Membrane Bioreactor Wastewater Treatment Plants Research Articles

Machine learning reveals the complex ecological interplay of microbiome in a full-scale membrane bioreactor wastewater treatment plant

Membrane bioreactor (MBR) systems are one of the most widely used wastewater treatment processes for various municipal and industrial waste streams. The present study aimed to advance the understanding of ecologically important keystone taxa that play an important role in full-scale MBR systems. A machine-learning (ML) modeling framework based on microbiome data was developed to successfully predict, with an average accuracy of >91.6%, the operational characteristics of three representative full-scale wastewater systems: an MBR, a conventional activated sludge system, and a sequencing batch reactor. ML-based feature-importance analysis identified Ferruginibacter as a keystone organism in the MBR system. The phylogeny and known ecophysiology of members of Ferruginibacter supported their role in metabolizing complex organic polymers (e.g., extracellular polymeric substances) in MBR systems characterized by high concentrations of mixed liquor suspended solids and a high solid retention time. ML regression modeling also revealed temporal patterns of Ferruginibacter in response to water temperature. ML modeling was thus successfully employed in the present study to investigate complex/non-linear relationships between keystone taxa and environmental conditions that cannot be detected using conventional approaches. Overall, our microbiome-data-enabled ML modeling approach represents a methodological advance for identifying keystone taxa and their complex ecological interactions, which has implications for the sustainable and predictive management of MBR systems.

Chromatographic and spectroscopic comparison of dissolved organic matter variation in anaerobic-anoxic-oxic process with tertiary filtration and membrane bioreactor

Anaerobic-anoxic-oxic process with tertiary filtration (A2OWTF) and membrane bioreactor (MBR) was compared from the perspective of dissolved organic matter (DOM) variation in this study. A2OWTF and MBR wastewater treatment plants (WWTPs) samples were compared via conventional wastewater quality indexes, excitation-emission matrix (EEM) spectra, UV–vis spectra and high-performance size exclusion chromatography (HPSEC), which gradually revealed differences between the two processes from phenomena to mechanism. Lower removal of dissolved organic carbon (DOC) by MBR phenomenally revealed its DOM removal deficiency. EEM fluorescence regional integration (FRI), EEM parallel factor analysis (PARAFAC) and UV–vis Gaussian deconvolution qualitatively revealed more abundant humic-like substances (HS) and more complex effluent DOM composition for MBR. HPSEC provided more quantitative characterization. As for effluent after biotreatment, MBR exhibited lower removal rates of HPSEC fractions I (mainly containing protein and polysaccharides), IV (mainly containing low molecular weight organic acids) and fractions II, III (mainly containing HS) than A2OWTF (e.g., removal rates of MBR vs. A2OWTF calculated with UV absorbance at 254 nm (UVA254): 43.6% vs. 66.2%; 5.1% vs. 67.0%; −14.4% vs. 30.8%; −5.7% vs. 36.8% respectively for fractions I, IV, II, III). The massive HS generation in MBR also led to its higher trihalomethane formation potential (THMFP) for final effluent than A2OWTF. In conclusion, MBR should be prudently considered in terms of DOM removal for municipal WWTP upgrading.

Microbial communities and interactions in full-scale A2/O and MBR wastewater treatment plants

Microorganisms are key to stable system operation and efficient pollutant removal in wastewater treatment plants (WWTPs), whereas the critical information on their seasonal variations is still lacking. Impacts of process types and seasonal variations on microbial communities, metabolisms, and interactions were examined in the anaerobic/anoxic/aerobic (A2/O) and membrane bioreactor (MBR) WWTPs. Environmental factors had a greater impact on pollutant removal than process types. Dissolved oxygen concentration and pH were crucial environmental factors that could simultaneously affect nitrogen metabolism and microbial interactions. Bacteroidetes, Proteobacteria, and Chloroflexi were the dominant phyla. Quorum sensing (QS) systems were detected in these WWTPs, and the N-acyl homoserine lactones QS system was the key pathway responsible for microbial interactions. The obtained microbial information in the full-scale A2/O-WWTP and MBR-WWTP and the potential correlations between microorganisms and environmental factors could provide valuable clues for system optimization.

