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1.
Chemosphere ; 243: 125446, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31995891

RESUMO

Multiple wall carbon nanotubes (MWCNTs), as an excellent material, have been used in various applications including preparation of polymer-MWCNTs composite membranes. However, few reports have combined the magnetic Ni@MWCNTs with polyether sulfone (PES) membrane to improve its antifouling performance to humic acid (HA), sodium alginate (SA), bovine serum albumin (BSA) and yeast (YE) solutions. In this study, the Ni@MWCNTs was generated by immersing MWCNTs into Ni2+ solution where in-situ reduction reaction was launched by the adsorbed Ag+ on MWCNTs. Since the loaded Ni endowed magnetism to MWCNTs, the Ni@MWCNTs can be easily attracted onto the membrane surface by an external magnetic field during the phase inversion process. The morphology measurements confirmed that the Ni@MWCNTs headed out of the PES-Ni@MWCNTs membrane surface. Because the MWCNTs played a role of free channels for water molecules, the composite membrane water flux reached to threefold flux of the pristine membrane. Moreover, the PES-Ni@MWCNTs membranes displayed the obviously enhanced antifouling ability during all the three alternative filtration cycles of water and BSA, SA, YE and HA solutions. In addition, the optimal PES-Ni@MWCNTs membrane demonstrated a flux recovery rate (FRR) of 67.89%, 85.53%, 60.28 and 90.12% for BSA, SA, YE and HA, respectively, which were not only much higher than that of the pristine membrane, but also exhibited significant improvements comparing with the previous studies. Further results of extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) theory indicated that the modified membrane possessed advantageous interaction energies with contaminant molecules over the pristine membrane.


Assuntos
Incrustação Biológica/prevenção & controle , Campos Magnéticos , Membranas Artificiais , Nanotubos de Carbono , Polímeros , Sulfonas , Adsorção , Alginatos/efeitos adversos , Filtração , Substâncias Húmicas/efeitos adversos , Permeabilidade , Soroalbumina Bovina/efeitos adversos , Água/química
2.
J Basic Microbiol ; 60(3): 198-206, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-31856349

RESUMO

The growth of technology and requirements globally for various commodities has brought about new challenges. Biofilms are aggregations of microbial cells, which contaminate and spoil industrial components and environments. These microbial cells with extracellular polymeric substances colonize living and nonliving surfaces and pose a serious problem for all industries, affecting their processes, leading to a reduction of product quality and economic loss. Industries, such as medical, food, water, dairy, wine, marine, power plants are exposed to biofilm formation. Pipe blockages, waterlogging and reduction of the heat-transfer efficiency, hamper the operating system of plants. Many industries do not set up remedial measures to control biofilm formation as they are not aware of this threat. Various conventional methods to control these biofilms are adopted by industries in their regular workflow, but these are temporary solutions. This calls for further research into remediation of the biofilm and its control for industrial components. This review article addresses the problems of biofilms and proposes solutions for various industrial components. Nanotechnology promises several options, and bring about a new aspect into the industrial economy, by solving the problems of environmental biofilms.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Microbiologia Ambiental , Indústrias , Biofilmes/crescimento & desenvolvimento , Indústrias/economia , Nanotecnologia
3.
Chemosphere ; 238: 124610, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31450112

RESUMO

Antifouling paint particles (APPs) are residues generated primarily during maintenance of vessels and marine structures, and usually occur in boat maintenance areas that are adjacent to aquatic environments, such as estuaries. APPs end up in sediment layers after their release into aquatic systems and represent a threat to benthic invertebrates, which have different habitat and feeding modes. Thus, the aim of the present study was to evaluate the toxicity of APPs-spiked sediment to the benthic microcrustaceans Monokalliapseudes schubarti (a tanaid) and Hyalella azteca (an amphipod), testing whole sediment and elutriate solutions under estuarine conditions. Whole sediment spiked with APPs was more toxic to these organisms than the elutriate solution. This toxicity was attributed to the high concentrations of Cu and Zn metals quantified in the APPs. During the whole sediment test, M. schubarti was more sensitive than H. azteca. M. schubarti is an infauna organism, and its interaction with sediments (e.g. by ingestion of sediment particles) makes it more susceptible to compounds released from APPs than H. azteca, which tends to interact with these compounds at the sediment-water interface. In addition, in tests with sediment elutriate and without sediment, M. schubarti was not affected, while elutriate with 1.50% APPs showed to be significantly toxic to H. azteca. Moreover, these results indicate that APPs act as continuous and localized sources of metals to benthic organisms, highlighting the importance of better APP management and disposal practices in boat maintenance areas to avoid local aquatic contamination.


