Estimates of methane loss and energy recovery potential in anaerobic reactors treating domestic wastewater

2012 ◽  
Vol 66 (12) ◽  
pp. 2745-2753 ◽  
Author(s):  
L. C. S. Lobato ◽  
C. A. L. Chernicharo ◽  
C. L. Souza
Keyword(s):  
Energy Recovery ◽  
Large Scale ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Energy Potential ◽  
Recovery Potential ◽  
Uasb Reactors

This work aimed at developing a mathematical model that could estimate more precisely the fraction of chemical oxygen demand (COD) recovered as methane in the biogas and which, effectively, represented the potential for energy recovery in upflow anaerobic sludge blanket (UASB) reactors treating domestic wastewater. The model sought to include all routes of conversion and losses in the reactor, including the portion of COD used for the reduction of sulfates and the loss of methane in the residual gas and dissolved in the effluent. Results from the production of biogas in small- and large-scale UASB reactors were used to validate the model. The results showed that the model allowed a more realistic estimate of biogas production and of its energy potential.

scholarly journals Energy potential of biogas and sludge from UASB reactors in the State of Paraná, Brazil

2020 ◽  
Vol 15 (1) ◽  
pp. 1
Author(s):  
Lucas Sampaio Lopes ◽  
Andre Pereira Rosa ◽  
Júlia Silva Marco ◽  
Gustavo Rafael Collere Possetti ◽  
Tayane Cristiele Rodrigues Mesquita
Keyword(s):  
Sewage Treatment ◽  
The State ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Energy Potential ◽  
Total Potential ◽  
Recovery Potential ◽  
Gis Tools ◽  
Uasb Reactors ◽  
By Products

 Upflow Anaerobic Sludge Blanket (UASB) reactors are widely used for domestic sewage treatment in Brazil, and generate sludge and biogas as by-products. Typically, the sludge is sent to sanitary landfills, and the biogas is burned in flares. This study assessed the energy potential of these by-products in sewage treatment plants (STPs) located in the state of Paraná, Brazil. First, an overview of biogas energy recovery potential in a full-scale STP based on UASB reactors was carried out. Afterwards, a total of 239 STPs in the state of Paraná were assessed, and the energy potential of the by-products was estimated by a mathematical model. Data were spatially classified using ArcGIS®, taking into account the different effluent characteristics (worst, typical and best scenario), sludge dehydration systems (drying bed and centrifuge) and sizes (small, medium and large). Among the states in Brazil, Paraná presented the highest biogas potential, although nowadays it exploits only 0.4% of its capacity. Biogas was the main by-product generated by UASB reactors in Paraná, and if used in the entire state, it could supply the energy demands of a city with 111,000 inhabitants. Biogas corresponded to 65, 64 and 74% of the total potential (sludge and biogas) for small, medium and large STPs, respectively. The study of the energy potential of the by-products associated with GIS tools positively contributes to the decision-making process in sanitation management and to improve energy sustainability.

Mathematical modeling of upflow anaerobic sludge blanket (UASB) reactor treating domestic wastewater

2013 ◽  
Vol 67 (1) ◽  
pp. 24-32 ◽  
Author(s):  
Tarek Elmitwalli
Keyword(s):  
Chemical Oxygen Demand ◽  
Dynamic Model ◽  
Empirical Model ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Model Based ◽  
Anaerobic Sludge Blanket

