scholarly journals Anaerobic treatment of domestic sewage at low temperature

2001 ◽  
Vol 44 (4) ◽  
pp. 33-40 ◽  
Author(s):  
T. Elmitwalli ◽  
Gr. Zeeman ◽  
G. Lettinga
Keyword(s):  
Low Temperature ◽  
Granular Sludge ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
The Novel ◽  
Reactor Performance ◽  
Batch Tests ◽  
Pre Treatment ◽  
Attached Form

The results of research concerning the feasibility of anaerobic treatment of domestic sewage at low temperature are summarized in this article. The batch tests demonstrated a high biodegradability of domestic sewage at 20°C (74%). Both batch and continuous experiments for the treatment of domestic sewage showed that the removal of SS prior to anaerobic treatment of domestic sewage not only provides a stable reactor performance but also improves the removal of both colloidal (CODcol) and dissolved COD (CODdis). The results of the pre-treatment of domestic sewage in an anaerobic filter (AF) and an anaerobic hybrid (AH) reactor showed that the AF reactor is an efficient process for the removal of suspended COD (CODss), viz. 82%, at an HRT of 4 h and 13°C. The novel AF reactor consists of vertical sheets of reticulated polyurethane foam with knobs, where the biomass was only in attached form. For the treatment of pre-settled sewage at 13°C, the AH reactor, with granular sludge, showed a higher total COD (CODt) removal than the UASB reactor as a result of higher CODcol removal. Therefore, the performance of a two-step system, AF+AH (with granular sludge) reactor, was investigated with different HRTs at 13°C. For optimization of CODss and CODdis an HRT of 4+4 h is needed, while for optimization of CODcol removal an HRT of 4+8 h is required. A CODt removal of 71% was achieved with 60% conversion to methane from the removed CODt when the AF+AH system was operated at an HRT of 4+8 h at 13°C.

Low temperature treatment of domestic sewage in upflow anaerobic sludge blanket and anaerobic hybrid reactors

1999 ◽  
Vol 39 (5) ◽  
pp. 177-185 ◽  
Author(s):  
Tarek A. Elmitwalli ◽  
Marcel H. Zandvoort ◽  
Grietje Zeeman ◽  
Harry Bruning ◽  
Gatze Lettinga
Keyword(s):  
Low Temperature ◽  
Sewage Treatment ◽  
Average Diameter ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Cod Removal ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Removal Efficiencies

The treatment of sewage at a temperature of 13°C was investigated in three reactors (each 3.84 litre) a UASB and two anaerobic hybrid (AH) reactors with small sludge granules with an average diameter of 0.73 mm. The media used in the AH reactors were vertical polyurethane foam sheets. The reactors were operated at a HRT of 8 h. The use of small sludge granules and operating the reactors at low upflow velocity (1.8 m/d) improved suspended COD removal efficiencies for the UASB reactor. Moreover, the use of sheets in the AH reactors significantly increased suspended COD removal efficiencies as compared to the UASB and reached to 87% for pre-settled sewage treatment. The treatment of pre-settled sewage instead of raw sewage in AH reactors significantly increased colloidal and dissolved COD removal efficiencies with 13% and 12% respectively and colloidal COD removal efficiency for the UASB reactor with 13%. At ‘steady state’ for pre-settled sewage treatment, the AH reactors removed 64% of the total COD which is significantly higher by 4% than the UASB reactor. Therefore, the anaerobic treatment of domestic sewage at low temperature can be improved by treating pre-settled sewage in shallow AH reactors containing small sludge granules.