Assuntos
Anfípodes/efeitos dos fármacos , Crustáceos/efeitos dos fármacos , Sedimentos Geológicos/análise , Pintura/toxicidade , Poluentes Químicos da Água/toxicidade , Animais , Incrustação Biológica/prevenção & controle
4.
Ecotoxicol Environ Saf ; 187: 109812, 2020 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-31669574

RESUMO

Marine biofouling represents a global economic and ecological challenge. Some marine organisms produce bioactive metabolites, such as steroids, that inhibit the settlement and growth of fouling organisms. The aim of this work was to explore bile acids as a new scaffold with antifouling (AF) activity by using chemical synthesis to produce a series of bile acid derivatives with optimized AF performance and understand their structure-activity relationships. Seven bile acid derivatives were successfully synthesized in moderate to high yields, and their structures were elucidated through spectroscopic methods. Their AF activities were tested against both macro- and microfouling communities. The most potent bile acid against the settlement of Mytilus galloprovincialis larvae was the methyl ester derivative of cholic acid (10), which showed an EC50 of 3.7 µM and an LC50/EC50 > 50 (LC50 > 200 µM) in AF effectiveness vs toxicity studies. Two derivatives of deoxycholic acid (5 and 7) potently inhibited the growth of biofilm-forming marine bacteria with EC50 values < 10 µM, and five bile acids (1, 5, and 7-9) potently inhibited the growth of diatoms, showing EC50 values between 3 and 10 µM. Promising AF profiles were achieved with some of the synthesized bile acids by combining antimacrofouling and antimicrofouling activities. Initial studies on the incorporation of one of these promising bile acid derivatives in polymeric coatings, such as a marine paint, demonstrated the ability of these compounds to generate coatings with antimacrofouling activity.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Ácidos e Sais Biliares/farmacologia , Incrustação Biológica/prevenção & controle , Desinfetantes/farmacologia , Pintura , Animais , Organismos Aquáticos/crescimento & desenvolvimento , Bactérias/efeitos dos fármacos , Bactérias/crescimento & desenvolvimento , Ácidos e Sais Biliares/síntese química , Biofilmes/efeitos dos fármacos , Biofilmes/crescimento & desenvolvimento , Desinfetantes/síntese química , Microalgas/efeitos dos fármacos , Microalgas/crescimento & desenvolvimento , Mytilus/efeitos dos fármacos , Poliuretanos/química , Silicones/química
5.
J Water Health ; 17(6): 910-920, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31850898

RESUMO

Antibiotic resistance genes (ARGs), as emerging environmental contaminants, are becoming a threat to human health. In this study, the combined processes of powdered activated carbon (PAC)/biological PAC (BPAC)-ultrafiltration (UF) were adopted to reduce the levels of ARGs in secondary effluents from a wastewater treatment plant. The removal of dissolved organic carbon (DOC) and the change of normalized flux in the UF process were investigated. In addition, the structural characteristics of the microorganisms of the BPAC were analyzed. The results showed that the appropriate dosage of PAC and BPAC was 40 mg/L. At this dosage, PAC/BPAC-UF combined processes could effectively remove the ARGs in secondary effluents by 1.26-2.69-log and 1.55-2.97-log, respectively; and the removal rates of DOC would be 60.7% and 54.1%, respectively. Relative to the direct UF, the membrane fluxes of the two combined processes were increased by 15.6% and 25.1%, respectively. Significant removal correlations were found between ARGs, intI1, DOC and 16SrDNA. These results revealed that the PAC/BPAC-UF combined process might play a promising role in ARG reduction in secondary effluents from wastewater treatment plants.


