but detected changes in the abundance of specific ribotypes in response to phenol mineralisation.

Rapid start-up of a nitrifying reactor using aerobic granular sludge as seed sludge

2012 ◽  
Vol 65 (3) ◽  
pp. 581-588 ◽  
Author(s):  
Naohiro Kishida ◽  
Goro Saeki ◽  
Satoshi Tsuneda ◽  
Ryuichi Sudo
Keyword(s):  
Removal Rate ◽  
Granular Sludge ◽  
Ammonia Removal ◽  
High Rate ◽  
Aerobic Granular Sludge ◽  
Nitrite Accumulation ◽  
Ammonia Oxidizing Bacteria ◽  
Continuous Stirred Tank Reactor ◽  
Start Up ◽  
Seed Sludge

In this study, the effectiveness of aerobic granular sludge as seed sludge for rapid start-up of nitrifying processes was investigated using a laboratory-scale continuous stirred-tank reactor (CSTR) fed with completely inorganic wastewater which contained a high concentration of ammonia. Even when a large amount of granular biomass was inoculated in the reactor, and the characteristics of influent wastewater were abruptly changed, excess biomass washout was not observed, and biomass concentration was kept high at the start-up period due to high settling ability of the aerobic granular sludge. As a result, an ammonia removal rate immediately increased and reached more than 1.0 kg N/m3/d within 20 days and up to 1.8 kg N/m3/d on day 39. Subsequently, high rate nitritation was stably attained during 100 days. However, nitrite accumulation had been observed for 140 days before attaining complete nitrification to nitrate. Fluorescence in situ hybridization analysis revealed the increase in amount of ammonia-oxidizing bacteria which existed in the outer edge of the granular sludge during the start-up period. This microbial ecological change would make it possible to attain high rate ammonia removal.

Advanced start up of UASB reactors by adding of water absorbing polymer

1997 ◽  
Vol 36 (6-7) ◽  
pp. 399-406 ◽  
Author(s):  
Tsuyoshi Imai ◽  
Masao Ukita ◽  
Jun Liu ◽  
Masahiko Sekine ◽  
Hiroshi Nakanishi ◽  
...  
Keyword(s):  
Volatile Fatty Acid ◽  
Granular Sludge ◽  
Pilot Scale ◽  
Synthetic Wastewater ◽  
Recommended Dosage ◽  
Digested Sludge ◽  
New Approach ◽  
Start Up ◽  
Scale Experiment ◽  
Uasb Reactors

We have developed a new approach to enhance granulation by adding water absorbing polymer (WAP) particles into the inoculated digested sludge. In this study, the effect of adding WAP on formation of anaerobic granular sludge was evaluated in lab-scale UASB reactors using two typical synthetic wastewater, i.e. glucose or volatile fatty acid (VFA) mixture solution. In addition, side by side with the lab-scale experiment, a pilot-scale experiment using the VFA mixture was carried out to evaluate the availability of accelerated start-up by adding WAP. The development of granular sludge was significantly enhanced by adding WAP. Granules developed on glucose and VFAs had high methanogenic activities and good settleability. From results of lab-scale experiment, the recommended dosage of WAP was about 750 mg/l of reactor volume. The results, pilot-scale experiment, indicated the availability of accelerated start-up by adding WAP.

Biological denitrification in a sequencing batch reactor

2004 ◽  
Vol 50 (10) ◽  
pp. 67-72 ◽  
Author(s):  
P. Dangcong ◽  
W. Yi ◽  
W. Hao ◽  
W. Xiaochang
Keyword(s):  
Sequencing Batch Reactor ◽  
Loading Rate ◽  
Batch Reactor ◽  
Granular Sludge ◽  
Filamentous Bacteria ◽  
Microscope Examination ◽  
Biological Denitrification ◽  
Effective Technology ◽  
Nitrate And Nitrite ◽  
Electronic Microscope

Biological denitrification was studied in an SBR to investigate the performance. The experimental results showed that granular sludge with high activity and good settling ability can be developed smoothly in the reactor. With the granular sludge, high nitrate loading rate (0.48 kg NO3-N dm−3 d−1) and removal efficiency (more than 99%) can be achieved. Scanning electronic microscope examination showed that only rod-shape bacteria existed on and within the granules, which confirmed indirectly that filamentous bacteria do not utilize nitrate and nitrite as electron acceptors. SBR is an alternative and effective technology for biological denitrification.

Removal of COD from Piggery Wastewater Using a Lab-Scale UASB Reactor

2012 ◽  
Vol 534 ◽  
pp. 221-224
Author(s):  
Fei Yan ◽  
Jin Long Zuo ◽  
Tian Lei Qiu ◽  
Xu Ming Wang
Keyword(s):  
Granular Sludge ◽  
Cod Removal ◽  
Upflow Anaerobic Sludge Blanket ◽  
Synthetic Wastewater ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Volume Loading ◽  
Piggery Wastewater ◽  
Start Up ◽  
Anaerobic Sludge Blanket

It took 55 days to start up a lab-scale upflow anaerobic sludge blanket (UASB) reactor at ambient temperature 27-28 oC by using the synthetic wastewater, and piggery wastewater was used as the influent after the reactor start-up. From day 120 onwards, COD removal efficiency maintained in the range of 85% to 95% with 6.79-9.66 kg COD/ (m3•d) of volume loading, and the effluent COD concentration ranged between 400 mg/L and 600 mg/L. Granular sludge formation was observed in the reactor after 40-day operation, and the sludge diameter reached 2-4 mm in the 120 day-old reactor. The pH changes in the influent had little influence on COD removal from piggery wastewater using the UASB reactor.

