Upflow Anaerobic Sludge Blanket Bioreactor Research Articles

Insights into nitrogen removal from leather wastewater by anaerobic ammonium oxidation process: Performance and microbial structure

This study aimed to assess the suitability of anaerobic ammonium oxidation (anammox) process for leather wastewater treatment using two up-flow anaerobic sludge blanket bioreactors by pumping synthetic and real wastewater (named SR and RR), respectively. Both reactors were operated steadily with an average nitrogen removal efficiency of 94–96 % at chemical oxygen demand (COD) level of 100–200 mg·L−1, which were rapidly deteriorated as the COD level increased to 300 mg·L−1 even if at the same COD to total nitrogen (TN) (COD/TN) ratio. The reactor performances could restore after pumping with synthetic wastewater, and then continued to effectively treat leather wastewater. Furthermore, the relative abundance of Candidatus Kuenenia in reactor RR was increased by 34.8 % compared with the reactor SR on day 120. The results revealed that the anammox process can be used for the leather wastewater treatment, thus broadening the engineering application of anammox-based process in industrial wastewater.

High-rate upflow anaerobic sludge blanket bioreactor for the treatment of olive mill effluents: Laboratory and pilot scale systems investigation

Olive mill effluents are amongst the most prominent waste streams produced in Mediterranean countries, with their uncontrolled disposal in soil, without any prior treatment, having significant environmental and social effects. Anaerobic digestion has been extensively studied for the treatment of various waste streams, from industrial waste to agricultural and livestock residues. Some of the major advantages of anaerobic digestion relate to energy and soil fertilizer production. The scope of this work was the experimental optimization of the organic loading rate of anaerobic UASB digesters processing olive mill wastewater effluents. The optimization procedure was performed in a laboratory and a pilot scale set-up. The results showed that the maximum organic loading rate that could be applied to such a system was 5–6 gCOD/LR/d, without the need for any pretreatment. Moreover, it was exhibited that the large period of inoculum acclimatization to the olive mill effluents improved the phenols degradation inside the reactor, which reached 59%.

Sulfate Reduction in an Upflow Anaerobic Sludge Blanket Bioreactor and Optimization of Operational Conditions: pH, Hydraulic Retention Time, Sulfate Loading Rate, COD/SO42- Ratio

Sulfate Reduction in an Upflow Anaerobic Sludge Blanket Bioreactor and Optimization of Operational Conditions: pH, Hydraulic Retention Time, Sulfate Loading Rate, COD/SO42- Ratio

Anaerobic domestic wastewater treatment in a sequencing granular UASB bioreactor: Feasibility study of the temperature effect on the process performance

A laboratory-scale sequencing granular up-flow anaerobic sludge blanket (UASB) reactor was applied for the treatment of synthetic domestic wastewater at 15, 25 and 35 °C. The experiments were performed at different hydraulic retention times (gradually decreasing from a maximum of 22 h to a minimum of 9 h). Results at 25 and 35 °C showed similar COD removal efficiency and specific biogas production in the range of 84–94% and 0.14–0.27 m3/kgCODremoved, respectively. At 15 °C lower COD removal kinetics were observed, and a minimum hydraulic retention time of 14 h was necessary to obtain an effluent in accordance with current Italian legislation. At all temperatures, high quality effluent was achieved in terms of total suspended solids (TSS) concentration, while nitrogen and phosphorus exceeded the Italian law limits, as they are not removed during the anaerobic digestion process. Moreover, dissolved methane in the liquid phase was analysed: methane lost with the effluents was on average ≈ 37% at 25 °C and ≈ 24% at 35 °C of the produced amount, thus revealing higher losses at lower temperatures for the increase of gas solubility. These results show the need of research on technologies aimed at removing or recovering such energetic greenhouse gas. However, effective biogas production and potentialities for nutrients’ recovery demonstrated in this study confirm the feasibility of the anaerobic process as sustainable treatment of low-strength wastewaters.