What removals of pathogen indicators can be expected within large-scale wastewater treatment facilities in the context of wastewater reuse in Paris conurbation?

The fate of pathogen indicators (Escherichia coli - EC, intestinal enterococci - IE, RNA-F bacteriophages and spores of sulfite reducing bacteria - SSR) was extensively studied in Parisian large-scale wastewater treatment plants (WWTPs), based on conventional activated sludge, biofiltration or membrane bioreactor (MBR) processes. Between 14 and 87 campaigns were performed between 2014 and 2018 in five WWTPs. High removals of 3 log for both EC and IE, and lower removals of 1-2 log for SSR and RNA-F bacteriophages, were observed in conventional activated sludge and biofiltration WWTPs. The MBR WWTP achieves notably greater removals of 4.5-5.5 log for faecal bacteria and 3-4 log for SSR and RNA-F bacteriophages. This WWTP is the only one already in compliance with reuse standards, the other ones being non-compliant because of SSR and RNA-F bacteriophages. The implementation of a micro-grain activated carbon process would increase the WWTP removals of 0.8 log for faecal bacteria, due to particles retention, with no significant effect on both other pathogens. Ozonation (0.9-1.3 g O3/g dissolved organic carbon) or performic acid (0.8-1.2 ppm) would have greater benefits with additional removals of 1.5-2.5 log for EC, 1-2 log for IE and 0.5-1 log for SSR and RNA-F bacteriophages. Correlations between pathogen indicator removals and initial concentrations were found, as well as a significant decrease of RNA-F bacteriophage concentrations in Parisian raw wastewater, below 2 log. Thus, RNA-F bacteriophages could be a real issue to evaluate the compliance of Parisian wastewater with reuse. The time evolution of removals demonstrated that SSR is the most problematic parameter regarding reuse in conventional activated sludge and biofiltration WWTPs, as its initial concentration is high (5 log) but removals insufficient (<2 log). In contrast, removals of RNA-F bacteriophages greater than 2 log can be obtained within WWTPs completed or not with a tertiary treatment when the initial concentration in raw wastewater is sufficient. Correlations were also found between the removals of pathogen indicators and the removals of physico-chemical parameters, but they are not good enough to allow performance predictions.

Fate of antibiotics, antibiotic-resistant bacteria, and cell-free antibiotic-resistant genes in full-scale membrane bioreactor wastewater treatment plants

The removal of antibiotics, antibiotic-resistant bacteria (ARB), and cell-free antibiotic-resistant genes (ARGs) and the microbial community of ARB were investigated in detail to understand their fate and provide valuable information on the feasibility of full-scale membrane bioreactor (MBR). The potential risks of cell-free ARGs to the receiving environment were discovered. High influent antibiotic concentration could inhibit the microbial activity of MBR sludge, whereas good antibiotic removal could be maintained because of relatively long solid retention time and high biomass retention. Approximately 61.8%–77.5% of the total antibiotics were degraded, and 22.5%–38.2% of the total antibiotics were adsorbed by MBR sludge on average. The individual antibiotic removal presented intense discrepancy because of the chemical construction and distribution coefficient of antibiotics. Aeromonas exhibited specific antibiotic resistance to ampicillin and erythromycin, Escherichia became the predominant genera in kanamycin-ARB and tetracycline-ARB, and Klebsiella and Bacteroides were the particular genera that exhibited distinct antibiotic resistance to ciprofloxacin. A significant correlation was found between cell-free ARG abundance and ARB content, and relatively high effluent cell-free ARG abundance facilitated the proliferation and transmission of ARB. The impacts of the receiving environment to eliminate the ecological risks and severe threats to human health should be investigated because of the low decay ratio and long-term persistence of cell-free ARGs.

