Lab-scale Upflow Anaerobic Sludge Research Articles

Treatment of citrus juice process wastewater with UASB and biogas production

A lab-scale up-flow anaerobic sludge blanket (UASB) reactor was used for biogas production from the citrus juice process wastewater (CPWW). The volume of the reactor was 11.5 L. During 200 days of the reactor, the organic loading rate (OLR) value changed from 1.8-21.9 kgCOD./m3.d, upflow velocities (Vup) 0.1-5.2 m/h and hydraulic retention time (HRT) changed from 0.042 to 4.16 days. The reactor showed a stable performance at all organic loadings. Experimental chemical oxygen demand (COD) removal efficiencies were 71.5 ± 21% and 83.3 ± 16.3% for total COD (TCOD) and soluble COD (SCOD), respectively. The acetic acid concentration changed from 135 to 650 mg/L. The temperature was kept in the range of 35.1 ± 1.4 oC, the pH in the range of 6.6 ± 0.2, and the alkalinity was controlled daily and kept in the range of 411 ± 273 CaCO3 mg/L. After anaerobic reactions, 6283 ± 3476 m3/d biogas was produced and the methane concentration in the biogas was 65.5 ± 11.5%. Depending on the methane production, the annual energy value potential that can be obtained from the existing UASB reactor is estimated as 48,768 kWh.

Enhancing Biodegradation of Industrial Wastewater into Methane-Rich Biogas Using an Up-Flow Anaerobic Sludge Blanket Reactor

Anaerobic digestion (AD), the oldest technology used for treating waste, converts organic matter into biogas in the absence of oxygen. The current efforts focuses on improving the digestion of a local industrial wastewater to produce biogas and treat water for reuse. A lab-scale up-flow anaerobic sludge blanket (UASB) reactor operated at 37 °C was employed for the biodegradation the industrial wastewater. A one-factor-at-a-time (OFAT) approach was used to study the effects of influent chemical oxygen demand (CODin), hydraulic retention time (HRT), and magnetic nanoparticles (magnetite) on UASB biogas and COD elimination from digestate wastewater. The optimum HRT for the biodegradation of municipal wastewater was found to be 21 days with contaminants’ removals of 94%, 90.1%, and 98.9% for COD, color, and turbidity, respectively. The addition of magnetite resulted in 225 mL of cumulative biogas produced with 73% methane content, and treatability efficiency of 85%. The most influential factor was magnetite load, which stimulated the microbial activity via redox catalytic reaction in degrading the high organic wastewater (9590 mg COD/L) into biogas production. The prospects of upgrading lab-scale of this technological concept for bioenergy production is viable to mitigate wastewater management and fossil fuel environmental challenges.

Microbial dynamics and methanogenic potential of co-digestion of sugarcane vinasse and dairy secondary effluent in an upflow anaerobic sludge blanket reactor

Co-digestion is a strategy that may prevent microbial inhibition during the anaerobic treatment of sugarcane vinasse, a substrate with highly biodegradable organic load, acidity, and toxic compound levels (e.g., sulfates, phenols). In this context, this study evaluated the microbial dynamics and methanogenic potential throughout the co-digestion of sugarcane vinasse and secondary effluent from the dairy industry in a mesophilic lab-scale upflow anaerobic sludge blanket (UASB) reactor. Periodic next-generation sequencing (NGS) analyses revealed an increase in the relative abundance of the phylum Euryarchaeota (+8.6 % after inoculation), predominating hydrogenotrophic methanogens (Methanobacterium and Methanobrevibacter) at the end of the operation. Moreover, the average methane yield was 221 mLCH4 gCODrem-1, with 69 % of organic matter removal. These results evidenced a progressive acclimation of the anaerobic microbial community to the substrate and a stable operation. Therefore, the proposed experiment demonstrates energy advantages for the agro-industrial sector by implementing a similar but full-scale treatment plant.

