Laboratory-scale Upflow Anaerobic Sludge Blanket Reactors Research Articles

Upflow Anaerobic Sludge Blanket (UASB) reactors for Bio-methane production from limed tannery fleshings: Lab and pilot scale reactors

The Upflow Anaerobic Sludge Blanket reactor is a viable high-rate anaerobic digestion design for the treatment of different wastewater with low to high solubility. This can also be used for the treatment of solid wastes with less HRT. In this study, the performance evaluation of a lab-scale UASB reactor was carried out for different hydraulic retention times of 24, 21, 18, 15 and 12 h for obtaining the best HRT for tannery fleshings. The gas production varied between 3.7 – 4.5 L with a methane content of 64.31 – 67.72%. It was observed that the maximum gas production was at 18 h HRT and this optimized condition was applied to the pilot-scale UASB reactor. The performance evaluation of the pilot-scale UASB reactor was carried out with an HRT of 18 h. The gas production of 450 ± 50 L, the maximum specific gas production of 0.274 m3/kg of VS destroyed and 0.239 m3/kg of TS destroyed was obtained and the maximum biogas productivity of 0.495 L was observed at 18 h HRT with the highest methane content of 67.86%. The payback period of the pilot scale reactor is 3.2 years.

Efficacies of a locust bean gum polymer on the startup of a novel upflow anaerobic sludge blanket reactor treating municipal sewage.

The present study investigates the potential of locust bean gum (LBG), in accelerating the startup of a novel upflow anaerobic sludge blanket (UASB) reactor handling municipal sewage. Under identical conditions, two lab-scale UASB reactors were operated in parallel, to substantiate this idea. The novel reactor (RH) with an inner centric hybrid UASB module and an outer concentric downflow hanging sponge (DHS) unit started off with an LBG polymer as an additive. Its performance was compared with a conventional system (RC). RH outclassed with an accelerated startup in 40 days, with the highest COD removal of 89% by the UASB compartment and 95% by the entire system (UASB + DHS). RC took nearly 85 days to achieve the highest COD removal of 83%. The polymer also succeeded with a dense sludge bed fastening most of the anaerobes, read by the least sludge volume index (SVI) of 26 mL/g. Specific methanogenic activity (SMA) (RH - 0.715 ± 0.05 and RC - 0.670 ± 0.07 g CH4-COD/g VSS/ day) and extracellular polymer (ECP) concentration (0.30-0.32 g/g VSS) of biomass in both reactors were almost similar. This further confirmed that early granulation was induced solely by the polymer and it also had no deleterious impact on substrate transfer.

The impact of semi-continuous and alternating microbial feeding patterns on methane yield from UASB reactors

Feeding strategy represents one of the most important bioreactor operation parameters, however, how different feeding patterns impact reactor microbiome development and treatment performance in up-flow anaerobic sludge blanket (UASB) reactors has not been systematically investigated. In the present study, three feeding strategies, including continuous feeding, semi-continuous feeding (with starvation-feast cycles), and alternate feeding (with high loading-low loading cycles) were assessed and compared using three laboratory-scale UASB reactors. It was observed that both long and short starvation-feast cycles provided by a semi-continuous feeding strategy failed to sustain stable anaerobic digestion under the conditions examined in the present study, while alternate feeding with high and low loading cycles supported microbial development. This feeding pattern resulted in an average methane yield of 74 ± 8.5% and an effluent COD removal efficiency of 89 ± 2.8%, which is comparable to the reactor operated under a continuous feeding pattern (Methane yield of 72 ± 2.4% and a COD removal efficiency of 87 ± 7.7%). Interestingly, as compared to continuous operation, reactors experienced starvation/feast stress (i.e., semi-continuous feeding) developed significantly higher methanogenic activities once continuous feeding was presumed, with dominant methanogens shifted from Methanosaeta in continuous feeding UASB to Methanosarcina in reactors undergone semi-continuous feeding. It was concluded that reactor feeding strategies can significantly impact microbiome communities in UASB, and an alternate feeding pattern is preferred, as compared to semi-continuous operation when reactor feeding cannot be continuously supplied.

