Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 2.957
Filtrar
1.
Ecotoxicol Environ Saf ; 188: 109887, 2020 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-31706237

RESUMO

To investigate the removal mechanisms of cadmium (Cd) by Zn-layer double hydroxides-modified zeolites substrates in constructed rapid infiltration systems (CRIS), the ZnAl-LDHs and ZnFe-LDHs were synthesized and in-situ coated on the original zeolites through co-precipitation method. The prepared Zn-LDHs-modified and original zeolites were characterized by scanning electron microscope (SEM) and energy dispersive spectroscopy (EDS) methods, whose results provided the evidences that the Zn-LDHs were successfully coated on the original zeolites. From the results of purification experiments, the average Cd removal rates of ZnAl-LDHs-modified, ZnFe-LDHs-modified and original zeolites were 88.40, 86.00 and 32.52%, respectively; demonstrating that the removal rates of zeolites could significantly improve. Additionally, the modification of Zn-LDHS could enhance the theoretical adsorption ability. According to the results of isothermal adsorption and desorption tests, the desorption rates of Zn-LDHs-modified zeolites were higher than that of original zeolites. Cd adsorption capacity of ZnFe-LDHs-modified zeolites was 1428.57 mg kg-1 and original zeolites was 434.783 mg kg-1. In the adsorption kinetic studies, the pseudo-second-order models were used to well describe the experimental results of Zn-LDHs-modified zeolites, indicating that their adsorption types were attributed to be more stable chemisorption. Besides, the relevant microbial tests also confirmed that microbial enzymatic activity and extracellular polymeric substances (EPS) were significantly promoted on surface of Zn-LDHs-modified zeolites. The contents of EPS on the surface of zeolites were as following: ZnAl-LDHs-modified zeolites (78.58128 µg/g) > ZnFe-LDHs-modified zeolites (71.85445 µg/g) > original zeolites (68.69904 µg/g). Meanwhile, the results of high-throughput sequencing showed that modification by Zn-LDHs improved microbial diversity and relative abundance. The Proteobacteria was the dominant phylum and the Acidobacteria was conducive to Cd removal. Overall, it could be concluded that ZnAl-LDHs-modified zeolites might be applied as an efficient substrate for Cd removal in CRIS.


Assuntos
Cádmio/isolamento & purificação , Hidróxidos/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Zeolitas/química , Zinco/química , Acidobacteria/química , Acidobacteria/metabolismo , Adsorção , Proteínas de Bactérias/metabolismo , Cádmio/química , Cinética , Poluentes Químicos da Água/química , Purificação da Água/instrumentação , Purificação da Água/normas
2.
Chemosphere ; 238: 124691, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31524626

RESUMO

In recent years, forward osmosis (FO) has represented numerous potential applications in safe water production. In this study, we improved the performance of FO thin film composite (TFC) membranes for the removal of trace organic compounds (TOrCs) by tuning the chemistry of its top active layer. The TFC membranes were synthesized by interfacial polymerization (IP) reaction between amine-containing monomers, e.g., meta-phenylene diamine (MPD) or para-phenylenediamine (PPD), and an acid chloride monomer, e.g., trimesoyl chloride (TMC). Owing to three free amine functionals over main core, melamine was used in the amine monomers solution to increase cross-linking among polyamide chains. Chemical and morphological characterization of the prepared membranes confirmed that melamine was successfully incorporated into the chemical structure of the top PA layer. Two agricultural toxic materials (atrazine and diazinon) were used to investigate the capability of the newly fabricated membranes in the removal of TOrCs. The obtained results showed that melamine-improved FO membranes provided higher atrazine and diazinon rejections in two different FO membrane configurations, including active layer facing feed solution (ALF) and active layer facing draw solution (ALD). The highest rejections of both diazinon (99.4%) and atrazine (97.3%) were achieved when the melamine modified MPD-based membrane served in ALF mode with 2 M NaCl as a draw solution.


