scholarly journals New Strategy for a Suitable Fast Stabilization of the Biomethanization Performance

Archaea ◽  
2012 ◽  
Vol 2012 ◽  
pp. 1-7 ◽  
Author(s):  
L. A. Fernández-Güelfo ◽  
C. J. Álvarez-Gallego ◽  
D. Sales Márquez ◽  
L. I. Romero García
Keyword(s):  
Solid Waste ◽  
Anaerobic Sludge ◽  
Continuous Stirred Tank Reactor ◽  
Operational Conditions ◽  
Anaerobic Reactors ◽  
Organic Solid ◽  
Start Up ◽  
New Strategy ◽  
Thermophilic Conditions ◽  
Dry Conditions

The start-up strategies for thermophilic anaerobic reactors usually consist of an initial mesophilic stage (35°C), with an approximate duration of 185 days, and a subsequent thermophilic stage (55°C), which normally requires around 60 days to achieve the system stabilizatio. During the first 8–10 days of the mesophilic stage, the reactor is not fed so that the inoculum, which is generally a mesophilic anaerobic sludge, may be adapted to the organic solid waste. Between mesophilic and thermophilic conditions the reactor is still not fed in an effort to prevent possible imbalances in the proces. As a consequence, the start-up and stabilization of the biomethanization performance described in the literature require, at least, around 245 days. In this sense, a new strategy for the start-up and stabilization phases is presented in this study. This approach allows an important reduction in the overall time necessary for these stages in an anaerobic continuous stirred tank reactor (CSTR) operated at thermophilic-dry conditions for treating the organic fraction of the municipal solid waste (OFMSW): 60 days versus 245 days of conventional strategies. The new strategy uses modified SEBAC technology to adapt an inoculum to the OFMSW and the operational conditions prior to seeding the CSTR.

The effect of operational conditions on the sludge specific methanogenic activity and sludge biodegradability

2009 ◽  
Vol 59 (9) ◽  
pp. 1847-1853 ◽  
Author(s):  
R. C. Leitão ◽  
S. T. Santaellla ◽  
A. C. van Haandel ◽  
G. Zeeman ◽  
G. Lettinga
Keyword(s):  
Municipal Wastewater ◽  
Pilot Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Treatment Unit ◽  
Methanogenic Activity ◽  
Operational Conditions ◽  
Anaerobic Reactors ◽  
Specific Methanogenic Activity

The effects of hydraulic retention time (HRT) and influent COD concentration (CODInf) on Specific Methanogenic Activity (SMA) and the biodegradability of an anaerobic sludge need to be elucidated because of the discordant results available in literature. This information is important for the operation of anaerobic reactors and design of the sludge post-treatment unit. For this study, sludge samples obtained from eight pilot-scale Upflow Anaerobic Sludge Blanket (UASB) reactors were tested. The reactors were fed with municipal wastewater and operated with different sets of HRT and influent concentrations until the steady state was established. The results show that at a lower HRT, sludge with relatively higher SMA develops. A slight trend of declining SMA at increasing CODInf was found for reactors operated at longer HRTs; however, further experiments are necessary for more definitive conclusions. The sludge from reactors operated at longer HRTs and with lower CODInf resulted in lower biodegradability. Results also showed that it is ineffective to design a UASB reactor with a longer HRT to cope with organic shock loads.

Effect of inoculum-substrate ratio on the start-up of solid waste anaerobic digesters

2001 ◽  
Vol 44 (4) ◽  
pp. 103-108 ◽  
Author(s):  
B. Fernández ◽  
P. Porrier ◽  
R. Chamy
Keyword(s):  
Solid Waste ◽  
Methane Production ◽  
Waste Treatment ◽  
Two Phase ◽  
Anaerobic Reactors ◽  
Start Up ◽  
Anaerobic Degradability ◽  
Substrate Ratio ◽  
Two Phases ◽  
Anaerobic System