Performance evaluation of three mesophilic upflow anaerobic sludge blanket bioreactors treating olive mill wastewater: Flocculent and granular inocula tests, organic loading rate effect and anaerobic consortia structure

This work evaluates the performance of two upflow anaerobic sludge blanket (UASB) bioreactors and a hybrid-UASB bioreactor treating olive mill wastewater (OMW) under mesophilic conditions. The UASB bioreactor, which was inoculated with flocculent sludge (UASB-F), achieved greater operation efficiency and higher methane production rate (1.13 L CH4/LR.d) than the other bioreactors seeded with granular sludge. The hybrid-UΑSB and the second UASB bioreactor, which were inoculated with granular sludge, exhibited low performance due to the loss of granulation. It appears that OMW phenolics have negative impact on granular sludge structure and performance efficiency. Acidogenesis was mainly carried out by Clostridiales and Sporolactobacillus spp. in all bioreactors examined. Molecular data also showed that the hydrogenotroph Methanobacterium beijingense was the main methanogen in the bioreactors inoculated with granular sludge, while the UASB-F bioreactor was exclusively dominated by a novel archaeal methanogenic linkage, distantly related to the rare methanol-reducing archaeon Methanosphaera stadtmanae.

Treatment of Effluent of Upflow Anaerobic Sludge Blanket Bioreactor for Water Reuse

The low-pressure reverse osmosis (LPRO) process is a recent development of reverse osmosis (RO) technology for the reduction in RO energy consumption and operation cost. The goal of this study was to investigate the performance of LPRO processes for the treatment and reuse of effluent discharged from brewery upflow anaerobic sludge blanket bioreactors (UASB). In this study, three different commercially available LPRO membranes were tested to evaluate the water quality that can be achieved under different operational and pretreatment conditions. It was found that the filtration performance and the effluent quality of the LPRO membranes can be considerably affected by the operation conditions and the selection of the pretreatment processes. The ultrafiltration (UF) pretreatment and the control of the operation pressure were found to be essential for mitigating LPRO membrane fouling, which could be caused by Ca2+ associated precipitates and organic gelation, in the treatment of the brewery UASB effluent. Water quality analyses showed that an integrated process of the UASB + UF + LPRO could achieve an effluent quality characterized by concentrations of 10.4–12.5 mg/L of chemical oxygen demand (COD), 1.8–2.1 mg/L of total nitrogen (TN), 1.3–1.8 mg/L of ammonia nitrogen (NH3-N) and 0.8–1.2 mg/L of total phosphorus (TP). The effluent quality and the LPRO performance could be further improved by adding a granular activated carbon (GAC) adsorption process between the UF and LPRO processes, which reduced the concentration of COD to 7–10 mg/L and those of TN, TP, NH3-N to below 1 mg/L. For the treatment of the UASB effluent tested in this study, the UF, UF + GAC (retention time 4 hrs), UF + LPRO, and UF + GAC + LPRO, respectively, achieved overall COD removal efficiencies of 89.6–93.7%, 94.5–96.7%, 99.3–99.1% and 99.3–99.4%; TN removal efficiencies of 73.0–78.2%, 89.2–97.2%, 97.1–98.2% and 94.3–99.7%; and TP removal efficiencies of 29.3–46.2%, 77.0–95.4%, 95.9–97.6z% and 98.0–98.3%. This study showed that both UASB + UF + LPRO and UASB + UF + GAC + LPRO are effective treatment processes for treating brewery wastewater toward reuse water quality standards set by the United States Environmental Protection Agency (US EPA). Therefore, the results of this study would help to answer whether a LPRO can treat the brewery UASB effluent to meet the requirements of wastewater reuse standards.

Effects of anaerobic granular sludge towards the treatment of flowback water in an up-flow anaerobic sludge blanket bioreactor: Comparison between mesophilic and thermophilic conditions

Cost-effective treatment of flowback water remains a challenge for the sustainability of shale gas development. This study evaluated the efficiency of anaerobic granular sludge (AnGS) technology for flowback water treatment under mesophilic and thermophilic conditions. The granule characteristics and metagenomic characterization were also investigated. Thermophilic AnGS achieved 70.9% of COD removal and 362 NmL/d of methane production, higher than those for mesophilic AnGS (60.0% and 241 NmL/d). Thermophilic AnGS had higher extracellular polymeric substances content but low granular size and settleability. Metagenomic analysis revealed the genes related to hydrolysis acidification and carbohydrate metabolism were upregulated during thermophilic condition. Thermophilic condition most likely improved the hydrolysis of complex organics in the flowback water such as guar gum and hydrolyzed polyacrylamide, and led to higher COD removal and methane production. These results suggest that AnGS technology is a promising alternative for the treatment of flowback water, particularly when operated at thermophilic condition.

