Membrane Bioreactor For Wastewater Treatment Research Articles

Benefits of Fungal-to-Bacterial quorum quenching as Anti-Biofouling strategy in membrane bioreactors for wastewater treatment and water reuse

This study addresses membrane biofouling in membrane bioreactors (MBRs) by exploring fungal-to-bacterial quorum quenching (QQ) strategies. While most research has been focused on bacterial-to-bacterial QQ tactics, this study identified fungal strain Vanrija sp. MS1, which is capable of degrading N-acyl-homoserine lactones (signaling molecules of Gram-negative bacteria). To determine the benefits of fungal over bacterial strains, after immobilization on fluidizing spherical beads in an MBR, MS1 significantly reduced the fouling rate by 1.8-fold compared to control MBR, decreased extracellular polymeric substance levels in the biofilm during MBR operation, and favorably changed microbial community and bacterial network, resulting in biofouling mitigation. It is noteworthy that, unlike Rhodococcus sp. BH4, MS1 enhanced QQ activity when switching from neutral to acidic conditions. These results suggest that MS1 has the potential for the effective treatment of acidic industrial wastewater sources such as semiconductor and secondary battery wastewater using MBRs.

Semi-interpenetrating network hydrogels-based microcapsule for quorum quenching bacteria biocontainment to enhance biofouling control in membrane bioreactor

Microbial quorum quenching (QQ) has been proven to be a sustainable anti-biological fouling strategy for membrane bioreactors (MBR), but the long-term stability and practical application in MBR were uncertain. We reported a novel semi-interpenetrating network (SIPN) hydrogels-based design of QQ bacteria (Rhodococcus sp. BH4) encapsulation for both biofouling control and enhancement of organic pollutants removal in MBR. The microcapsule included the alginate core, chitosan thin intermediate compartment and SIPN (sodium alginate / polyacrylamide) shell, which exhibited near-perfect biocontainment, including preventing detectable QQ bacteria escape and improving mechanical strength. The QQ-microcapsules in the MBR demonstrated its significant anti-biofouling effect for treating synthetic wastewater (i.e., membrane fouling was delayed by 233%-280% compared to the control MBR membrane). Meanwhile, the efficiency of phosphorus removal was developed in QQ-microcapsule MBR because of the enhanced phosphorus removal triggered by the flocculation of polyacrylamide (PAM) fraction in SIPN. This promising QQ media brings the broad potential for biofouling control and long-term efficient operation in actual MBR wastewater treatment.

Exploring novel quorum quenching strain: Enhanced disrupting autoinducer-2 bacterial communication to combat biofouling in membrane bioreactor for wastewater treatment

Prior investigations concerning quorum quenching (QQ), which hinders quorum sensing (QS) in microbial communication, concentrated predominantly on N-acylhomoserine lactones (AHLs), which are communicated merely by gram-negative bacteria. However, to combat biofouling more effectively, particularly biofilm-related issues, it is important to explore the inhibition of autoinducer-2 (AI-2), a universal signal (interspecies communication) employed by both gram-negative and gram-positive bacteria. This study aimed to isolate and identify novel strains capable of more effectively inhibiting AI-2 signaling for use in engineering fields. The results revealed that the newly isolated strain Pantoea sp. PL-1 demonstrated remarkable efficacy in attenuating AI-2 signals, leading to a substantial reduction in the AI-2 precursor (S)-4,5-dihydroxy-2,3-pentandione (DPD) in both its pellet (with a DPD removal efficiency of 90.8 % after 180 min, with a rate constant of k = 0.8 h−1) and supernatant form (66.9 %, k = 0.37 h−1). Interestingly, the findings indicate that strain DKY-1, a strain previously reported to exhibit AI-2 QQ activity, only reduced DPD levels in its supernatant form (extracellular activity), while both the pellet and the supernatant of strain PL-1 demonstrated AI-2 QQ activity, indicating both intracellular and extracellular QQ activity. Adding the PL-1 supernatant to co-cultures of two AI-2 QS strains, E. coli K12 and P. mirabilis, successfully reduced DPD by 40 % and 70 %, respectively, without impeding their growth. Additionally, when assessing the impact of PL-1 to minimize membrane biofouling in a membrane bioreactor, it demonstrated superior performance compared to the DKY-1 strain, with a 40 % improvement. The AI-2 QQ compound of PL-1 has been identified as highly hydrophilic and low-molecular-weight, and its exact properties have not yet been fully elucidated. Therefore, uncovering its identity may be an important goal for future research.

