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1.
Water Res ; 266: 122371, 2024 Sep 02.
Artículo en Inglés | MEDLINE | ID: mdl-39236500

RESUMEN

Ambient operation and large-scale demonstration have limited the implementation and evaluation of anaerobic membrane bioreactors (AnMBRs) for low-strength wastewater treatment. Here, we studied these issues at an AnMBR demo plant that treats domestic wastewater and food waste together at ambient temperatures (7-28 °C). At varied hydraulic retention times (HRTs, 8-42 h), the AnMBR achieved a COD removal efficiency and biogas production of 80.4% ± 3.9% and 66.5 ± 9.4 NL/m3-Influent, respectively. Moreover, a stable high membrane flux of 14.4 L/m2/h was reached. The electric energy consumption for the AnMBR operation was 0.269-0.433 kW·h/m3, and 49.4%-91.3% could be compensated by the electric energy produced from methane production. At an HRT of 10 h, the AnMBR system demonstrated an impressively low net electric energy consumption of merely 0.05 kW·h/m3, resulting in a net greenhouse gas emission of 0.015 CO2-eq/m3, cutting 85% compared to the conventional activated sludge process. Achievements in this study provide key parameters for the ambient operation of AnMBR and demonstrate that AnMBR is an energy-saving and low-carbon solution for low-strength wastewater treatment.

2.
Sci Total Environ ; : 176192, 2024 Sep 17.
Artículo en Inglés | MEDLINE | ID: mdl-39299305

RESUMEN

Wastewater from seafood processing is a significant source of pollution, containing many harmful organic and inorganic compounds such as proteins, lipids, carbohydrates, nitrogen and phosphorus. This study investigated the enhancement of organic and nutrient removal efficiencies in seafood processing wastewater by integrating an Anaerobic Membrane Bioreactor (AnMBR) with an anoxic/oxic (AO) processes. A pilot-scale system was constructed with a capacity of 0.5 m3/day directly at the factory operated continuously, featuring an AnMBR process with a 24-hour hydraulic retention time (HRT) and an AO process with HRT values and internal recycle changes. The AnMBR system exhibited consistent and high-performance biochemical oxygen demand (COD) elimination, approximately 80 ±â€¯5 %. However, this system demonstrated low-efficiency removal of total nitrogen (TN) at about 20 ±â€¯5 %, and total phosphorus (TP) 15 ±â€¯5 %, under organic loading rates (OLR) of 0.6 to 1.3 kg-COD/(L·d). The AO process was then continually employed to improve the treatment efficacy (at HRT, 5 h in the anoxic phase, and 8.3 h in the oxic phase, at a recycling rate of 300 %) resulting in the final post-treatment concentrations of COD 27-41 mg/L (removal 98.3 ±â€¯0.3 %), TN 12-25 mg/L (90 ±â€¯2 %), and TP 18 ±â€¯2 mg/L (35 ±â€¯5 %). The performance of the integrated AnMBR-AO system met the established Vietnamese discharge standards for seafood processing wastewater, as outlined in QCVN 11-MT: 2015/BTNMT.