Assuntos
Antibacterianos/análise , Carvão Vegetal/química , Resistência Microbiana a Medicamentos/genética , Genes Bacterianos , Ultrafiltração/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Biodegradação Ambiental , Incrustação Biológica/prevenção & controle , Humanos , Membranas Artificiais , Pós , Águas Residuárias/química , Águas Residuárias/microbiologia
6.
Biofouling ; 35(8): 945-957, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31687858

RESUMO

Ocean uptake of anthropogenic CO2 causes ocean acidification (OA), which not only decreases the calcification rate, but also impairs the formation of calcareous shells or tubes in marine invertebrates such as the dominant biofouling tubeworm species, Hydroides elegans. This study examined the ability of tubeworms to resume normal tube calcification when returned to ambient pH 8.1 from a projected near-future OA level of pH 7.8. Tubeworms produced structurally impaired and mechanically weaker calcareous tubes at pH 7.8 compared to at pH 8.1, but were able to recover when the pH was restored to ambient levels. This suggests that tubeworms can physiologically recover from the impacts of OA on tube calcification, composition, density, hardness and stiffness when returned to optimal conditions. These results help understanding of the progression of biofouling communities dominated by tubeworms in future oceans with low pH induced by OA.


Assuntos
Organismos Aquáticos/efeitos dos fármacos , Incrustação Biológica , Calcificação Fisiológica/efeitos dos fármacos , Poliquetos/efeitos dos fármacos , Água do Mar/química , Ácidos , Exoesqueleto/química , Exoesqueleto/efeitos dos fármacos , Animais , Organismos Aquáticos/fisiologia , Incrustação Biológica/prevenção & controle , Dióxido de Carbono/toxicidade , Previsões , Concentração de Íons de Hidrogênio , Oceanos e Mares , Poliquetos/fisiologia , Poluentes Químicos da Água/toxicidade
7.
Environ Sci Pollut Res Int ; 26(36): 36296-36307, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31713819

RESUMO

Cake formed by flocs is a crucial factor to affect membrane fouling during coagulation-ultrafiltration process. To investigate the role of floc properties on cake, cake characteristics under various coagulant dosage conditions were calculated by scanning electron microscope (SEM) imaging. Results found that one SEM image with × 5000 magnification could accurately estimate cake porosity with relative error lower than 5.00% for all conditions, whereas more SEM images with × 10,000 magnification or × 20,000 magnification should be applied to calculate cake porosity precisely. This could be explained by different pore information of SEM images with various magnifications. Compared to single SEM image with × 10,000 magnification and × 20,000 magnification, single SEM image with × 5000 magnification contained the most comprehensive pore information and slightly overestimated pore area for pore smaller than 0.4 µm2 due to lower resolution. To verify feasibility by SEM image evaluating cake characteristics, cake porosity calculated by SEM image and Carman-Kozeny equation were analyzed. The results showed that cake porosity estimated by these two methods were nearly the same, proving the feasibility of this method. Moreover, with the increase of coagulant dosage, cake porosity presented similar variation with floc average size, indicating that floc average size was likely to dominate cake porosity in this study. For pore characteristics, pore average characteristic length and pore average area were in accordance with floc fractal dimension, whereas pore fractal dimension and pore amount were consistent with floc average size. This gives specific information about the relation between floc properties and cake characteristics.