Although the upflow anaerobic sludge blanket (UASB) reactor has been widely applied for domestic wastewater treatment in many developing countries, there is no sufficient mathematical model for proper design and operation of the reactor. An empirical model based on non-linear regression was developed to represent the physical and chemical removal of suspended solids (SS) in the reactor. Moreover, a simplified dynamic model based on ADM1 and the empirical model for SS removal was developed for anaerobic digestion of the entrapped SS and dissolved matter in the wastewater. The empirical model showed that effluent suspended chemical oxygen demand (CODss) concentration is directly proportional to the influent CODss concentration and inversely proportional to both the hydraulic retention time (HRT) of the reactor and wastewater temperature. For obtaining sufficient CODss removal, the HRT of the UASB reactor must be higher than 4 h, and higher HRT than 12 h slightly improved CODss removal. The dynamic model results showed that the required time for filling the reactor with sludge mainly depends on influent total chemical oxygen demand (CODt) concentration and HRT. The influent CODt concentration, HRT and temperature play a crucial role on the performance of the reactor. The results indicated that shorter HRT is needed for optimization of CODt removal, as compared with optimization of CODt conversion to methane. Based on the model results, the design HRT of the UASB reactor should be selected based on the optimization of wastewater conversion and minimization of biodegradable SS accumulation in the sludge bed, not only based on COD removal, to guarantee a stable reactor performance.

Anaerobic Treatment of Domestic Wastewater in Small Scale UASB Reactors

1993 ◽  
Vol 27 (9) ◽  
pp. 75-82 ◽  
Author(s):  
J. J. Bogte ◽  
A. M. Breure ◽  
J. G. van Andel ◽  
G. Lettinga
Keyword(s):  
Organic Matter ◽  
The Netherlands ◽  
Volatile Fatty Acids ◽  
Domestic Wastewater ◽  
Anaerobic Treatment ◽  
Gas Production ◽  
Upflow Anaerobic Sludge Blanket ◽  
Small Scale ◽  
Anaerobic Sludge ◽  
Uasb Reactors

A survey was made on the feasibility of on-site anaerobic treatment of domestic wastewater from small scale emissions in The Netherlands. Three 1.2 m3 UASB-reactors (Upflow Anaerobic Sludge Blanket) were tested in different rural locations. The survey made clear that the efficiency of the process is highly dependent on the reactor temperature. Below 12 °C purification was predominantly based on settling, while above 12 °C microbial degradation of organic matter increased. Efficiencies for the removal of total COD and BOD of two of the reactors ranged between 33 and 60%, equalising well performing septic tanks. In one of the reactors the average production of biogas, with a methane content of 78%, was 67 liters per day. Complete transformation of volatile fatty acids (VFA) into biogas was achieved during 3 to 4 months a year at temperatures above 15 °C. In this period, during the second year of operation, the average efficiencies for COD and BOD removal were 60 and 72% respectively, while the maximum gas production reached 300 liters per day. In the latter period the mineralisation rate exceeded the input rate of organic matter, resulting in a decrease of settled material in the reactor. The possibility of high efficiencies during summertime in The Netherlands and the positive results of similar experiments in Indonesia and Latin America lead to the conclusion that anaerobic digestion is a promising process for the (pre-)treatment of domestic waste water in (sub)tropical countries.

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.

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.

Treatment of a Domestic Wastewater with UASB Reactors

1993 ◽  
Vol 27 (1) ◽  
pp. 195-203 ◽  
Author(s):  
A. Gnanadipathy ◽  
C. Polprasert
Keyword(s):  
Domestic Wastewater ◽  
Upflow Anaerobic Sludge Blanket ◽  
Anaerobic Sludge ◽  
Digested Sludge ◽  
Stabilization Pond ◽  
Waste Stabilization Pond ◽  
Waste Stabilization ◽  
Anaerobically Digested Sludge ◽  
Low Strength ◽  
Uasb Reactors