Performance of the UASB reactor during wastewater treatment and the effect of the biogas bubbles on its hydrodynamics

ABSTRACT A lab-scale Upflow Anaerobic Sludge Blanket (UASB) reactor was used as a model for evaluating synthetic and complex industrial wastewater treatment, using a solar heater to control temperature. Also, hydrodynamics was assessed using the Computational Fluid Dynamics (CFD) method. Initially, the UASB reactor was operated with synthetic wastewater at Hydraulic Retention Time (HRT) of 24 h in 20 ± 2 °C and 30 ± 2 °C to measure the biogas bubbles production for CFD study. COD removal efficiencies of 85 ± 3% and 95 ± 3%, respectively, with production of 27 and 39 ml CH4/h, correspondingly, were observed. After that, the reactor was fed with complex industrial wastewater. It was evaluated at 24 h in both temperatures. At 30 °C, low COD removal efficiency was observed, being 48 ± 13%, with methane production of 20 ± 3 ml CH4/h. The plug flow pattern was observed in the CFD modelling at HRT of 24 h and 20 °C without considering biogas bubbles interaction. Similar hydrodynamic behaviour was observed at HRT of 24 h and 30 °C. Nonetheless, when biogas bubbles were considered in the CFD modelling, hydrodynamics significantly changed, passing from a plug flow to a complete mix flow pattern.

Microaeration improves the removal/biotransformation of organic micropollutants in anaerobic wastewater treatment systems

This work assessed the effect of increasing microaeration flow rates (1–6 mL min−1 at 28 °C and 1 atm, equivalent to 0.025–0.152 L O2 L−1 feed) on the removal/biotransformation of seven organic micropollutants (OMPs) (three hormones, one xenoestrogen, and three pharmaceuticals), at 200 μg L−1 each, in a lab-scale upflow anaerobic sludge blanket reactor operated at a hydraulic retention time (HRT) of 7.4 h. Additionally, the operational stability of the system and the evolution of its microbial community under microaerobic conditions were evaluated. Microaeration was demonstrated to be an effective strategy to improve the limited removal/biotransformation of the evaluated OMPs in short-HRT anaerobic wastewater treatment systems. The rise in the airflow rate considerably increased the removal efficiencies of all OMPs. However, there seems to be a saturation limit for the biochemical reactions. Then, the best results were obtained with 4 mL air min−1 (0.101 L O2 L−1 feed) (~90%) because, above this flow rate, the efficiency increase was negligible. The long-term exposure to microaerobic conditions (249 days) led the microbiota to a gradual evolution. Consequently, there was some enrichment with species potentially associated with the biotransformation of OMPs, which may explain the better performance at the end of the microaerobic term even with the lowest airflow rate tested.

Adaption strategy of up-flow anaerobic sludge blanket reactor on tetracycline stress during tetracycline antibiotic wastewater treatment

Tetracycline antibiotic wastewater with high chemical oxygen demand (COD) concentration and containing bio-refractory compounds was investigated in a lab-scale up-flow anaerobic sludge blanket (UASB) and anoxic-oxic (A/O) reactor. Specific methanogenic activity (SMA) was determined to reveal the inhibition levels of methane production and volatile fatty acid (VFA) accumulation. The results showed that microorganisms can adapt to tetracycline or oxytetracycline when the concentration of antibiotics is less than 400 mg/L. Acetic acid, propanoic acid, and n-butyric acid accounted for more than 90% of VFA with increasing antibiotic concentration from 50 mg/L to 600 mg/L. During the 215 d of operation, the concentration of tetracycline antibiotic increased from 0 to 95 mg/L, and the COD concentration from 3,500 to 6,500 mg/L. The average COD and tetracycline antibiotic removal rates of the reactors were maintained above 90%. The methane production of the UASB reactor achieved 0.32 L/g COD. VFA accumulation was observed when tetracycline antibiotic concentration increased to 47.5 mg/L. The sludge granule diameter increased from 0–300 μm to 300–1,500 μm during the operation. Rod-shaped and coccus-shaped organisms with pores and internal channels on the granule surface were observed using scanning electron microscopy. In the internal space, methanogenic filamentous bacteria constitute a rock-steady structure.

Microbial properties of the granular sludge in a psychrophilic UASB reactor fed with electronics industry wastewater containing organic chemicals

In this study, a lab-scale upflow anaerobic sludge blanket (UASB) reactor was applied to the treatment of artificial electronics industry wastewater containing tetramethylammonium-hydroxide (TMAH), monoethanolamine (MEA), and isopropyl-alcohol (IPA) in order to evaluate process performance and degradation properties. During 800 days of operation, 96% efficiency of chemical oxygen demand (COD) removal was stably achieved at an organic loading rate of 8.5 kgCOD/m3/day at 18–19 °C. MEA degradation, carried out by acid-forming eubacteria, was confirmed within a week. The physical properties of the retained granular sludge were degraded by feeding with TMAH wastewater, but maintained by feeding with MEA wastewater due to an accumulation of species from the genus Methanosaeta and family Geobacteraceae. Analysis of the microbial community structure via SEM and 16S rRNA genes showed a proliferation of Methanomethylovorans-like cells and Methanosaeta-like cells at the surface and in the core of the granular sludge with TMAH, MEA and IPA acclimation. Furthermore, a batch degradation experiment confirmed that process inhibition due to increasing chemical concentration was relatively stronger for TMAH than for MEA or IPA. Thus, controlling the TMAH concentration of the influent to below 1 gCOD/L will be important for the stable treatment of electronics industry wastewater by UASB technology.