Reviewing the potential of anaerobic membrane bioreactors in wastewater treatment

Anaerobic membrane bioreactors (AnMBRs) represent an innovative approach to wastewater treatment, combining anaerobic digestion with membrane filtration to achieve efficient organic pollutant removal and resource recovery. This review critically examines the potential of AnMBRs in wastewater treatment, highlighting their principles, advantages, challenges, recent advancements, and future prospects. AnMBRs offer several advantages over traditional aerobic treatment methods, including higher organic loading rates, reduced energy requirements, and biogas production through methane generation. However, challenges such as membrane fouling, reactor complexity, and operational costs have limited their widespread adoption. Recent advancements in membrane materials, fouling mitigation strategies, and process optimization have improved AnMBR performance and feasibility. Novel membrane materials with enhanced fouling resistance and durability have been developed, while innovative cleaning techniques and operational protocols have been implemented to mitigate membrane fouling and prolong membrane lifespan. Process optimization strategies, including reactor design modifications and operational parameter adjustments, have enhanced treatment efficiency and reduced energy consumption in AnMBRs. Future research directions in AnMBR technology focus on optimizing reactor configurations, exploring novel membrane materials and fouling control strategies, and conducting comprehensive techno-economic assessments to evaluate the environmental and economic sustainability of AnMBRs. Integration of AnMBRs with emerging technologies such as membrane distillation, forward osmosis, and bioelectrochemical systems holds promise for further enhancing treatment performance and resource recovery capabilities. Additionally, addressing knowledge gaps in membrane fouling mechanisms, microbial community dynamics, and long-term system stability is crucial for advancing AnMBR technology and facilitating its widespread implementation in wastewater treatment. Overall, AnMBRs offer significant potential for sustainable wastewater treatment, providing opportunities for organic pollutant removal, energy recovery, and resource reuse. By addressing technical challenges, optimizing process parameters, and conducting interdisciplinary research, AnMBRs can contribute to the development of efficient, cost-effective, and environmentally friendly wastewater treatment solutions, ultimately supporting the goal of achieving cleaner water resources and a more sustainable future.

Performance of Fe-dosing membrane bioreactor and evaluation of phosphorus recovery as vivianite after long-term operation

In this study, the influence of high concentration of iron on the nutrient removal, membrane fouling and microbial diversity of membrane bioreactor for wastewater treatment were systematically investigated. Moreover, the potential of phosphorus recovery in the form of vivianite was assessed after the long-term operation. The results show that TP concentration in effluent was decreased to 1.07 ± 0.47 mg/L (without Fe addition), 0.41 ± 0.23 mg/L (Fe/P = 2), 0.20 ± 0.12 mg/L (Fe/P = 4). Compared with control group, the TN concentration in effluent was higher at the high concentration of iron, which was due to the decreased nitrite-oxidizing bacteria (NOB) by microbial population analysis. Membrane fouling was alleviated by enlarging floc size and reducing supernatant COD via adding iron. Besides, it was detected that the amorphous ferric oxide and Fe(III) bound phosphorus were the main Fe and P speciation and vivanite (ca. 29 %). The anaerobic environment was conducive to the formation of vivianite and the phosphorus recovery as vivanite was recommended based on the results of current study.

A novel γ-Fe3O4-N-BC combined membrane bioreactor for wastewater treatment: Performance and mechanism