Anaerobic Treatment of Domestic Sewage under Moderate Climatic (Dutch) Conditions Using Upflow Reactors at Increased Superficial Velocities

1992 ◽  
Vol 25 (7) ◽  
pp. 167-178 ◽  
Author(s):  
A. R. M. van der Last ◽  
G. Lettinga
Keyword(s):  
Removal Efficiency ◽  
Suspended Solids ◽  
Granular Sludge ◽  
Weather Conditions ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Fluidised Bed ◽  
Methanogenic Activity ◽  
Volumetric Loading

This paper describes experiments with domestic sewage using a 120 litre expanded granular sludge bed (EGSB) reactor and a 205 litre fluidised bed (FB) reactor. Presettled domestic sewage was used in the experiments, because these reactor systems are inadeguate in removing SS. Compared to conventional UASB reactors, the advantage of EGSB systems is the significantly better contact between sludge and wastewater. A batch recirculation system was used to assess the maximum achievable removal of the different COD fractions under EGSB and UASB conditions. The results obtained with the EGSB reactor reveal a removal efficiency of 90% with respect to the maximum obtainable efficiency of the soluble COD fraction under dry weather conditions. This efficiency can be obtained at hydraulic retention times (HRT) exceeding 3 hours. Even at HRT's ranging from 2 - 1.5 hours, still 84% - 77% of the maximum possible removal efficiency as assessed in batch recirculation experiments can be achieved at temperatures exceeding 13°C. The advantage of EGSB systems is the high volumetric loading rate that can be applied while maintaining a high removal of the dissolved COD fraction. Moreover, little if any accumulation of inert suspended solids occurs in the sludge bed. On the other hand, the poor removal of suspended solids can be considered as a disadvantage of these systems in treating domestic sewage. Conventional FB systems using sand as carrier material were shown to have little prospect for treating settled domestic sewage, because hardly any methanogenic activity will develop in such a system. However, it was also found that a very satisfactory guality granular sludge developed on settled sewage when operating FB systems in a mode similar to EGSB systems. This granular sludge appeared to be of a guality egual or even better than that of granular seed sludge, cultivated in a UASB reactor treating papermill wastewater.

scholarly journals The effect of sludge recirculation rate on a UASB-digester treating domestic sewage at 15 °C

2012 ◽  
Vol 66 (12) ◽  
pp. 2597-2603 ◽  
Author(s):  
Lei Zhang ◽  
Tim L. G. Hendrickx ◽  
Christel Kampman ◽  
Grietje Zeeman ◽  
Hardy Temmink ◽  
...  
Keyword(s):  
Low Temperature ◽  
Flow Rate ◽  
Biogas Production ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Recirculation Rate ◽  
The Stability ◽  
Influent Flow

The anaerobic treatment of low strength domestic sewage at low temperature is an attractive and important topic at present. The upflow anaerobic sludge bed (UASB)-digester system is one of the anaerobic systems to challenge low temperature and concentrations. The effect of sludge recirculation rate on a UASB-digester system treating domestic sewage at 15 °C was studied in this research. A sludge recirculation rate of 0.9, 2.6 and 12.5% of the influent flow rate was investigated. The results showed that the total chemical oxygen demand (COD) removal efficiency rose with increasing sludge recirculation rate. A sludge recirculation rate of 0.9% of the influent flow rate led to organic solids accumulation in the UASB reactor. After the sludge recirculation rate increased from 0.9 to 2.6%, the stability of the UASB sludge was substantially improved from 0.37 to 0.15 g CH4-COD/g COD, and the bio­gas production in the digester went up from 2.9 to 7.4 L/d. The stability of the UASB sludge and bio­gas production in the digester were not significantly further improved by increasing sludge recirculation rate to 12.5% of the influent flow rate, but the biogas production in the UASB increased from 0.37 to 1.2 L/d. It is recommended to apply a maximum sludge recirculation rate of 2–2.5% of the influent flow rate in a UASB-digester system, as this still allows energy self-sufficiency of the system.

scholarly journals Simple estimation of granule size distribution and sludge bed porosity in a UASB reactor

2013 ◽  
Vol 10 (1) ◽  
pp. 73-79
Keyword(s):  
Size Distribution ◽  
Granular Sludge ◽  
Granule Size ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Reactor Performance ◽  
Efficient Operation ◽  
Mathematical Algorithm ◽  
Bed Porosity

Granular sludge is the key factor for an efficient operation of an upflow anaerobic sludge blanket (UASB) reactor. In order to monitor the granularity of anaerobic sludge, the determination of the granule size distribution is of vital importance. Another critical parameter for the UASB reactor performance is the sludge bed porosity. For this reason, several techniques have been proposed, however they are either tedious, imprecise or expensive and hardly applicable in full scale treatment plants. There was then the need for a simple and low cost technique. This technique involves the determination of the settling velocities of a sludge sample and of extrapolating the corresponding diameters using a mathematical algorithm. In the proposed algorithm, the granules density was calculated, the flow regime was examined and finally the granule size distribution was obtained. Some very important correlations were suggested by the experimental results. The granule density and diameter as well as the sludge bed porosity were strongly correlated with the VSS/TSS ratio.