Assuntos
Floculação , Microscopia Eletrônica de Varredura , Ultrafiltração/métodos , Incrustação Biológica/prevenção & controle , Coagulantes/análise , Fractais , Membranas Artificiais , Porosidade , Ultrafiltração/instrumentação
8.
Biofouling ; 35(8): 883-899, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31663364

RESUMO

Biofilm growth is a significant source of contamination in the food industry. Enzymes are considered green countermeasures against biofilm formation in the food industry owing to their biodegradability and low toxicity. In this study, the synergistic effect of enzymes was studied against biofilm cleaning from hard surfaces. A mixed-microbial sample was sourced from a meat packaging line and biofilms were grown under high shear conditions on stainless steel and polyethylene surfaces. A model cleaning-in-place (CIP) parallel-plate flow chamber was used for firstly, the enzymatic cleaning and secondly, a disinfection step. The cleaning effectiveness was evaluated in response to different formulations containing non-foaming commercial surfactants among with amylase, protease and lipase at neutral pH. The formulation combining all three enzymes was the most effective, showing a synergy essential for the deformation of biofilm structure and consequently better disinfection of both material surfaces.


Assuntos
Biofilmes/crescimento & desenvolvimento , Detergentes/química , Desinfecção/métodos , Indústria de Processamento de Alimentos/normas , Hidrolases/química , Saneamento/métodos , Incrustação Biológica/prevenção & controle , Modelos Teóricos , Plásticos , Aço Inoxidável , Propriedades de Superfície
9.
Int J Mol Sci ; 20(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31574976

RESUMO

Biofouling causes major economic losses in the maritime industry. In our site study, the Bay of La Paz (Gulf of California), biofouling on immersed structures is a major problem and is treated mostly with copper-based antifouling paints. Due to the known environmental effect of such treatments, the search for environmentally friendly alternatives in this zone of high biodiversity is a priority to ensure the conservation and protection of species. The aim of this work was to link chemical ecology to marine biotechnology: indeed, the natural defense of macroalgae and sponge was evaluated against biofoulers (biofilm and macrofoulers) from the same geographical zone, and some coatings formulation was done for field assays. Our approach combines in vitro and field bioassays to ensure the selection of the best AF agent prospects. The 1st step consisted of the selection of macroalgae (5 species) and sponges (2 species) with surfaces harboring a low level of colonizers; then extracts were prepared and assayed for toxicity against Artemia, activity towards key marine bacteria involved in biofilm formation in the Bay of La Paz, and the potency to inhibit adhesion of macroorganisms (phenoloxidase assays). The most active and non-toxic extracts were further studied for biofouling activity in the adhesion of the bacteria involved in biofilm formation and through incorporation in marine coatings which were immersed in La Paz Bay during 40 days. In vitro assays demonstrated that extracts of Laurencia gardneri, Sargassum horridum (macroalgae), Haliclona caerulea and Ircinia sp. (sponges) were the most promising. The field test results were of high interest as the best formulation were composed of extracts of H. caerulea and S. horridum and led to a reduction of 32% of biofouling compared with the control.


Assuntos
Anti-Infecciosos/farmacologia , Biofilmes/efeitos dos fármacos , Incrustação Biológica/prevenção & controle , Biomimética , Desenvolvimento de Medicamentos , Organismos Aquáticos , Bactérias/crescimento & desenvolvimento , Aderência Bacteriana , Biomarcadores , Extratos Celulares/química , Extratos Celulares/farmacologia , Materiais Revestidos Biocompatíveis/química , Materiais Revestidos Biocompatíveis/farmacologia , Testes de Sensibilidade Microbiana , Monofenol Mono-Oxigenase/metabolismo , Alga Marinha/química
10.
Int J Mol Sci ; 20(19)2019 Sep 30.
Artigo em Inglês | MEDLINE | ID: mdl-31575022

RESUMO

The rapid increase in the emergence of antibiotic-resistant bacterial strains combined with a dwindling rate of discovery of novel antibiotic molecules has lately created an alarming issue worldwide [...].