In this study, a new type of iron–nitrogen doped biochar (γ- Fe3O4-N-BC) was developed to improve nutrient removal efficiency and mitigate membrane fouling in combination with MBR. The characteristion of γ-Fe3O4-N-BC, N-BC, and BC revealed that the BET surface area (SBET) of γ-Fe3O4-N-BC, which was 1320.86 m2/g, was greater than that of N-BC (702.75 m2/g) and BC (1033.63 m2/g). The excellent SBET exhibited by γ-Fe3O4-N-BC compared to that of the other biochars is attributed to hydrogen bonding and electrostatic interactions. Compared to the addition of N-BC or BC or the absence of biochar, the addition of γ-Fe3O4-N-BC in the membrane bioreactor (MBR) resulted in superior wastewater treatment performance, for which the average removal efficiencies of chemical oxygen demand (COD), ammonia nitrogen (NH4+-N), and total phosphorus (TP) were 94.65 %, 82.56 %, and 65.90 %, respectively. Moreover, after inoculation with γ-Fe3O4-N-BC, the TMP increase rate and time required to reach 42.37 kPa were 2.35 kPa/d and 18 d, respectively. The investigation of the effect of the γ-Fe3O4-N-BC concentration on MBR performance showed that the nutrient removal efficiency in the 500-MBR greater than that in the 350-MBR, 650-MBR, and 800-MBR, and that the membrane fouling was more ameliorative. A mechanistic investigation demonstrated that the 500-MBR had a beneficial influence on sludge biomass growth and helped to improve the nutrient removal capacity of the MBR. The 500-MBR improved the flocculability and stability of the sludge flocs in the MBR by increasing particle size and zeta potential. Changes in the extracellular polymeric substance (EPS) concentration and the smaller protein (PN) / polysaccharide (PS) ratio in 500-MBR also had significant impacts on alleviating the adhesion and accumulation of fouling layers on the improved membrane surface. Consequently, this study provides a new method for nutrient removal and membrane fouling mitigation in the MBR process.

Microbial dark matter sequences verification in amplicon sequencing and environmental metagenomics data.

Although microorganisms constitute the most diverse and abundant life form on Earth, in many environments, the vast majority of them remain uncultured. As it is based on information gleaned mainly from cultivated microorganisms, our current body of knowledge regarding microbial life is partial and does not reflect actual microbial diversity. That diversity is hidden in the uncultured microbial majority, termed by microbiologists as "microbial dark matter" (MDM), a term borrowed from astrophysics. Metagenomic sequencing analysis techniques (both 16S rRNA gene and shotgun sequencing) compare gene sequences to reference databases, each of which represents only a small fraction of the existing microorganisms. Unaligned sequences lead to groups of "unknown microorganisms" that are usually ignored and rarefied from diversity analysis. To address this knowledge gap, we analyzed the 16S rRNA gene sequences of microbial communities from four different environments-a living organism, a desert environment, a natural aquatic environment, and a membrane bioreactor for wastewater treatment. From those datasets, we chose representative sequences of potentially unknown bacteria for additional examination as "microbial dark matter sequences" (MDMS). Sequence existence was validated by specific amplification and re-sequencing. These sequences were screened against databases and aligned to the Genome Taxonomy Database to build a comprehensive phylogenetic tree for additional sequence classification, revealing potentially new candidate phyla and other lineages. These putative MDMS were also screened against metagenome-assembled genomes from the explored environments for additional validation and for taxonomic and metabolic characterizations. This study shows the immense importance of MDMS in environmental metataxonomic analyses of 16S rRNA gene sequences and provides a simple and readily available methodology for the examination of MDM hidden behind amplicon sequencing results.

Zero-valent iron to advance anaerobic membrane bioreactors for wastewater treatment and reuse: A critical review

Anaerobic membrane bioreactors (AnMBRs) have been widely applied for wastewater treatment and resource recovery, but face several technical challenges, such as unstable methane (CH4) production, limited contaminant removal, and membrane fouling. Zero-valent iron (ZVI) can be a potential additive to improve AnMBRs performance by regulating anaerobic reaction conditions, electron transfer modes and microbial community structure. Thus, this review critically evaluated the role of ZVI to advance AnMBRs performance for wastewater treatment and resource recovery. Key physicochemical characteristics of ZVI were analyzed to highlight its potential for AnMBRs enhancement. The performance of ZVI and its modification to assist AnMBRs, regarding CH4 production, contaminant removal and membrane fouling, were discussed. Furthermore, future perspectives to the development of ZVI-assisted AnMBRs toward industrial application for practical wastewater treatment and resource recovery were provided.