Assuntos
Substâncias Húmicas/análise , Osmose/fisiologia , Purificação da Água/instrumentação , Purificação da Água/métodos , Atrazina/análise , Diazinon/análise , Membranas Artificiais , Nylons/química , Fenilenodiaminas/química , Polimerização , Cloreto de Sódio/química , Triazinas/química , Ácidos Tricarboxílicos/química , Água/química
3.
World J Microbiol Biotechnol ; 35(10): 149, 2019 Sep 23.
Artigo em Inglês | MEDLINE | ID: mdl-31549239

RESUMO

The goal of this study was to investigate the relationship between the denitrification process and carbon metabolism in a full-scale tannery wastewater treatment plant bioaugmented with the microbial consortium BM-S-1. The metagenomic analysis of the microbial community showed that Brachymonas denitrificans, a known denitrifier, was present at a high level in the treatment stages of buffering (B), primary aeration (PA), and sludge digestion (SD). The occurrences of the amino acid-degrading enzymes alpha ketoglutarate dehydrogenase (α-KGDH) and tryptophan synthase were highly correlated with the presence of denitrification genes, such as napA, narG, nosZ and norB. The occurrence of glutamate dehydrogenase (GDH) was also highly paralleled with the occurrence of denitrification genes such as napA, narG, and norZ. The denitrification genes (nosZ, narG, napA, norB and nrfA) and amino acid degradation enzymes (tryptophan synthase, α-KGDH and pyridoxal phosphate dependent enzymes) were observed at high levels in B. This indicates that degradation of amino acids and denitrification of nitrate may potentially occur in B. The high concentrations of the fatty acid degradation enzyme groups (enoyl-CoA hydratase, 3-hydroxyacyl-CoA dehydrogenase and ß-ketothiolase) were observed together with the denitrification genes, such as napA, narG and nosZ. Phospholipase/carboxylesterase, enoyl-CoA hydratase/isomerase, acyl-CoA dehydrogenase, phenylacetate degradation enzyme and 3-hydroxyacyl-CoA dehydrogenase 2 were also dominant in B. All these results clearly indicate that the denitrification pathways are potentially linked to the degradation pathways of amino acids and fatty acids whose degradation products go through the TCA cycle, generating the NADH that is used as electron donors for denitrification.


Assuntos
Bactérias/genética , Bactérias/metabolismo , Carbono/metabolismo , Águas Residuárias/microbiologia , Bactérias/classificação , Bactérias/isolamento & purificação , Proteínas de Bactérias/genética , Proteínas de Bactérias/metabolismo , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Desnitrificação , Complexo Cetoglutarato Desidrogenase/genética , Complexo Cetoglutarato Desidrogenase/metabolismo , Metagenômica , Consórcios Microbianos , Nitratos/metabolismo , Esgotos/química , Esgotos/microbiologia , Triptofano Sintase/genética , Triptofano Sintase/metabolismo , Purificação da Água/instrumentação , Purificação da Água/métodos
4.
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
5.
Chemosphere ; 236: 124384, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31545191

RESUMO

This study evaluates a novel adsorbent for ciprofloxacin (CPX) removal from water using a composite derived from municipal solid waste biochar (MSW-BC) and montmorillonite (MMT). The composite adsorbent and pristine materials were characterized using powder X-Ray Diffraction (PXRD), Fourier-Transform Infrared (FTIR) spectroscopy, and Scanning Electron Microscope (SEM) before and after the adsorption. Batch experiments were conducted to study the mechanisms involved in the adsorption process. Ciprofloxacin sorption mechanisms were interpreted in terms of its pH-dependency and the distribution coefficients. The SEM images confirmed the successful binding of MMT onto the MSW-BC through flaky structure along with a porous morphology. Encapsulation of MMT onto MSW-BC was exhibited through changes in the basal spacing of MMT via PXRD analysis. Results from FTIR spectra indicated the presence of functional groups for both pristine materials and the composite that were involved in the adsorption reaction. The Hill isotherm model and pseudo-second-order and Elovich kinetic models fitted the batch sorption data, which explained the surface heterogeneity of the composite and cooperative adsorption mechanisms. Changes made to the MSW-BC through the introduction of MMT, enhanced the active sites on the composite adsorbent, thereby improving its interaction with ionizable CPX molecules giving high sorption efficiency.