This study investigated a feasibility of employing pilot-scale upflow anaerobic sludge blanket (UASB) reactors to treat a domestic (or relatively low-strength) wastewater. Four 30-1 UASB reactors, each with a 0.15-m inner diameter and 2-m height were used in this study which was conducted at an average ambient temperature of 30°C. Three reactors were inoculated with different types of seed sludge, namely: sludge from a facultative waste stabilization pond, anaerobically digested sludge and sludge from a UASB reactor treating a distillery wastewater. The fourth reactor was started without inoculum and was studied for possible self inoculation. Domestic wastewater was mixed with a stock glucose solution to increase the influent COD concentrations to about 600 mg/l. All four reactors were started with a hydraulic retention time (HRT) of 24 h, and this HRT was later reduced to 12, 6 and 3 h, consecutively, corresponding to the organic loading rates (OLR) of 0.4-0.6, 0.9-1.4, 1.8-2.8 and 3.6-6.0 kg COD/(m3.d), respectively. At the highest OLR or shortest HRT, there was about 90% removal of the influent COD in Reactors 1-3 while the methane (CH4) production rate was found to be 150 N1/kg COD removed with a methane (CH4) content of 75%. Reactor 4, without inoculation, could not develop sufficient amount of biomass to withstand the high OLR and its performance deteriorated at the HRT of 3 and 6h. The scanning electron microscopic (SEM) examinations of the sludge floc revealed the predominance of Methanothrix-like bacteria in all reactors. The experimental results obtained have suggested a technical feasibility of employing UASB reactors to treat domestic wastewaters. The facultative waste stabilization pond sludge and anaerobically digested sludge were found to be suitable inoculum sources for the UASB reactors treating this low-strength wastewater.

Toxicity of Sodium and Potassium Ions on Performance of UASB System

2014 ◽  
Vol 953-954 ◽  
pp. 1105-1108 ◽  
Author(s):  
Seni Karnchanawong ◽  
Kraiwet Kabtum
Keyword(s):  
Biogas Production ◽  
Cod Removal ◽  
Upflow Anaerobic Sludge Blanket ◽  
Synthetic Wastewater ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Working Volume ◽  
Anaerobic Sludge Blanket ◽  
Uasb Reactors ◽  
Sodium And Potassium

The objective of this study was to investigate the toxicity of Na+and K+ions on performance of upflow anaerobic sludge blanket (UASB) system. Three laboratory-scale UASB reactors, 15.8 - l working volume, were employed with 1 reactor operated as control. They were loaded at organic loading rate (OLR) of 5 kg COD/(m3-d), treating synthetic wastewater with COD concentration ~ 5000 mg/l. Na+and K+ions were added in the range of 1010 - 7180 and 41 - 7320 mg/l, respectively. No toxicity was observed at influent Na+and K+concentrations up to 3340 and 2750 mg/l, respectively. Slight inhibitions on COD removal were founded at Na+and K+concentrations of 4610 and 3920 mg/l, respectively, but moderate effect on biogas production had occurred. When Na+and K+concentrations were increased to 7180 and 7320 mg/l, respectively, strong inhibitions were observed with COD removal dropped to 45.5 and 48.8 %, respectively. Ratios of biogas productions, as compared to the control reactor, were dropped to 0.31 and 0.32, respectively. Increasing cation concentrations had more detrimental effect on biogas production than COD removal.

Herbal pharmaceutical wastewater treatment by a pilot scale upflow anaerobic sludge blanket (UASB) reactor

2009 ◽  
Vol 59 (11) ◽  
pp. 2265-2272 ◽  
Author(s):  
S. Satyanarayan ◽  
A. Karambe ◽  
A. P. Vanerkar
Keyword(s):  
Biogas Production ◽  
Oxygen Demand ◽  
High Strength ◽  
Cost Effective ◽  
Pilot Scale ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Anaerobic Sludge ◽  
Reactor Performance ◽  
Anaerobic Sludge Blanket

Herbal pharmaceutical industry has grown tremendously in the last few decades. As such, literature on the treatment of this wastewater is scarce. Water pollution control problems in the developing countries need to be solved through application of cost effective aerobic/anaerobic biological systems. One such system—the upflow anaerobic sludge blanket (UASB) process which is known to be cost effective and where by-product recovery was also feasible was applied for treatment of a high strength wastewater for a period of six months in a pilot scale upflow anaerobic sludge blanket (UASB) reactor with a capacity of 27.44 m3. Studies were carried out at various organic loading rates varying between 6.26 and 10.33 kg COD/m3/day and hydraulic retention time (HRT) fluctuating between 33 and 43 hours. This resulted in chemical oxygen demand (COD), biochemical oxygen demand (BOD) and suspended solids (SS) removal in the range of 86.2%–91.6%, 90.0%–95.2% and 62.6%–68.0% respectively. The biogas production varied between 0.32–0.47 m3/kg COD added. Sludge from different heights of UASB reactor was collected and subjected to scanning electron microscopy (SEM). The results indicated good granulation with efficient UASB reactor performance.