Integrating of electrocoagulation process with submerged membrane bioreactor for wastewater treatment under low voltage gradients

Treating and reusing wastewater has become an essential aspect of water management worldwide. However, the increase in emerging pollutants such as polycyclic aromatic hydrocarbons (PAHs), which are presented in wastewater from various sources like industry, roads, and household waste, makes their removal difficult due to their low concentration, stability, and ability to combine with other organic substances. Therefore, treating a low load of wastewater is an attractive option. The study aimed to address membrane fouling in the submerged membrane bioreactor (SMBR) used for wastewater treatment. An aluminum electrocoagulation (EC) device was combined with SMBR as a pre-treatment to reduce fouling. The EC-SMBR process was compared with a conventional SMBR without EC, fed with real grey water. To prevent impeding biological growth, low voltage gradients were utilized in the EC deviceThe comparison was conducted over 60 days with constant transmembrane pressure and infinite solid retention time (SRT). In phase I, when the EC device was operated at a low voltage gradient (0.64 V/cm), no significant improvement in the pollutants removal was observed in terms of color, turbidity, and chemical oxygen demand (COD). Nevertheless, during phase II, a voltage gradient of 1.26 V/cm achieved up to 100%, 99.7%, 92%, 94.1%, and 96.5% removals in the EC-SMBR process in comparison with 95.1%, 95.4%, 85%, 91.7% and 74.2% removals in the SMBR process for turbidity, color, COD, ammonia nitrogen (NH3–N), total phosphorus (TP), respectively. SMBR showed better anionic surfactant (AS) removal than EC-SMBR. A voltage gradient of 0.64 V/cm in the EC unit significantly reduced fouling by 23.7%, while 1.26 V/cm showed inconsistent results. Accumulation of Al ions negatively affected membrane performance. Low voltage gradients in EC can control SMBR fouling if Al concentration is controlled. Future research should investigate EC-SMBR with constant membrane flux for large-scale applications, considering energy consumption and operating costs.

Mitigating marine hazardous contaminants: A sustainable management perspective

Marine hazardous contaminants, such as cadmium (Cd) and lead (Pb), pose significant risks to both human health and aquatic organisms. Traditional methods may not remove contaminants to safe levels, leading to the release of hazardous materials into marine environments. This research proposes polymeric membrane bioreactors as a potential solution to this problem. We determined Cd and Pb levels in three freshwater fish species (Rita, Ompok bimaculatus, and Heteropneustes fossils) from two distinctive regions (Zone 1 and Zone 2). Additionally, Cd and Pb concentrations in feeding materials, water, and sediments were analyzed to estimate daily intake and potential hazardous effects of these contaminants on the fish species. These findings underscore the need for effective regulatory measures and policies to reduce the discharge of hazardous contaminants into freshwater and marine environments, protecting both human health and the environment. Implementing polymeric membrane bioreactors in wastewater treatment and industrial facilities could mitigate the risks associated with consuming contaminated fish species. Significantly, the Cd and Pb levels in all three fish species from both fishponds exceeded the Food and Agriculture Organization's (FAO) maximum permissible limits. These findings carry important implications for policymakers, regulators, and industries, urging them to act appropriately to ensure the safety of the environment and public health. This study suggests that polymeric membrane bioreactors are a promising technological approach to address marine contamination, emphasizing their potential role in safeguarding human health and aquatic ecosystems.

Unraveling microbial community by next-generation sequencing in living membrane bioreactors for wastewater treatment

This study delves into the microbial community complexity and its role in self-forming dynamic membrane (SFDM) systems, designed to remove nutrients and pollutants from wastewater, by means of the analysis of Next-Generation Sequencing (NGS) data. In these systems, microorganisms are naturally incorporated into the SFDM layer, which acts as a biological and physical filter. The microorganisms present in an innovative and highly efficient aerobic, electrochemically enhanced, encapsulated SFDM bioreactor were studied to elucidate the nature of the dominant microbial communities present in sludge and in encapsulated SFDM, patented as living membrane® (LM) of the experimental setup. The results were compared to those obtained from the microbial communities found in similar experimental reactors without an applied electric field. The data gathered from the NGS microbiome profiling showed that the microbial consortia found in the experimental systems are comprised of archaeal, bacterial, and fungal communities. However, the distribution of the microbial communities found in e-LMBR and LMBR had significant differences. The results showed that the presence of an intermittently applied electric field in e-LMBR promotes the growth of some types of microorganisms (mainly electroactive microorganisms) responsible for the highly efficient treatment of the wastewater and for the mitigation of the membrane fouling found for those bioreactors.