Soybean molasses as feedstock for sustainable generation of biomethane using high-rate anaerobic reactor

Anaerobic digestion of agro-industrial wastes is an environmentally friendly green biotechnology of significant interest in order to facilitate sustainable development of bioenergy production. Thus, it becomes important to invest in management processes for agro-industrial wastes, particularly low-cost ones. In this paper, the main purposes were to investigate the performance of a high-rate reactor and biogas generation potential by anaerobic digestion of soybean molasses, which is a viscous liquid of brown color obtained as a byproduct from processing of the soy protein industry concentrate. A lab-scale up-flow anaerobic sludge blanket reactor (UASB reactor), with a total volume of 12 L, was operated at six different organic loading rates (OLR) ranging from 0.28 to 6.98kgCODm−3d−1 (COD of 500–4000 mg L−1). The reactor was fed with soybean molasses for 134 days and maintained under mesophilic conditions. Different values were tested for the hydraulic retention time (HRT of 48, 24 and 12 h). After the fast startup period (52 days), the mean values of removal efficiencies (CODTotal) ranged from 70% to 83% in all experimental periods. In a UASB reactor, a higher organic loading rate of 6.98kgCODm−3d−1 could be tolerated, but it resulted in a lower biomethane yield of 356.1mLCH4gCOD−1. In addition, for all the tested COD concentrations and HRT, high concentrations of methane in the biogas were obtained from 72.5% to 82.1%. Based on the experimental results, it can be verified that this high-rate anaerobic configuration can be used for the biomethane generation of soybean molasses and the produced effluent can be reutilized in the dilution of soybean molasses for reactor feed.

Start-up study of biohydrogen production from palm oil mill effluent in a lab-scale up-flow anaerobic sludge blanket fixed-film reactor

A start-up study of lab-scale up-flow anaerobic sludge blanket fixed-film reactor (UASFF) was conducted to produce biohydrogen from palm oil mill effluent (POME). The reactor was fed with POME at different hydraulic retention time (HRT) and organic loading rate (OLR) to obtain the optimum fermentation time for maximum hydrogen yield (HY). The results showed the HY, volumetric hydrogen production rate (VHPR), and COD removal of 0.5–1.1 L H2/g CODconsumed, 1.98–4.1 L H2 L−1 day−1, and 33.4–38.5%, respectively. The characteristic study on POME particles was analyzed by particle size distribution (PSD), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX). The microbial Shannon and Simpson diversity indices and Principal Component Analysis assessed the alpha and beta diversity, respectively. The results indicated the change of bacterial community diversity over the operation, in which Clostridium sensu stricto 1 and Lactobacillus species were contributed to hydrogen fermentation.

Magnetite enhances anaerobic digestion of high salinity organic wastewater

Biological treatment of high salinity organic wastewater is a significant challenge because many microorganisms involved in the anaerobic digestion process cannot survive high osmotic pressures. In order to alleviate some of the stresses associated with the treatment of high salinity wastewater, two lab-scale up-flow anaerobic sludge bed reactors with or without magnetite (100 g/L) were used to treat high salinity organic wastewater. This study showed that the bioreactor amended with magnetite had higher chemical oxygen demand removal efficiencies (90.2% ± 0.54% vs 73.1% ± 1.9%) and methane production rates (4082 ± 334 ml (standard temperature and atmospheric pressure, STP)/d vs 2640 ± 120 ml (STP)/d) than the non-amended control reactor. In addition, the consumption of volatile fatty acids (20.9 ± 3.4 mM vs 61.7 ± 2.0 mM) was accelerated. Microbial community analysis revealed that the addition of magnetite caused the enrichment of many bacterial genera known to form robust biofilms (i.e. Pseudomonas) that are also capable of extracellular electron transfer and methanogens from the genus Methanosarcina which have been shown to participate in direct interspecies electron transfer. These results show that magnetite addition could enhance the performance of anaerobic digesters treating high salinity wastewater.