Use of artificial neural network and adaptive neuro-fuzzy inference system for prediction of biogas production from spearmint essential oil wastewater treatment in up-flow anaerobic sludge blanket reactor

Two artificial intelligence (AI)-based models, namely feed-forward backpropagation artificial neural network (ANN) and multi-layer adaptive neuro-fuzzy inference system (ANFIS), were developed to estimate the biogas production in an up-flow anaerobic sludge blanket (UASB) reactor. The models' input variables including influent chemical oxygen demand (COD), pH, effluent mixed liquor suspended solids, effluent mixed liquor volatile suspended solids, turbidity removal, oil and grease removal, COD removal, phenol removal, and effluent volatile fatty acids and alkalinity were collected from an UASB reactor fed with spearmint essential oil wastewater (SEOW) during 141 consecutive operating days. The determination coefficient, root mean square error, and relative root mean the ANN model's square error reached 0.975, 2650 mL/d, and 0.234%, respectively, while those of ANFIS model reached 0.956, 3517 mL/d, and 0.315%, respectively. The results achieved herein demonstrated that two AI-based models were successful to estimate the biogas production in a lab-scale UASB reactor treating SEOW with high accuracy and low error.

Approaches in Design of Laboratory-Scale UASB Reactors

Up-flow Anaerobic Sludge Blanket (UASB) reactors are popular tools in wastewater treatment systems due to the ability to work with high feed rates and wastes with high concentration of organic contaminants. While full-scale industrial applications of UASB reactors are developed and described in the available literature, laboratory-scale designs utilized for treatability testing are not well described. The majority of published studies do not describe the laboratory UASB construction details or do use reactors that already had developed a trophic network in microbial consortia under laboratory environment and therefore are more stable. The absence of defined guidelines for geometry design, selection of materials, construction, operation rules, and, especially, the start-up conditions, significantly hamper researchers who desire to conduct treatability testing using UASB reactors in laboratory scale. In this article, we compiled and analyzed the information available in the refereed literature concerning UASB reactors used in laboratory environment, where information on geometry and/or operational conditions were provided in detail. We utilized the information available in the literature and the experience gained in our laboratory (Sustainable Waste to Bioproducts Engineering Center) to suggest a unified operation flowchart and for design, construction, operation, and monitoring for a laboratory-scale UASB reactors.

Influence of electrochemical advanced oxidation on the long-term operation of an Upflow Anaerobic Sludge Blanket (UASB) reactor treating 4-chlorophenol containing wastewater

Abstract Upflow anaerobic sludge blanket (UASB) systems are of specific interest for the treatment of high organic wastewater since they offer the opportunity to recover energy in the form of methane (biogas). The technology is highly suitable for the degradation of biodegradable organics, but its efficiency can be significantly hampered by the presence of toxic pollutants in the water. In this study, the use of electrochemical advanced oxidation (eAOP) coupled to a lab-scale UASB reactor for the degradation of 4-chlorophenol (4-CP) in wastewater was investigated. The eAOP treatment consisted of the electrochemical production of active chlorine at a Ti/RuO2–IrO2 anode with a fixed current density of 25 mA/cm2 in the recycle of the UASB reactor. It was noticed that the total COD removal efficiency decreased from 75.8% when no 4-CP was present in the wastewater to 25.6% and 13.6% after the addition of 100 ppm and 50 ppm 4-CP, respectively. Furthermore, elevated levels of volatile fatty acids and ORP were observed in the effluent of the reactor, indicating process failure. It was postulated that the decrease in COD removal efficiency was due to the release of high amounts of hypochlorite, causing an oxidative environment in the anaerobic reactor. This hypochlorite may have reacted with several components such as ammonia to form other toxic components (e.g., chloramine).