Purified Terephthalic Acid Wastewater Treatment Using Modified Two-Stage UASB Bioreactor Systems.

Microbial community dynamics and PTA wastewater degradation performance of sequentially connected two-stage upflow anaerobic sludge blanket (UASB) bioreactors have been studied for 225days. The working volume of acidogenic (R1) and methanogenic reactors (R2) have sixfold differences. Thus, the reactors operated under different hydraulic retention time (HRT) conditions, which are preferential for PTA wastewater content. Archeal and bacterial profiles of granules were analyzed with denaturing gradient gel electrophoresis (DGGE) and real-time quantitative PCR (Q-PCR) techniques. According to high-pressure liquid chromatography (HPLC) results, 4-Carboxybenzaldehyde (4-CBA) and acetic acid (AA) completely degraded in the first stage, whereas terephthalate (TA) and p-toluic acid (p-TA) degradation ratios were 90% and 47% in the second stage, respectively. The methane content of the UASB reactor was determined as 76% by gas chromatography (GC) analysis. Microbial community analysis indicated that the members of hydrogenotrophic methanogen groups Methanobacteriales and Methanomicrobiales were dominantly responsible for methane production throughout the 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.

Simultaneous removal of sulfate and selenate from wastewater by process integration of an ion exchange column and upflow anaerobic sludge blanket bioreactor

ABSTRACTThe application of an integrated process configuration comprising of an ion exchange (IX) column and an upflow anaerobic sludge blanket (UASB) bioreactor for the simultaneous removal of SO42- and total Se from synthetic mine wastewater was evaluated. Use of an IX column as a pre-treatment (not as post-treatment) to the UASB bioreactor gave the best overall removal performance. The combined treatment reduced the total Se and SO42- concentration from 8.0 and 1441 mg/L to 0.2 and 28.0 mg/L, respectively. This study demonstrated for the first time that an IX process as a pre-treatment to a biological process can significantly improve the oxyanion removal efficiency and the overall treatment of Se-laden wastewaters.

Insights into the effects of bio-augmentation on the granule-based anammox process under continuous oxytetracycline stress: Performance and microflora structure

Three up-flow anaerobic sludge blanket bioreactors treating wastewater containing 2 mg L−1 oxytetracycline (OTC) were used to examine the enhancement of bio-augmentation (BA) tactics on the resistance and resilience of the anammox performance. The BA tactics were carried out by the BA-addition and BA-exchange modes, and the optimized mode was first proposed. The results showed that prior to OTC suppression, excellent anammox performance was observed in the reactors, with a total nitrogen removal efficiency (TNRE) above 92.0% and a nitrogen removal rate (NRR) greater than 3.3 kg N m−3 d−1. Upon inhibition by continuous OTC, the NRR decreased to 2.0 ± 0.6 kg N m−3 d−1 without BA assistance, 2.3 ± 0.6 kg N m−3 d−1 for BA-addition mode assistance and 2.8 ± 0.3 kg N m−3 d−1 for the BA-exchange mode one. Redundancy analysis indicated that BA mode regulation may maintain system stability by microbial communities gradual acclimation and thus functional bacteria to be potential antibiotic resistance species is the main reason for performance stabilization. Our findings elucidate for the first time that the BA-exchange mode is feasible to remit 2 mg L−1 OTC-stressed anammox performance.

Feedforward neural network model estimating pollutant removal process within mesophilic upflow anaerobic sludge blanket bioreactor treating industrial starch processing wastewater

In this a, three-layered feedforward-backpropagation artificial neural network (BPANN) model was developed and employed to evaluate COD removal an upflow anaerobic sludge blanket (UASB) reactor treating industrial starch processing wastewater. At the end of UASB operation, microbial community characterization revealed satisfactory composition of microbes whereas morphology depicted rod-shaped archaea. pH, COD, NH4+, VFA, OLR and biogas yield were selected by principal component analysis and used as input variables. Whilst tangent sigmoid function (tansig) and linear function (purelin) were assigned as activation functions at the hidden-layer and output-layer, respectively, optimum BPANN architecture was achieved with Levenberg-Marquardt algorithm (trainlm) after eleven training algorithms had been tested. Based on performance indicators such the mean squared errors, fractional variance, index of agreement and coefficient of determination (R2), the BPANN model demonstrated significant performance with R2 reaching 87%. The study revealed that, control and optimization of an anaerobic digestion process with BPANN model was feasible.