3.
Water Res ; 264: 122243, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-39142046

RESUMEN

Bound extracellular polymeric substances (EPS) are complex, high-molecular-weight polymer mixtures that play a critical role in pore clogging, foulants adhesion, and fouling layer formation during membrane filtration, owing to their adhesive properties and gelation tendencies. In this study, a novel electrochemical anaerobic membrane bioreactor (EC-AnMBR) was constructed to investigate the effect of sludge bound-EPS solubilization on methane bioconversion and membrane fouling mitigation. During the 150-days' operation, the EC-AnMBR demonstrated remarkable performance, characterized by an exceptionally low fouling rate (transmembrane pressure (TMP) < 4.0 kPa) and high-quality effluent (COD removal > 98.2 %, protein removal > 97.7 %, and polysaccharide removal > 98.5 %). The highest methane productivity was up to 38.0 ± 3.1 mL/Lreactor/d at the applied voltage of 0.8 V with bound-EPS solubilization, 107.6 % higher than that of the control stage (18.3 ± 2.4 mL/Lreactor/d). Morphological and multiplex fluorescence labeling analyses revealed higher fluorescence intensities of proteins, polysaccharides, total cells and lipids on the surface of the fouling layer. In contrast, the interior exhibited increased compression density and reduced activity, likely attributable to compression effect. Under the synergistic influence of the electric field and bound-EPS solubilization, biomass characteristics exhibited a reduced propensity for membrane fouling. Furthermore, the bio-electrochemical regulation enhanced the electroactivity of microbial aggregates and enriched functional microorganisms, thereby promoting biofilm growth and direct interspecies electron transfer. Additionally, the potential hydrogenotrophic and methylotrophic methanogenesis pathways were enhanced at the cathode and anode surfaces, thereby increasing CH4 productivity. The random forest-based machine learning model analyzed the nonlinear contributions of EPS characteristics on methane productivity and TMP values, achieving R² values of 0.879 and 0.848, respectively. Shapley additive explanations (SHAP) analysis indicated that S-EPSPS and S-EPSPN were the most critical factors affecting CH4 productivity and membrane fouling, respectively. Partial dependence plot analysis further verified the marginal and interaction effects of different EPS layers on these outcomes. By combining continuous operation with interpretable machine learning algorithms, this study unveils the intricate impacts of EPS characteristics on methane productivity and membrane fouling behaviors, and provides new insights into sludge bound-EPS solubilization in EC-AnMBR.


Asunto(s)
Reactores Biológicos , Aprendizaje Automático , Membranas Artificiales , Metano , Aguas del Alcantarillado , Aguas del Alcantarillado/microbiología , Anaerobiosis , Incrustaciones Biológicas , Matriz Extracelular de Sustancias Poliméricas , Solubilidad , Eliminación de Residuos Líquidos/métodos
4.
Water Res ; 263: 122166, 2024 Oct 01.
Artículo en Inglés | MEDLINE | ID: mdl-39088880

RESUMEN

Anaerobic Membrane Bioreactor (AnMBR) are employed for solid-liquid separation in wastewater treatment, enhancing process efficiency of digestion systems treating digestate. However, membrane fouling remains a primary challenge. This study operated a pilot-scale AnMBR (P-AnMBR) to treat high-concentration organic digestate, investigating system performance and fouling mechanisms. P-AnMBR operation reduced acid-producing bacteria and increased methane-producing bacteria on the membrane, preventing acid accumulation and ensuring stable operation. The P-AnMBR effectively removed COD and VFA, achieving removal rates of 82.3 % and 92.0 %, respectively. Higher retention of organic nitrogen and lower retention of ammonia nitrogen were observed. The membrane fouling consisted of organic substances (20.3 %), predominantly polysaccharides, and inorganic substances (79.7 %), primarily Mg ions (10.1 %) and Ca ions (4.5 %). To reduce the increased transmembrane pressure (TMP) caused by fouling (a 10.6-fold increase in filtration resistance), backwash frequency experiment was conducted. It revealed a 30-min backwash frequency minimized membrane flux decline, facilitating recovery to higher flux levels. The water produced amounted to 70.3 m³ over 52 days. The research provided theoretical guidance and practical support for engineering applications, offering practical insights for scaling up P-AnMBR.


Asunto(s)
Reactores Biológicos , Membranas Artificiales , Eliminación de Residuos Líquidos , Anaerobiosis , Eliminación de Residuos Líquidos/métodos , Proyectos Piloto , Aguas Residuales/química , Purificación del Agua/métodos , Análisis de la Demanda Biológica de Oxígeno , Filtración , Metano/metabolismo
5.
Sci Total Environ ; 947: 174600, 2024 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-38986708