Assuntos
Antibacterianos/isolamento & purificação , Bentonita/química , Carvão Vegetal/química , Ciprofloxacino/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Antibacterianos/química , Ciprofloxacino/química , Cinética , Resíduos Sólidos/análise , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/química , Purificação da Água/instrumentação
6.
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
7.
Sci Total Environ ; 692: 844-853, 2019 Nov 20.
Artigo em Inglês | MEDLINE | ID: mdl-31539990

RESUMO

High-quality meso/micropore-controlled hierarchical porous carbon (HPC) was synthesized by a hard template method utilizing rice husk biochar and then used to adsorb copper ions from an aqueous solution. The preparation procedure included two main steps: base leaching and physicochemical activation. During the activation process, the porosity characteristics (i.e., specific surface area and meso/micropore ratio) were controlled by altering the KOH impregnation ratio, activation time, and temperature under the CO2 atmosphere. In addition, a copper adsorption study was performed using three HPC samples with different pore structures and characteristics. The results of this study indicate that the adsorption capacity of HPC material derived from rice husk biochar is strongly influenced by its meso/micropore ratio. As evidenced, HPC 3-0.5-800, which was impregnated by a KOH:biochar ratio of 3 and activated at 800°C for 0.5h under a CO2 atmosphere, has a very high specific surface area of 2330 m2g-1 with an 81% mesopore to total specific surface area. Importantly, it exhibited a superior adsorption capacity of 265mgg-1 and rapid adsorption kinetics for copper ions. The improvement is ascribed to the high specific surface area and favorable hierarchical structure. The findings demonstrate the feasibility of controlling the hierarchical pore structure of rice husk biochar-derived carbons as high-performance adsorbents for copper ion removal from water.


Assuntos
Carvão Vegetal/química , Cobre/análise , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Adsorção , Hidróxidos/química , Cinética , Oryza/química , Porosidade , Compostos de Potássio/química , Eliminação de Resíduos Líquidos/instrumentação , Purificação da Água/instrumentação
8.
Environ Pollut ; 254(Pt B): 113005, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31473389

RESUMO

Norfloxacin (NOR) is a persistent organic pollutant and can be effectively removed from effluent by adsorption of biochar. However, the presence of other emerging contaminants, such as surfactants, will potentially alter adsorption performance of norfloxacin by biochar and the molecular-scale mechanisms of the interaction between surfactants and biochar remain poorly understood. In this study, adsorption of norfloxacin on magnetic biochar prepared with iron-containing furfural residue (FRMB) in the presence or absence of anionic surfactants was investigated. The adsorption of NOR was significantly affected by the initial pH and anionic surfactants-sodium dodecyl sulfate (SDS) and sodium dodecyl benzene sulfonate (SDBS). In the presence of SDS and SDBS, the maximum sorption capacities of NOR were 2.33 and 1.97 times higher than that in the absence of surfactants, reached to 698.6 mg g-1 and 589.9 mg g-1, respectively. The optimal pH condition which was 4 indicated that electrostatic adsorption played a decisive role in the adsorption process after introduction of SDS/SDBS. The adsorption data were fitted well by the Elovich model and Freundlich model at the optimal conditions in which both SDS and SDBS were hemimicelle (0.8 mM SDS or 0.4 mM SDBS), indicating surface heterogeneity of FRMB and the adsorption mechanism was related to the assembly of surfactants on biochar. FTIR results showed that FRMB and SDS/SDBS interacted through hydrophobic action, and more complex or aggregates were formed between the NOR and biochar/SDS/SDBS. This work highlights the synergistic enhancement effects of tested surfactants on the removal of NOR by magnetic biochar from aqueous systems.


Assuntos
Antibacterianos/química , Carvão Vegetal/química , Resíduos de Drogas/química , Magnetismo/métodos , Norfloxacino/química , Tensoativos/química , Purificação da Água/métodos , Adsorção , Antibacterianos/isolamento & purificação , Benzenossulfonatos/química , Resíduos de Drogas/isolamento & purificação , Magnetismo/instrumentação , Norfloxacino/isolamento & purificação , Dodecilsulfato de Sódio/química , Poluentes Químicos da Água/química , Purificação da Água/instrumentação
9.
Sci Total Environ ; 695: 133814, 2019 Dec 10.
Artigo em Inglês | MEDLINE | ID: mdl-31421339