Anaerobic pre-treatment of petrochemical effluents: terephthalic acid wastewater

1997 ◽  
Vol 36 (2-3) ◽  
pp. 237-248 ◽  
Author(s):  
Robbert Kleerebezem ◽  
Joost Mortier ◽  
Look W. Hulshoff Pol ◽  
Gatze Lettinga
Keyword(s):  
Acetic Acid ◽  
Benzoic Acid ◽  
Terephthalic Acid ◽  
Anaerobic Degradation ◽  
Anaerobic Treatment ◽  
High Rate ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Pre Treatment ◽  
Uasb Reactors

During petrochemical production of purified terephthalic acid (PTA, 1,4-benzene dicarboxylic acid), a large quantity of concentrated effluent is produced. Main polluting compounds in this wastewater are terephthalic acid, acetic acid and benzoic acid in decreasing order of concentration. Acetic acid and benzoic acid are known to be rapidly degraded in high rate anaerobic treatment systems, such as Upflow Anaerobic Sludge Bed (UASB) reactors. Concerning the kinetics of anaerobic mineralization of terephthalic acid, however, no information is available in literuature. Therefore our work focused on the anaerobic degradation of neutralized terephthalic acid (disodium terephthalate) in laboratory scale UASB-reactors and batch reactors. It was found that high rate anaerobic treatment of terephthalate was difficult to obtain due to the low growth rate (μ ≈ 0.04 day−1) of the terephthalate mineralizing mixed culture. The maximum removal capacity of a lab-scale UASB-reactor was found to be 3.9 g COD.1−1 .day−1 at a loading rate of 4.5 g COD.1−1 .day−1 and a hydraulic retention time of 24 hours. Terephthalate was used as sole carbon source during these experiments. Addition of small amounts of sucrose (co-substrate) to the influent, as a source of reducing equivalents, was found to have a negative influence on the anaerobic degradation of terephthalate. Also benzoate was found to inhibit the mineralization of terephthalate. Batch-toxicity experiments showed that terephthalate is not toxic to any of the species involved in its mineralization. Based on these observations, a staged anaerobic reactor system is suggested for the anaerobic pre-treatment of PTA-wastewater.

Anaerobic treatment of a medium strength industrial wastewater at low-temperature and short hydraulic retention time: a pilot-scale experience

2011 ◽  
Vol 64 (8) ◽  
pp. 1629-1635 ◽  
Author(s):  
M. Esparza Soto ◽  
C. Solís Morelos ◽  
J. J. Hernández Torres
Keyword(s):  
Low Temperature ◽  
Hydraulic Retention Time ◽  
Loading Rate ◽  
Pilot Scale ◽  
Anaerobic Treatment ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Organic Loading ◽  
Processing Industry ◽  
Industry Wastewater

The aim of this work was to evaluate the performance of a pilot-scale upflow anaerobic sludge blanket (UASB) reactor during the treatment of cereal-processing industry wastewater under low-temperature conditions (17 °C) for more than 300 days. The applied organic loading rate (OLRappl) was gradually increased from 4 to 6 and 8 kg CODsol/m3d by increasing the influent soluble chemical oxygen demand (CODsol), while keeping the hydraulic retention time constant (5.2 h). The removal efficiency was high (82 to 92%) and slightly decreased after increasing the influent CODsol and the OLRappl. The highest removed organic loading rate (OLRrem) was reached when the UASB reactor was operated at 8 kg CODsol/m3d and it was two times higher than that obtained for an OLRappl of 4 kg CODsol/m3d. Some disturbances were observed during the experimentation. The formation of biogas pockets in the sludge bed significantly complicated the biogas production quantification, but did not affect the reactor performance. The volatile fatty acids in the effluent were low, but increased as the OLRappl increased, which caused an increment of the effluent CODsol. Anaerobic treatment at low temperature was a good option for the biological pre-treatment of cereal processing industry wastewater.

Low temperature microwave and conventional heating pre-treatments to improve sludge anaerobic biodegradability

2013 ◽  
Vol 69 (3) ◽  
pp. 518-524 ◽  
Author(s):  
P. Vergine ◽  
J. Zábranská ◽  
R. Canziani
Keyword(s):  
Low Temperature ◽  
Activated Sludge ◽  
Oxygen Demand ◽  
Cost Effective ◽  
Conventional Heating ◽  
Waste Activated Sludge ◽  
Experimental Conditions ◽  
Primary Sludge ◽  
Batch Tests ◽  
Pre Treatment

This paper presents the results of lab-scale experiments on low temperature thermal pre-treatment (less than 100 °C) prior to anaerobic digestion of sewage sludge. Two heating ways, microwave heating (MH) and conventional heating (CH), and two types of sludge, primary and waste activated sludge, were compared under the same experimental conditions. The degree of solubilisation produced by MH and CH up to 72, 82 and 93 °C was firstly estimated. For both types of heating, increase in soluble chemical oxygen demand (COD) caused by the pre-treatment was about 14% on waste activated sludge and only 3% on primary sludge. The final temperature of 72 °C resulted as the most cost-effective in terms of additional soluble COD per unit of energy required. Subsequently, five series of biochemical methane potential mesophilic assays were run in 120 mL serum bottles on sludge samples pre-treated at 72 °C. When compared with control reaction vessels, no significant differences were noticed in net methane production of pre-treated primary sludge, whereas a relevant increase occurred regarding the pre-treated waste activated sludge. It was also observed that the trend of methane content in biogas during the batch tests can be described by a second order polynomial.

Anaerobic treatment of domestic sewage in modified septic tanks at low temperature

2014 ◽  
Vol 35 (17) ◽  
pp. 2123-2131 ◽  
Author(s):  
Zhiqiang Chen ◽  
Qinxue Wen ◽  
Huabin Guan ◽  
Rune Bakke ◽  
Nanqi Ren
Keyword(s):  
Low Temperature ◽  
Anaerobic Treatment ◽  
Domestic Sewage ◽  
Septic Tanks

Anaerobic treatment of crude glycerol from biodiesel production

2015 ◽  
Vol 72 (8) ◽  
pp. 1383-1389 ◽  
Author(s):  
M. M. Nakazawa ◽  
W. R. S. Silva Júnior ◽  
M. T. Kato ◽  
S. Gavazza ◽  
L. Florencio
Keyword(s):  
Crude Glycerol ◽  
Denaturing Gradient Gel Electrophoresis ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Experimental Period ◽  
Anaerobic Treatment ◽  
Biodiesel Production ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Reactor Performance

In this study, we evaluated the use of an up-flow anaerobic sludge blanket (UASB) reactor to treat crude glycerol obtained from cottonseed biodiesel production. The laboratory-scale UASB reactor (7.0 L) was operated at ambient temperature of 26.5°C with chemical oxygen demand (COD) concentrations between 0.5 and 8.0 g/L. The volatile fatty acid contents, pH, inorganic salt contents and biogas production were monitored during a 280-day experimental period. Molecular biology techniques were used to assess the microbial diversity in the bioreactor. The reactor achieved COD removal efficiencies of up to 92% except during one phase when the efficiency decreased to 81%. Biogas production remained stable throughout the experimental period, when the fraction converted to methane reached values as high as 68%. The profile of the denaturing gradient gel electrophoresis (DGGE) bands suggested slight changes in the microbial community during reactor operation. The overall results indicated that the crude glycerol from biodiesel production can serve as a suitable substrate for anaerobic degradation with a stable reactor performance and biogas production as long as the applied organic loads are up to 8.06 kg COD/m3·d.

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