Assuntos
Anti-Infecciosos/farmacologia , Anti-Infecciosos/química , Biofilmes/efeitos dos fármacos , Incrustação Biológica/prevenção & controle , Biopolímeros/química , Humanos , Nanopartículas/química
11.
Nat Commun ; 10(1): 4860, 2019 10 24.
Artigo em Inglês | MEDLINE | ID: mdl-31649273

RESUMO

Membrane fouling is a considerable challenge for the stable operation of anaerobic membrane-based bioreactors. Membrane used as a cathode is a common measure to retard fouling growth in anaerobic electrochemical membrane bioreactors (AnEMBR), which; however, cannot avoid the fouling growth. Here we report a strategy using the membrane as an anode to resist membrane fouling in an AnEMBR. Although aggravating in the initial stage, the fouling on the anode membrane is gradually alleviated by the anode oxidation with enriching exoelectrogens to finally achieve a dynamic equilibrium between fouling growth and decomposition to maintain the operation stable. A mesh-like biofilter layer composed of cells with less extracellular polymeric substance (EPS) is formed on the membrane surface to lower the trans-membrane pressure and promote the interception of the anode membrane. The membrane has high electron storage and transfer capacities to accelerate the oxidation of the intercepted fouling materials, especially, the redundant EPSs of the biofilter layer.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Reatores Biológicos , Membranas Artificiais , Nanotubos de Carbono , Técnicas Eletroquímicas , Eletrodos , Matriz Extracelular de Substâncias Poliméricas , Águas Residuárias , Purificação da Água
12.
Artigo em Inglês | MEDLINE | ID: mdl-31597309

RESUMO

Quorum quenching-membrane bioreactors (QQ-MBRs) have been studied widely in recent decades. However, limited information is known about the influence of QQ on the microbial community. In this study, the indigenous QQ bacterium Bacillus cereus HG10 was immobilized and used to control biofouling in a bioreactor. QQ beads caused extracellular polymeric substance reduction and significantly hindered biofilm formation on a submerged membrane. Community profiling of 16S rRNA gene amplicons revealed that QQ beads dramatically altered the bacterial community structure in activated sludge but not in biofilm. Bacterial structure in the presence of QQ beads showed a clear divergence from that of the control groups at phylum, class, order, family, and genus taxonomic ranks. A significant enrichment of several bacterial genera, including Acinetobacter, Aeromonas, Delftia, Bacillus, and Pseudomonas, and depletion of over 12 bacterial genera were observed. These findings would contribute to a better understanding of why and how immobilized QQ bacteria impair membrane biofouling in QQ-MBRs.


Assuntos
Bacillus cereus/metabolismo , Incrustação Biológica/prevenção & controle , Reatores Biológicos/microbiologia , Matriz Extracelular de Substâncias Poliméricas/metabolismo , Águas Residuárias/microbiologia , Purificação da Água/métodos , Percepção de Quorum
13.
Biofouling ; 35(8): 856-869, 2019 09.
Artigo em Inglês | MEDLINE | ID: mdl-31603000

RESUMO

Microbial contamination during fuel storage can cause fuel system fouling and corrosion. Characterizing microbial contamination is critical for preventing and solving these problems. In this study, culture-based combing with the culture-independent methods, were used to profile the microbial contamination in aviation fuel. High-throughput sequencing (HTS) modified by propidium monoazide (PMA) revealed a higher diversity of contaminating microorganisms in samples than the culture method. Proteobacteria (47%), Actinobacteria (21%) and Ascomycota (>99%, fungi) were the most abundant phyla, and the neglected archaea was also detected. Additionally, qPCR-based methods revealed all samples contained a heavy level of microbial contamination, which was more accurate than its culturable counterparts, and fungal contamination was still a problem in aviation fuel. The application of a PCR-based method gives deeper insight into microbial contamination in aviation fuel than the conventional culture method, thus using it for regular detection and accurate description of fuel contamination is strongly recommended in the case of explosive microbial growth.