RESUMEN

Membrane fouling is a persistent challenge that has impeded the broader application of anaerobic membrane bioreactors (AnMBRs). To mitigate membrane fouling, between the outlet of the UASB anaerobic bioreactor and the PVDF membrane to form the anaerobic filter membrane bioreactor (AnFMBR) system. Through comprehensive experiments, the optimal pore size for cloth filters was determined to be 50 µm. A comprehensive assessment over 140 days of operation shows that the novel AnFMBR had significantly greater resistance to membrane pollution than the traditional AnMBR. The AnFMBR system membrane tank exhibited lower mixed liquor suspended solid and mixed liquor volatile suspended solid concentrations, smaller sludge particle sizes, increased hydrophilicity of sludge flocs, and optimized microbial community distribution compared to those of conventional AnMBRs. The total solids foulant accumulation rate in the AnMBR was 5.1 g/m2/day, while in the AnFMBR, the rate was 2.4 g/m2/day, marking a 53.7 % decrease in fouling rate for the AnFMBR compared with the AnMBR. This decrease indicates that integrating the filtration assembly significantly lowered the rate of solid foulant accumulation on the membrane surface, primarily by controlling the buildup of solid foulants in the cake layer, thereby alleviating membrane fouling. AnFMBR compared to AnMBR, the membrane fouling rate halved, effectively doubled the interval between membrane cleaning from seven days, as observed in the AnMBR system, to fourteen days. These findings underscore the potential of integrating cloth media filters into AnMBRs to improve operational efficiency, economic viability, and sustainability.


Asunto(s)
Reactores Biológicos , Filtración , Membranas Artificiales , Eliminación de Residuos Líquidos , Filtración/métodos , Filtración/instrumentación , Eliminación de Residuos Líquidos/métodos , Anaerobiosis , Aguas del Alcantarillado
6.
J Environ Manage ; 366: 121855, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-39025005

RESUMEN

Anaerobic membrane bioreactor (AnMBR) offer promise in municipal wastewater treatment, with potential benefits including high-quality effluent, energy recovery, sludge reduction, and mitigating greenhouse gas emissions. However, AnMBR face hurdles like membrane fouling, low energy recovery, etc. In light of net-zero carbon target and circular economy strategy, this work sought to evaluate novel AnMBR configurations, focusing on performance, fouling mitigation, net-energy generation, and nutrients-enhancing integrated configurations, such as forward osmosis (FO), membrane distillation (MD), bioelectrochemical systems (BES), membrane photobioreactor (MPBR), and partial nitrification-anammox (PN/A). In addition, we highlight the essential role of AnMBR in advancing the circular economy and propose ideas for the water-energy-climate nexus. While AnMBR has made significant progress, challenges, such as fouling and cost-effectiveness persist. Overall, the use of novel configurations and energy recovery strategies can further improve the sustainability and efficiency of AnMBR systems, making them a promising technology for future sustainable municipal wastewater treatment.


Asunto(s)
Reactores Biológicos , Eliminación de Residuos Líquidos , Aguas Residuales , Eliminación de Residuos Líquidos/métodos , Anaerobiosis , Membranas Artificiales
7.
J Environ Sci (China) ; 146: 304-317, 2024 Dec.
Artículo en Inglés | MEDLINE | ID: mdl-38969460

RESUMEN

A biochar-assisted anaerobic membrane bioreactor (BC-AnMBR) was conducted to evaluate the performance in treating swine wastewater with different organic loading rates (OLR) ranging from 0.38 to 1.13 kg-COD/(m3.d). Results indicated that adding spent coffee grounds biochar (SCG-BC) improved the organic removal efficiency compared to the conventional AnMBR, with an overall COD removal rate of > 95.01%. Meanwhile, methane production of up to 0.22 LCH4/gCOD with an improvement of 45.45% was achieved under a high OLR of 1.13 kg-COD/(m3.d). Furthermore, the transmembrane pressure (TMP) in the BC-AnMBR system was stable at 4.5 kPa, and no irreversible membrane fouling occurred within 125 days. Microbial community analysis revealed that the addition of SCG-BC increased the relative abundance of autotrophic methanogenic archaea, particularly Methanosarcina (from 0.11% to 11.16%) and Methanothrix (from 16.34% to 24.05%). More importantly, Desulfobacterota and Firmicutes phylum with direct interspecific electron transfer (DIET) capabilities were also enriched with autotrophic methanogens. Analysis of the electron transfer pathway showed that the concentration of c-type cytochromes increased by 38.60% in the presence of SCG-BC, and thus facilitated the establishment of DIET and maintained high activity of the electron transfer system even at high OLR. In short, the BC-AnMBR system performs well under various OLR conditions and is stable in the recovery energy system for swine wastewater.