Calibration and validation of an activated sludge model for membrane bioreactor wastewater treatment plants

ABSTRACTA mathematical model to simulate the biological processes occurring in a membrane bioreactor (MBR) is presented. The model accounts for different MBR technical features by introducing specific permeability parameters for the applied membrane system. The model considers for the heterotrophic storage process and the formation of soluble microbial products. The introduction of an inhibition coefficient influencing the anoxic kinetics enables the model to simulate the particular operating conditions of the plant, such as a high or low dissolved oxygen concentration in the denitrification tank. The model was applied at the MBR wastewater treatment plant of Vila Nova do Ceira (Portugal) which uses a classic pre-denitrification cycle. Data for calibration and validation were sampled at the same wastewater treatment plant. Calibration was achieved by varying the kinetic parameters of the model to match the simulation results to the experimental data. The values of the kinetic parameters were similar to those found in the literature. The validation was performed by two different methodologies to analyse the model response to diverse operating conditions, and to evaluate the resilience of the MBR. Calibration and validation results were evaluated with mean average error, root mean square error and fractional mean bias as performance indexes. In most cases, these indexes confirmed the high accuracy of the model. Overall, the results of the calibration and validation steps enriched the proposed model by providing an effective biological description of the processes characterizing the MBR. Thus, the model is a reliable tool for the management and designing of MBR.

Waste activated sludge dewaterability: comparative evaluation of sludge derived from CAS and MBR systems

Sludge dewatering represents, nowadays, one of the greatest operational cost to wastewater treatment cycle. Physical–chemical and biological parameters are recognized to influence the sludge dewaterability. However, many authors agree in identifying the sludge origin as one of the main aspect involved in sludge dewaterability. Indeed, the sludge origin such as the processes involved in liquid–solid separation, seriously affect the sludge features. In order to elucidate the key factors influencing the dewaterability process, the present work is aimed to investigate the influence of the treatment plant lay-out on sludge dewaterability. The analyzed sludge samples were derived from four conventional activated sludge and two membrane bioreactor wastewater treatment plants. Experimental investigation was focused to highlight difference in sludge dewaterability derived from the application of European Standards adopted for sludge characterization. The achieved results confirmed the complexity of the inter-relationships between many factors affecting the sludge dewaterability.

A novel bioaugmentation treatment approach using a confined microbial environment: a case study in a Membrane Bioreactor wastewater treatment plant

ABSTRACTA novel bioaugmentation treatment approach, the Small-Bioreactor Platform (SBP) technology, was developed to increase the biological stabilization process in the treatment of wastewater in order to improve wastewater processing effectiveness. The SBP microfiltration membrane provides protection against the natural selection forces that target exogenous bacterial cultures within wastewater. As a result, the exogenous microorganisms culture adapt and proliferate, thus providing a successful bioaugmentation process in wastewater treatment. The new bioaugmentation treatment approach was studied in a full configuration Membrane Bioreactor (MBR) plant treating domestic wastewater. Our results present the potential of this innovative technology to eliminate, or reduce, the intensity of stress events, as well as shortening the recovery time after stress events, consequently elevating the treatment effectiveness. The effective dose of SBP capsules per cubic metre per day of wastewater was achieved during the addition of 3000 SBP capsules (1.25 SBP capsules per cubic metre per day), which provided approximately 4.5 L of high concentration exogenous biomass culture within the SBP capsules internal medium. This study demonstrates an innovative treatment capability which provides an effective bioaugmentation treatment in an MBR domestic wastewater treatment plant.

Membrane bioreactor wastewater treatment plants reveal diverse yeast and protist communities of potential significance in biofouling

The yeast community was studied in a municipal full-scale membrane bioreactor wastewater treatment plant (MBR-WWTP). The unexpectedly high diversity of yeasts indicated that the activated sludge formed a suitable environment for them to proliferate, with cellular concentrations of 2.2 ± 0.8 × 103 CFU ml−1. Sixteen species of seven genera were present in the biological reactor, with Ascomycetes being the most prevalent group (93%). Most isolates were able to grow in a synthetic wastewater medium, adhere to polyethylene surfaces, and develop biofilms of variable complexity. The relationship between yeast populations and the protists in the MBR-WWTP was also studied, revealing that some protist species preyed on and ingested yeasts. These results suggest that yeast populations may play a role in the food web of a WWTP and, to some extent, contribute to membrane biofouling in MBR systems.