Application of ethanol-type fermentation in establishment of direct interspecies electron transfer: A practical engineering case study

A promising strategy for establishing direct interspecies electron transfer (DIET)-based syntrophic metabolism during anaerobic digestion (AD) is to stimulate the methanogenic communities with ethanol to rapidly produce biological electrical connections. In this study the strategy was further explored in an engineering-scale up-flow anaerobic sludge blanket (UASB) reactor treating bagasse wastes. The results demonstrated that, under the conditions employed, the ethanol-abundant acidogenic products from ethanol-type fermentation could stimulate the UASB reactor to form the aggregates with a higher conductivity (22.6 ± 0.6 uS/cm) than that in the laboratory-scale UASB reactor treating brewery wastes (8.1 ± 1.7 uS/cm), in which DIET was the primary working mode of interspecies electron exchange. Furthermore, these aggregates also presented a positive response with granular active carbon (GAC) to methanogenesis, suggesting that the DIET-based methanogenic communities were established. As a result, the engineering-scale UASB reactor was capable of maintaining stability in response to the environmental disturbance. Microbial community analysis revealed that specific and substantial enrichments of Petrimonas (21.8% of abundance) and Methanothrix species (64.8%) were detected in the aggregates. These results, and the known ability of Petrimonas species to transfer electrons to elemental sulfur, suggested that Petrimonas species might participate in DIET with Methanothrix species.

Calcium addition to increase the production of phosphate granules in anaerobic treatment of black water

Simultaneous recovery of calcium phosphate granules (CaP granules) and methane from vacuum collected black water (BW), using an upflow anaerobic sludge blanket (UASB) reactor was previously investigated. It was calculated that only 2% of the total phosphorus (P) fed was present as CaP granules whereas 51% of the P accumulated dispersed in the reactor, limiting the applicability of this process for recovery of phosphate. This study proposes adding calcium to increase the P accumulation in the reactor and the production of CaP granules. Calcium was added in a lab-scale UASB reactor fed with BW. An identical UASB reactor was used as reference, to which no calcium was added. The treatment performance was evaluated by weekly monitoring of influent, effluent and produced biogas. Sludge bed development and CaP granulation were assessed through particle size analysis. The composition and structure of CaP granules were chemically and optically assessed. Calcium addition increased accumulation of P in the reactor and formation and growth of granules with size > 0.4 mm diameter (CaP granules). Moreover, with calcium addition, CaP granules contained 5.6 ± 1.5 wt% of P, while without calcium a lower P content was observed (3.7 ± 0.3 wt%). By adding Ca, 89% of the incoming P from BW accumulated in the reactor and 31% was sampled as CaP granules (> 0.4 mm diameter). Addition of 250 mgCa L−1 of BW was the optimum loading found in this study. Furthermore, no significant reduction in CODTotal removal (> 80%) and CH4 production (0.47 ± 0.10 gCOD-CH4 g−1CODTotal-BW) was observed. Therefore, adding calcium can significantly increase the CaP granulation without inhibiting the simultaneous CH4 recovery. This further indicates the potential of this process for phosphate recovery.

Modeling of biogas production from cattle manure with co-digestion of different organic wastes using an artificial neural network

The present study utilizes an artificial neural network (ANN) as an estimation model of biogas production from laboratory-scale up-flow anaerobic sludge blanket (UASB) reactors treating cattle manure with co-digestion of different organic wastes. It can be estimated depending on working days, influent chemical oxygen demand, influent pH, influent alkalinity, influent ammonia, influent total phosphorus, hydraulic retention time, waste adding ratio, pretreatment and additive waste sorts. The suitable architecture of an ANN for use in biogas prediction consists of 10 input factors, tangent sigmoid transfer function (tansig) at the four hidden layer neurons and a linear transfer function (purelin) at the output layer neuron. The R 2 was found to equal 0.89, 0.79 and 0.75 in the training, validation and testing steps, respectively. ANN estimation modeling can effectively predict the biogas production performance of laboratory-scale UASB reactors. These results indicate that biogas production was optimized to occur in the 20–30% addition range with different organic wastes.