Asunto(s)
Reactores Biológicos , Carbón Orgánico , Eliminación de Residuos Líquidos , Aguas Residuales , Animales , Aguas Residuales/química , Carbón Orgánico/química , Porcinos , Eliminación de Residuos Líquidos/métodos , Anaerobiosis , Membranas Artificiales , Metano/metabolismo
8.
J Water Health ; 22(6): 967-977, 2024 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-38935449

RESUMEN

The anaerobic membrane bioreactor (AnMBR) is a promising technology for not only water reclamation but also virus removal; however, the virus removal efficiency of AnMBR has not been fully investigated. Additionally, the removal efficiency estimation requires datasets of virus concentration in influent and effluent, but its monitoring is not easy to perform for practical operation because the virus quantification process is generally time-consuming and requires specialized equipment and trained personnel. Therefore, in this study, we aimed to identify the key, monitorable variables in AnMBR and establish the data-driven models using the selected variables to predict virus removal efficiency. We monitored operational and environmental conditions of AnMBR in Sendai, Japan and measured virus concentration once a week for six months. Spearman's rank correlation analysis revealed that the pH values of influent and mixed liquor suspended solids (MLSS) were strongly correlated with the log reduction value of pepper mild mottle virus, indicating that electrostatic interactions played a dominant role in AnMBR virus removal. Among the candidate models, the random forest model using selected variables including influent and MLSS pH outperformed the others. This study has demonstrated the potential of AnMBR as a viable option for municipal wastewater reclamation with high microbial safety.


Asunto(s)
Reactores Biológicos , Membranas Artificiales , Reactores Biológicos/virología , Anaerobiosis , Eliminación de Residuos Líquidos/métodos , Aguas Residuales/virología , Proyectos Piloto , Purificación del Agua/métodos , Purificación del Agua/instrumentación , Tobamovirus/aislamiento & purificación , Japón
9.
Bioresour Technol ; 406: 130975, 2024 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-38879058

RESUMEN

Particulate matter hydrolysis is the bottleneck in anaerobic treatment of municipal wastewater in temperate climates. Low temperatures theoretically slow enzyme-substrate interactions, hindering utilization kinetics, but this remains poorly understood. ß-glucosidase, protease, and lipase activities were evaluated in two pilot-scale upflow anaerobic sludge blanket (UASB) reactors, inoculated with different sludges and later converted to anaerobic membrane bioreactors (AnMBRs). Despite similar methane production and solids hydrolysis rates, significant differences emerged. Specific activity peaked at 37 °C, excluding the predominance of psychrophilic enzymes. Nevertheless, the Michaelis-Menten constant (Km) indicated high enzyme-substrate affinity at the operational temperature of 15-20 °C, notably greater in AnMBRs. It is shown, for the first time, that different seed sludges can equally adapt, as hydrolytic enzymatic affinity to the substrate reached similar values in the two reactors at the operational temperature and identified that membrane ultrafiltration impacted hydrolysis by a favourable enzyme Michaelis-Menten constant.


Asunto(s)
Reactores Biológicos , Aguas Residuales , Purificación del Agua , Hidrólisis , Aguas Residuales/química , Anaerobiosis , Purificación del Agua/métodos , Clima , Lipasa/metabolismo , Aguas del Alcantarillado , Temperatura , Cinética , Péptido Hidrolasas/metabolismo , Metano/metabolismo , beta-Glucosidasa/metabolismo , Eliminación de Residuos Líquidos/métodos
10.
Water Res ; 260: 121867, 2024 Aug 15.
Artículo en Inglés | MEDLINE | ID: mdl-38878312