Assuntos
Actinobacteria/isolamento & purificação , Aeroportos , Ascomicetos/isolamento & purificação , Incrustação Biológica/prevenção & controle , Gasolina/microbiologia , Proteobactérias/isolamento & purificação , Gasolina/normas , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , RNA Ribossômico 16S , Reação em Cadeia da Polimerase em Tempo Real
14.
Chem Biodivers ; 16(11): e1900349, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31515922

RESUMO

In this work, the antifouling activity of five alkaloids, isolated from trees of the Atlantic rainforest, was studied. The tested alkaloids were olivacine (1), uleine (2) and N-methyltetrahydroellipticine (3) from Aspidosperma australe ('yellow guatambú') and the furoquinoline alkaloids kokusaginine (4) and flindersiamine (5) from Balfourodendron riedelianum ('white guatambú'). All these compounds can be isolated from their natural sources in high yields in a sustainable way. The five compounds were subjected to laboratory tests (attachment test of the mussel Mytilus edulis platensis) and field trials, by incorporation into soluble matrix paints, and 45 days of exposure of the painted panels in the sea. The results show that compound 3 is a very potent antifoulant, and that compounds 4 and 5 are also very active, while compounds 1 and 2 did not show any significant antifouling activity. These results open the way for the development of environmentally friendly antifouling agents, based on abundant and easy-to-purify compounds that can be obtained in a sustainable way.


Assuntos
Aspidosperma/química , Incrustação Biológica/prevenção & controle , Alcaloides Indólicos/farmacologia , Quinolinas/farmacologia , Rutaceae/química , Animais , Bivalves , Brasil , Alcaloides Indólicos/química , Alcaloides Indólicos/isolamento & purificação , Quinolinas/química , Quinolinas/isolamento & purificação
15.
Chemosphere ; 237: 124475, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549636

RESUMO

Two commercial coating systems, each one consisting of both a primer and an antifouling ("System 1" based on Copper Oxide and "System 2" based on Zinc Oxide), have been analyzed in order to investigate their environmental impacts through Life Cycle Assessment (LCA) and laboratory tests. A cradle-to-grave analysis has been performed in order to quantify the environmental footprint of each coating solution and to define which element, material, or process mainly affect the environmental impact of such products. Moreover, it was performed a comparison between the different products to determine the most environmentally sustainable choice. In addition to LCA, several incubations of coated metal samples, by means of an innovative incubation system developed by the authors, have also been performed in marine water (Gulf of Naples, Mediterranean Sea, Italy), as critical environment favoring metal corrosion and biofouling generation. The life cycle analysis has showed that the production phase presents the highest environmental impact in almost all categories, mainly due to the use of chemical compounds. Moreover, after the laboratory tests, strong biotoxicity and contaminant diffusion, contributing to the marine toxicity potential, have been observed for both the commercial paints. As a final remark, there are straightforward indications of a strong need for anti-Microbial-Induced-Corrosion commercial coatings to substitute the toxic compounds with others in order to develop a greener solution.


Assuntos
Incrustação Biológica/prevenção & controle , Desinfetantes/toxicidade , Poluentes Químicos da Água/toxicidade , Cobre , Ecossistema , Itália , Vida , Mar Mediterrâneo , Metais/análise , Pintura , Óxido de Zinco/análise
16.
Chemosphere ; 237: 124544, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31549656

RESUMO

This study evaluated the effects of co-existing cations (Na+ or Ca2+) on the lamellar structure of cross-linked graphene oxide (GO) layers and GO modified membrane performance in terms of their fouling behaviours and retention for single-model organic matter, namely, bull serum albumin (BSA), sodium alginate (SA), humic acid (HA) and tannic acid (TA). In the absence of co-existing cations, the GO layers mitigated membrane fouling for large molecules (SA, BSA, and HA) but led to severer pore blocking for small molecules (TA) compared with pristine membrane. Na+ and Ca2+ altered the performance impacts of the GO modified membrane due to different interactions with the cross-linked GO layers. Low concentrations of Na+ (<0.4 mM) enlarged interlayer spacing of the GO layers and caused a decrease in flux after physical cleaning, but the GO layers maintained the uniform lamellar structure. High concentrations of Na+ (>0.4 mM) promoted the aggregation of cross-linked GO layers through charge shielding and reduced the uniformity of lamellar structure, which weakened the antifouling performance for large molecules and promoted the passage of small molecules through the membrane. However, Ca2+ complexed with GO sheets and reinforced the uniform lamellar structure of the GO layers, leading to a better antifouling performance for the filtration of large molecules than the pristine membrane but aggravated TA fouling.


