Intermittent vs continuous operation of upflow anaerobic sludge bed reactors for dairy wastewater and related microbial changes

2006 ◽  
Vol 54 (2) ◽  
pp. 103-109 ◽  
Author(s):  
H. Nadais ◽  
I. Capela ◽  
L. Arroja
Keyword(s):  
Continuous Operation ◽  
Dairy Wastewater ◽  
Anaerobic Sludge ◽  
Methanogenic Activity ◽  
Beneficial Effects ◽  
Effluent Recirculation ◽  
Intermittent Operation ◽  
Acetoclastic Methanogenesis ◽  
Uasb Reactors ◽  
Stabilization Period

This work compares continuous vs intermittent UASB reactors inoculated with flocculent sludge for the treatment of dairy effluents. The effects of effluent recirculation on the performance of intermittent reactors were assessed as well as the differences in specific methanogenic activity (SMA) with different substrates for the biomass from continuous and intermittent UASB reactors. Compared to the continuous operation the intermittent operation resulted in higher methanization of the removed COD (64–78% and 65–88%, respectively) whilst the effluent recirculation presented beneficial effects when applied during the stabilization period and was clearly detrimental when applied during the feed period of the intermittent operation. The SMA tests showed that the intermittent operation causes a shift in the microbial populations towards a better adaptation for the degradation of complex substrates confirmed by the meaningfull contribution of methane production through a pathway other than acetoclastic methanogenesis observed in the biomass taken from intermittent UASB reactors.

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.

Startup of thermophilic (55°C) UASB reactors using different mesophilic seed sludges

1996 ◽  
Vol 34 (5-6) ◽  
pp. 445-452 ◽  
Author(s):  
Herbert H. P. Fang ◽  
Ivan W. C. Lau
Keyword(s):  
Oxygen Demand ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Methanogenic Activity ◽  
The Third ◽  
Uasb Granules ◽  
Thermophilic Condition ◽  
Anaerobic Sludge Blanket ◽  
The Impact ◽  
Uasb Reactors

Performances during startup of three 2.8-litre UASB (upflow anaerobic sludge blanket) reactors operated under thermophilic condition were investigated. All reactors were seeded with mesophilic sludges: one with flocculent digester sludge (Reactor-F), another with UASB granules (Reactor-G), and the third with disintegrated granules (Reactor-D). The reactors were operated in parallel at 55°C and 24 hours of retention time, using sucrose and milk as substrate at COD (chemical oxygen demand) loadings up to 10 g-COD/l·day. Immediately after temperature was step-increased from 37°C to 55°C, all reactors encountered sludge washout and deterioration of COD removal efficiency; however, the impact of temperature increase was more severe on Reactor-F. Sludge granulation took place in all reactors; first granules became noticeable after 45 days in Reactor-D, and after 90 days in Reactor-F. Reactor-G and Reactor-D were capable of removing 95% of soluble COD after 75 days, while Reactor-F after 110 days. Throughout this study, there was little difference in performance between Reactors G and D. The thermophilic granule were estimated to have a yield of 0.099 g-VSS/g-COD, and a methanogenic activity of 0.71-1.55 g-methane-COD/g-VSS·day, comparable to that of mesophilic granules.

Methanogenic Toxicity and Anaerobic Biodegradation of Chemical Products in Use in a Brewery

1999 ◽  
Vol 40 (8) ◽  
pp. 169-176 ◽  
Author(s):  
P. Nagel ◽  
A. Urtubia ◽  
G. Aroca ◽  
R. Chamy ◽  
M. Schiappacasse
Keyword(s):  
Wastewater Treatment Plants ◽  
Industrial Effluent ◽  
Methanogenic Bacteria ◽  
Effluent Treatment ◽  
Anaerobic Sludge ◽  
Compound A ◽  
Methanogenic Activity ◽  
Toxicity Effect ◽  
Chemical Products ◽  
Uasb Reactors

Brewery industry effluents, as any other industrial effluent, contain a number of chemical products that could be toxic in biological wastewater treatment plants. Most of these products come from clean in place (CIP) systems, i.e. detergents and disinfectant, and from lubrication systems. To evaluate the toxicity effect of these compounds on an anaerobic effluent treatment pilot plant, studies of methanogenic activity were carried out. The results showed that the synthetic lubricant evaluated had a high toxicity level, compared to the organic lubricant; the disinfectant showed inhibition to some extent. To decrease the toxicity effect, the recovery and reutilization of these chemicals are suggested. Experiments to study the feasibility of adapting anaerobic sludge to these compounds were carried out. Working with UASB reactors, the adaptation of the sludge takes place in the presence of the most toxic chemical products; certain inhibition was observed on methanogenic bacteria in the reactor where a disinfectant was added, even though there was sludge wash out. In general a decrease in the operational behaviour was observed after adding the compound, a new steady state was reached in absence of the toxic compounds, in terms of alkalinity ratio, removal of COD, methane production. The reactors were able to be recovered and to be adapted again.

