The potential of anaerobic bacteria to degrade chlorinated compounds

2001 ◽  
Vol 44 (8) ◽  
pp. 49-56 ◽  
Author(s):  
M.H.A. van Eekert ◽  
G. Schraa
Keyword(s):  
Anaerobic Bacteria ◽  
Granular Sludge ◽  
Chlorinated Ethenes ◽  
Contaminated Sites ◽  
Contaminated Site ◽  
Anaerobic Conditions ◽  
Chlorinated Aromatics ◽  
Start Up ◽  
Acetogenic Bacteria ◽  
Uasb Reactors

Chlorinated ethenes and chlorinated aromatics are often found as pollutants in sediments, groundwater, and wastewater. These compounds were long considered to be recalcitrant under anaerobic conditions. In the past years however, dechlorination of these compounds has been found to occur under anaerobic conditions at contaminated sites and in wastewater treatment systems. This dechlorination is mainly attributed to halo-respiring bacteria, which are able to couple this dechlorination to energy conservation via electron transport coupled phosphorylation. The dechlorinating activities of the halo-respiring bacteria seem to be confined to the dechlorination of chloroethenes and chlorinated aromatic compounds. In addition, methanogenic and acetogenic bacteria are also able to reduce the chlorinated ethenes via a-specific cometabolic pathways. Although these latter reactions may not be important in the remediation of contaminated sites, they may be of substantial influence in the start-up of remediation processes and in the application of granular sludge from UASB reactors. Specific halo-respiring bacteria may be used to increase the dechlorination activities via bioaugmentation in the case that the appropriate microorganisms are not present at the contaminated site or in the sludge.

The effect of extreme temperatures (70–80°C) on the effluent quality and sludge characteristics of UASB reactors

1997 ◽  
Vol 36 (6-7) ◽  
pp. 325-332 ◽  
Author(s):  
Raghida Lepistö ◽  
Jukka Rintala
Keyword(s):  
Volatile Fatty Acids ◽  
Granular Sludge ◽  
Anaerobic Sludge ◽  
Methanogenic Activity ◽  
Sludge Characteristics ◽  
Effluent Quality ◽  
Start Up ◽  
Thermomechanical Pulping ◽  
Increasing Temperature ◽  
Uasb Reactors

The study focused on the effluent quality and sludge characteristics during the start-up and operation of extreme thermophilic (70 to 80°C) upflow anaerobic sludge bed (UASB) reactors, inoculated with mesophilic and thermophilic granular sludge and fed with acetate, volatile fatty acids (VFA), and thermomechanical pulping (TMP) whitewater. Low effluent quality and long start-up periods were observed during the start-up of the 70 to 76°C, VFA-fed UASB reactors inoculated with mesophilic granulae, while better effluent quality and considerably shorter start-up periods were observed when thermophilic (55/70°C) inocula were used. With VFA feed, a significant amount of acetate was removed at 70°C and even at 80°C, while propionate removal was negligible. With TMP whitewater feed, low VFA effluent concentration was obtained at 70°C. The volatile solids (VS) and the VS/total solids (TS) content of the sludge decreased significantly during the first 2–3 months of operation when mesophilic inocula were used. The initial specific methanogenic activity (ISMA) of the extreme thermophilic sludge decreased with increasing temperature and was slightly higher on glucose than on acetate. At 70 to 80°C, various rod-like bacteria were dispersed through the granulae in either individual or in low density micro colonies surrounded with a varying degree of precipitates.

The bacterial numeration and an observation of a new syntrophic association for granular sludge

1997 ◽  
Vol 36 (6-7) ◽  
pp. 133-140 ◽  
Author(s):  
Zhu Jianrong ◽  
Hu Jicui ◽  
Gu Xiasheng
Keyword(s):  
Anaerobic Bacteria ◽  
Granular Sludge ◽  
Methanogenic Bacteria ◽  
Uasb Reactor ◽  
Two Phase ◽  
Methanogenic Activity ◽  
Syntrophic Association ◽  
Group I ◽  
Acetogenic Bacteria ◽  
Fermentative Bacteria