RESUMEN

Biofouling is the main challenge in the operation of anaerobic membrane bioreactors (AnMBRs). Biofouling strongly depends on temperature; therefore, we hypothesize that the interactions and viscoelastic properties of soluble microbial products (SMP) and extracellular polymeric substances (EPS) vary with temperature, consequently influencing membrane permeability. This study compares the performance of an AnMBR operated at a similar permeate flux at two temperatures. The transmembrane pressure (TMP) rose rapidly after 5 ± 2 days at 25 °C but only after 18 ± 2 days at 35 °C, although the reactor's biological performance was similar at both temperatures, in terms of the efficiency of dissolved organic carbon removal and biogas composition, which were obtained by changing the hydraulic retention time. Using confocal laser scanning microscopy (CLSM), a higher biofilm amount was detected at 25 °C than at 35 °C, while quartz crystal microbalance with dissipation (QCM-D) showed a more adhesive, but less viscous and elastic EPS layer. In situ optical coherence tomography (OCT) of an ultra-filtration membrane, fed with the mixed liquor suspended solids (MLSS) at the two temperatures, revealed that while a higher rate of TMP increase was obtained at 25 °C, the attachment of biomass from MLSS was markedly less. Increased EPS adhesion to the membrane can accelerate TMP increase during the operation of both the AnMBR and the OCT filtration cell. EPS's reduced viscoelasticity at 25 °C suggests reduced floc integrity and possible increased EPS penetration into the membrane pores. Analysis of the structures of the microbial communities constituting the AnMBR flocs and membrane biofilms reveals temperature's effects on microbial richness, diversity, and abundance, which likely influence the observed EPS properties and consequent AnMBR fouling.


Asunto(s)
Incrustaciones Biológicas , Reactores Biológicos , Matriz Extracelular de Sustancias Poliméricas , Membranas Artificiales , Temperatura , Anaerobiosis , Matriz Extracelular de Sustancias Poliméricas/metabolismo , Biopelículas
11.
J Hazard Mater ; 471: 134296, 2024 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-38643574

RESUMEN

The effective removal of viruses from swine wastewater using anaerobic membrane bioreactor (AnMBR) is vital to ecological safety. However, most studies have focused only on disinfectants, whereas the capabilities of the treatment process have not been investigated. In this study, the performance and mechanism of an AnMBR in the removal of porcine hepatitis E virus (HEV), porcine kobuvirus (PKoV), porcine epidemic diarrhea virus (PEDV), and transmissible gastroenteritis coronavirus (TGEV) are systematically investigated. The results show that the AnMBR effectively removes the four viruses, with average removal efficiencies of 1.62, 3.05, 2.41, and 1.34 log for HEV, PKoV, PEDV and TGEV, respectively. Biomass adsorption contributes primarily to the total virus removal in the initial stage of reactor operation, with contributions to HEV and PKoV removal exceeding 71.7 % and 68.2 %, respectively. When the membrane is fouled, membrane rejection dominated virus removal. The membrane rejection contribution test shows the significant contribution of membrane pore foulants (23-76 %). Correlation analysis shows that the surface characteristics and size differences of the four viruses contribute primarily to their different effects on biomass adsorption and membrane rejection. This study provides technical guidance for viral removal during the treatment of high-concentration swine wastewater using an AnMBR.


Asunto(s)
Reactores Biológicos , Membranas Artificiales , Aguas Residuales , Animales , Aguas Residuales/virología , Porcinos , Anaerobiosis , Virus ARN/aislamiento & purificación , Purificación del Agua/métodos , Adsorción , Biomasa , Virus de la Diarrea Epidémica Porcina/aislamiento & purificación , Eliminación de Residuos Líquidos/métodos
12.
Water Res ; 256: 121557, 2024 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-38581982