Fabrication and characterization of different braid‐reinforced PVC hollow fiber membranes to use in membrane bioreactor for wastewater treatment

AbstractIn this research, polyvinyl chloride (PVC) polymer was applied for the first time in the fabrication of braid‐reinforced hollow fiber membranes for ultrafiltration applications. Different concentrations of PVC solutions were cast on tubular braids and coagulated by the phase inversion method in a pure water bath to produce membranes with various porosities and pore sizes. The characterizations such as scanning electron microscopy, overall porosity, contact angle and mean pore size were done to understand membrane morphology. The antifouling property of membranes was explained using bovine serum albumin (BSA). The contact angles of membranes were increased from 64.9° ± 2.2 to 72.8° ± 2.1, while the overall porosity decreased from 43.8 ± 1.2% and 19.6 ± 3.3% for 11 wt% and 17 wt% PVC membranes, respectively. Permeate flow decreased due to decreased pore size of membranes as a result of increased PVC content. Besides, the flux recovery ratio, reversible and irreversible fouling studies showed that better antifouling characteristics observed with increasing of PVC content. A high removal efficiency of 87.2% for BSA was also demonstrated by the optimal membrane (15 wt% PVC), along with an increased flux recovery ratio of 96.6%. After investigating the rejection of COD in a membrane bioreactor setup, all membranes revealed that they were higher than 98%.

Macroalgal biochar synthesis and its implication on membrane fouling mitigation in fluidized bed membrane bioreactor for wastewater treatment

The intensification of biochar into fluidized bed membrane bioreactor was investigated to mitigate membrane fouling. Different biochars from algal biomass were produced and used as biomaterials for wastewater treatment. In this study, different macroalgal biochar was synthesized at different pyrolysis temperatures and characterized using Scanning Electron Microscopy (SEM), X-ray Diffraction (XRD), Brunauer Emmett-Teller (BET) and Fourier transform infrared spectroscopy (FTIR) techniques to implicate their effect on membrane fouling reduction in fluidized bed membrane bioreactor. The combined effect of macroalgal biochars and biocarriers with gas sparging was evaluated for fouling mitigation. Macroalgal biochar curtailed membrane fouling effectively at low gas sparging rate. Transmembrane pressure (TMP) was reduced to 0.053 bar; under the fluidization of biochar-650 and biocarriers with gas sparging; from 0.27 bar (gas sparging only). Combined effect of gas sparging, biocarriers and biochar-650 instigated 92.1% fouling reduction in comparative to gas sparging alone. Mechanical scouring driven by biocarriers could reduce fouling due to removing surface deposit of foulants from membrane surface effectively and biochar can efficiently adsorb foulants because of its active functional groups resulting in reduction of colloidal fouling. The addition of divalent ions (Ca2+) further enhanced the fouling reduction in fluidized bed membrane bioreactor.

Progress on the Development of Techniques to Remove Contaminants from Wastewater: A Review

The continuous depletion of fresh drinking water resources throughout the world has increased the necessity for the development of new techniques for wastewater treatment and recycling process. Domestic, industrial and agricultural wastes are major sources of aquatic contamination all over the world. Before discharging wastewater into natural water bodies, it must be treated. Apart from primary, secondary and tertiary treatment, membrane separation techniques and electrochemical membrane bioreactors for wastewater treatment have all been studied in this review paper. The electrochemical membrane bioreactor (EMBR) system has a lot of potential for treatment of wastewater and energy recovery. These novel EMBR techniques give feasible solutions for renewable treatment of wastewater and resource resumption.

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.

Innovative microbial disease biocontrol strategies mediated by quorum quenching and their multifaceted applications: A review.