Performance of a high-rate anammox reactor under high hydraulic loadings: Physicochemical properties, microbial structure and process kinetics

In this study, a lab-scale upflow anaerobic sludge blanket (UASB) reactor was applied to studying the high-rate nitrogen removal of granule-based anammox process. The nitrogen removal rate (NRR) finally improved to 15.77 kg/m3/d by shortening hydraulic retention time (HRT) to 1.06 h. Well-shaped red anammox granules were extensively enriched inside the reactor. The results of nitrogen removal kinetics indicated that the present bioreactor has great nitrogen removal potential, because the maximum rate of substrate utilization (Umax) predicted by Stover-Kincannon model is suggested as 55.68 kg/(m3·d). Analysis of the microbial community showed that the anammox genus Candidatus Kuenenia dominated the bacterial communities. The relative abundance of Candidatus Kuenenia rose from 12.29% to 36.95% after progressively shorter HRT and higher influent substrate concentrations, illustrating the stability of nitrogen removal performance and biomass enrichment offered by the UASB in carrying out high-rate anammox process.

Influences of Temperature and Substrate Particle Content on Granular Sludge Bed Anaerobic Digestion

Influences of temperature (25–35 °C) and substrate particulate content (3.0–9.4 g total suspended solids (TSS)/L) on granular sludge bed anaerobic digestion (AD) were analyzed in lab-scale reactors using manure as a substrate and through modeling. Two particle levels were tested using raw (RF) and centrifuged (CF) swine manure slurries, fed into a 1.3-L lab-scale up-flow anaerobic sludge bed reactor (UASB) at temperatures of 25 °C and 35 °C. Biogas production increased with temperature in both high- and low-particle-content substrates; however, the temperature effect was stronger on high-particle-content substrate. RF and CF produced a comparable amount of biogas at 25 °C, suggesting that biogas at this temperature came mainly from the digestion of small particles and soluble components present in similar quantities in both substrates. At 35 °C, RF showed significantly higher biogas production than CF, which was attributed to increased (temperature-dependent) disintegration of larger solid particulates. Anaerobic Digestion Model No.1 (ADM1) based modeling was carried out by separating particulates into fast and slow disintegrating fractions and introducing temperature-dependent disintegration constants. Simulations gave a better fit for the experimental data than the conventional ADM1 model.

Anaerobic treatment of glutamate-rich wastewater in a continuous UASB reactor: Effect of hydraulic retention time and methanogenic degradation pathway.

To investigate the anaerobic treatment efficiency and degradation pathways of glutamate-rich wastewater under various hydraulic retention times (HRTs), a lab-scale upflow anaerobic sludge blanket (UASB) reactor was operated continuously for 180 days. Results showed that high chemical oxygen demand (COD) removal efficiencies of 95.5%-96.5% were achieved at HRTs of 4.5h-6h with a maximum methane yield of 0.31L-CH4/g-COD. When the HRT was shortened to less than 3h, the removal performance of the reactor declined. There also was an excessive accumulation of volatile fatty acids, which implies that an appropriately small HRT is applicable to the UASB reactor treating glutamate-rich wastewater. Methanogenic degradation of glutamate in the UASB reactor depended on the HRT applied, and the typical methane-producing capability of the sludge at an HRT of 3h, in descending order, was acetate>glutamate>butyrate>H2/CO2>valerate>propionate. Clostridium and Methanosaeta were predominant in the glutamate-degrading sludge. At least three degradation pathways most likely existed in the UASB reactor, and the pathway via 3-methlaspartate by Clostridium pascui was expected to be dominant.

Temperature effects on the methanogenesis enhancement and sulfidogenesis suppression in the UASB treatment of sulfate-rich methanol wastewater

This study aims at investigating that the temperature effects on the overall organics removal capability and the reaction kinetic properties of methanogenesis/sulfidogenesis in anaerobic treatment of sulfate-rich methanol wastewater. A lab-scale upflow anaerobic sludge blanket (UASB) reactor was operated for 285 days treating sulfate-rich methanol wastewater at a temperature range of 17.5–50 °C. The COD/SO42− ratio of synthetic wastewater is 0.5. Experimental results indicate that both methanogens and sulfidogens showed lower metabolic activities at 17.5–25 °C. The average chemical oxygen demand (COD) removal efficiencies were higher than 90% at 40–50 °C. During these experimental periods, larger than 85% of influent COD was confirmed to be utilized for methanogenesis, revealing that methanogens prevailed over sulfidogens and dominated significantly in the COD utilization. In contrast, the sulfidogenesis-based COD utilization was effectively limited under the temperature range of 40–50 °C.