RESUMEN

Electrochemical anaerobic membrane bioreactor (EC-AnMBR) by integrating a composite anodic membrane (CAM), represents an effective method for promoting methanogenic performance and mitigating membrane fouling. However, the development and formation of electroactive biofilm on CAM, and the spatio-temporal distribution of key functional microorganisms, especially the degradation mechanism of organic pollutants in metabolic pathways were not well documented. In this work, two AnMBR systems (EC-AnMBR and traditional AnMBR) were constructed and operated to identify the role of CAM in metabolic pathway on biogas upgrading and mitigation of membrane fouling. The methane yield of EC-AnMBR at HRT of 20 days was 217.1 ± 25.6 mL-CH4/g COD, about 32.1 % higher compared to the traditional AnMBR. The 16S rRNA analysis revealed that the EC-AnMBR significantly promoted the growth of hydrolysis bacteria (Lactobacillus and SJA-15) and methanogenic archaea (Methanosaeta and Methanobacterium). Metagenomic analysis revealed that the EC-AnMBR promotes the upregulation of functional genes involved in carbohydrate metabolism (gap and kor) and methane metabolism (mtr, mcr, and hdr), improving the degradation of soluble microbial products (SMPs)/extracellular polymeric substances (EPS) on the CAM and enhancing the methanogens activity on the cathode. Moreover, CAM biofilm exhibits heterogeneity in the degradation of organic pollutants along its vertical depth. The bacteria with high hydrolyzing ability accumulated in the upper part, driving the feedstock degradation for higher starch, sucrose and galactose metabolism. A three-dimensional mesh-like cake structure with larger pores was formed as a biofilter in the middle and lower part of CAM, where the electroactive Geobacter sulfurreducens had high capabilities to directly store and transfer electrons for the degradation of organic pollutants. This outcome will further contribute to the comprehension of the metabolic mechanisms of CAM module on membrane fouling control and organic solid waste treatment and disposal.


Asunto(s)
Biocombustibles , Reactores Biológicos , Membranas Artificiales , Reactores Biológicos/microbiología , Anaerobiosis , ARN Ribosómico 16S/genética , Metano/metabolismo , Biopelículas , Bacterias/metabolismo , Incrustaciones Biológicas
13.
Environ Technol ; : 1-14, 2024 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-38488119

RESUMEN

Anaerobic Membrane Bioreactors (AnMBR) offer numerous advantages in wastewater treatment, yet they are prone to membrane fouling after extended operation, impeding their long-term efficiency and stability. In this study, a coupled system was developed using modified conductive membranes as the filtration membrane for the AnMBR and as the anodic conductive membrane in the microbial electrochemical system, with a total volume of approximately 2.57 L. The research focused on understanding the membrane fouling characteristics of the AnMBR when treating wastewater containing sodium ion (Na+) and magnesium ion (Mg2+). When the system was treating wastewater containing Na+, organic pollutants such as proteins and polysaccharides were identified as the primary causes of membrane fouling. Three experimental groups generating different electric currents exhibited extended operational times compared to the open-circuit control group, with extensions of 30, 24, and 15 days, respectively. Conversely, when treating wastewater with Mg2+, organic-inorganic composite fouling, primarily driven by Mg2+ bridging, emerged as the key challenge, with the experimental groups showing operational extensions of 5, 8, and 23 days, respectively, in comparison to the control group. Analysis of proteins and polysaccharides indicated that electric current played a crucial role in reducing organic fouling in the sludge cake layer. When treating wastewater containing Na+, the effectiveness of membrane fouling control was directly proportional to the electric current, while when treating wastewater containing Mg2+, it was directly proportional to the voltage.

14.
Membranes (Basel) ; 14(3)2024 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-38535288

RESUMEN

A simple model is developed for membrane fouling, taking into account two main fouling phenomena: cake formation, due to attached solids on the membrane surface, and pore clogging, due to retained compounds inside the pores. The model is coupled with a simple anaerobic digestion model for describing the dynamics of an anaerobic membrane bioreactor (AnMBR). In simulations, we investigate its qualitative behavior: it is shown that the model exhibits satisfying properties in terms of a flux decrease due to membrane fouling. Comparing simulation and experimental data, the model is shown to predict quite well the dynamics of an AnMBR. The simulated flux best fits the experimental flux with a correlation coefficient r2=0.968 for the calibration data set and r2=0.938 for the validation data set. General discussions are given on possible control strategies to limit fouling and optimize the flux production. We show in simulations that these strategies allow one to increase the mean production flux to 33 L/(h·m2),whereas without control, it was 18 L/(h·m2).