Stability and activity of anaerobic sludge from UASB reactors treating sewage in subtropical regions

2006 ◽  
Vol 54 (2) ◽  
pp. 223-229 ◽  
Author(s):  
L. Seghezzo ◽  
C.M. Cuevas ◽  
A.P. Trupiano ◽  
R.G. Guerra ◽  
S.M. González ◽  
...  
Keyword(s):  
Rate Constant ◽  
Pilot Scale ◽  
Hydrolysis Rate ◽  
Anaerobic Sludge ◽  
Decay Rate Constant ◽  
Methanogenic Activity ◽  
Biological Sludge ◽  
Organic Matter Concentration ◽  
Aerobic Wastewater Treatment ◽  
Uasb Reactors

The production of small amounts of well-stabilized biological sludge is one of the main advantages of upflow anaerobic sludge bed (UASB) reactors over aerobic wastewater treatment systems. In this work, sludge produced in three pilot-scale UASB reactors used to treat sewage under subtropical conditions was assessed for both stability and specific methanogenic activity. Stability of primary sludge from settling tanks and digested sludge from conventional sludge digesters was also measured for comparison purposes. Kinetic parameters like the hydrolysis rate constant and the decay rate constant were calculated. High stability was observed in sludge from UASB reactors. Methanogenic activity in anaerobic sludges was relatively low, probably due to the low organic matter concentration in influent sewage. Knowledge on sludge growth rate, stability, and activity might be very useful to optimize sludge management activities in full-scale UASB reactors.

scholarly journals Anaerobic Degradation of Dairy Wastewater in Intermittent UASB Reactors: Influence of Effluent Recirculation

2021 ◽  
Vol 15 ◽  
pp. 1-6
Author(s):  
A. Silva ◽  
C. Couras ◽  
I. Capela ◽  
L. Arroja ◽  
H. Nadais
Keyword(s):  
Methane Production ◽  
Anaerobic Degradation ◽  
Removal Rate ◽  
Treatment Plant ◽  
Dairy Wastewater ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Specific Substrate ◽  
Substrate Removal ◽  
Effluent Recirculation

This work studied the influence of effluent recirculation upon the kinetics of anaerobic degradation of dairy wastewater in intermittent UASB (Upflow Anaerobic Sludge Bed) reactors. Several laboratory-scale tests were performed with different organic loads in a UASB reactor inoculated with flocculent sludge from an industrial wastewater treatment plant. The data obtained were used for determination of specific substrate removal rates and specific methane production rates and adjusted to kinetic models. A high initial substrate removal was observed in all tests due to adsorption of organic matter onto the anaerobic biomass which was not accompanied by biological substrate degradation as measured by methane production. Initial methane production was about 45% of initial soluble and colloidal substrate removal rate. This discrepancy was observed mainly in the first day of all experiments and was attenuated in the second day. Effluent recirculation raised significantly the rate of removal of soluble and colloidal substrate and methane productivity as compared to literature results for batch assays without recirculation.

Methanogenic granule development in full scale internal circulation reactors

1994 ◽  
Vol 30 (8) ◽  
pp. 9-21 ◽  
Author(s):  
J. H. F. Pereboom ◽  
T. L. F. M. Vereijken
Keyword(s):  
Loading Rate ◽  
Gas Production ◽  
Full Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Internal Circulation ◽  
Methanogenic Activity ◽  
Average Shear ◽  
Biomass Retention ◽  
Uasb Reactors

Internal Circulation (IC) reactors can be operated at higher reactor volume loading rates than Upflow Anaerobic Sludge Blanket (UASB) reactors. This results in increased gas production rates and subsequently higher average shear rates in IC-reactors. Furthermore, the liquid upflow velocity is 8-20 times higher, still granules develop successfully in IC-reactors. To investigate the granule development in IC-reactors and elucidate the process limitations with respect to granule development and biomass retention, granule samples from three full scale IC-reactors are characterized. Characterization included size distribution, strength, settling velocity, density, ash content and methanogenic activity. Granules were compared with samples from UASB reactors treating similar types of wastewaters. A hydrodynamic model was developed to describe the liquid circulation in IC reactors. The average shear rate in IC reactors is approximately twice as high compared to UASB-reactors. The two stage design of the IC-reactor allows 3-6 times higher loading rate. The experimental results showed that IC-granules are larger than UASB-granules grown on similar wastewater, while the strength of IC-granules is lower as a result of the higher sludge loading rate. Although wash-out is slightly enhanced in IC-reactors, the conditions in the second stage are tranquil enough to ensure adequate biomass retention in IC-reactors. The development of characteristic IC-granules after seeding proceeds within a few months. Physical characteristics of granules are determined mainly by biological factors.

scholarly journals Anaerobic degradation of dairy wastewater in intermittent UASB reactors: influence of effluent recirculation