The anaerobic systems start-up for solid waste treatment is a fundamental step, especially for those with two phases. It is necessary to know both the waste characteristics and the inoculum conditions. The objective of this work was to study the inoculum-substrate ratio (ISR) influence as a previous step of the start-up of an anaerobic system for the solid waste digestion. During this research spent grain was chosen as residue, working at three different concentrations (7; 13 and 20% w/v), studying the ISR effect in terms of anaerobic degradability (AD) and specific methane productivity (SMP). The initial acetoclastic activities (A0) were calculated based on the equation which describes the methane accumulation during each test. The model constants were also calculated and were adjusted to the experimental data. The results showed that in general the ISR variation has less impact on AD than on SMP. While maximum AD were reached in those tests with high ISR, the greatest values of SMP were with the lowest values of ISR ratio. A low ISR caused a slow hydrolysis, although the methane production was fast. So, during the start-up of a two-phase anaerobic system an elevated ISR would not be necessary in order to reach a good AD and a good intermediate products production, because the hydrolysis and the VFA production must be optimised in the first phase of these systems. While in conventional systems, where phases are together, it is much better to optimise the methane production. The ISR and the SMP indicated which inoculum percentage would be interesting based on the objective of the whole system: methane or intermediate compounds (VFA) production. All this information is important during the conventional anaerobic reactors operation because these tests would show which ISRs avoid inhibition.

scholarly journals Start-up of horizontal anaerobic reactors with sludge blanket and fixed bed for wastewater treatment from coffee processing by wet method

2013 ◽  
Vol 33 (2) ◽  
pp. 353-366 ◽  
Author(s):  
Roberto A. de Oliveira ◽  
Natani M. N. Bruno
Keyword(s):  
Fixed Bed ◽  
Oxygen Demand ◽  
Anaerobic Treatment ◽  
Mean Value ◽  
Treatment System ◽  
Anaerobic Sludge ◽  
Mean Values ◽  
Anaerobic Reactors ◽  
Start Up ◽  
The Mean

In this study it was evaluated the start-up procedures of anaerobic treatment system with three horizontal anaerobic reactors (R1, R2 and R3), installed in series, with volume of 1.2 L each. R1 had sludge blanket, and R2 and R3 had half supporter of bamboo and coconut fiber, respectively. As an affluent, it was synthesized wastewater from mechanical pulping of the coffee fruit by wet method, with a mean value of total chemical oxygen demand (CODtotal) of 16,003 mg L-1. The hydraulic retention time (HRT) in each reactor was 30 h. The volumetric organic loading (VOL) applied in R1 varied from 8.9 to 25.0 g of CODtotal (L d)-1. The mean removal efficiencies of CODtotal varied from 43 to 97% in the treatment system (R1+R2+R3), stabilizing above 80% after 30 days of operation. The mean content of methane in the biogas were of 70 to 76%, the mean volumetric production was 1.7 L CH4 (L reactor d)-1 in the system, and the higher conversions were around at 0.20 L CH4 (g CODremoved)-1 in R1 and R2. The mean values of pH in the effluents ranged from 6.8 to 8.3 and the mean values of total volatile acids remained below 200 mg L-1 in the effluent of R3. The concentrations of total phenols of the affluent ranged from 45 to 278 mg L-1, and the mean removal efficiency was of 52%. The start-up of the anaerobic treatment system occurred after 30 days of operation as a result of inoculation with anaerobic sludge with active microbiota.

Comparison of start-up of an upflow anaerobic sludge blanket reactor and a polyurethane carrier reactor

1996 ◽  
Vol 34 (5-6) ◽  
pp. 509-515 ◽  
Author(s):  
Huub J. Gijzen ◽  
Frank Kansiime
Keyword(s):  
Volatile Fatty Acids ◽  
Biogas Production ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Operational Conditions ◽  
Start Up ◽  
And Performance ◽  
Anaerobic Sludge Blanket

The start-up and performance of an Upflow Anaerobic Sludge Blanket (UASB) reactor and a Polyurethane Carrier Reactor (PCR) was investigated under similar operational conditions. The presence of polyurethane cubes as a carrier material in the PCR resulted in fast reactor start-up due to quick immobilization of methanogenic associations. Start-up of the UASB was slower compared to the PCR, which was mainly reflected in a lower biogas production and acetate degradation efficiency. However, when enough biomass had accumulated in the UASB reactor after 15 weeks of operation, the performance of the two reactors was almost the same in terms of biogas production and volatile fatty acids degradation. Efficient VFA degradation (about 90%) and biogas production (5.2 l/l.d) were achieved at an organic loading rate of 13.2 g/l.d) and HRT of 6 h. When hydraulic retention time was subsequently reduced from 6 to 2 h, the performance of the UASB reactor was better than that of the PCR. The inferior performance of the PCR may have been attributed to channelling of the influent in the reactor at high liquid flow rate.

