Upflow Anaerobic Sludge Blanket Reactor Research Articles

Isolation and physiological properties of methanogenic archaea that degrade tetramethylammonium hydroxide

Tetramethylammonium hydroxide (TMAH) is a known toxic chemical used in the photolithography process of semiconductor photoelectronic processes. Significant amounts of wastewater containing TMAH are discharged from electronic industries. It is therefore attractive to apply anaerobic treatment to industrial wastewater containing TMAH. In this study, a novel TMAH-degrading methanogenic archaeon was isolated from the granular sludge of a psychrophilic upflow anaerobic sludge blanket (UASB) reactor treating synthetic wastewater containing TMAH. Although the isolate (strain NY-STAYD) was phylogenetically related to Methanomethylovorans uponensis, it was the only isolated Methanomethylovorans strain capable of TMAH degradation. Strain NY-STAYD was capable of degrading methylamine compounds, similar to the previously isolated Methanomethylovorans spp. While the strain was able to grow at temperatures ranging from 15 to 37°C, the cell yield was higher at lower temperatures. The distribution of archaeal cells affiliated with the genus Methanomethylovorans in the original granular sludge was investigated by fluorescence in situ hybridization (FISH) using specific oligonucleotide probe targeting 16S rRNA. The results demonstrated that the TMAH-degrading cells associated with the genus Methanomethylovorans were not intermingled with other microorganisms but rather isolated on the granule's surface as a lone dominant archaeon. KEY POINTS: • A TMAH-degrading methanogenic Methanomethylovorans strain was isolated • This strain was the only known Methanomethylovorans isolate that can degrade TMAH • The highest cell yield of the isolate was obtained at psychrophilic conditions.

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.

New insights into multi-strategies of sludge granulation in up-flow anaerobic sludge blanket reactors from community succession and interaction

This study aimed to elucidate the multiple strategies employed by anaerobes during granulation in a laboratory upflow anaerobic sludge blanket reactor, based on microbial succession and interactions. The anaerobic granulation process featured staged dominance of microbial genera, corresponding well with the environmental traits. Across the stages (selection, seeding, expansion, and maturation), chemotaxis attraction of nitrogen and/or carbon sources and flagellar motion were the primary strategy of microbial assembly. The second messengers – cyclic adenosine and guanosine monophosphates – partially regulated the agglomeration of filamentous Euryachaeota and Chloroflexi as the inner cores, while quorum sensing mediated the expansion of granules prior to maturation. Antagonism or competition governed the interactions within the phylogenetic molecular ecological network during sludge granulation, which were largely driven by the low-abundance (<1%) taxa. These new insights suggest that better engineering solutions to enhance chemotaxis attraction and species selection could achieve more efficient anaerobic granular sludge processes.

Upflow anaerobic sludge blanket reactor operation under high pressure for energy-rich biogas production

Autogenerative high-pressure digestion has an advantage of producing CH4-rich biogas directly from the reactor. However, its continuous operation has rarely been reported, and has never been attempted in an upflow anaerobic sludge blanket reactor (UASB). Here, UASB was continuously operated at 10 g COD/L/d with increasing pressure from 1 to 8 bar. As the pressure increased, the CH4 content in the biogas increased gradually, reaching 96.7 ± 0.8% at 8 bar (309 MJ/m3 biogas). The pH was dropped from 8.2 to 7.2 with pressure increase, but COD removal efficiency was maintained > 90%. The high pressure up to 8 bar did not adversely impact the physicochemical properties of granules, which was due to the increased production of extracellular polymeric substances (EPS), particularly, tightly bound EPS (34% increase). With pressure increase, there was no changes in the microbial community and ATPase gene expression, but 41% increase in carbonic anhydrase gene expression was observed.