Aerobic granular sludge: a promising technology for decentralised wastewater treatment

2006 ◽  
Vol 53 (9) ◽  
pp. 79-85 ◽  
Author(s):  
Z.H. Li ◽  
T. Kuba ◽  
T. Kusuda
Keyword(s):  
Sequencing Batch Reactor ◽  
Loading Rate ◽  
Batch Reactor ◽  
Granular Sludge ◽  
Volume Index ◽  
Synthetic Wastewater ◽  
Aerobic Granular Sludge ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Fast Settling

In order to evaluate the characteristics of aerobic granular sludge, a sequencing batch reactor, feeding with synthetic wastewater at the organic loading rate of 8 kg COD/m3 d, was employed on the laboratory scale. Granules occurred in the reactor within 1 week after the inoculation from conventional flocculent sludge. Aerobic granular sludge was characterised by the outstanding settling properties and considerable contaminates removal efficiencies. The SVI30 values were in the range of 20 to 40 ml g−1. However, the sludge volume index of short settling time (e.g. SVI10 – 10 min) is suggested to describe the fast settling properties of aerobic granular sludge. The potential application in the decentralised system is evaluated from the point view of footprint and high bioactivity. The occurrence of sloughing, resulting from the outgrowth of filamentous organisms, would be responsible for the instability of aerobic granules. The starvation phase should therefore be carefully controlled for the maintenance and stability of aerobic granular sludge system.

High-Rate Nitrification Using Aerobic Granular Sludge

2006 ◽  
Vol 53 (3) ◽  
pp. 147-154 ◽  
Author(s):  
S. Tsuneda ◽  
M. Ogiwara ◽  
Y. Ejiri ◽  
A. Hirata
Keyword(s):  
Activated Sludge ◽  
Removal Rate ◽  
Granular Sludge ◽  
Ammonia Removal ◽  
High Rate ◽  
Pure Oxygen ◽  
Synthetic Wastewater ◽  
Aerobic Granular Sludge ◽  
Fluidised Bed ◽  
High Concentration

The performance of nitrifying granules, which had been produced in an aerobic upflow fluidised bed (AUFB) reactor, was investigated in various types of ammonia-containing wastewaters. When pure oxygen was supplied to the AUFB reactor with a synthetic wastewater containing a high concentration of ammonia (500 g-N/m3), the ammonia removal rate reached 16.7 kg-N/m3/day with a sustained ammonia removal efficiency of more than 80%. The nitrifying granules possessing a high settling ability could be retained with a high density (approximately 10,000 g-MLSS/m3) in a continuous stirring tank reactor (CSTR) even under a short hydraulic retention time (44 min), which enabled a high-rate and stable nitrification for an inorganic wastewater containing low concentrations of ammonia (50 g-N/m3). Moreover, the nitrifying granules exhibited sufficient performance in the nitrification of real industrial wastewater containing high concentrations of ammonia (1,000–1,400 g-N/m3) and salinity (1.2–2.2%), which was discharged from metal-refinery processes. When the nitrifying granules were used in cooperation with activated sludge to treat domestic wastewater containing organic pollutants as well as ammonia, they fully contributed to nitrification even though a part of activated sludge adhered onto the granule surfaces to form biofilms. These results show the wide applicability of nitrifying granules to various cases in the nitrification step of wastewater treatment plants.

Study on Cultivation and Morphology of Granular Sludge in Improved Methanogenic UASB

2012 ◽  
Vol 209-211 ◽  
pp. 1152-1157 ◽  
Author(s):  
Jian Ping Huang ◽  
Li Li Liu ◽  
Yu Min Shao ◽  
Hong Jie Song ◽  
Lian Cheng Wu ◽  
...  
Keyword(s):  
Loading Rate ◽  
Ph Value ◽  
Biogas Production ◽  
Removal Rate ◽  
Granular Sludge ◽  
Maturity Stage ◽  
Two Phase ◽  
Term Operation ◽  
Start Up ◽  
Manual Regulation

Based on the mesophilic two-phase anaerobic reactor for maize ethanol wastewater treatment, the start-up, cultivation and the morphology of mature granular sludge in improved methanogenic UASB were studied. The reactor was initiated at a low loading rate. By means of increasing volume loading rate gradually and regulating internal circulation, the improved methanogenic UASB was operated under an optimal condition. After more than two months of operation, the size for the 63% of total granular sludge was more than 1.3mm, the biogas production rate and COD removal rate achieved 539L/d and 90%, respectively. Start-up of improved methanogenic UASB was accomplished successfully. Improved UASB, served as methanogenic phase of two phase anaerobic process, can adjust pH value of influent automatically. The manual regulation of pH value during start-up could be stopped when the granular sludge in improved methanogenic UASB went into maturity stage. The microfloras of mature methanogenic granular sludge are mainly brevibacterium and filamentous bacteria. Methanothrix soehngenii is the dominant consortium after the long-term operation under low-strength.

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