The bacterial numeration and microbial observation were made on granular sludge from laboratory single and two-phase UASB reactors. It was shown that the fermentative bacteria (group I), H2-producing acetogenic bacteria (group II) and methanogenic bacteria (group III) of granular sludge in single UASB reactor were 9.3 × 108−4.3 × 109, 4.3 × 107−4.3 × 108, 2.0−4.3 × 108, respectively, during the granulation process. The sludge of methanogenic reactor exhibited the similar results. That indicates there is no big difference between suspended and granular sludge, and bacterial population for three groups of anaerobic bacteria are similar. The formation of granular sludge depends mainly on the organization and arrangement of bacteria. An observation of granular sludge using electron microscope revealed that the fermentative bacteria and hydrogenotrophic methanogens existed on outer surface of granules, and aceticlastic methanogens and H2-producing acetogenic bacteria occupied the inner layer. A new syntrophic association between Methanosaeta sp. and Syntrophomonas sp. (even plus Methanobrevibacter sp.) was observed. Because Methanosaeta can effectively convert the acetate (the end product of propionate and butyrate) to methane, such a new syntrophic association is supposed to support the degradation of short fatty acids and high methanogenic activity of granular sludge. Based on structural pattern, a hypothesis on mechanism of granulation called “crystallized nuclei formation” is proposed.

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.

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.

The Effect of Calcium on Microbial Aggregation during UASB Reactor Start-Up

1987 ◽  
Vol 19 (1-2) ◽  
pp. 249-260 ◽  
Author(s):  
E. M. Mahoney ◽  
L. K. Varangu ◽  
W. L. Cairns ◽  
N. Kosaric ◽  
R G. E. Murray
Keyword(s):  
Loading Rate ◽  
Granular Sludge ◽  
Biomass Accumulation ◽  
Uasb Reactor ◽  
Physical Parameters ◽  
Granule Formation ◽  
Highly Active ◽  
Start Up ◽  
Positive Reactor ◽  
Uasb Reactors

The dynamics of granule formation were studied using cells from two bench-scale UASB Reactors. The objective was to elucidate factors which influence formation and maintenance of highly active self-agglomerated microbial biomass. Simultaneous examination of biological and physical parameters was performed during the start-up of a calcium-positive (100 mg/1) reactor and a reactor without added calcium. The influence of carbon nutrients and Ca++ on the cell surface and microbial aggregation was studied. The granules formed in both reactors but were larger in the calcium-positive reactor in which they settled 3-4 times faster. A higher rate of biomass accumulation also was evident in the calcium-positive reactor and this allowed a more frequent increase in the substrate loading rate and earlier development of the granular sludge.

Performance of aerobic granular sludge at variable circulation rate in anaerobic–aerobic conditions

2014 ◽  
Vol 69 (11) ◽  
pp. 2252-2257 ◽  
Author(s):  
Hasnida Harun ◽  
Aznah Nor Anuar ◽  
Zaini Ujang ◽  
Noor Hasyimah Rosman ◽  
Inawati Othman
Keyword(s):  
Municipal Wastewater ◽  
Granular Sludge ◽  
Ammonia Removal ◽  
Soy Sauce ◽  
Volume Index ◽  
Aerobic Granular Sludge ◽  
Circulation Rate ◽  
Anaerobic Conditions ◽  
Aerobic Conditions ◽  
Mixed Liquor

Aerobic granular sludge (AGS) has been applied to treat a broad range of industrial and municipal wastewater. AGS can be developed in a sequencing batch reactor (SBR) with alternating anaerobic–aerobic conditions. To provide anaerobic conditions, the mixed liquor is allowed to circulate in the reactor without air supply. The circulation flow rate of mixed liquor in anaerobic condition is the most important parameter of operation in the anaerobic-AGS processes. Therefore, this study investigates the effect of circulation rate on the performance of the SBR with AGS. Two identical reactors namely R1 and R2 were operated using fermented soy sauce wastewater at circulation rate of 14.4 and 36.0 l/h, respectively. During the anaerobic conditions, the wastewater was pumped out from the upper part of the reactor and circulated back into the bottom of the reactor for 230 min. A compact and dense AGS was observed in both reactors with a similar diameter of 2.0 mm in average, although different circulation rates were adopted. The best reactor performance was achieved in R2 with chemical oxygen demand removal rate of 89%, 90% total phosphorus removal, 79% ammonia removal, 10.1 g/l of mixed liquor suspended solids and a sludge volume index of 25 ml/g.