2015 ◽  
Vol 36 (17) ◽  
pp. 2227-2238 ◽  
Author(s):  
C.S. Couras ◽  
V.L. Louros ◽  
T. Gameiro ◽  
N. Alves ◽  
A. Silva ◽  
...  
Keyword(s):  
Anaerobic Degradation ◽  
Dairy Wastewater ◽  
Effluent Recirculation ◽  
Uasb Reactors

scholarly journals Anaerobic Degradation of Dairy Wastewater in Intermittent UASB Reactors: Influence of Effluent Recirculation

2021 ◽  
Vol 15 ◽  
pp. 35-40
Author(s):  
A. Silva ◽  
I. Capela ◽  
L. Arroja ◽  
H. Nadais
Keyword(s):  
Methane Production ◽  
Anaerobic Degradation ◽  
Removal Rate ◽  
Treatment Plant ◽  
Dairy Wastewater ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Specific Substrate ◽  
Substrate Removal ◽  
Effluent Recirculation

This work studied the influence of effluent recirculation upon the kinetics of anaerobic degradation of dairy wastewater in intermittent UASB (Upflow Anaerobic Sludge Bed) reactors. Several laboratory-scale tests were performed with different organic loads in a UASB reactor inoculated with flocculent sludge from an industrial wastewater treatment plant. The data obtained were used for determination of specific substrate removal rates and specific methane production rates and adjusted to kinetic models. A high initial substrate removal was observed in all tests due to adsorption of organic matter onto the anaerobic biomass which was not accompanied by biological substrate degradation as measured by methane production. Initial methane production was about 45% of initial soluble and colloidal substrate removal rate. This discrepancy was observed mainly in the first day of all experiments and was attenuated in the second day. Effluent recirculation raised significantly the rate of removal of soluble and colloidal substrate and methane productivity as compared to literature results for batch assays without recirculation.

Grey water treatment in upflow anaerobic sludge blanket (UASB) reactor at different temperatures

2011 ◽  
Vol 64 (3) ◽  
pp. 610-617 ◽  
Author(s):  
Tarek Elmitwalli ◽  
Ralf Otterpohl
Keyword(s):  
Oxygen Demand ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Septic Tank ◽  
Anaerobic Sludge ◽  
Grey Water ◽  
Methanogenic Activity ◽  
Operational Conditions ◽  
Anaerobic Sludge Blanket ◽  
Uasb Reactors

The treatment of grey water in two upflow anaerobic sludge blanket (UASB) reactors, operated at different hydraulic retention times (HRTs) and temperatures, was investigated. The first reactor (UASB-A) was operated at ambient temperature (14–25 °C) and HRT of 20, 12 and 8 h, while the second reactor (UASB-30) was operated at controlled temperature of 30 °C and HRT of 16, 10 and 6 h. The two reactors were fed with grey water from ‘Flintenbreite’ settlement in Luebeck, Germany. When the grey water was treated in the UASB reactor at 30 °C, total chemical oxygen demand (CODt) removal of 52–64% was achieved at HRT between 6 and 16 h, while at lower temperature lower removal (31–41%) was obtained at HRT between 8 and 20 h. Total nitrogen and phosphorous removal in the UASB reactors were limited (22–36 and 10–24%, respectively) at all operational conditions. The results showed that at increasing temperature or decreasing HRT of the reactors, maximum specific methanogenic activity of the sludge in the reactors improved. As the UASB reactor showed a significantly higher COD removal (31–64%) than the septic tank (11–14%) even at low temperature, it is recommended to use UASB reactor instead of septic tank (the most common system) for grey water pre-treatment. Based on the achieved results and due to high peak flow factor, a HRT between 8 and 12 h can be considered the suitable HRT for the UASB reactor treating grey water at temperature 20–30 °C, while a HRT of 12–24 h can be applied at temperature lower than 20 °C.

Immobilization strategies for bioaugmentation of anaerobic reactors treating phenolic compounds

2000 ◽  
Vol 42 (5-6) ◽  
pp. 245-250 ◽  
Author(s):  
S.R. Guiot ◽  
K. Tawfiki-Hájji ◽  
F. Lépine
Keyword(s):  
Phenolic Compounds ◽  
Hydraulic Retention Time ◽  
Alginate Beads ◽  
Continuous Operation ◽  
Anaerobic Sludge ◽  
Anaerobic Reactors ◽  
Degrading Bacteria ◽  
Free Cells ◽  
Specific Activities ◽  
Uasb Reactors

Degradation of phenol, ortho- and para-cresol was investigated in upflow anaerobic sludge bed (UASB) reactors bioaugmented with a methanogenic enrichment consortium able to degrade a mixture of phenolic compounds, in comparison to a reactor, which was inoculated only with anaerobic granules: 1) natural attachment of free cells to the granules, and 2) encapsulation within alginate beads. The increase of the percentage of enrichment from 2 to 5% improved considerably the startup of the reactors. Going from 5 to 10% had no effect on the removal of the phenolic compounds. Following a period of continuous operation at a hydraulic retention time of 3 days, the bioaugmented reactors showed specific activities on phenol, ortho- and para-cresol, at least twofold higher than those of the control reactor. This increase was attributed to the immobilization of phenol, ortho- and para-cresol-degrading bacteria on the granules.

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