Impacts and mechanism of total organic sulfur in extracellular polymeric substances on fouling of the anaerobic self-forming dynamic membrane bioreactor

A side-stream cross-flow anaerobic self-forming dynamic membrane bioreactor (AnSFDMBR) connected with an up-flow anaerobic sludge blanket (UASB) reactor was used to replace the UASB and middle settling tank in sulfate reduction, autotrophic denitrification, and nitrification integrated (SANI) process. To reduce the water and energy consumption for AnSFDMBR backwashing, the optimum condition of trans-membrane pressure (TMP)-based backwashing were investigated under sequential batch operations. Based on the optimum condition, a lab-scale AnSFDMBR was operated continuously for 243 days without a drop in flux, with good effluent quality. In the sequential batch operation study, AnSFDMBR showed no significant accumulation of total extracellular polymeric substances (EPSs) during 40 days of operation without backwashing. Polysaccharides slightly accumulated in the dynamic layer regardless of the final TMP and operation duration, indicating that TMP-based backwashing is suitable for the studied AnSFDMBR system. In long-term operation with TMP-based backwashing, total EPSs in dynamic layer to sludge ratio dramatically dropped during the fouling phase. According to the evaluation of total organic sulfur (TOS) in dynamic layer and mesh EPSs, it was found that TOS, mainly poly-sulfur generated in UASB reactor, played a critical role in fouling in saline wastewater treatment. TOS deposited on the mesh over 40% by weight of the total EPS in the fouling phase clearly led to system fouling. Additional sequential batch operations with different seawater percentages (%V/V) (control, 10%, 20%, 30% and 50%) demonstrated that the TOS accumulation on the mesh increased with time and salinity which also aligned with the long-term operation.

From start-up to maximum loading: An approach for methane production in upflow anaerobic sludge blanket reactor fed with the liquid fraction of fruit and vegetable waste

This investigation provides a reproducible approach for determining the limits of an upflow anaerobic sludge blanket (UASB) reactor designed for the methanization of the liquid fraction of fruit and vegetable waste (FVWL). Two identical mesophilic UASB reactors were operated for 240 days with a three-day fixed hydraulic retention time and an organic load rate (OLR) increased from 1.8 to 10 gCOD L−1 d−1. Because of the previous estimation of flocculent-inoculum methanogenic activity, it was possible to design a safe OLR for the quick start-up of both UASB reactors. The operational variables obtained from the operation of the UASB reactors did not show statistical differences, ensuring the experiment's reproducibility. As a result, the reactors achieved methane yield close to 0.250 LCH4 gCOD−1 up to the OLR of 7.7 gCOD L−1 d−1. Furthermore, the maximum volumetric methane production rate of 2.0 LCH4 L−1 d−1 was discovered for the OLR ranges between 7.7 and 10 gCOD L−1 d−1. The possible overload at OLR of 10 gCOD L−1 d−1 resulted in a significant reduction of methane production in both UASB reactors. Based on the methanogenic activity of the UASB reactors sludge, a maximum loading capacity of approximately 8 gCOD L−1 d−1 was estimated.

Deciphering the role of granular activated carbon (GAC) in anammox: Effects on microbial succession and communication

Anaerobic ammonium oxidation (anammox) offered an energy-efficient option for nitrogen removal from wastewater. Granular activated carbon (GAC) addition has been reported that improved biomass immobilization, but the role of GAC in anammox reactors has not been sufficiently revealed. In this study, it was observed that GAC addition in an upflow anaerobic sludge blanket (UASB) reactor led to the significantly shortened anammox enrichment time (shortened by 45 days) than the reactor without GAC addition. The nitrogen removal rate was 0.83 kg N/m3/day versus 0.76 kg N/m3/day in GAC and non-GAC reactors, respectively after 255 days’ operation. Acyl-homoserine lactone (AHL) quorum sensing signal molecule C8-HSL had comparable concentrations in both anammox reactors, whereas the signal molecule C12-HSL was more pervasive in the reactor containing GAC than the reactor without GAC. Microbial analysis revealed distinct anammox development in both reactors, with Candidatus Brocadia predominant in the reactor that did not contain GAC, and Candidatus Kuenenia predominant in the reactor that contained GAC. Denitrification bacteria likely supported anammox metabolism in both reactors. The analyses of microbial functions suggested that AHL-dependent quorum sensing was enhanced with the addition of GAC, and that GAC possibly augmented the extracellular electron transfer (EET)-dependent anammox reaction.