Impacts of biostimulation and bioaugmentation on the performance and microbial ecology in methanogenic reactors treating purified terephthalic acid wastewater

Up-flow anaerobic sludge blanket (UASB) processes treating purified terephthalic acid (PTA) wastewater often face challenges associated with biomass loss. As excessive biomass loss could lead to deterioration of PTA removal, biostimulation and bioaugmentation were often practiced without understanding the microbial impact in UASB. Three laboratory-scale UASB reactors were operated with synthetic PTA wastewater as the feed, with two added with co-substrate (glucose or molasses) on Day 170 for 90 days, and one with external granules on Day 118. Throughout the operation, treatment performance was measured together with the analysis of microbial communities of biomass samples using 16S rRNA-based gene Illumina sequencing. Glucose amendment destabilized both terephthalic acid and para-toluic acid removal, while molasses amendment improved para-toluic acid removal. Both substrate addition generally led to decreases in the abundances of syntrophs and methanogens and increases in carbohydrate-fermenting bacteria in the granular sludge. Regarding bioaugmentation, paper mill granule addition led to a temporary crash of terephthalic acid removal for 42 days, and deterioration of para-toluic acid removal throughout the operation. Syntrophs and methanogens were observed to colonize on the paper mill granules after three months, meanwhile growth of methanogens were stimulated on the PTA granules added initially. Overall, proper level of molasses amendment and external granule inoculation could be promising strategies to make up for biomass loss during the operation of PTA-degrading UASB.

A Single-Granule-Level Approach Reveals Ecological Heterogeneity in an Upflow Anaerobic Sludge Blanket Reactor.

Upflow anaerobic sludge blanket (UASB) reactor has served as an effective process to treat industrial wastewater such as purified terephthalic acid (PTA) wastewater. For optimal UASB performance, balanced ecological interactions between syntrophs, methanogens, and fermenters are critical. However, much of the interactions remain unclear because UASB have been studied at a “macro”-level perspective of the reactor ecosystem. In reality, such reactors are composed of a suite of granules, each forming individual micro-ecosystems treating wastewater. Thus, typical approaches may be oversimplifying the complexity of the microbial ecology and granular development. To identify critical microbial interactions at both macro- and micro- level ecosystem ecology, we perform community and network analyses on 300 PTA–degrading granules from a lab-scale UASB reactor and two full-scale reactors. Based on MiSeq-based 16S rRNA gene sequencing of individual granules, different granule-types co-exist in both full-scale reactors regardless of granule size and reactor sampling depth, suggesting that distinct microbial interactions occur in different granules throughout the reactor. In addition, we identify novel networks of syntrophic metabolic interactions in different granules, perhaps caused by distinct thermodynamic conditions. Moreover, unseen methanogenic relationships (e.g. “Candidatus Aminicenantes” and Methanosaeta) are observed in UASB reactors. In total, we discover unexpected microbial interactions in granular micro-ecosystems supporting UASB ecology and treatment through a unique single-granule level approach.

Anaerobic Treatment of Wastewater in Colder Climates Using UASB Reactor and Anaerobic Membrane Bioreactor

Direct anaerobic treatment in the main line of a wastewater treatment plant is a promising way of recovering chemical energy, even in moderate climates. Full-scale applications of upflow anaerobic sludge blanket (UASB) reactors are common in warm climates and have recently begun to appear in areas with colder climate. Several new types of reactors optimized for low temperature treatment were proposed such as UASB-Digester or anaerobic membrane bioreactor (AnMBR). However, long-term operation of such systems treating real wastewater at winter temperatures is needed to assess their suitability. The aim of this article is to evaluate the operation of a laboratory-scale UASB reactor (1.9 L) before and after the installation of ultrafiltration membrane for solids separation from the effluent. The laboratory model treated wastewater at 15°C for over 850 days. The organic loading rate of the UASB reactor and AnMBR was 1.4 and 1.6 g COD/[L·d], respectively, while the hydraulic retention time was around 9 and 10 h. Energy recovery from the wastewater in gaseous methane was 4% and 6% in the UASB reactor and AnMBR, respectively. The methane content was 63% ± 17% and 64% ± 2%, respectively. In the UASB reactor, 64% of the influent chemical oxygen demand (COD) was removed in long term. The AnMBR ran at average 85% COD removal. Results show that AnMBR can deliver more stable effluent quality for wastewater treatment even at low (15°C) temperature. However, even the AnMBR effluent requires further posttreatment. Thus, simpler and less energy demanding UASB appears more relevant for wastewater pretreatment under European conditions.