With the increasing resistance exhibited by undesirable bacteria to traditional antibiotics, the need to discover alternative (or, at least, supplementary) treatments to combat chemically resistant bacteria is becoming urgent. Quorum sensing (QS) refers to a novel bacterial communication system for monitoring cell density and regulation of a network of gene expression that is mediated by a group of signaling molecules called autoinducers (AIs). QS-regulated multicellular behaviors include biofilm formation, horizontal gene transfer, and antibiotic synthesis, which are demonstrating increasing pathogenicity to plants and aquacultural animals as well as contamination of wastewater treatment devices. To inhibit QS-regulated microbial behaviors, the strategy of quorum quenching (QQ) has been developed. Different quorum quenchers interfere with QS through different mechanisms, such as competitively inhibiting AI perception (e.g., by QS inhibitors) and AI degradation (e.g., by QQ enzymes). In this review, we first introduce different signaling molecules, including diffusible signal factor (DSF) and acyl homoserine lactones (AHLs) for Gram-negative bacteria, AIPs for Gram-positive bacteria, and AI-2 for interspecies communication, thus demonstrating the mode of action of the QS system. We next exemplify the QQ mechanisms of various quorum quenchers, such as chemical QS inhibitors, and the physical/enzymatic degradation of QS signals. We devote special attention to AHL-degrading enzymes, which are categorized in detail according to their diverse catalytic mechanisms and enzymatic properties. In the final part, the applications and advantages of quorum quenchers (especially QQ enzymes and bacteria) are summarized in the context of agricultural/aquacultural pathogen biocontrol, membrane bioreactors for wastewater treatment, and the attenuation of human pathogenic bacteria. Taken together, we present the state-of-the-art in research considering QS and QQ, providing theoretical evidence and support for wider application of this promising environmentally friendly biocontrol strategy.

Modeling and Simulation of ASM1-SMP Model to Better Control Fouling in a Submerged Membrane Bioreactor for Wastewater Treatment Under Different COD: N Ratios Using Matlab and Aquasim

Modeling and Simulation of ASM1-SMP Model to Better Control Fouling in a Submerged Membrane Bioreactor for Wastewater Treatment Under Different COD: N Ratios Using Matlab and Aquasim

Feasibility of hydrophilic polyethylene separator for membrane bioreactor for wastewater treatment: Fouling behaviors and cleaning

The increasing cost of polyvinylidene fluoride has motivated efforts of researchers to seek a cheap membrane material for membrane bioreactors (MBRs). An inexpensive hydrophilic polyethylene (PE) lithium-ion battery separator was used in this study to construct a flat-sheet membrane module for MBRs treating synthetic municipal wastewater (PE-MBR). The PE separator showed an interconnected and open pore structure with a pore size of 50–60 ​nm. Its hydrophilicity was confirmed by the contact angle (77.65°) and relatively high pure water permeability of 412.17 LMH. The operation of the PE-MBR under 15 LMH below the critical flux last more than 50 ​d before the trans-membrane pressure reached 25 ​kPa and the COD removal was higher than 90%. The revised Hermia model fitting suggested that cake formation was the predominant fouling mechanism on the PE separator with polysaccharides as the main organic pollutant. A cleaning efficiency of 76.26% of the PE separator was achieved using 1 ​g/L of Oxalic acid, 3 ​g/L of NaOH, and 100 ​mg/L of EDTA as the cleaning reagents. This study establishes the feasibility of the PE separator in MBRs and provides a new strategy to lower the operation cost and broaden the real applications of MBR in wastewater treatment.

Hybrid powdered activated carbon-activated sludge biofilm formation to mitigate biofouling in dynamic membrane bioreactor for wastewater treatment

Membrane costs and biofouling limit applications of membrane bioreactors (MBRs) for wastewater treatment. Here, powdered activated carbon (PAC) utilization in the formation and performance of a self-forming dynamic membrane consisting of activated sludge and PAC during hybrid wastewater treatment process was studied. Short-term agitation helped (non)biological particles to quickly uniformly settle on mesh filter, forming more uniform PAC-containing dynamic membranes (PAC-DMs). PAC adsorbed adhesive materials, resulting in an increase in average floc size and DM permeability while decreasing biofouling. The most efficient PAC concentration was 4 g L−1 considering techno-economics, i.e. the highest effluent quality (turbidity of 19.89 NTU) and the lowest biofouling (transmembrane pressure rise of 2.89 mbar). Short-term performance of hybrid PAC-DM bioreactor (PAC-DMBR) showed stability in effluent quality improvement including 92%, 95%, 83%, 84% and 98% reductions in turbidity, chemical oxygen demand, total dissolved solids, total nitrogen, and total phosphorous, respectively. Accordingly, adopting hybrid PAC-DMBR has potential to alleviate biofouling and capital cost.

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.