Evaluating the Potential of Renewable Energy Sources in a Full-Scale Upflow Anaerobic Sludge Blanket Reactor Treating Municipal Wastewater in Ghana

Wastewater management remains a major challenge in developing countries due to the lack of adequate infrastructure, making the need for economically viable and efficient technologies that can be sustained by emerging economies imperative. The upflow anaerobic sludge blanket (UASB) reactor represents an efficient and low-cost technology that produces by-products from which valuable resources can be recovered. This study assessed the energy recovery potential in the form of electricity from biogas and sludge by-products produced by a full-scale UASB reactor. Biogas production rate and composition were monitored to determine the biogas energy recovery potential. Dehydrated sludge from sludge drying beds was likewise quantified and characterised for its elemental composition, immediate composition, gross calorific value and net calorific value to estimate sludge energy recovery potential. The average daily biogas production was found to be 611 ± 275 Nm3/d, with 65% methane in the biogas output. Average sludge dry matter production was determined to be 358.24 TS kg/d. The net energy recovery potential was estimated to be 534.1 MWh/yr, 36% more than the yearly energy demand (392.7 MWh/yr) of the entire plant. Conservative energy recovery at a UASB-based municipal wastewater treatment facility could serve as a self-supply energy option to support its operations.

Effect of selenate on treatment of glycerol containing wastewater in UASB reactors

The effect of selenate on the removal of glycerol in up-flow anaerobic sludge blanket (UASB) reactors was investigated. Two UASB reactors, RControl and RSelenium, were operated at a hydraulic retention time of 48 h and an upflow velocity of 2 m/h at 37 °C. A GAL (glucose, acetate and lactate) and glycerol mixture were used as the only feedstock throughout the experiment for RControl. After acclimation to GAL and glycerol in the start-up period, RSelenium was additionally exposed to selenate (SeO42−) concentrations from 1.43 to 71.49 mg/L (10–500 μM) in a stepwise manner. An average daily methane yield of about 150 mL/g COD, which was comparable with RControl, and 90% Se removal were achieved until 400 μM SeO42−. Simultaneously, SeO42− was reduced to elemental Se or metal selenide, supported by X-ray diffraction, as well as scanning and transmission electron microscopy. However, the methane production rapidly deteriorated when the influent SeO42− concentration was increased to 500 μM. The Se toxicity was evident from the reduction in the activity of Methanosaeta. This study showed that the SeO42− concentration, but not the COD/SeO42− ratio, governs the AD of selenate rich wastewaters.

Enabling efficient phosphorus recovery from cow manure: Liberation of phosphorus through acidification and recovery of phosphorus as calcium phosphate granules

Cow manure (CM) is one of the largest secondary sources of phosphorus, while mined phosphorus rock is becoming scarce and diminishing in quality. Phosphorus recovery from CM is essential for increasing the phosphorus use efficiency and, therefore, securing future food production. Calcium phosphate (CaP) granulation can enable efficient phosphorus recovery during anaerobic digestion. However, in CM, the absence of phosphorus in the ionic form and the high presence of inorganic carbon and magnesium inhibits CaP granulation. In this study, CaP granulation was achieved for the first time during CM treatment, using an up-flow anaerobic sludge blanket (UASB) reactor preceded by an acidifying continuously stirred tank reactor (CSTR). The UASB reactor and CSTR ran for 190 days at organic loading rates of 1 and 22.5 gCOD Lreactor-1 d-1, respectively. The acidification of CM at pH 5 dissolved struvite and calcium carbonate, causing > 94% of phosphorus, calcium and magnesium to be present as ions. In the UASB reactor fed with the CSTR effluent, 83 ± 3% of phosphorus was removed and mainly present as CaP granules > 2.5 mm in diameter. The CaP granules had a phosphorus content of 8.4 ± 1.3%P w/w with amorphous and crystalline calcium phosphate being the dominant phases. The formation of large and concentrated CaP granules causes accumulation at the bottom of the reactor and allows for simple size separation leading to efficient phosphorus recovery The recovery of CaP granules improves CM valorization and can reduce the transport of manure by up to 87%. The acidification prior to digestion thus promotes a more efficient use of phosphorus from CM in agriculture and can replace phosphorus from primary phosphorus sources.