RESUMO

Reverse osmosis (RO) membrane is widely used for household water treatment in areas with limited access to safe drinking water; however, some studies documented deterioration in the quality of RO permeate. Repeated pressurization from intermittent operation in households is suspected to have an adverse effect on RO. This study aimed to evaluate virus removal by RO used in actual households as well as the water quality of permeate, and to elucidate the main cause of RO deterioration. We conducted a survey in households in Hanoi, Vietnam, to collect 27 membranes along with their usage history, where virus removal was investigated in laboratory. Of the used RO membranes, 22% did not show the protective level, >3 log10 (99.9%) virus removal, recommended by World Health Organization. The differences in virus removal among Aichi virus, MS2 and φX-174 were <0.5 log10. All membranes with estimated pressurization times of <4000 showed >3 log10 virus removal, while 17% of membranes used for <3years, the manufacturers' warranty period, did not achieve the criterion. Therefore, virus removal performance may not be assured even if the users replace the membrane following the warranty period. Furthermore, more pressurized membranes exhibited significantly lower virus removal than less pressurized ones, suggesting a major role of repeated pressurization in the deterioration of RO. Coliforms were detected from 44% of the permeate of the point-of-use devices applying RO (RO-POU), raising concerns on the extrinsic contamination and regrowth of bacteria. Consequently, RO in households may deteriorate more rapidly than the manufactures' expectation due to repeated pressurization. RO in households should be replaced based on not only membrane age but also total pressurized times (i.e., 4000 times) to keep the protective level of virus removal. The deteriorated bacterial quality in RO permeate suggested the need for installing post-treatment, such as UV irradiation.


Assuntos
Água Potável/virologia , Membranas Artificiais , Purificação da Água/métodos , Filtração , Osmose , Purificação da Água/instrumentação , Qualidade da Água
10.
Environ Pollut ; 254(Pt B): 113014, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31446359

RESUMO

A new carboxylate-functionalized hydrochar (CFHC) was successfully prepared by reaction of hydrochar with maleic anhydride under solvent-free conditions and followed by deprotonating carboxyl group of hydrochar with NaHCO3 solution. CFHC was characterized using X-ray photoelectron spectroscopy (XPS), elemental analysis (EA), zeta potential, Brunauer-Emmett-Teller surface area (BET) and Fourier-transform infrared spectroscopy (FTIR), and its adsorption properties and mechanisms to methylene blue (MB) and Cd(II) were investigated using the batch method. The isotherm adsorption data were accorded with Langmuir model and the maximum uptakes were 1155.57 and 90.99 mg/g for MB and Cd(II) at the temperature of 303 K, respectively. The joint analysis of batch experiments and characterizations of hydrochar confirmed the π-π interaction was accompanied by electrostatic interaction and hydrogen bond for MB adsorption, while the surface complexation and ion exchange were predominant mechanisms for Cd(II) adsorption. Therefore, a highly effective adsorbent CFHC prepared by a simple and environmentally friendly solid-phase synthesis is a promising candidate for wastewater treatment.


Assuntos
Cádmio/química , Carvão Vegetal/química , Azul de Metileno/química , Poluentes Químicos da Água/química , Purificação da Água/métodos , Adsorção , Cádmio/isolamento & purificação , Troca Iônica , Cinética , Azul de Metileno/isolamento & purificação , Espectroscopia de Infravermelho com Transformada de Fourier , Eletricidade Estática , Águas Residuárias/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação
11.
Bioelectrochemistry ; 130: 107200, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31382227

RESUMO

In this study, a microbial electrochemical system (MES) was employed to investigate the effect of isoelectric point (IEP) on cheese whey wastewater treatment. The experiments were carried out in a bioreactor equipped with a semicircular carbon cloth and stainless steel electrodes as anode and cathode, respectively. The effects of IEP, whey protein concentration, electrical current, and time were studied. The IEP of the whey protein was determined at pH 5.9. The optimum electrical current was obtained at 6 mA for synthetic cheese whey wastewater. The results of rotary exponential doping showed that the third structure of proteins chenges to the second structure at the IEP. The highest protein removal (98%) was obtained at pH 6. The results showed that 76%, 83%, and 98% protein removal were achieved at 2, 4, and 8 h, respectively.


