Preparation and performance evaluation of high-density polyethylene/silica nanocomposite membranes in membrane bioreactor system

Nanostructure-manipulated filtration performance in nanocomposite membranes: A comprehensive investigation for water and wastewater treatment

The main objective of this article is to examine one of the most important challenges facing researchers in the field of nanocomposite membranes: what is the most suitable arrangement (unmodified, functionalized, coated, or composite) and the most suitable loading site for the nanostructure? In the review articles published on nanocomposite membranes in recent years, the focus has been either on a specific application area (such as nanofiltration or desalination), or on a specific type of polymeric materials (such as polyamide), or on a specific feature of the membrane (such as antibacterial, antimicrobial, or antifouling). However, none of them have targeted the aforementioned objectives on the efficacy of improving filtration performance (IFP). Through IFP calculation, the results will be repeatable and generalizable in this field. The novelty of the current research lies in examining and assessing the impact of the loading site and the type of nanostructure modification on enhancing IFP. Based on the performed review results, for the researchers who tend to use nanocomposite membranes for treatment of organic, textile, brine and pharmaceutical wastewaters as well as membrane bioreactors, thePES NH 2 - PDA - Fe 3 O 4 M ,PAN Fe 3 O 4 / ZrO 2 M ,PVDF CMC - ZnO M ,AA AA - CuS PSf M andPVDF OCMCS / Fe 3 O 4 M with IFP equal to 132.27, 15, 423.6, 16.025 and 5, were proposed, respectively.

Smoke filtration performances of membranes produced from commercial PVA and recycled PET by electrospinning method and ANN modeling

Plastic waste and air pollution are becoming a great concern due to their adverse effect on human health and the environment. There is increasing number of evidence showing that recycling plastic and filtering harmful air pollutants are one of the most effective and promising way to eliminate their hazard on the environment. In this purpose, we developed eco-friendly filtration materials from recycled PET by electrospinning method to be used in air filtration and compared them with conventional PVA membranes. Filtration efficiency of prepared membranes were tested homemade membrane system using cigarette smoke source. Characterization results and smoke filtration performance of recycled PET and PVA membranes before and after smoke filtration were examined. The results demonstrated that the removal efficiencies of PVA-5 wt.%, PVA-10 wt.%, and PVA-15 wt.% were 4.11%, 11.32%, and 12.14%, respectively. A similar trend was also observed in recycled PET-5 wt.%, PET-10 wt.%, and PET-15 wt.% membranes with 4.32%, 10.79%, and 11.68% of filtration efficiency, respectively. Based on this result, using recycled PET can be an alternative way to produce a higher value product compared to traditional polymer membranes used commercially. This result is also supported by the neural network model of this study.

Pharmaceutical residues: One of the significant problems in achieving 'clean water for all' and its solution

With the rapid emergence of various metabolic and multiple-drug-resistant infectious diseases, new pharmaceuticals are continuously being introduced in the market. The excess production and use of pharmaceuticals and their untreated/unmetabolized release in the environment cause the contamination of aquatic ecosystem, and thus, compromise the environment and human-health. The present review provides insights into the classification, sources, occurrence, harmful impacts, and existing technologies to curb these problems. A comprehensive detail of various biological and nanotechnological strategies for the removal of pharmaceutical residues from water is critically discussed focusing on their efficiencies, and current limitations to design improved-technologies for their lab-to-field applications. Furthermore, the review highlights and suggests the scope of integrated bionanotechnological methods for enhanced removal of pharmaceutical residues from water to fulfill the United Nations Sustainable Development Goal (UN-SDG) for providing clean potable water for all.