Response of dissimilatory perchlorate reducing granular sludge (DPR-GS) system to high-strength perchlorate and starvation stress in UASB reactor: Performance, kinetics and recovery mechanism

Under high-strength perchlorate concentration ranging from 300 to 1300 mg/L, the dissimilatory perchlorate reducing granular sludge (DPR-GS) was successfully cultivated in an up-flow anaerobic sludge blanket (UASB) reactor to investigate performance and starvation recovery for treating perchlorate wastewater. The mature DPR-GS had excellent perchlorate removal efficiency (98.47%) at 1200 mg/L. Microbial community analysis suggested that the dominant genera in mature DPR-GS were Sulfurospirillum and Acinetobacter. The DPR-GS system conformed well to the modified Stover-Kincannon model with the maximum substrate utilization (Umax) of 90.01 kg/(m3·d) and the saturation value constant (KB) of 83.93 kg/(m3·d). Additionally, the starvation recovery of DPR-GS system was first investigated. The perchlorate removal efficiency recovered to 91.39% after 8 days under the 30-day starvation stress, and the microbial activity also recovered to normal condition. The three-dimensional excitation-emission matrix (3D-EEM) proved that the tryptophan-like component in extracellular polymeric substance (EPS) increased during the starvation period, which was associated with immune functions and played an important role in maintaining the microbial activity. Meanwhile, the secretion of humic acid-like component in EPS promoted electron transfer efficiency, thus improving microbial metabolic activity during the recovery period. Further analysis by the parallel factor (PARAFAC) of 3D-EEM confirmed that the decrease of immune substances and the increase of metabolic products in EPS during the starvation recovery period, which enhanced the recovery of microbial activity and the improvement of perchlorate removal performance. This study revealed the response of the DPR-GS system to high-strength perchlorate and starvation stress, thus provided a further basis of perchlorate tolerance and starvation recovery for the application of DPR-GS system to remove high-strength concentrated perchlorate from contaminated water.

EFFECT OF TRACE METAL FECL3 ON BIOGAS PRODUCTION IN INDUSTRIAL WASTEWATER TREATMENT WITH HIGH ORGANIC LOAD

Wastewater from the food industry that contains a high organic load, such as wastewater from the tofu manufacturing process, requires an appropriate and efficient treatment system to reduce pollutants before being discharged into water bodies. The most suitable treatment for high organic loads is the anaerobic treatment system. The anaerobic treatment process is a system of suspended media, attached media, or the combination thereof as a hybrid. This study uses a Hybrid Upflow Anaerobic Sludge Blanket (HUASB) reactor with the consideration that this reactor has advantages in maintaining high concentrations of biomass, high operating load rates, good decomposition capabilities, and good solid-liquid separation due to suitable granulation. The purpose of this study was to determine the effect of the addition of the trace metal FeCl3 on biogas production and the ability to remove pollutants in the tofu industrial process wastewater treatment in the HUASB reactor. The operation of the reactor uses variations in the concentration of tofu industrial waste water (75 and 100%) and trace metal concentrations (0.3–0.6 mg/L). The optimum biogas production was obtained with 8190 mL at a concentration of 75% tofu industrial waste water, a trace metal concentration of 0.6 mg/L FeCl3, and removal of COD and TSS of 94.09% and 94.2%, respectively. The role of the trace metal FeCl3in the anaerobic process shows that it is a source of nutrition for increasing the growth of microorganisms in anaerobic systems so that biogas production and pollutant removal are increased.

Anaerobic digestion of liquid dairy manure pretreated by the microwave-enhanced advanced oxidation process

ABSTRACT The microwave-enhanced advanced oxidation process (MW-AOP) was utilized for the treatment of liquid dairy manure, prior to anaerobic digestion (AD). A significant amount of soluble chemical oxygen demand (SCOD) was formed in the treated solution, but there was no or little increase in volatile fatty acid (VFA). In this study, up-flow anaerobic sludge blanket (UASB) reactors were used in both the conventional AD system and as the methane phase reactor in a two-phase anaerobic digestion (TPAD) system. Both AD systems were capable of operating at very short hydraulic retention times (HRTs) to as low as about 3 days, and very high methane production rates were achieved. However, much higher methane production was obtained in the TPAD system. The phase separation of the acidogenesis and the methanogenesis in the TPAD system not only increased methane production but also maintained reactor stability throughout the experimental period. Thus, the combination of MW-AOP treatment and TPAD appears to be an effective means of energy recovery from dairy manure.