15.
Environ Sci Technol ; 58(5): 2360-2372, 2024 Feb 06.
Artículo en Inglés | MEDLINE | ID: mdl-38261758

RESUMEN

Having a tool to monitor the microbial abundances rapidly and to utilize the data to predict the reactor performance would facilitate the operation of an anaerobic membrane bioreactor (AnMBR). This study aims to achieve the aforementioned scenario by developing a linear regression model that incorporates a time-lagging mode. The model uses low nucleic acid (LNA) cell numbers and the ratio of high nucleic acid (HNA) to LNA cells as an input data set. First, the model was trained using data sets obtained from a 35 L pilot-scale AnMBR. The model was able to predict the chemical oxygen demand (COD) removal efficiency and methane production 3.5 days in advance. Subsequent validation of the model using flow cytometry (FCM)-derived data (at time t - 3.5 days) obtained from another biologically independent reactor did not exhibit any substantial difference between predicted and actual measurements of reactor performance at time t. Further cell sorting, 16S rRNA gene sequencing, and correlation analysis partly attributed this accurate prediction to HNA genera (e.g., Anaerovibrio and unclassified Bacteroidales) and LNA genera (e.g., Achromobacter, Ochrobactrum, and unclassified Anaerolineae). In summary, our findings suggest that HNA and LNA cell routine enumeration, along with the trained model, can derive a fast approach to predict the AnMBR performance.


Asunto(s)
Ácidos Nucleicos , Anaerobiosis , Citometría de Flujo , Ácidos Nucleicos/análisis , Ácidos Nucleicos/metabolismo , ARN Ribosómico 16S/genética , Reactores Biológicos , Eliminación de Residuos Líquidos , Metano
16.
Chemosphere ; 342: 140151, 2023 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-37714478

RESUMEN

Anaerobic membrane bioreactor is advantageous over traditional processes for food waste treatment, i.e. short retention time, high loading rate, and particulate clean permeate. However, establishing a sustainable membrane filtration is a long-standing challenge because of its high viscosity and solids concentration characteristics. Therefore, this study investigated the changes in the membrane permeability before and after the cleaning during a 130-day thermophilic anaerobic experiment. Results show that the AnMBR system could maintain high stability even under a short HRT of 10 days and OLR of 9.0 kg-COD/(m3·d) with low volatile fatty acid of 50 mg/L. The membrane filtration deteriorates with the concurrence of a sharp increase of viscosity when the volatile solids reached 23 g/L. A critical flux was achieved at 5.5 L/(m2·h) under optimized operation conditions, membrane filtration/relaxing ratio with less than 4:1 at a hydraulic retention time of 15 d. Membrane fouling can be removed by soaking the membrane in NaClO (1 g/L, 15 h) and citric acid (2 g/L, 2 h). Conclusively, this work provides insight to establish the operation strategy for a thermophilic AnMBR treating food waste.


Asunto(s)
Alimentos , Eliminación de Residuos , Residuos Sólidos , Anaerobiosis , Filtración/métodos , Reactores Biológicos , Eliminación de Residuos Líquidos/métodos , Membranas Artificiales , Metano
17.
Water Res ; 245: 120618, 2023 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-37716297

RESUMEN

The bio-cake layer is one of the most negative effects during water and wastewater filtration, but its potential behoof of biodegradation is poorly understood. In this study, we activated and reconstructed the bio-cake by using the carbon nanotube membrane (25 cm2 area, 17 LMH flux) as the anode in an anaerobic membrane bioreactor (AnMBR), and investigated its positive role in advanced removal of dissolved organic matter from up-flow anaerobic sludge bed unit (3 L/d) when treating synthetic municipal wastewater. At the anodic membrane interface, the enhanced biodegradation was proved to dominate the DOM reduction (contribution >40%), controlling the effluent COD as low as 19.2 ± 2.5 mg/L. Bio-cake characterizations suggested that the positive potential induced electroactive improvement, cell viability boost, and metabolic optimization. Metatranscriptomic analyses revealed that anode respiratory out-compete methanogenesis, forwarding a synergetic metabolism between enriched fermenters like Proteiniphilum sp. and exoelectrogens like Geobacter sp. Thus, electroactive bio-cake not only accelerated the decomposition of inside foulants to maintain the high flux, but also efficiently intercepted flow-through DOM due to reduced mass-transfer limitations and enhanced metabolic activity. An ordered, non-clogging, and potentially functional "cell filter" was established to achieve a win-win situation between fouling control and effluent improvement, which is promising to upgrade the AnMBR technology for maximizing the sustainable regeneration in future wastewater treatment.