Endocrine disrupting chemicals in the environment: Environmental sources, biological effects, remediation techniques, and perspective

Endocrine disrupting chemicals (EDCs) have been identified as emerging contaminants, which poses a great threat to human health and ecosystem. Pesticides, polycyclic aromatic hydrocarbons, dioxins, brominated flame retardants, steroid hormones and alkylphenols are representative of this type of contaminant, which are closely related to daily life. Unfortunately, many wastewater treatment plants (WWTPs) do not treat EDCs as targets in the normal treatment process, resulting in EDCs entering the environment. Few studies have systematically reviewed the related content of EDCs in terms of occurrence, harm and remediation. For this reason, in this article, the sources and exposure routes of common EDCs are systematically described. The existence of EDCs in the environment is mainly related to human activities (Wastewater discharges and industrial activities). The common hazards of these EDCs are clarified based on available toxicological data. At the same time, the mechanism and effect of some mainstream EDCs remediation technologies (such as adsorption, advanced oxidation, membrane bioreactor, constructed wetland, etc.) are separately mentioned. Moreover, our perspectives are provided for further research of EDCs.

Nanomaterials in membrane bioreactors: Recent progresses, challenges, and potentials

The use of nanomaterials (NMs) in the fabrication and modification of membranes as well as the coupling of nanomaterial-based processes with membrane processes have been attracted many researchers today. The NMs due to a wide range of types, different chemistry, the possibility of various kinds of functionality, different properties like antibacterial activity, hydrophilicity, and large surface area were applied to enhance the membrane properties. In the membrane bioreactors (MBRs) as a highly successful process of membrane technology in wastewater treatment, the NMs have been applied for improving the efficiency of MBR process. This review assessed the application of NMs both as the modifiers of membrane and as the effective part of hybrid techniques with MBR system for wastewater treatment. The efficiency of NMs blended membranes in the MBR process has been reviewed in terms of antifouling and antibacterial improvement and removal performance of the pollutants. Novel kinds of NMs were recognized and discussed based on their properties and advantages. The NMs-based photocatalytic and electrochemical processes integrated with MBR were reviewed with their benefits and drawbacks. In addition, the effect of the presence of mobilized NPs in the sludge on MBR performance was surveyed. As a result of this review, it can be concluded that nanomaterials generally improve MBR performance. The high flux and antifouling properties can be obtained by adding nanomaterials with hydrophilic and antibacterial properties to the membrane, and further studies are required for photocatalytic NMs applications. In addition, this review shows that the low amounts of NMs in the membrane structure could have an effective influence on the MBR process. Besides, since many studies in the literature are carried out at the laboratory scale, it is thought that pilot and real-scale studies should be carried out to obtain more reliable data.

Influence of alumina nanoparticles on the performance of polyacrylonitrile membranes in MBR

This study aims to investigate the effect of using Al₂O₃ nanoparticles (NPs) in membrane structure on the operation condition of the membrane bioreactor. To this end, alumina NPs as the high hydrophilic agents with an approximate size of 40 nm and a concentration of 0-3 wt.% were placed within the PAN polymeric membrane matrix structure with high hydrophilicity and high mechanical resistance over the others via the phase inversion method. Characterization of synthesized nanocomposite membranes was carried out by SEM analysis. In the presence of the alumina NPs, the porosity of the membranes improved. The water contact angle measurement confirmed the superior hydrophilicity of mixed PAN membranes compared to the pure polymeric membranes. The best nanocomposite membrane with better antifouling properties was selected to evaluate the MBR's performance in wastewater treatment and assessed in terms of the resistance, flux recovery, and COD removal rates. The result of a comparison with pure membrane showed that by increasing the Al₂O₃ amount up to 2wt.%, irreversible fouling resistance mitigated as much as 50%. Moreover, the flux recovery ratio was increased by 15%, and the COD removal rate was also raised as large as 16%. Our investigation illustrated that the presence of alumina NPs has improved the MBR performance and decreased the irreversible fouling resistance of the membrane.