Treatment of Copper Contaminated Municipal Wastewater by Using UASB Reactor and Sand-Chemically Carbonized Rubber Wood Sawdust Column.

The performance of a laboratory scale upflow anaerobic sludge blanket (UASB) reactor and its posttreatment unit of sand-chemically carbonized rubber wood sawdust (CCRWSD) column system for the treatment of a metal contaminated municipal wastewater was investigated. Copper ion contaminated municipal wastewater was introduced to a laboratory scale UASB reactor and the effluent from UASB reactor was then followed by treatment with sand-CCRWSD column system. The laboratory scale UASB reactor and column system were observed for a period of 121 days. After the posttreatment column the average removal of monitoring parameters such as copper ion concentration (91.37%), biochemical oxygen demand (BODT) (93.98%), chemical oxygen demand (COD) (95.59%), total suspended solid (TSS) (95.98%), ammonia (80.68%), nitrite (79.71%), nitrate (71.16%), phosphorous (44.77%), total coliform (TC) (99.9%), and fecal coliform (FC) (99.9%) was measured. The characterization of the chemically carbonized rubber wood sawdust was done by scanning electron microscope (SEM), X-ray fluorescence spectrum (XRF), and Fourier transforms infrared spectroscopy (FTIR). Overall the system was found to be an efficient and economical process for the treatment of copper contaminated municipal wastewater.

Effect of Granule Sizes on the Performance of Upflow Anaerobic Sludge Blanket (UASB) Reactors for Cassava Wastewater Treatment

The laboratory-scale UASB reactors were operated at five different hydraulic retention times (HRTs). The various sizes of granules from three different sources: a cassava factory (CS), a seafood factory (SS), and a palm oil mill (PS), having the size range of 1.5-1.7mm, 0.7-1.0mm and 0.1-0.2mm. respectively, were used as inocula for anaerobic digestion of cassava wastewater. For comparison, the first reactor with only granules from its own source (R1, CS) was treated as control. The other two reactors were inoculated with mixed granules from different sources (R2, CS+SS and R3, CS+PS). As HRT decreased from 5 days to 1 day, the organic removal efficiencies decreased from 91.49 to 43.23%, 89.36 to 45.13% and 87.23 to 32.69% for R1, R2 and R3 respectively (or inversely with increasing OLR). In this study selected mathematical models including Monod, Contois, Grau second-order and Modified Stover-Kicannon kinetic models were applied to determine the substrate removal kinetics of UASB reactors. Kinetic parameters were determined through linear regression using experimental data obtained from the steady-state experiments and subsequently used to predict effluent COD. The results showed that Grau second-order and Modified Stover-Kicannon kinetic models were more suitable than the others for predicting the substrate removal for all different sizes of granules. In addition the Upflow Anaerobic Sludge Blanket (UASB) reactor with only granules from a cassava factory gave the best performance.