Variations of Organic Loading Rate on Tofu Wastewater Degradation using Upflow Anaerobic Sludge Blanket Reactor by Modified Stover-Kincannon Model

This research aims to examine the varians of organic loading rate (OLR) on degradation of tofu wastewater using the hybrid upflow anaerobic sludge blanket (hybrid UASB) reactor using the modified kinetic model of Stover Kincannon. This reactor was operated at OLRs variation of 1.5-12 kg COD m-3 d-1 and HRT of 12 - 24 hours for 328 days. Higher COD removal efficiency of 86.41% and biogas production of 7700 mL were achieved at OLR 4.8 kg COD m-3 d-1 and HRT 24 hours on 140 days. Modified Stover-Kincannon model was observed and matched data sets were obtained. The kinetic values of model obtained at HRT variations, the parameters KB and μmax were 3.7, 12.97, 2.42 mgL-1 d-1 and 0.59, 9.41, 0.014 mgL-1 d-1, respectively. This model was a plot of the inverse of the removal rate, versus inverse of the total loading rate resulted in a straight line. It showed that the Stover-Kincannon Model is the rate of substrate removal was affected by the organic load rate (OLR) that flowed into the hybrid UASB reactor.

Enhanced Degradation of the Substrate Using Modified Upflow Anaerobic Sludge Blanket Reactor–Static Granular Bed Reactor Series with Varying Hydraulic Retention Time at Lab Scale

The performance of a modified upflow anaerobic sludge blanket (MUASB) reactor with a modified three-phase separator and a rope matrix, combined with SGBR in series was analyzed for the treatment of synthetic wastewater. The performance of the reactor series in terms of chemical oxygen demand (COD) removal was evaluated by varying the operational hydraulic retention times (HRT) from 12 to 30 h. The optimum HRT for the reactor series was found to be 24 h, with a corresponding organic loading rate (OLR) of 8 kg COD/m3/day. The maximum overall COD removal of the reactor series of 98.75% ±0.62% was obtained with the corresponding overall biogas production of 0.339%±0.01 m3/kg CODdigested. The reactor series was found to be stable during the operational period in terms of volatile fatty acids (VFAs)/alkalinity ratio. The analytical hierarchy process was used for choosing a better treatment option among the alternatives based on the selected criteria. MUASB–static granular bed reactor (SGBR) series was found to be superior to the MUASB and the SGBR individually based on COD removal. The payback period for the reactor series was calculated to be 8 years (approximately). The MUASB-SGBR series was found to be robust, stable, and economical, with better performance in terms of COD removal.

Kinetics of Substrate degradation in Upflow Anaerobic Sludge Blanket Reactor

Kinetics of Substrate degradation in Upflow Anaerobic Sludge Blanket Reactor

The role of protein contents in promoting wastewater phosphorus and bioenergy recovery during anaerobic digestion

Proteins present in domestic and industrial wastewater, yet their role in nutrient and energy recovery during anaerobic digestion (AD) has not been well understood. This study aimed to examine the impact of feedwater protein content on the calcium phosphate (CaP) precipitation under a low supersaturation condition and the methane production in an AD process. Four 1.0 L upflow anaerobic sludge blanket (UASB) reactors were fed with the synthetic feeds with different protein contents. The results showed that the amino acid degradation caused the pH elevation, triggering the CaP precipitation. A 25% bovine serum albumin (BSA) content in the feedwater helped shape a superior microbial community that contributed to a methanisation rate of 82.7%. The high prevalence of the phylum Synergistetes and the methanogen Methanosaeta suggested that methane was mainly produced through the acetate utilization.