Employing magnetism of Fe3O4 and hydrophilicity of ZrO2 to mitigate biofouling in magnetic MBR by Fe3O4-coated ZrO2/PAN nanocomposite membrane

The aim of this research is benefiting from the synergistic effect of the simultaneous presence of Fe₃O₄ and ZrO₂ in the form of Fe₃O₄-coated ZrO₂ (Fe₃O₄@ZrO₂) nanoparticles within the structure of PAN membrane to reduce membrane fouling. The role of Fe₃O₄ nanoparticles in increasing the pore size and magnetic saturation as well as the role of ZrO₂ in decreasing surface roughness and hydrophobicity can mitigate membrane fouling in magnetic-assisted membrane bioreactors. For this purpose, Fe₃O₄, ZrO₂, and Fe₃O₄@ZrO₂ nanoparticles were embedded into PAN membrane structure and magnetic (M _nM), hydrophilic (H _nM), and magnetic-hydrophilic (HM _nM) membranes were synthesized. H ₁M (1ZrO₂/PAN) membrane with a contact angle of 31 degrees, M ₁N (1Fe₃O₄/PAN) with a pore size of 90 nm, and H ₃M (3ZrO₂/PAN) membrane with an RMS roughness of 13.5 nm were the most hydrophilic, porous, and smoothest membranes, respectively. High sensitivity to magnetic field along with high porosity, high hydrophilicity and low surface roughness simultaneously exist within the structure of MHMs membranes, such that MH ₁M (1Fe₃O₄@ZrO₂/PAN) indicated 116% greater flux, 121% greater flux recovery, and 85% less total filtration resistance in comparison with the blank membrane in magnetic membrane bioreactor, at a magnetic field intensity of 120 mT and MLSS = 10,000 mg/l. As an overall conclusion, the output of this research was compared with other research in term of normalized flux. Results reveal that at MLSS = 10,000 mg/l, HRT = 8 h and TMP = 0.3 bar, MH ₁M membrane has normalized flux equal to 1.56 g/m² h bar which is an acceptable value compared to normalized flux reported by other researchers.

Application of zinc oxide and sodium alginate for biofouling mitigation in a membrane bioreactor treating urban wastewater

This research aimed to mitigate fouling in membrane bioreactors (MBR) through concurrent usage of zinc oxide as an antibacterial agent (A) and sodium alginate as a hydrophilic agent (H) within a polyacrylonitrile membrane (PM) structure. The antibacterial polymeric membranes (APM) and antibacterial hydrophilic polymeric membranes (AHPM) synthesized showed a higher porosity, mechanical strength and bacterial inhibition zone, and a lower contact angle in comparison with PM membranes. EDS, SEM and AFM analyses were used to characterize the chemical, structural, and morphological properties of PM, APM, and AHPM. The flux of PM, APM, and AHPM in MBR was 37, 48, and 51 l m^-2 h^-1 and COD removal was 81, 93.5, and 96.7%, respectively. After MBR operation for 35 days in an urban wastewater treatment, only 50% of the flux of PM was recovered, while the antibacterial and hydrophilic agents yielded a flux recovery of 72.7 and 100% for APM and AHPM, respectively.

Investigation of antifouling properties of polypropylene/TiO2 nanocomposite membrane under different aeration rate in membrane bioreactor system

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PP/TiO₂ membrane was fabricated via thermally induced phase separation (TIPS) method.

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Effect of aeration rate was investigated on antifouling properties of both membranes in MBR system.

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Fouling properties of membranes under different aeration rates were analyzed using Hermia’s models.

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Nanocomposite membrane showed high antifouling compared to neat membrane.

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Increasing in high aeration rate resulted in sludge floc breakage as well as pore blockage.

This paper presents the results of aeration rate effect on antifouling properties of polypropylene (PP)/TiO₂ nanocomposite membrane in membrane bioreactor (MBR) system in order to oil refinery wastewater treatment. For this purpose, three levels of aeration rate with specific aeration demand per membrane area (SADm) of 0.5, 1, and 1.5 m³/m²h was used. According to the obtained results, PP nanocomposite membrane showed high hydrophilicity, porosity, and high flux compared to neat PP membrane. Also, either low or high aeration rate had a negative influence on permeability and antifouling properties of neat PP and nanocomposite membranes. The analysis of fouling mechanism for both membranes based on Hermia’s model revealed that the cake formation is dominant mechanism for lower aeration rate while by increasing aeration rate, all models couldn’t predict experimental data. Meanwhile, by increasing aeration rate, chemical oxygen demand (COD) removal for activated sludge and both membranes decreased and increased, respectively.