Assuntos
Reatores Biológicos/microbiologia , Águas Residuárias/análise , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação , Proteínas do Soro do Leite/isolamento & purificação , Análise da Demanda Biológica de Oxigênio , Queijo/análise , Desenho de Equipamento , Tecnologia de Alimentos , Ponto Isoelétrico
12.
Bioelectrochemistry ; 130: 107230, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31326774

RESUMO

The present study was conducted to investigate the effect of alternating current (AC) on phenol removal in a microbial electrochemical system (MES) and determine its by-products. The bioreactor used for this purpose operates in the batch mode supplied with an AC power supply. The factors stimulating this process including frequency, applied voltage, duty cycle, carbon to nitrogen ratio, and the initial phenol concentration were investigated. The optimum operating conditions of the bioreactor were obtained at 5 Hz frequency, 0.4 peak-to-peak voltage (Vpp), C0 = 100 mg.L-1 phenol, pH = 7, C/N = 1, and the sine wave. Phenol was completely degraded under the optimum operating conditions for 2 h. The GC-MS analysis showed the presence of carboxylic acid, oxalic acid, and propionic acid. It was observed that the generated by-products are non-toxic and phenol is completely removed to nontoxic compounds. The results show that under optimum conditions, using an alternating current, the proposed system generated low-hazard byproducts with a low energy consumption.


Assuntos
Bactérias/metabolismo , Reatores Biológicos/microbiologia , Fenol/metabolismo , Poluentes Químicos da Água/metabolismo , Biodegradação Ambiental , Eletricidade , Técnicas Eletroquímicas/instrumentação , Desenho de Equipamento , Redes e Vias Metabólicas , Fenol/isolamento & purificação , Águas Residuárias/análise , Águas Residuárias/microbiologia , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/instrumentação
13.
Chemosphere ; 236: 124374, 2019 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-31344619

RESUMO

The degradation of irgarol, a frequently detected algaecide in the aquatic environment, by ozonation was investigated in this study. The second-order rate constants for the reaction of irgarol with ozone (O3) and hydroxyl radical (OH) were determined to be 505 M-1 s-1 and 4.96 × 109 M-1 s-1, respectively. During ozonation, sixteen transformation products (TPs) of irgarol were proposed using an electrospray ionization quadrupole time-of-flight mass spectrometer. Most of the TPs are ozone-refractory compounds and therefore could only be further transformed by oxidation with OH generated from O3 decomposition during ozonation. Toxicity analysis using the ecological structure activity relationship class program indicates that some of the TPs (e.g., irgarol sulfoxide) still exhibit high acute or chronic toxicity to aquatic organisms (fish, daphnia, and algae) as the parent compound. With a typical ozone dose applied in water treatment (2 mg/L, corresponding to a specific ozone dose of 0.8 mg O3/mg dissolved organic carbon), irgarol could be completely abated in a selected surface water by ozonation. However, most of the TPs persisted in the ozonation effluent because of their low ozone reactivity. The results of this study suggest that ozonation with typical ozone doses applied in water treatment may not be able to sufficiently reduce the ecotoxicological effects of irgarol on aquatic organisms. More effective treatment processes such as ozone-based advanced oxidation processes may be required to enhance the removal of toxic TPs of irgarol in water treatment.


Assuntos
Herbicidas/química , Herbicidas/toxicidade , Ozônio/química , Ozônio/toxicidade , Triazinas/química , Purificação da Água/instrumentação , Radical Hidroxila/química , Cinética , Estrutura Molecular , Oxirredução , Triazinas/toxicidade , Águas Residuárias/química
14.
Carbohydr Polym ; 222: 115016, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31320089

RESUMO

In this research, an innovative biomass derived spongy adsorbent was fabricated by adopting dialdehyde cellulose nanocrystals (DCNC) as crosslinking and reinforcing building block, which showed high mechanical strength, satisfying adsorption performance and good recyclability. The improved shape integrity and specific surface area resulted from DCNC incorporation contribute to high adsorption performance of this sponge. Adsorption behaviors of the adsorbent were comprehensively studied. The qe for Pb2+ and Cd2+ by the adsorbent could reach as high as 767 and 517 mg/g, respectively. Also, this adsorbent showed excellent recyclability. In addition, the adsorbent exhibited satisfying fixed-bed column adsorption performance. Thus, it could be considered as promising high efficiency adsorbent.