18.
Biofouling ; 39(4): 349-358, 2023.
Artículo en Inglés | MEDLINE | ID: mdl-37325870

RESUMEN

Anaerobic membrane reactors (AnMBRs) offer an alternative wastewater treatment system, presenting both reclamation of value through biogas production, and efficient treatment of recalcitrant contaminants such as antibiotics from wastewater. The effects of bioaugmentation with the green alga Haematococcus pluvialis on anaerobic treatment of pharmaceutical wastewaters, alleviating membrane biofouling, biogas production and impact on the indigenous microbial communities were evaluated using AnMBRs. The outputs of the bioreactor experiments revealed that bioaugmentation strategies with the green alga increased removal of chemical oxygen demand by 12% and delayed membrane fouling by 25% and increased biogas production by 40%. Furthermore, bioaugmentation with the green alga led to a significant change in relative abundance of archaea and the main methanogenesis pathway shifted from Methanothermobacter to Methanosaeta, accompanied by their respective syntrophic bacteria.


Asunto(s)
Chlorophyta , Eliminación de Residuos Líquidos , Anaerobiosis , Biocombustibles , Biopelículas , Aguas Residuales , Reactores Biológicos/microbiología , Metano , Membranas Artificiales
19.
Chemosphere ; 335: 139075, 2023 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-37263509

RESUMEN

Carbon transformation is important for an anaerobic process but is often overlooked when using an anaerobic membrane bioreactor (AnMBR). Material flow in an AnMBR treating calcium-rich MSW leachate was thus quantitatively investigated to illustrate how chemical and biological factors affect carbon transformation. The results show that a remarkable amount of carbon in the leachate was degraded, with 50.1% of it should be converted into CH4 and 37.7% of it into CO2. However, a much smaller value of 40.6% and 14.2% were experimentally obtained. Chemical analysis indicated that the precipitation of calcium carbonate captured 1.23 g/day of carbon. At the same time, about 23.2 g/L HCO3- and 16.6 mg/L CH4 (both as carbon) were dissolved in the liquid. Those features facilitated the high CH4 (74%) content in biogas. A carbon transformation model was therefore established and showed carbon flow into the gas, liquid, and solid phases, respectively. Carbon existed in biogas, permeate, and discharged sludge was also obtained.


Asunto(s)
Biocombustibles , Carbono , Anaerobiosis , Reactores Biológicos , Aguas del Alcantarillado/química , Metano/metabolismo
20.
Bioresour Technol ; 382: 129222, 2023 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-37217144

RESUMEN

Membrane fouling presents a big challenge for the real-world implementation of anaerobic membrane bioreactors (AnMBRs) in digesting high-solid biowastes. In this study, an electrochemical anaerobic membrane bioreactor (EC-AnMBR) with a novel sandwich-type composite anodic membrane was designed and constructed for controlling membrane fouling whilst improving the energy recovery. The results showed that EC-AnMBR produced a higher methane yield of 358.5 ± 74.8 mL/d, rising by 12.8% compared to the AnMBR without applied voltage. Integration of composite anodic membrane induced a stable membrane flux and low transmembrane pressure through forming an anodic biofilm while total coliforms removal reached 97.9%. The microbial community analysis further provided compelling evidence that EC-AnMBR enriched the relative abundance of hydrolyzing (Chryseobacterium 2.6%) bacteria and methane-producing (Methanobacterium 32.8%) archaea. These findings offered new insights into anti-biofouling performance and provided significant implications for municipal organic waste treatment and energy recovery in the new EC-AnMBR.


Asunto(s)
Eliminación de Residuos , Aguas del Alcantarillado , Anaerobiosis , Reactores Biológicos , Membranas Artificiales , Metano , Aguas del Alcantarillado/microbiología , Eliminación de Residuos Líquidos/métodos , Aguas Residuales
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