The Incorporation of Ceramic Membranes in MBR Systems for Wastewater Treatment: Advantages and Patented New Developments

The membrane biological reactor (MBR) configuration has proven to be optimal for treatment of many industrial wastewaters, especially when optimized treatment efficiencies are an important consideration. Ceramic MBR is being consolidated as a reliable technology for industrial applications, due to the benefits of the system, while ceramic membranes may be an adequate alternative for anaerobic MBR application, due to evidence of low membrane fouling rate and the ability to rigorously clean their surface without at the same time reducing the effective membrane life. This review summarizes Recent Patents on Engineering that disclose key data for both the functioning of MBRs and the use of ceramic membranes. Specifically, an advanced control system for a membrane bioreactor wastewater treatment plant is disclosed, while an integrated biological treatment coupled to membrane filtration is proposed for advanced nutrients removal and reuse of treated waters. Recent studies have been focused on the production of a specific bioceramic membrane with selective adsorption effects and simultaneous digestion ability. Bioceramic membranes may provide effective carbon sources and required minerals to activated sludge microorganisms, while they can be used as biological media filter material for air filtration and wastewater treatment. Furthermore, bioceramics may adsorb phosphate ions and remove oxygen rich components such as nitrates from aqueous solutions. Keywords: Bioceramic, ceramic membranes, control system, MBR systems, water treatment, wastewater treatment.

Removal of pharmaceuticals and personal care products in a membrane bioreactor wastewater treatment plant.

Ninety-nine pharmaceuticals and personal care products (PPCPs) were analyzed in influent, final effluent, and biosolids samples from a wastewater treatment plant employing a membrane bioreactor (MBR). High concentrations in influent were found for acetaminophen, caffeine, metformin, 2-hydroxy-ibuprofen, paraxanthine, ibuprofen, and naproxen (10(4)-10(5) ng/L). Final effluents contained clarithromycin, metformin, atenolol, carbamazepine, and trimethoprim (>500 ng/L) at the highest concentrations, while triclosan, ciprofloxacin, norfloxacin, triclocarban, metformin, caffeine, ofloxacin, and paraxanthine were found at high concentrations in biosolids (>10(3) ng/g dry weight). PPCP removals varied from -34% to >99% and 23 PPCPs had ≥90% removal. Of the studied PPCPs, 26 compounds have been rarely or never studied in previous membrane bioreactor (MBR) investigations. The removal pathway showed that acetaminophen, 2-hydroxy-ibuprofen, naproxen, ibuprofen, codeine, metformin, enalapril, atorvastatin, caffeine, paraxanthine, and cotinine exhibited high degradation/transformation. PPCPs showing strong sorption to solids included triclocarban, triclosan, miconazole, tetracycline, 4-epitetracycline, norfloxacin, ciprofloxacin, doxycycline, paroxetine, and ofloxacin. Trimethoprim, oxycodone, clarithromycin, thiabendazole, hydrochlorothiazide, erythromycin-H2O, carbamazepine, meprobamate, and propranolol were not removed during treatment, and clarithromycin was even formed during treatment. This investigation extended our understanding of the occurrence and fate of PPCPs in an MBR process through the analysis of the largest number of compounds in an MBR study to date.