Assuntos
Celulose/análogos & derivados , Plumas/química , Queratinas/química , Metais Pesados/isolamento & purificação , Nanopartículas/química , Poluentes Químicos da Água/isolamento & purificação , Adsorção , Animais , Biomassa , Celulose/química , Reagentes para Ligações Cruzadas/química , Reutilização de Equipamento , Metais Pesados/química , Porosidade , Poluentes Químicos da Água/química , Purificação da Água/instrumentação , Purificação da Água/métodos
15.
Artigo em Inglês | MEDLINE | ID: mdl-31322048

RESUMO

This study aims to evaluate the evapotranspiration (EVP) rate of the willow species Salix humboldtiana to be used as a plant species for evapotranspirative willow system (EWS) to treat domestic wastewater in highland climate conditions in Latin America. Twelve lysimeters were installed in Bogotá, Colombia (2,600 m.a.s.l.). Two parameters were evaluated to determine the effect on EVP rate as follows: (a) the plant's age at the plantation time (one year or six months), and (b) the type of water (domestic wastewater or fertilized water). The plant's age was the most important parameter influencing the EVP rate. In addition, the growth of plants was similar (p > 0.05) between individuals irrigated with domestic wastewater and fertilized water. Thus, Salix humboldtiana over one-year-old was recommended to be used in EWS because its EVP rate of 1456 mm y-1, can treat 372 mm y-1 of domestic wastewater under the highland climate conditions. Finally, one EWS planted with Salix humboldtiana to treat domestic wastewater for a Colombian family located in these climate conditions would need an area of 400 m2. This value for area, although similar to other parts of the world, is higher when considering the solar radiation in tropical or sub-tropical climate conditions.


Assuntos
Salix/metabolismo , Purificação da Água/métodos , Biodegradação Ambiental , Clima , Colômbia , Salix/química , Salix/crescimento & desenvolvimento , Águas Residuárias/análise , Purificação da Água/instrumentação
16.
Sci Total Environ ; 689: 945-957, 2019 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-31280175

RESUMO

Desalination is increasingly put forward as a sustainable local solution to water scarcity in combination with the exploitation of renewable energy sources. However, the complexity of the resource nexus entails the unavoidable existence of pros and cons across its various dimensions that can only be assessed at different scales of analysis. In turn, these pros and cons entail different winners and losers among the different social actors linked through the nexus. To address these challenges, a novel approach to resource nexus assessment is put forward, based on multi-scale integrated analysis of societal and ecosystem metabolism (MuSIASEM) and recognizing the resource nexus as a wicked problem. The integrated representation identifies the existence of biophysical constraints determined by processes both under human control (in the technosphere) and beyond human control (in the biosphere). The approach is illustrated with a local case study of desalination in the Canary Islands, Spain. The material presented has been generated in the context of the project "Moving towards adaptive governance in complexity: Informing nexus security" (MAGIC) for use in participatory processes of co-production of knowledge claims about desalination, a prerequisite for informed policy deliberation.


Assuntos
Conservação de Recursos Energéticos/métodos , Purificação da Água/métodos , Vento , Ilhas , Energia Renovável , Espanha , Purificação da Água/instrumentação
17.
Environ Sci Pollut Res Int ; 26(25): 26276-26285, 2019 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-31286373

RESUMO

Tricholorethylene (TCE) has been recognized as second common organic pollutant found in groundwater in Taiwan. Several advanced oxidation processes (AOPs) have been applied for TCE removal and photocatalytic is one of promising AOP techniques. In this study, LaFeO3 is successfully synthesized via sol-gel method and investigated for its photocatalytic oxidation rate toward TCE in water. Experimental results indicate that 95% removal efficiency of TCE can be achieved in aqueous solution with LaFeO3 (2 g/L) as photocatalyst within 1 h of Xenon lamp illumination. Additionally, the influences of initial TCE concentration, light intensity, photocatalyst loading, and pH value on the TCE removal efficiency are evaluated as well. The highest energy efficiency obtained in this study is 10.8 mg TCE/kWh and the value is higher than those reported in previous studies. Besides, removal mechanisms have been identified and the results indicate that the overall removal efficiency reaches 82%, with adsorption and photolysis accounting for 20% and 39%, respectively.


Assuntos
Óxidos/química , Tricloroetileno/isolamento & purificação , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodos , Adsorção , Água Subterrânea/química , Concentração de Íons de Hidrogênio , Oxirredução , Processos Fotoquímicos , Fotólise , Purificação da Água/instrumentação
18.
Chemosphere ; 235: 58-69, 2019 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-31255766