Influence of thermal and chemical pretreatment on structural stability of granular sludge for high-rate hydrogen production in an UASB bioreactor

Fermentation of organic waste materials presents an alternate route instead of photosynthetic and chemical routes for hydrogen production. Low yield of biohydrogen production is the major challenge in the fermentative hydrogen-producing technology. Improvement of fermentation process by various sludge pretreatment methods is one of the ways that have been applied to boost hydrogen productivity. This study sheds new light on the impact of thermal and chemical pretreatments on the hydrogen-producing granular sludge morphology and strength as well as up-flow anaerobic sludge blanket (UASB) reactor performance treating palm oil mill effluent (POME). Thermal pretreatment showed devastating effects on the morphological and structural characteristics of the granules. However, the chemically pretreated granules remained structurally stable and relatively undamaged. The thermal pretreatment increased the cumulative hydrogen production by 40% and 76% over chemical pretreatment and control test (untreated), respectively.

Can artificial neural network and response surface methodology reliably predict hydrogen production and COD removal in an UASB bioreactor?

Artificial Neural Network (ANN) and Response Surface Methodology (RSM) modeling was employed in an Upflow Anaerobic Sludge Blanket (UASB) bioreactor for optimization of hydrogen yield and COD (Chemical Oxygen Demand) removal efficiency. Experimental data were generated by running seventeen fermentation experiments at varying hydraulic retention times, immobilized cell volumes and temperatures. RSM and ANN models predicted similar optimum conditions for these process parameters. Upon validation, the prediction error for ANN and RSM was observed to be 2.22 and 9.64% on hydrogen yield and 1.01 and 6.34% on COD removal. These results suggested a greater accuracy and higher reliability of ANN in modeling and optimizing the bioprocess parameter interactions associated to the fermentation process. In addition, the study demonstrated a higher molar biohydrogen yield (0.90 mol-H2/mol glucose) and COD removal efficiency (84.81%) in the UASB system optimized by ANN modeling.

Biogas production from a native beverage vinasse using a modified UASB bioreactor

This work evaluated the redesign of an Upflow Anaerobic Sludge Blanket (UASB) bioreactor to increase biogas production from anaerobic digestion of vinasse and compared the redesign UASB bioreactor with a conventional UASB design. Vinasse contains a high level of organic matter, 120.2±18.4gO2/L of chemical organic demand (COD), and a 0.8 biodegradability index (BI). Thus, vinasse is a potential nutrient source for biogas production by anaerobic digestion. The modified UASB bioreactor has an innovation that consisted in a second leach bed sludge, which improved the methane proportion in biogas producing 2140mLCH4/day as compared to the traditional bioreactor (1840mLCH4/day).

Evaluation of an Upflow Anaerobic Sludge Blanket Bioreactor for the Treatment of Vinasse

En esta investigacion se presenta la evaluacion de un biorreactor de manto de lodo anaerobio de flujo ascendente (uasb) de 4.4 L durante un periodo de 90 dias, el cual fue alimentado con vinazas de una empresa de bebidas fermentadas provenientes de Comitan, Chiapas. Se investigo principalmente la eficiencia de la remocion de la demanda quimica de oxigeno (dqo) y la estabilidad del reactor con respecto al factor alfa (α) y potencial de hidrogeno (pH). La eficiencia de remocion de la dqo fue de 90 %. Durante el estudio, se mantuvo un sistema estable con α =0.28 y pH=7.1