Start-Up Evaluation of a Full-Scale Wastewater Treatment Plant Consisting of a UASB Reactor Followed by Activated Sludge

UASB (upflow anaerobic sludge blanket) reactors have been recognized as a viable option for sewage treatment. However, in order to improve the UASB effluent quality, some type of post-treatment must be implemented. The aims of this study were (i) to establish a start-up methodology of a full-scale anaerobic–aerobic system treating sewage, (ii) to evaluate the concentrations of different constituents in the influent and effluent of the anaerobic and aerobic reactors as well as the removal efficiencies in every step of the system, and (iii) to define relevant operative aspects of the anaerobic and aerobic reactors. The Tunja (Colombia) wastewater treatment plant consists of three modules with preliminary treatment followed by UASB reactors with post-treatment of activated sludge. The results of this investigation showed that the effluent system meets the Colombian environmental legislation with average removal efficiency values of BOD (88 +/− 5%), COD (87 +/− 4%), and TSS (94 +/− 5%). The UASB reactor start-up was conducted without an inoculum, requiring a period of 120 days. The evaluation of the combined systems was conducted over 300 days. Moreover, a methodology to operate the system during and after the start-up of the anaerobic reactor was defined. It was demonstrated that the anaerobic effluent can deteriorate the sludge in the aerobic tank. In order to avoid this, important operational aspects must be considered during the operation of the system, such as the implementation of a raw wastewater bypass higher than 15% and monitoring of the anaerobic effluent settleable solid concentration (&lt;0.3 mL/L).

Monte Carlo-based model for estimating methane generation potential and electric energy recovery in swine wastewater treated in UASB systems

This work aimed to develop a mathematical model based on Monte Carlo simulation to predict the energy potential of biogas produced in an up-flow anaerobic sludge blanket (UASB) reactor treating swine wastewater (SWW) for a farm with up to 10,000 pigs. In order to determine the SWW energy potential, various organic loading rates (OLRs) were studied in lab-scale experiments, complemented with information found in the literature. Then, the energy potential of biogas was evaluated considering three categories of pig farms (small, medium, and large), which corresponded to different scales (250, 500, and 1000 pigs). The potential for electrical energy recovery was 227.0, 500.8, and 1103.6 kWh d−1 for small, medium, and large-scale pig farm, respectively. The simulation results show that the model allowed an estimation close to reality, with reduced errors. R2 value of 0.934 was found to estimate methane and electric energy flow as a function of the removed load, and 0.823 in terms of reactor inflow function. Thus, the model proved to be a relevant tool for entrepreneurship, and its use can enable studies to implement energy self-sufficiency projects. It was also inferred that biogas plants have great potential for profitability in electricity generation and cost reduction in projects. In conclusion, this research presents an alternative model for estimating methane and electrical energy potential for UASB reactors treating SWW.

Effect of organic loading rate and effluent recirculation on biogas production of desulfated skim latex serum using up-flow anaerobic sludge blanket reactor

High sulfate contents in skim latex serum (SLS) can be reduced by rubber wood ash (RWA). Subsequently, the desulfated skim latex serum (DSLS) can be further anaerobically treated more effectively with the accompanying generated biomethane. In this study, DSLS was treated using an up-flow anaerobic sludge blanket (UASB) reactor operated at 10-day HRT and under mesophilic (37 °C) conditions. The effect of organic loading rates (OLR) at 0.89, 1.79 and 3.57 g-COD/L-reactor∙d on DSLS biodegradability was investigated in Phase I-IV using NaHCO3 as an external buffering agent. Maximum methane production yield of 226.35 mL-CH4/g-CODadded corresponding to 403.25 mL-CH4/L reactor·d was achieved at the suitable OLR of 1.79 g-COD/L-reactor∙d. UASB effluent recirculation which was then applied to replace the NaHCO3. It was found that with 53% effluent recirculation similar to an OLR of 2.01 g-COD/L-reactor∙d, an average of 185.70 mL-CH4/g-CODadded corresponding to 371.40 mL/L reactor·d of methane production was reached. The dominant bacteria in UASB reactor were members of Proteobacteria, Bacteroidota, Firmicutes, and Desulfobacterota phyla. Meanwhile, the archaeal community was majorly dominated by the genera Methanosaeta sp. and Methanomethylovorans sp. The study clearly indicates the capabilities of UASB reactor with effluent recirculation to treat DSLS anaerobically.