Settling velocity and size distribution measurement of anaerobic granular sludge using microscopic image analysis

Settling velocity and size distribution of anaerobic granular sludge samples were studied using microscopic image analysis and settling column experiments. Five granule samples were considered in this study. Three samples were collected at the Top, Middle and Bottom sections of a lab scale upflow anaerobic sludge bed reactor (UASB). Two other granule samples were obtained from industries. This paper aims to establish a method that uses microscopic image analysis and shape factor as a tool to determine the size distribution and settling velocity of anaerobic granules. Image analysis technique was used to calculate the shape factor and equivalent diameter of granules. The equivalent diameter was then used to calculate the theoretical settling velocities based on Allen's formula and estimate size distributions.The results showed that there was a good agreement between the theoretical and experimental mean settling velocity values. Both measured and calculated settling velocities increased with increasing Reynolds number (Re). However, the agreement between measured and calculated values was found to be weaker at higher Re values. Size distribution analyses of the granules have revealed that there was significant difference in the size distribution of granule samples collected at different heights of the lab scale reactor. Overall, granules from the bottom section of the reactor had larger diameter, settling velocity and shape factor than those at the middle and top section granules. Whereas granules collected from the top section exhibited the smallest granular diameter, settling velocity and shape factor.

Population Changes of Eubacteria, Sulfate-Reducing Bacteria and Methanogenic Archaea in an Anaerobic Reactor Processing Ethanol Distillery Vinasse

Abstract The microbiological characterization by molecular techniques (DGGE and quantitative PCR) of Archaea, Bacteria domain and sulfate-reducing bacteria (SRB) from a laboratory scale Up-flow Anaerobic Sludge Blanket (UASB) processing sugar cane vinasse was performed during the operational phase with increasing organic loads. The organic load removal efficiency was between 97% and 75% for volumetric organic loads (VOL) in the range of 0.6 to 15.4 kgCOD.m-3.d−1 and for higher VOL (until 27.0 kgCOD.m-3 .d−1) the removal efficiency decreased to 48%. Archaea represented the majority of the estimated population (107 copies of 16S RNA ribosomal gene. mL-1) followed by bacteria (106 copies of 16S RNA ribosomal gene. mL-1) and sulfate-reducing bacteria (SRB) (105 copies of dsrB gene. mL-1). There was a significant difference between the populations of Archaea and SRB with increasing VOL. DGGE profiles show differences among populations with increasing VOL, especially with respect to sulfate-reducing bacteria. The presence of SRB together with a high sulfate removal percentage (97%) of about 15 kgCOD.m-3d-1h, indicates the establishment of a sulfidogenic process.

A comprehensive insight into the functional bacteria and genes and their roles in simultaneous denitrification and anammox system at varying substrate loadings.

Simultaneous denitrification and anammox process are newly developed wastewater treatment processes with high-nitrogen removal efficiency, but little information is available regarding its optimal operational conditions and molecular mechanisms. In this study, a lab-scale up-flow anaerobic sludge blanket bioreactor fed with nitrate and ammonia was continuously operated for 180days to establish the simultaneous denitrification and anammox system, so as to investigate the changing patterns of nitrogen removal efficiency and functional bacteria and genes at varying substrate loadings. Results showed that the optimal removal efficiency of total nitrogen (TN) reached 92.47%, corresponding to TN loading removal rate of 0.9kg-Nm-3day-1 that was achieved at low influent substrate concentrations and short hydraulic retention time (HRT) (4h). High-throughput sequencing of 16S rRNA gene amplicons revealed that the predominant denitrifying and anammox bacteria in the coupling system were Thauera (relative abundance of 25.30%) and Candidatus Brocadia (relative abundance of 6.85%), respectively. Quantitative real-time PCR showed that the anammox genes (hzsA, hzsB, and hzo) and denitrifying genes (narG, napA, and nirS) demonstrated high abundance in the optimized bioreactor. Batch experiments were also conducted to determine the temporal difference in the expression of the anammox and denitrifying genes. NarG was found to play a crucial role in nitrate reduction to produce nitrite for anammox bacteria, while nirS was identified as the key genes for nitrite reduction to produce nitric oxide, which acted as an important role in both denitrification and anammox reaction.