Production of high concentrations of H2O2 in a bioelectrochemical reactor fed with real municipal wastewater

Bioelectrochemical systems can be used to energy-efficiently produce hydrogen peroxide (H2O2) from wastewater. Organic compounds in the wastewater are oxidized by microorganisms using the anode as electron acceptor. H2O2 is produced by reduction of oxygen on the cathode. In this study, we demonstrate for the first time production of high concentrations of H2O2 production from real municipal wastewater. A concentration of 2.26 g/L H2O2 was produced in 9 h at 8.3 kWh/kgH2O2. This concentration could poTENTially be useful for membrane cleaning at membrane bioreactor wastewater treatment plants. With an acetate-containing nutrient medium as anode feed, a H2O2 concentration of 9.67 g/L was produced in 21 h at an energy cost of 3.0 kWh/kgH2O2. The bioelectrochemical reactor used in this study suffered from a high internal resistance, most likely caused by calcium carbonate deposits on the cathode-facing side of the cation exchange membrane separating the anode and cathode compartments.

Two years of the operation of a domestic MBR wastewater treatment plant

Two years of the operation of a domestic MBR wastewater treatment plantThe paper evaluates the results of data obtained from two years of observing an actual domestic wastewater treatment plant (WWTP) with an immersed membrane module. The domestic MBR (membrane bioreactor) WWTP was linked to a dwelling with four residents. Two different commercial flat sheet membrane modules were investigated. The membrane modules, as well as the whole WWTP, were tested with different fluxes as well as the response of the membrane and activated sludge to different conditions, such as actual peak wastewater flows, extremes temperatures (a winter below 5 °C), and high pH values.

Calicivirus Removal in a Membrane Bioreactor Wastewater Treatment Plant

To evaluate membrane bioreactor wastewater treatment virus removal, a study was conducted in southwest France. Samples collected from plant influent, an aeration basin, membrane effluent, solid sludge, and effluent biweekly from October 2009 to June 2010 were analyzed for calicivirus (norovirus and sapovirus) by real-time reverse transcription-PCR (RT-PCR) using extraction controls to perform quantification. Adenovirus and Escherichia coli also were analyzed to compare removal efficiencies. In the influent, sapovirus was always present, while the norovirus concentration varied temporally, with the highest concentration being detected from February to May. All three human norovirus genogroups (GI, GII, and GIV) were detected in effluent, but GIV was never detected in effluent; GI and GII were detected in 50% of the samples but at low concentrations. In the effluent, sapovirus was identified only once. An adenovirus titer showing temporal variation in influent samples was identified only twice in effluent. E. coli was always below the limit of detection in the effluent. Overall, the removal of calicivirus varied from 3.3 to greater than 6.8 log units, with no difference between the two main genogroups. Our results also demonstrated that the viruses are blocked by the membrane in the treatment plant and are removed from the plant as solid sludge.

Removal of human enteric viruses by a full-scale membrane bioreactor during municipal wastewater processing

In the US, human enteric viruses are the main etiologic agents of childhood gastroenteritis, resulting in several hospitalizations and deaths each year. These viruses have been linked to several waterborne diseases, such as acute gastroenteritis, conjunctivitis and respiratory illness. The removal of human enterovirus (EV) and norovirus genogroup II (NoV GGII) was studied in a full-scale membrane bioreactor (MBR) wastewater treatment plant (WWTP) and compared with the removal of human adenovirus (HAdV). In total, 32 samples were quantified using real-time reverse transcription-PCR (RT-PCR) from four separate locations throughout the treatment process; influent, primary settling effluent, membrane influent (which includes the MLSS) and membrane effluent. EV was detected in all 32 samples (100%) with an average concentration of 1.1 × 10 7 and 7.8 × 10 1 viruses/L for the membrane influent and membrane effluent, respectively. NoV GGII was detected in 20 of 32 samples (63%) with an average membrane influent and membrane effluent concentration of 2.8 × 10 5 and 1.2 × 10 1 viruses/L, respectively. HAdV was detected in all 32 samples with an average membrane influent concentration of 5.2 × 10 8 and 2.7 × 10 3 viruses/L in the membrane effluent. Our findings indicate that this particular full-scale MBR treatment was able to reduce the viral loads by approximately 5.1 and 3.9 log units for EV and NoV GGII as compared to 5.5 log units for HAdV. This full-scale MBR system outperformed the removal observed in previous pilot and bench scale studies by 1 to 2 log units. To the best of our knowledge, this is the first study focusing on the removal of EV in a full-scale MBR WWTP using real-time RT-PCR, and on the solid–liquid distribution of EV and NoV GII in secondary biological treatment.

Biogenic Nanoscale Colloids in Wastewater Effluents

The size, surface area, metal complexation capacity, organic pollutant sorption potential, reactivity with disinfectants, and elevated nitrogen content of biogenic organic nanoscale material (BONM) can potentially affect aquatic environments. BONM in effluents from 11 full-scale wastewater treatment plants (WWTPs), which use a range of biological processes, were characterized in two ways. First, BONM was measured by hydrodynamic size-exclusion chromatography coupled with an online organic carbon and UV detector. Second, BONM was isolated from the wastewater using rotary evaporation and dialysis and then characterized by elemental analysis, transmission electron microscopy, and Fourier transform infrared spectroscopy. The wastewaters contained 6-10 mg/L of dissolved organic carbon (DOC). BONM accounted for 5%-50% of the DOC in wastewater effluent organic matter, and the largest size fraction (>10 kDa) of organic carbon correlated with the organic carbon content determined after rotary evaporation and dialysis. Membrane bioreactor WWTPs had the lowest fraction of BONM (<10% of the DOC), followed by conventional activated sludge (10% to 30% of the DOC), with other processes (e.g., trickling filters, aerated lagoons) containing larger BONM percentages. BONM had a lower carbon to nitrogen ratio (6.2 ± 1.7) compared with the literature values for humic or fulvic acids, exhibited chemical bonds that were indicative of amides and polysaccharides, and contained fibril entangled networks. This work has important implications for operations efficiency of WWTPs, including controlling membrane fouling and release of organic nitrogen into sensitive environments.

Fate and removal of pharmaceuticals and illicit drugs in conventional and membrane bioreactor wastewater treatment plants and by riverbank filtration

Pharmaceutically active compounds (PhACs) and drugs of abuse (DAs) are two important groups of emerging environmental contaminants that have raised an increasing interest in the scientific community. A number of studies revealed their presence in the environment. This is mainly due to the fact that some compounds are not efficiently removed during wastewater treatment processes, being able to reach surface and groundwater and subsequently, drinking waters. This paper reviews the data regarding the levels of pharmaceuticals and illicit drugs detected in wastewaters and gives an overview of their removal by conventional treatment technologies (applying activated sludge) as well as advanced treatments such as membrane bioreactor. The paper also gives an overview of bank filtration practices at managed aquifer recharge sites and discusses the potential of this approach to mitigate the contamination by PhACs and DAs.

The Design, Operation and Performance of the New Membrane Bioreactor (MBR) WWTP for the Becket-Chimney Corners YMCA Camps in Western Massachusetts

The increasingly stringent requirements for effluent quality and the need to reclaim water are promoting the application of membrane bioreactor (MBR) systems for wastewater treatment. The membrane replaces the solids separation function carried out by the secondary clarifier and sand filter in a conventional activated sludge system. The MBR process effectively overcomes the problems associated with poor settling of sludge. In addition, the use of membranes permits the operation of the bioreactor at higher mixed liquor suspended solids (MLSS) concentrations of 8,000 to 12,000 milligrams per litre (mg/L) compared to a conventional system, which may operate between 2,000 to 4,000 mg/L. The elevated biomass concentration allows for improved removal of both soluble and particulate biodegradable material from the wastewater. The MBR design also reduces the area as well as the reactor volume required for treatment. Two-State YMCA operates Camp Chimney Corners and Camp Becket in Becket, Massachusetts. These two camps were under consent orders to address deficient septic systems and decided to construct a 40,000 gallons per day (151,400 litres/day) wastewater treatment plant and wastewater collection and conveyance system to address septic system problems. A MBR wastewater treatment plant was designed and constructed and began treating wastewater in May 2007. This paper presents the design, operation, and performance of the MBR WWTP.