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The feasibility of an anammox (anaerobic ammonium oxidation) UASB (upflow anaerobic sludge blanket) bioreactor to treat ammonium-rich brines was investigated in batch and continuous-flow experiments. The evidence from batch tests indicated that the anammox activity was significantly inhibited under highly saline conditions while the inhibition was reversible. Saline shock loading of 30 g NaCl l−1 caused a 67.5% decrease in specific anammox activity (SAA) compared to reference biomass (not exposed to salt). However, the acclimatized biomass displayed a SAA value just 45.1% lower than that of the reference biomass. When transferred from brine to freshwater, the salt-exposed biomass resumed its activity by 43.1%. Subsequent to appropriate acclimatization, careful manipulation nitrite concentration, nitrogen loading rate (NLR), and other operational parameters for 77 days, the results of continuous-flow experiment revealed that under the salinity of 30 g NaCl l−1 the reactor performed well and the substrate removal capacity (nitrogen removal rate, NRR, of 448 ± 15 mgl−1 d−1) was comparable to the condition of freshwater (NRR of 464 ± 13 mgl−1 d−1). However, the anammox UASB bioreactor was prone to malfunction under transient operating conditions.

Biogas Production and Removal COD – BOD and TSS from Wastewater Industrial Alcohol (Vinasse) by Modified UASB Bioreactor

Biogas production and decreased organic loading of vinasse using a modified UASB bioreactor has been done successfully. Vinasse is waste from the ethanol industry which contains COD: 9.360 mg / L , BOD : 4.013 mg/L, and TSS: 317.5 mg/L. The purpose of this research was to study the performance of bioreactors Upflow Anaerobic Sludge Blanket (UASB) to decompose the vinasse into biogas or methane. UASB operating principle is to distribute wastewater in the bioreactor to flow upward through the sludge blanket by setting the hidrolic retention time (HRT). Four UASB bioreactor columns were used in this experiment wherein each with a capacity of 50 L in volume; 23 cm inside diameter, and 120 cm. The variations of hydraulic capacity followed the variations of HRT in the range of 72-36 hours. Modifications were carried out on the top of column UASB with the aim of preventing gas losses and increasing the flowrate of gas out from the top of the column. The results showed that HRT increased from 36 h to 72 h followed by an increase in COD removal efficiency of 55.64% to 66.81%; BOD5 from 67.85% to 74.58%; and TSS from 66.69% to 84.19%. The maximum volume of biogas produced was in the range of 5.826 L / day (42.89% methane) to 7.930 L / day (methane 58.06%).

Noteworthy Facts about a Methane-Producing Microbial Community Processing Acidic Effluent from Sugar Beet Molasses Fermentation

Anaerobic digestion is a complex process involving hydrolysis, acidogenesis, acetogenesis and methanogenesis. The separation of the hydrogen-yielding (dark fermentation) and methane-yielding steps under controlled conditions permits the production of hydrogen and methane from biomass. The characterization of microbial communities developed in bioreactors is crucial for the understanding and optimization of fermentation processes. Previously we developed an effective system for hydrogen production based on long-term continuous microbial cultures grown on sugar beet molasses. Here, the acidic effluent from molasses fermentation was used as the substrate for methanogenesis in an upflow anaerobic sludge blanket bioreactor. This study focused on the molecular analysis of the methane-yielding community processing the non-gaseous products of molasses fermentation. The substrate for methanogenesis produces conditions that favor the hydrogenotrophic pathway of methane synthesis. Methane production results from syntrophic metabolism whose key process is hydrogen transfer between bacteria and methanogenic Archaea. High-throughput 454 pyrosequencing of total DNA isolated from the methanogenic microbial community and bioinformatic sequence analysis revealed that the domain Bacteria was dominated by Firmicutes (mainly Clostridia), Bacteroidetes, δ- and γ-Proteobacteria, Cloacimonetes and Spirochaetes. In the domain Archaea, the order Methanomicrobiales was predominant, with Methanoculleus as the most abundant genus. The second and third most abundant members of the Archaeal community were representatives of the Methanomassiliicoccales and the Methanosarcinales. Analysis of the methanogenic sludge by scanning electron microscopy with Energy Dispersive X-ray Spectroscopy and X-ray diffraction showed that it was composed of small highly heterogeneous mineral-rich granules. Mineral components of methanogenic granules probably modulate syntrophic metabolism and methanogenic pathways. A rough functional analysis from shotgun data of the metagenome demonstrated that our knowledge of methanogenesis is poor and/or the enzymes responsible for methane production are highly effective, since despite reasonably good sequencing coverage, the details of the functional potential of the microbial community appeared to be incomplete.