Roles and correlations of functional bacteria and genes in the start-up of simultaneous anammox and denitrification system for enhanced nitrogen removal

Simultaneous anammox and denitrification (SAD) is a newly developed wastewater treatment process efficient in nitrogen removal, but its underlying microbiological mechanisms during start-up remains unknown. This study investigated the changing patterns of functional bacteria and genes, as well as their correlation during the start-up (260 d) of the SAD systems in two lab-scale up-flow anaerobic sludge blanket bioreactors separately inoculated with anaerobic granular sludge (R1) and aerobic floccular sludge (R2). Results showed that high total nitrogen removal was achieved in the SAD systems of both R1 (88.25%) and R2 (89.42%). High-throughput sequencing of 16S rRNA gene amplicons revealed that Armatimonadetes phylum had a high abundance (44.34%) in R2, while was not detectable in R1 during the anammox stage. However, the SAD bioreactors retained inherent microbial community and the inoculation with different sludge showed less notable effects on their microbial composition. In the SAD systems, Candidatus Brocadia had high abundance in R1 (2.93%) and R2 (4.64%) and played important role in anammox. Network analysis indicated that Denitratisoma and Dokdonella were positively correlated with nitrite reductase genes nirS and nirK (p < 0.05), while Thermomonas and Pseudomonas showing a positive correlation with nitrate reductase gene narG (p < 0.05) were mainly responsible for the nitrate reduction in the SAD systems. Moreover, the overwhelming dominance of narG v.s. napA revealed the crucial roles of respiratory nitrate reduction in the bioreactors. The results extend our knowledge regarding the microbial ecology of the SAD system, which might be practically helpful for application of the process in wastewater treatment.

Exploration of the formation of self-forming dynamic membrane in an upflow anaerobic sludge blanket reactor

Self-forming dynamic membrane bioreactor (SFDMBR) technology has drawn increased attention recently, especially for its potential application in anaerobic conditions to retain slow growing sludge in the system. To attain maximum sludge retention, quick development of a self-forming dynamic membrane (SFDM) is deemed necessary. A lab-scale upflow anaerobic sludge blanket (UASB) reactor with a side-stream anaerobic SFDMBR was used in this study to investigate the factors affecting the successful formation of a SFDM and identify the indicators of success. The SFDM formed successfully within 60 to 90 min to produce permeates of less than 10 NTU after system optimization. The short formation period and low permeate turbidity provide strong support for the potential of retaining a large amount of sludge in the UASB reactor. The thickness and wet density of the SFDM increased continuously with the decrease in surface area during the formation period. Extracellular polymeric substances (EPS) played an essential role in SFDM formation. Humic acid was the dominant EPS in the sludge, but it did not significantly affect the SFDM formation. Even though polysaccharides only represented 3.7% of the total EPS in sludge, it accumulated on the supporting material as a percentage of the total EPS increased significantly from 6.2% after 60 min to 10.8% after 720 min. Therefore, polysaccharides were the primary reason for the formation of the SFDM. β-polysaccharides were more important because it mainly accumulated on the fiber of the supporting material.

Effect of Organic Loading Rate on Anaerobic Digestion Performance of Mesophilic (UASB) Reactor Using Cattle Slaughterhouse Wastewater as Substrate.

In this study, the performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor operating at mesophilic temperature (35 °C) was examined. Cattle slaughterhouse wastewater (CSWW) was used as the main substrate. The total and effective volumes of the reactor were 8 L and 6 L, respectively. Twelve different organic loading rates (OLR) were applied and the performance was evaluated. The chemical oxygen demand (COD) removal efficiency was more than 90% during batch study. In the continuous study, COD removal was also approximately 90% at OLR 0.4 g/L d−1 which subsequently dropped to below 50% when the loading rate increased to 15 g/L d−1. Approximately 5 L/d of biogas was obtained with high methane concentration at stages VI and XI corresponding to OLR of 2 and 10 g/L d−1, respectively. It was observed that the concentration of volatile fatty acids was low and that the alkalinity of the wastewater was sufficient to avoid acidification. Specific methane yields of 0.36 and 0.38 LCH4/g COD added were achieved at OLR 7 and 10 g/L d−1. A hydraulic retention time (HRT) of 1 day was sufficient to remove greater than 70% of COD which correspond to 89% methane concentration. Parameters like soluble COD, NH3-N, pH, alkalinity, total suspended solid (TSS), fats, oil, and grease were also investigated. The results show that the UASB reactor could serve as a good alternative for anaerobic treatment of CSWW and methane production.