Assuntos
Cátions Bivalentes/química , Filtração/métodos , Grafite/química , Membranas Artificiais , Purificação da Água/instrumentação , Alginatos/química , Incrustação Biológica/prevenção & controle , Reagentes para Ligações Cruzadas/química , Filtração/instrumentação , Substâncias Húmicas , Óxidos/química , Tamanho da Partícula , Polivinil/química , Soroalbumina Bovina/química , Purificação da Água/métodos
17.
Chemosphere ; 235: 1154-1161, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31561306

RESUMO

A MBBR-MBR system has been developed with marine microorganisms enriched for saline wastewater treatment in this work, showing high COD and NH3-N removals. The behaviour of fouling-related components (EPS and SMP) has been studied as functions of operating time (40-90 days), salinity (0-30 g/L NaCl) and backflow ratio (0-300%, from MBR to MBBR). High biodegradability of the MBBR-MBR at optimal conditions can induce more biodegradation of humic acid-like (λex/λem: 350nm/430 nm) and fulvic acid-like (260nm/445 nm) molecules to soluble microbial by-product-like molecules (275nm/325 nm), reducing the membrane biofouling rate. The biodegradation process is suggested by the excitation-emission matrix (EEM) images. In the study of sudden salinity shock, results show that real-time monitoring the concentration of biofoulants is more effective (operative time extended by 60%) than monitoring the transmembrane pressure (operative time extended by 33%) to prevent membrane fouling. Due to an early warning from the real-time monitoring, the coming membrane-fouling is predictable and the operating conditions, such as backflow ratio, can be changed to minimize the biofouling rate.


Assuntos
Biofilmes , Incrustação Biológica/prevenção & controle , Reatores Biológicos , Membranas Artificiais , Águas Residuárias/química , Biodegradação Ambiental , Salinidade , Análise Espectral , Purificação da Água/métodos
18.
Environ Pollut ; 254(Pt B): 113086, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31479812

RESUMO

Previous studies have shown the effect of surface coatings on biofouling; however, they did not take into account the interaction of the micro and macrofouling communities, the effect of substrate orientation and the zooplankton-zoobenthic coupling together. Therefore, the aim of this study was to evaluate the effect of Zn- and Cu2O-based coatings on micro and macrofouling on steel surfaces, while also observing the role of substrate orientation and zooplankton supply. An experiment was carried out in the Patos Lagoon Estuary in southern Brazil for three months between spring and summer, where ASTM-36 steel plates represented different coatings (Zn- and/or Cu2O-based) and orientations (vertical and horizontal). To assess the zooplankton supply, sampling was carried out weekly using a 200 µm plankton net. Zn-based coating positively affected microfouling density compared to uncoated surfaces. The same pattern was observed with macrofouling, associated with vagile fauna preference, which represented 70% of the settled macrofoulers. Cu2O-based antifouling painted surfaces showed the highest microfouling density inhibition, while Zn + Cu2O-based coating did not affect the bacteria adhesion but showed lower density compared to Zn-based coating alone. The coatings combination showed the highest invertebrate inhibition. In this way, the macrofouling community was more sensitive than microfouling was to the antifouling coatings tested. The substrate orientation only affected macrofouling, horizontal surfaces being more attractive than vertical. Meroplankton, tychoplankton and holoplankton were recorded on the surfaces, although their representation in plankton was not proportional to the recruits recorded on the substrates. This was probably due to fast dispersion, the interactions of other factors and/or ecological succession stage. Surface coating, substrate orientation, and zooplankton supply interacted with the biofouling process on steel in different ways depending on the organism evaluated. Therefore, copper oxide- and zinc-based coatings were not suitable as coatings to avoid the total biofouling establishment.