Biocatalysis conversion of methanol to methane in an upflow anaerobic sludge blanket (UASB) reactor: Long-term performance and inherent deficiencies

Long-term performance of methanol biocatalysis conversion in a lab-scale UASB reactor was evaluated. Properties of granules were traced to examine the impact of methanol on granulation. Methanolic wastewater could be stably treated during initial 240d with the highest biogas production rate of 18.6±5.7L/Ld at OLR 48g-COD/Ld. However, the reactor subsequently showed severe granule disintegration, inducing granule washout and process upsets. Some steps (e.g. increasing influent Ca2+ concentration, etc.) were taken to prevent rising dispersion, but no clear improvement was observed. Further characterizations in granules revealed that several biotic/abiotic factors all caused the dispersion: (1) depletion of extracellular polymeric substances (EPS) and imbalance of protein/polysaccharide ratio in EPS; (2) restricted formation of hard core and weak Ca-EPS bridge effect due to insufficient calcium supply; and (3) simplification of species with the methanol acclimation. More efforts are required to solve the technical deficiencies observed in methanolic wastewater treatment.

Decreasing levels of the fish pathogen Streptococcus iniae following inoculation into the sludge digester of a zero-discharge recirculating aquaculture system (RAS)

Disease outbreaks are a major concern in aquaculture. This is particularly true in intensive recirculating aquaculture systems (RASs), due to the high rearing densities in a system where high concentrations of organic matter are produced with minimal water exchange. This study assessed the survivability of the common fish pathogen Streptococcus iniae in a solid-removal unit of a RAS, the upflow anaerobic sludge blanket (UASB). A PCR detection method, along with an improved protocol for the extraction of high-quality DNA from sludge samples, were utilized for this purpose. This method enabled detection of S. iniae at a minimum concentration of 7.6×105CFUmL−1 raw sludge. We examined the survivability of S. iniae in batch digesters, which consisted of sealed serum bottles filled with sludge from the UASB reactor, and in laboratory-scale flow-through UASB reactors that were continuously fed with fish waste sludge. Results demonstrated a gradual decrease in the intensity of the PCR-amplified product to the point of no detection in either batch or UASB digesters, suggesting that the conditions present in the UASB reactor are not favorable for S. iniae. The PCR-based detection method was successfully applied to sludge from a commercial RAS enabling detection of potentially pathogenic bacteria. Statement of relevanceThe manuscript addresses the control of bacterial disease-causing agent in a near-zero discharge aquaculture system which contains a novel solid removal unit. The bacteria studied is S. iniae, a significant disease-causing agent in aquaculture. The potential threat of disease outbreaks increases with the intensification of the culture system, such as the one described and analyzed in this study. This intensification is of high relevance to the industry, as it reduces environmental contamination due to fish production as well as enables fish culture in places distant from a natural water source.

Mathematical modeling of upflow anaerobic sludge blanket (UASB) reactors: Simultaneous accounting for hydrodynamics and bio-dynamics

Hydrodynamics and bio-dynamics are equally important in upflow anaerobic sludge blanket (UASB) reactors, but few studies have been conducted to consider both issues when developing a mathematical model. Therefore a novel ADM1-based dispersive model was developed in this study to provide a better description of UASB reactor performance by simultaneously taking into account the hydrodynamics and bio-dynamics of the reactor. Organic overloading shock experiments were carried out in a laboratory-scale UASB reactor to validate the developed model. The results of the simulation model were in good agreement with experimental data. Although considerable calculation time was required, the ADM1-based dispersive model showed obvious advantages in predicting reactor status, which may give an early warning of reactor abnormalities. The models developed here are expected to simulate UASB reactors more effectively and to provide useful information for their design and operation.