scholarly journals Management challenges for a more decentralized treatment and reuse of domestic wastewater in metropolitan areas

2017 ◽  
Vol 8 (1) ◽  
pp. 113-122 ◽  
Author(s):  
Martín Alejandro Iribarnegaray ◽  
María Soledad Rodriguez-Alvarez ◽  
Liliana Beatriz Moraña ◽  
Walter Alfredo Tejerina ◽  
Lucas Seghezzo
Keyword(s):  
Urban Planning ◽  
Oxygen Demand ◽  
Domestic Wastewater ◽  
Upflow Anaerobic Sludge Blanket ◽  
Uasb Reactor ◽  
Septic Tank ◽  
Anaerobic Sludge ◽  
Social Perspectives ◽  
Open Debate ◽  
Filtration Step

Abstract In a case study located in suburban sectors of the metropolitan area of the Lerma Valley (Valle de Lerma), in the province of Salta (Argentina), 24 informal decentralized wastewater treatment systems (DWWTS) were evaluated. The analyzed systems had three general configurations: A, septic tank; B, septic tank combined with upflow anaerobic sludge blanket (UASB) reactor; C, septic tank combined with UASB and a final filtration step. Statistically significant differences (p < 0.05) were observed in effluent quality, measured as total coliforms, thermotolerant coliforms, and chemical oxygen demand (COD). Treatment A was the most inefficient, and was statistically different from B and C; there were no significant differences between the latter two. Thermotolerant coliform concentrations were high in all analyzed systems and did not comply with local discharge standards in soakaway pits or in the ground. The lack of a final disinfection step in these systems is thus a weakness that needs to be addressed. The formal inclusion of DWWTS in urban planning could reduce overall investment costs, as long as the best technologies are selected for each case. Incorporation of DWWTS in formal urban planning requires an open debate in which the social perspectives of all relevant users need to be considered.

Modeling simultaneous removal of primary substrates and chlorinated phenols in upflow anaerobic sludge blanket reactors

2001 ◽  
Vol 28 (6) ◽  
pp. 910-921 ◽  
Author(s):  
K J Kennedy ◽  
Z Ning ◽  
L Fernandes
Keyword(s):  
Dynamic Model ◽  
Model Development ◽  
Oxygen Demand ◽  
Upflow Anaerobic Sludge Blanket ◽  
Organic Loading Rate ◽  
Anaerobic Sludge ◽  
Chlorinated Phenols ◽  
Degradation Rates ◽  
Anaerobic Sludge Blanket ◽  
Uasb Reactors

A dynamic model describing the simultaneous degradation of easily degradable substrates (sucrose and acetic acid (HAc)) and 2,4-dichlorophenol (2,4-DCP) in upflow anaerobic sludge blanket (UASB) reactors was developed. The two critical factors considered in the model development were sorption and substrate interaction during degradation. Data obtained from experiments on the multiple substrate degradation in continuous UASB reactors were used to validate and verify the dynamic model. The model predicts the system responses for 2,4-DCP, 4-monochlorophenol (4-MCP), HAc, propionic acid (HPr), and chemical oxygen demand (COD) concentration in the effluent. The modeling results indicated that the degradation rates for 2,4-DCP and for cosubstrates, HAc and HPr, changed inversely as a function of the specific organic loading rate for UASB reactors.Key words: dynamic, modeling, UASB, 2,4-dichlorophenol, sorption, degradation, co-metablism.

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