Improved chamber for the isolation of anaerobic microorganisms

1976 ◽  
Vol 4 (1) ◽  
pp. 40-45
Author(s):  
M E Cox ◽  
J I Mangels
Keyword(s):  
Anaerobic Bacteria ◽  
Gas Mixture ◽  
Anaerobic Conditions ◽  
Co2 Gas ◽  
Anaerobic Microorganisms ◽  
The Media ◽  
To Receive ◽  
Latex Rubber

A small portable chamber for the recovery of anaerobic bacteria is described. This rigid chamber is constructed of clear acrylic with dimensions of 30 inches (ca. 76.2 cm) wide, 18 inches (ca. 44.7 cm) deep, and 18 inches (ca. 44.7 cm) high. Conventional bacteriological techniques can be used inside the chamber to efficiently isolate strict anaerobic organisms. An adapter allows the attachment of a standard anaerobic jar to the outside of the chamber. The jar can be used to store reduced media. Once the jar is attached to the chamber and the media is removed to the interior of the chamber, the jar is available to receive inoculated media. The anaerobic jar can then be removed from the chamber, without contaminating the jar or chamber with oxygen, and be placed in a conventional 37degreesC incubator. This chamber also allows the microbiologist to process cultures without wearing gloves as was necessary with previous anaerobic chambers. Air-tight latex rubber sleeves seal around the microbiologists arms and to the armport flange of the chamber to prevent the introduction of oxygen into the chamber. Anaerobic conditions are maintained by circulating a 80% N2, 10% H2, 10% CO2 gas mixture through alumina pellets coated with palladium. This study indicates that anaerobic conditions obtained in this chamber are sufficient for recovery of obligate anaerobes.

Biodegradation of selected azo dyes under methanogenic conditions

1997 ◽  
Vol 36 (6-7) ◽  
pp. 65-72 ◽  
Author(s):  
Elías Razo-Flores ◽  
Maurice Luijten ◽  
Brian Donlon ◽  
Gatze Lettinga ◽  
Jim Field
Keyword(s):  
Azo Dyes ◽  
Textile Industry ◽  
Azo Dye ◽  
Biological Treatment ◽  
Present Report ◽  
Anaerobic Bacteria ◽  
Aminosalicylic Acid ◽  
Batch Experiments ◽  
Azo Reduction ◽  
Uasb Reactors

Biological treatment of wastewaters discharged by the textile industry could potentially be problematic due to the high toxicity and recalcitrance of the commonly-used azo dye compounds. In the present report, the fate of two azo dyes under methanogenic conditions was studied. Mordant Orange 1 (MO1) and Azodisalicylate (ADS) were completely reduced and decolorised in continuous UASB reactors in the presence of cosubstrates. In the MO1 reactor, both 5-aminosalicylic acid (5-ASA) and 1,4-phenylenediamine were identified as products of azo cleavage. After long adaptation periods, 5-ASA was detected at trace levels, indicating further mineralization. ADS, a pharmaceutical azo dye constructed from two 5-ASA units, was completely mineralized even in the absence of cosubstrate, indicating that the metabolism of 5-ASA could provide the reducing equivalents needed for the azo reduction. Batch experiments confirmed the ADS mineralization. These results demonstrate that some azo dyes could serve as a carbon, energy, and nitrogen source for anaerobic bacteria.

Biofilm development during the start-up of a sulfate-reducing down-flow fluidized bed reactor at different COD/SO42− ratios and HRT

2011 ◽  
Vol 64 (4) ◽  
pp. 910-916 ◽  
Author(s):  
E. Z. Piña-Salazar ◽  
F. J. Cervantes ◽  
M. Meraz ◽  
L. B. Celis
Keyword(s):  
Fluidized Bed ◽  
Granular Sludge ◽  
Fluidized Bed Reactor ◽  
Sulfate Reducing ◽  
Sulfate Removal ◽  
Start Up ◽  
Effective Removal ◽  
Suspended Biomass ◽  
High Sulfate ◽  
Biofilm Development

In sulfate-reducing reactors, it has been reported that the sulfate removal efficiency increases when the COD/SO42− ratio is increased. The start-up of a down-flow fluidized bed reactor constitutes an important step to establish a microbial community in the biofilm able to survive under the operational bioreactor conditions in order to achieve effective removal of both sulfate and organic matter. In this work the influence of COD/SO42− ratio and HRT in the development of a biofilm during reactor start-up (35 days) was studied. The reactor was inoculated with 1.6 g VSS/L of granular sludge, ground low density polyethylene was used as support material; the feed consisted of mineral medium at pH 5.5 containing 1 g COD/L (acetate:lactate, 70:30) and sodium sulfate. Four experiments were conducted at HRT of 1 or 2 days and COD/SO42− ratio of 0.67 or 2.5. The results obtained indicated that a COD/SO42− ratio of 2.5 and HRT 2 days allowed high sulfate and COD removal (66.1 and 69.8%, respectively), whereas maximum amount of attached biomass (1.9 g SVI/L support) and highest sulfate reducing biofilm activity (10.1 g COD-H2S/g VSS-d) was achieved at HRT of 1 day and at COD/sulfate ratios of 0.67 and 2.5, respectively, which suggests that suspended biomass also played a key role in the performance of the reactors.

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