Acclimation of mesophilic anaerobic sludge to thermophilic conditions: PCR genera detection methodology

2003 ◽  
Vol 48 (6) ◽  
pp. 81-86 ◽  
Author(s):  
N. Cabirol ◽  
F.J. Fernández ◽  
L. Mendoza ◽  
A. Noyola
Keyword(s):  
Microbial Population ◽  
Wastewater Treatment Plants ◽  
Synthetic Medium ◽  
Public Health Problem ◽  
Anaerobic Sludge ◽  
Specific Detection ◽  
Thermophilic Anaerobic Digestion ◽  
Start Up ◽  
Thermophilic Conditions ◽  
Polymerase Chain

In Mexico, sludge from wastewater treatment plants is a public health problem, especially for the infant population due to the presence of pathogens and parasite eggs. Therefore, it is of great interest to apply proper treatment methods for those wastes. An option proposed for the removal of possible infectious sources is thermophilic anaerobic digestion, even though a limitation for its acceptance is the slow start-up of the reactors. The transformation of a mesophilic anaerobic sludge for its utilization as a thermophilic inoculum, by means of direct temperature increase up to 55°C and feeding of the inoculum with synthetic medium was possible in two months. As a main part of the work and with the objective of evaluating the changes in the methanogenic microbial population during the sludge treatment, a specific detection technique for these bacteria has been developed and validated, based on the use of the polymerase chain reaction (PCR).

The Kinetic Basis of a New Start-Up Method to Ensure the Rapid Granulation of Anaerobic Sludge

1992 ◽  
Vol 25 (7) ◽  
pp. 113-122 ◽  
Author(s):  
L. Morvai ◽  
P. Miháltz ◽  
L. Czakó
Keyword(s):  
Substrate Inhibition ◽  
Type Equation ◽  
Granular Sludge ◽  
Anaerobic Sludge ◽  
Granule Formation ◽  
Granulation Process ◽  
Inhibition Response ◽  
Start Up ◽  
New Strategy ◽  
Kinetics Of

The control of the granulation process seems to be a kind of microbial selection: the enrichment of Methanothrix sp. against the Methanosarcina sp. Because of a lower KS value of Methanothrix, keeping a low (below 200 mg.dm−3) acetate concentration has been advised to be beneficial for granulation. This method results a 70-100 days start-up time. This approach assumes Monod-type kinetics, although a substrate inhibition model may describe better the biomethanation of acetate. We found that the best fit was yielded by a Haldane-type equation modified by an inhibition response coefficient (n). The major difference between the kinetics of raw and granular sludges has been manifested in this dimensionless parameter. The n was 4 times higher for raw sludge (3.6-4.1) than for granular sludge (0.95-1.13) which means that the granular sludge (formed mainly by Methanothrix sp.) is less sensitive to substrate inhibition. Continuous UASB experiments gave a similar result: the n-value continuously decreased (from 2.3 to 0.2) following granule formation. On the basis of the above findings we developed a new strategy for granulation control which ensured fast (35-40 day) granulation on carbohydrate-containing wastewaters.

Anaerobic Thermophilic (55°C) Treatment of TMP Whitewater in Reactors Based on Biomass Attachment and Entrapment

1999 ◽  
Vol 40 (11-12) ◽  
pp. 67-75 ◽  
Author(s):  
Sigrun J. Jahren ◽  
Jukka A. Rintala ◽  
Hallvard Ødegaard
Keyword(s):  
Granular Sludge ◽  
Biofilm Reactor ◽  
Upflow Anaerobic Sludge Blanket ◽  
Hybrid Reactor ◽  
Anaerobic Sludge ◽  
Loading Rates ◽  
Anaerobic Reactors ◽  
Multi Stage ◽  
Degradation Rates ◽  
Thermomechanical Pulping

Thermomechanical pulping (TMP) whitewater was treated in thermophilic (55°C) anaerobic laboratory-scale reactors using three different reactor configurations. In all reactors up to 70% COD removals were achieved. The anaerobic hybrid reactor, composed of an upflow anaerobic sludge blanket (UASB) and a filter, gave degradation rates up to 10 kg COD/m3d at loading rates of 15 kg COD/m3d and hydraulic retention time (HRT) of 3.1 hours. The anaerobic multi-stage reactor, consisting of three compartments, each packed with granular sludge and carrier elements, gave degradation rates up to 9 kg COD/m3d at loading rates of 15-16 kg COD/m3d, and HRT down to 2.6 hours. Clogging and short circuiting eventually became a problem in the multi-stage reactor, probably caused by too high packing of the carriers. The anaerobic moving bed biofilm reactor performed similar to the other reactors at loading rates below 1.4 kg COD/m3d, which was the highest loading rate applied. The use of carriers in the anaerobic reactors allowed short HRT with good treatment efficiencies for TMP whitewater.

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