RESUMO

In this study, ultrafiltration membrane fouling was alleviated by hydrophilic modification and coagulation pretreatment. A polydopamine (PDA) layer was used as a bridge to introduce the nano titanium dioxide (TiO2) onto the polysulfone (PSf) membranes, forming a hydrophilic modified layer. A relationship model was established between the coagulation efficiencies and floc properties and membrane fouling of the modified PSf membranes during the coagulation/ultrafiltration (C-UF) process. The combination styles of flocculants, poly dimethyldiallylammonium chloride (PDMDAAC) and polyaluminum chloride (PAC) were used in C-UF hybrid process. The characterization results indicated that the hydrophilicity was significantly enhanced in the modified PSf membranes. Scanning electron microscopy (SEM) tests proved that the PDA layer could be tightly bound to TiO2 by coordination bond onto PSf membrane surface. In the acidic conditions, more TiO2 nano-particles were adhered on the PDA particles surface as the pH of (NH4)2TiF6 solution was increased, which resulted in higher hydrophilicity of membranes. In addition, the C-UF tests exhibited that the coagulation efficiency was greatly improved in the PAC/PDMDAAC system, and the PSf membrane modified by PDA/TiO2 in UF tests significantly reduced the membrane fouling, this was partially due to the formation of TiO2 modified coating with higher hydrophilicity.


Assuntos
Incrustação Biológica/prevenção & controle , Membranas Artificiais , Ultrafiltração/métodos , Hidróxido de Alumínio , Floculação , Interações Hidrofóbicas e Hidrofílicas , Indóis , Polímeros , Sulfonas , Titânio , Ultrafiltração/instrumentação , Purificação da Água/instrumentação , Purificação da Água/métodos
19.
Artigo em Inglês | MEDLINE | ID: mdl-31361190

RESUMO

This work investigated the influence of dye class on permeate flux and color rejection by comparing direct contact membrane distillation (DCMD) and vacuum membrane distillation (VMD) applied to remediation of dyeing wastewater. The same operating system at the feed side was used and the driving force of each configuration was determined. Reactive and disperse dye solutions were considered, and a commercial membrane was employed. Final color rejection > 90.79% was obtained, and water was recovered at the permeate side (final normalized permeate flux up to 38.92 kg m-2day-1kPa-1). VMD showed higher normalized permeate flux when compared to DCMD. However, the performance according to dye class depended on MD configuration. Reactive dye resulted in higher permeate flux than the disperse dye solution in DCMD. Contrarily, disperse dye solution showed higher permeate flux in VMD. The formation of a concentration boundary layer at the permeate membrane interface was suggested with disperse dye solution in DCMD, decreasing thus the driving force. In VMD, the boundary effect is negligible with disperse dye solution. This result implies that the VMD performance in the textile industry may depend more on driving force rather than the dye class of the dyeing bath.


Assuntos
Corantes/química , Destilação/métodos , Águas Residuárias/química , Purificação da Água/métodos , Destilação/instrumentação , Membranas Artificiais , Indústria Têxtil , Vácuo , Purificação da Água/instrumentação
20.
Chemosphere ; 233: 234-244, 2019 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-31176124

RESUMO

Single and multi-component fertilizers were used as a draw solution (DS) in forward osmosis (FO) to produce high-quality water from synthetic and seawater solution, eliminating the need for DS regeneration and reducing the operational energy. The effect of DS type, concentration, circulation flow rates on the FO water flux (WF), specific water flux (SWF), percentage water recovery (%Wrecovery), reverse salt flux (RSF) and percentage salt rejection (%R) were studied. The results showed that single fertilizer draw solution (SFDSs) produced higher WF (4.43 L/m2.h), %Wrecovery (30%) and RSF (60%) in comparison with multi-component draw solution (MCDS) with WF, %Wrecovery and RSF of 2.57 L/m2.h, 17% and 46%, respectively. DS with higher concentration produced the highest SWF and %Wrecovery and consumed less energy. MCDS with concentration of 200 g/L showed SWF in the range of 14.0 to 10.4 L/m2h and energy consumption of 0.312 kW/h m3 in comparison with 10 to 7.8 L/m2h and 0.23 kW/h m3 for MCDS with concentration of 100  g/L. Increasing the recirculation flow rate showed minimum effect on WF and up to 35% energy saving. Pure water extracted using liquid fertilizers utilizing the unique FO mass transport properties balanced nutrient requirement and the water quality parameters, thereby sustaining the aquaponics industry.


Assuntos
Purificação da Água/métodos , Fertilizantes , Membranas Artificiais , Osmose , Água do Mar/química , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/instrumentação , Qualidade da Água
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA