Control of scum accumulation in a double stage biogas collection (DSBC) UASB reactor treating domestic wastewater

2009 ◽  
Vol 59 (6) ◽  
pp. 1077-1083 ◽  
Author(s):  
J. O. Pereira ◽  
J. S. S. Celani ◽  
C. A. L. Chernicharo
Keyword(s):  
Mass Balance ◽  
Municipal Wastewater ◽  
Control Mechanism ◽  
Domestic Wastewater ◽  
Uasb Reactor ◽  
Uasb Reactors

This paper presents an innovative reactor concept which is based on a double-stage biogas collection (DSBC) device aimed at controlling scum formation and accumulation in UASB reactors treating municipal wastewater. Scum production inside a control reactor and a DSBC-UASB reactor was compared and much lower scum yield coefficients were observed for the DSBC-UASB reactor. However, the mass balance indicated that the dominant control mechanism was scum disaggregation and exit to settler zone rather than scum degradation.

The effect of operational conditions on the performance of UASB reactors for domestic wastewater treatment

2005 ◽  
Vol 52 (1-2) ◽  
pp. 299-305 ◽  
Author(s):  
R.C. Leitão ◽  
J.A. Silva-Filho ◽  
W. Sanders ◽  
A.C. van Haandel ◽  
G. Zeeman ◽  
...  
Keyword(s):  
Removal Efficiency ◽  
Municipal Wastewater ◽  
Domestic Wastewater ◽  
Pilot Scale ◽  
Cod Removal ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Operational Conditions ◽  
Cod Removal Efficiency ◽  
Uasb Reactors

In this investigation, the performance of Upflow Anaerobic Sludge Blanket (UASB) reactors treating municipal wastewater was evaluated on the basis of: (i) COD removal efficiency, (ii) effluent variability, and (iii) pH stability. The experiments were performed using 8 pilot-scale UASB reactors (120 L) from which some of them were operated with different influent COD (CODInf ranging from 92 to 816 mg/L) and some at different hydraulic retention time (HRT ranging from 1 to 6 h). The results show that decreasing the CODInf, or lowering the HRT, leads to decreased efficiencies and increased effluent variability. During this experiment, the reactors could treat efficiently sewage with concentration as low as 200 mg COD/L. They could also be operated satisfactorily at an HRT as low as 2 hours, without problems of operational stability. The maximum COD removal efficiency can be achieved at CODInf exceeding 300 mg/L and HRT of 6 h.

scholarly journals Reduction of scum production in a modified UASB reactor treating domestic sewage

2019 ◽  
Vol 79 (9) ◽  
pp. 1657-1666
Author(s):  
J. O. Pereira ◽  
J. M. Rocha ◽  
W. B. C. C. Pinto ◽  
C. T. S. Moreira
Keyword(s):  
Domestic Wastewater ◽  
Domestic Sewage ◽  
Uasb Reactor ◽  
Total Solids ◽  
Proposed Modification ◽  
Solid Liquid ◽  
Uasb Reactors

Abstract The scum accumulation inside gas–solid–liquid separators (GSL) is one of the main limitations of upflow anaerobic sequencing batch (UASB) reactors during treatment of domestic sewage. Although this type of reactor can be equipped with devices that periodically remove scum, this solution has been proved to be very expensive in addition to being inefficient when discharging procedures are not correctly performed. The main goal of this study was to investigate the performance of a modified UASB reactor concept with a GSL separator which promotes continuous scum discharge to the settling compartment. Furthermore, this proposal was compared with a conventional UASB reactor which was used as control. Both reactors in demo-scale were fed with domestic wastewater and scum production was measured. The results demonstrated volumetric reduction of 50%, and 75% reduction in the mass of total solids in the modified reactor. Additionally, the amount of biogas recovered from the modified reactor was higher than the amount that the control reactor recovered. Therefore, the proposed modification has been proved to be effective, bringing new possibilities to the GSL project.

Combined treatment of leachate from sanitary landfill and municipal wastewater by UASB reactors

2009 ◽  
Vol 60 (2) ◽  
pp. 491-495 ◽  
Author(s):  
Patricia Torres ◽  
Jenny A. Rodríguez ◽  
Luz E. Barba ◽  
Luis F. Marmolejo ◽  
Carlos A. Pizarro
Keyword(s):  
Municipal Wastewater ◽  
Combined Treatment ◽  
Domestic Wastewater ◽  
Anaerobic Treatment ◽  
Uasb Reactor ◽  
Organic Load ◽  
Leachate Treatment ◽  
Wastewater Systems ◽  
Efficient Alternative ◽  
Chemical Inputs

Landfills are among the most affordable and acceptable methods in terms of public health and environmental protection for the final disposal of solid waste. Leachate treatment incorporated into anaerobic domestic wastewater systems could be a viable and efficient alternative which would allow minimizing implementation and operation costs of the landfill, to reduce requirements of chemical inputs such as pH conditioners and phosphorus supply. This study showed the potential of anaerobic treatment in an UASB reactor treating a combination of domestic wastewater and leachate in a 5% volumetric ratio of leachate. Under these conditions the reactor assimilated properly the leachate fraction incorporated. With a HRT of 8 h and a mean volumetric organic load of 2.84 kg m−3 d−1 COD removal efficiencies around 70% were obtained, without inhibition problems; however, the necessity of a complementary treatment for improving carbonaceous and nitrogenous organic matter reduction is evident.

Granular biomass selection in a double-stage biogas collection UASB reactor: effects on SMA, abundance and diversity of the methanogenic population

2012 ◽  
Vol 66 (12) ◽  
pp. 2570-2577 ◽  
Author(s):  
J. O. Pereira ◽  
E. F. A. Mac Conell ◽  
S. Q. Silva ◽  
C. A. L. Chernicharo
Keyword(s):  
Denaturing Gradient Gel Electrophoresis ◽  
Cell Activity ◽  
Domestic Wastewater ◽  
Pilot Scale ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Methanogenic Activity ◽  
Gradient Gel Electrophoresis ◽  
Abundance And Diversity ◽  
Uasb Reactors

The present work aimed at investigating biomass selection in a pilot-scale double-stage biogas collection (DSBC) upflow anaerobic sludge bed (USAB) reactor treating domestic wastewater. Specific methanogenic activity (SMA) measurements and FISH countings were applied to sludge samples collected during 102 days of operation of the DSBC–UASB and of a control reactor. Results showed that both reactors presented similar SMA values in early stages of operation however the UASB–DSBC reactor showed much higher SMA after day 45, when the biomass was in granular stage. In terms of archaeal abundance, no statistical difference was observed between the reactors. Polymerase chain reaction–denaturing gradient gel electrophoresis (PCR–DGGE) revealed a similar composition of the archaeal communities in the two reactors and during the operational period, mainly constituted by Methanosaeta concilii. The results suggest that cell activity rather than archaeal abundance or diversity drive the methane production in the UASB reactors.

Anaerobic bioprocessing of sewage sludge, focusing on degradation of linear alkylbenzene sulfonates (LAS)

2004 ◽  
Vol 49 (10) ◽  
pp. 115-122 ◽  
Author(s):  
I. Angelidaki ◽  
L. Toräng ◽  
C.M. Waul ◽  
J.E. Schmidt
Keyword(s):  
Mass Balance ◽  
Anaerobic Degradation ◽  
Uasb Reactor ◽  
Second Step ◽  
Anaerobic Sludge ◽  
Continuous Stirred Tank Reactor ◽  
Anaerobic Process ◽  
Linear Alkylbenzene ◽  
Linear Alkylbenzene Sulfonates ◽  
Uasb Reactors

Anaerobic degradation of sludge amended with linear alkylbenzene sulfonates (LAS) was tested in a one stage continuous stirred tank reactor (CSTR) and a two stage reactor system consisting of a CSTR as first step and upflow anaerobic sludge bed (UASB) reactor as the second step. Anaerobic removal of LAS was only observed at the second step but not at the first step. Removal of LAS in the UASB reactors was approx. 80% where half was due to absorption and the other half was apparently due to biological removal as shown from the LAS mass balance. At the end of the experiment the reactors were spiked with 14C-LAS which resulted in 5.6% 14CO2 in the produced gas. Total mass balance of the radioactivity was however not achieved. In batch experiments it was found that LAS at concentrations higher than 50 mg/l is inhibitory for most microbial groups of the anaerobic process. Therefore, low initial LAS concentration is a prerequisite for successful LAS degradation. The results from the present study suggest that anaerobic degradation of LAS is possible in UASB reactors when the concentration of LAS is low enough to avoid inhibition of microorganisms active in the anaerobic process.

Anaerobic treatment of municipal wastewater using the UASB-technology

2007 ◽  
Vol 56 (10) ◽  
pp. 37-44 ◽  
Author(s):  
I. Urban ◽  
D. Weichgrebe ◽  
K.-H. Rosenwinkel
Keyword(s):  
Co2 Emission ◽  
Municipal Wastewater ◽  
Clean Energy ◽  
Anaerobic Treatment ◽  
Relevant Effect ◽  
Different Temperatures ◽  
High Concentrations ◽  
New Applications ◽  
Uasb Reactors ◽  
Positive Effect

The anaerobic treatment of municipal wastewater enables new applications for the reuse of wastewater. The effluent could be used for irrigation as the included nutrients are not affected by the treatment. Much more interesting now are renewable energies and the retrenchment of CO2 emission. With the anaerobic treatment of municipal wastewater, not only can the CO2 emission be reduced but “clean” energy supply can be gained by biogas. Most important for the sustainability of this process is the gathering of methane from the liquid effluent of the reactor, because the negative climate-relevant effect from the degassing methane is much higher than the positive effect from saving CO2 emission. In this study, UASB reactors were used with a flocculent sludge blanket for the biodegradation of the carbon fraction in the wastewater with different temperatures and concentrations. It could be shown that the positive effect is much higher for municipal wastewater with high concentrations in hot climates.

Nitrite reduction and methanogenesis in a single-stage UASB reactor

2015 ◽  
Vol 72 (12) ◽  
pp. 2236-2242 ◽  
Author(s):  
L. I. Borges ◽  
C. M. López-Vazquez ◽  
H. García ◽  
J. B. van Lier
Keyword(s):  
Domestic Wastewater ◽  
High Strength ◽  
Single Stage ◽  
Nitrite Reduction ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
N Removal

In this study, nitrite reduction and methanogenesis in a single-stage upflow anaerobic sludge blanket (UASB) reactor was investigated, using high-strength synthetic domestic wastewater as substrate. To assess long-term effects and evaluate the mechanisms that allow successful nitrite reduction and methanogenesis in a single-stage UASB, sludge was exposed to relatively high nitrite loading rates (315 ± 13 mgNO2−-N/(l.d)), using a chemical oxygen demand (COD) to nitrogen ratio of 18 gCOD/gNO2−-N, and an organic loading rate of 5.4 ± 0.2 gCOD/(l.d). In parallel, the effects of sludge morphology on methanogenesis inhibition were studied by performing short-term batch activity tests at different COD/NO2−-N ratios with anaerobic sludge samples. In long-term tests, denitrification was practically complete and COD removal efficiency did not change significantly after nitrite addition. Furthermore, methane production only decreased by 13%, agreeing with the reducing equivalents requirement for complete NO2− reduction to N2. Apparently, the spatial separation of denitrification and methanogenesis zones inside the UASB reactor allowed nitrite reduction and methanogenesis to occur at the same moment. Batch tests showed that granules seem to protect methanogens from nitrite inhibition, probably due to transport limitations. Combined COD and N removal via nitrite in a single-stage UASB reactor could be a feasible technology to treat high-strength domestic wastewater.

Application of the UASB-Reactor for Anaerobic Treatment of Paper and Board Mill Effluent

1985 ◽  
Vol 17 (1) ◽  
pp. 61-75 ◽  
Author(s):  
L H A Habets ◽  
J H Knelissen
Keyword(s):  
Waste Water ◽  
Water Treatment ◽  
Energy Savings ◽  
Hydraulic Retention Time ◽  
Waste Water Treatment ◽  
Anaerobic Treatment ◽  
Raw Material ◽  
Uasb Reactor ◽  
Seed Sludge ◽  
Uasb Reactors

Within the holding of Bührmann-Tetterode NV, 7 Dutch paper and board mills are operating, all of them using mainly waste paper as raw material. While three of them completely closed their watercircuits, two other mills put into practice biological waste water treatment namely anaerobic and anaerobic/aerobic. Number 6 is realising an anaerobic plant this year and for number 7 research is still being carried out, dealing with several unfavourable aspects. In September 1981 research for anaerobic treatment (UASB reactors) was started. After good results had been achieved on laboratory scale (301), further investigations were started on semitechnical scale (50 m3). In both cases the anaerobic seed sludge granulated after a while and loadings up to 20 kg COD/m3.d could be handled. COD-removal was 70 per cent, even when the hydraulic retention time was only 2.5 hours. In April 1983 a 70 m3 practical scale UASB reactor was started up at the solid board mill of Ceres. In October 1983 a full scale plant was started up at Papierfabriek Roermond. This plant consists of a 1,000 m3 UASB reactor and a 70 m3 gasholder. It has been designed and constructed by Paques BV and is used for pretreatment of effluent, in order to reduce the loading of the activated sludge plant. Besides energy savings on the oxygen input, about 1 million m3/year of biogas is being generated and is used for steamproduction. Both plants are working satisfactorily. Investment costs appeared to be relatively low. At Ceres, pay-out time is 1.5 year, while at Papierfabriek Roermond waste water treatment is cheaper than before, although capacity is doubled.

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