Assuntos
Aderência Bacteriana/efeitos dos fármacos , Incrustação Biológica/prevenção & controle , Aço/análise , Zinco/farmacologia , Bactérias/efeitos dos fármacos , Fenômenos Fisiológicos Bacterianos/efeitos dos fármacos , Biofilmes/efeitos dos fármacos , Brasil , Cobre/química , Cobre/farmacologia , Pintura/análise , Zinco/química
19.
Chemosphere ; 236: 124396, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545199

RESUMO

Palygorskite (Pal) is a highly hydrophilic clay mineral with tubular structure and high aspect ratio, which facilitates the attachment of nanoparticles to their surface. It has become a promising new membrane preparation additive due to its lotus root like tubular structure, low price and environmental friendliness. Silver nanoparticles (AgNPs) have excellent antibacterial ability, and their incorporation into the membrane can significantly improve the bacteriostasis of the membrane. Herein, Pal was coated by polydopamine (PDA), which acted as both the adhesive and reducing agent for AgNPs. The incorporation of the Pal/Ag nanocomposite resulted in a thin polyamide (PA) layer with rough surface morphology, which facilitated the improvement of membrane permeability. Furthermore, the Pal's parallel tubes with a 0.37 × 0.63 nm2 cross-sectional area provided nanochannels allowing fast pass through of water molecules. The as-prepared TFN-7.5Pal/Ag membrane exhibited a permeate flux of 39.9 LMH at 16 bar, which was 1.6 times as high as that of the TFC membrane, accompanied with an acceptable NaCl rejection of 98.3%. Besides, antibacterial tests demonstrated that the TFN membrane presented excellent antibacterial performance against Escherichia coli (98.0%).


Assuntos
Anti-Infecciosos/farmacologia , Compostos de Magnésio/química , Membranas Artificiais , Nanopartículas Metálicas/química , Nanocompostos/química , Compostos de Silício/química , Antibacterianos/química , Antibacterianos/farmacologia , Anti-Infecciosos/química , Incrustação Biológica/prevenção & controle , Escherichia coli/efeitos dos fármacos , Interações Hidrofóbicas e Hidrofílicas , Nylons/química , Permeabilidade , Prata/química , Água , Purificação da Água/instrumentação , Purificação da Água/métodos
20.
Biosens Bioelectron ; 142: 111553, 2019 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-31377575

RESUMO

In this work, an antifouling electrochemiluminescent (ECL) ratiometric biosensor is designed for the accurate, selective and sensitive detection of DNA methyltransferase (MTase) activity based on a dual-signaling strategy. Briefly, an ITO electrode is used to construct the anti-fouling interfaces with the modification of polyaniline (PANI), AuNPs and peptide. Hairpin DNA molecules containing the symmetric sequence of 5'-CATC-3' are attached onto the modified ITO electrode and the ds-DNA can be cut off in the presence of Dam MTase and DpnI. The residual DNA and two hairpin DNA could lead to the extension of ds-DNA due to the Hybridization Chain Reaction (HCR). ECL signal is amplified significantly with the insertion of PTC-NH2 molecules into the dsDNA grooves. The ECLPTC-NH2/ECLAu@luminol is found in a logarithmic linear relation with the concentration of Dam MTase. Moreover, owing to the presence of antifouling peptide on the sensing interface, the ECL biosensor was capable of sensing MTase activity in complex biological media, such as FBS samples and human serum with significantly reduced nonspecific adsorption effect. Assaying Dam MTase in complex sample mixture containing 5% calf serum and 5% human serum further proved the feasibility of this ECL biosensor for early clinical diagnosis.


Assuntos
Compostos de Anilina/química , Técnicas Biossensoriais/métodos , Medições Luminescentes/métodos , Peptídeos/química , DNA Metiltransferases Sítio Específica (Adenina-Específica)/análise , Animais , Incrustação Biológica/prevenção & controle , Bovinos , Eletrodos , Ensaios Enzimáticos/métodos , Células HeLa , Humanos , DNA Metiltransferases Sítio Específica (Adenina-Específica)/sangue
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