Helminth Egg Removal Capacity of UASB Reactors under Subtropical Conditions

This research was conducted to study the anaerobic sludge filtration capacity regarding helminth egg removal in upflow anaerobic sludge blanket (UASB) reactors. Two 25 L lab-scale UASB reactors were operated at an ambient temperature which varied between 17.1 and 28.6 °C. Ascaris suum egg was selected as the model egg considering its similarity in terms of size and morphology to Ascaris lumbricoides, a human pathogen. Ascaris suum eggs were obtained from female parasites of infected pigs. The anaerobic sludge filtration capacity was performed applying upflow velocities between 0.09 and 0.68 m·h−1. Three sludge bed heights in the range of 0.30–0.40 m, 0.50–0.60 m and 0.60–0.70 m were applied. These sludge bed heights corresponded to 19%–25%, 31%–38% and 38%–44% of the total reactor height, respectively. Under the mentioned conditions, the average helminth egg removal efficiency was reciprocally correlated to the imposed upflow velocity. The studied lab-scale reactors reported an average helminth egg removal between 34%–100%, 30%–91% and 34%–56%, when the sludge bed in the UASB reactor was 19%–25%, 31%–38% and 38%–44% of the total reactor height, respectively. The decreased filtration capacity at increasing sludge bed heights might be likely related to biogas production and channeling formation. The average helminth egg removal efficiency in the control experiments performed without any sludge bed, by plain sedimentation, varied between 44% and 66%.

Operation performance and granule characterization of upflow anaerobic sludge blanket (UASB) reactor treating wastewater with starch as the sole carbon source

Long-term performance of a lab-scale UASB reactor treating starch wastewater was investigated under different hydraulic retention times (HRT). Successful start-up could be achieved after 15days’ operation. The optimal HRT was 6h with organic loading rate (OLR) 4g COD/Ld at COD concentration 1000mg/L, attaining 81.1–98.7% total COD removal with methane production rate of 0.33L CH4/g CODremoved. Specific methane activity tests demonstrated that methane formation via H2–CO2 and acetate were the principal degradation pathways. Vertical characterizations revealed that main reactions including starch hydrolysis, acidification and methanogenesis occurred at the lower part of reactor (“main reaction zone”); comparatively, at the up converting acetate into methane predominated (“substrate-shortage zone”). Further reducing HRT to 3h caused volatile fatty acids accumulation, sludge floating and performance deterioration. Sludge floating was ascribed to the excess polysaccharides in extracellular polymeric substances (EPS). More efforts are required to overcome sludge floating-related issues.

Performance of an UASB Reactor at Lab-Scale Treating Domestic Wastewater with Low Concentrations of Copper

Aims: The objective was to investigate the effect of copper at low concentrations in an Upflow Anaerobic Sludge Blanket (UASB) reactor performance under continuous conditions and its geochemical distribution in anaerobic sludge through sequential extraction. Study Design: Continuous operation. Original Research Article Barcelo-Quintal et al.; BJAST, 7(5): 456-466, 2015; Article no.BJAST.2015.164 457 Place and Duration of Study: Department of Basic Science, Universidad Autonoma Metropolitana -Azcapotzalco, between July 2013 and December 2013. Methodology: A lab scale UASB reactor was inoculated with sludge from a full-scale UASB reactor treating brewery wastewater and it was allowed to acclimate during two months. After acclimation period, three different copper concentrations were added to UASB influent: 0.25, 0.65 and 1.35 mg l -1 , during one month each one. At the end of the experiment, freeze-dried samples of inoculum and UASB reactor sludge were treated with a series of solvents to perform sequential extractions. pH, temperature, oxidation reduction potential (ORP), total chemical oxygen demand (COD), the ratio between partial and total alkalinity, total suspended solids and volatile suspended solids were measured in UASB reactor influent and effluent. Results: Sequential extractions showed that the fraction with the major affinity with copper was organic/sulfide bound, with a percentage distribution of 96%. Regarding UASB performance, copper caused a total alkalinity diminution in the effluent; however, the system buffer capacity was enough to overcome such instability, as partial alkalinity/total alkalinity ratio results confirmed. COD removal decreased 15% when 1.35 mg l Cu was added in comparison to acclimation period. Conclusion: Copper addition in UASB reactor influent at low concentrations affected adversely its performance; though, did not cause complete inhibition to anaerobic microorganisms. Metal speciation results in the inoculum and the UASB reactor evidenced that the fraction which had the major affinity with copper was the organically/sulfide bound fraction, however, further studies are needed to establish which is the weight of organic matter and sulfide in copper binding.