Your browser doesn't support javascript.
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
Mais filtros










Base de dados
Intervalo de ano de publicação
1.
Chemosphere ; 248: 126014, 2020 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-31995737

RESUMO

Microbial fuel cell constructed wetlands (CW-MFCs) with different circuit operation conditions and hydraulic retention time (HRT) were constructed to evaluate their ability to remove and accumulate pharmaceutical and personal care products (PPCPs) (sulfadiazine (SDZ), carbamazepine (CBZ), naproxen (NPX) and ibuprofen (IBP)) during four months running process. The abundance level of corresponding sulfonamide antibiotic resistance genes (ARGs) was also investigated. The results showed that closed circuit operation of CW-MFC contributed to the decrease in mass loading of COD, NH4+-N, PPCPs, and wastewater toxicity in the effluent. Additionally, closed circuit operation with low HRT contributed to enhancing selected PPCP mass accumulation on electrodes by electro-adsorption, and thus the higher sulfonamide ARG abundance was detected in the electrodes and effluent. Moreover, the composition of bacteria was greatly influenced by the mass accumulation of PPCPs revealed by redundancy analysis results. Procrustes analysis results further demonstrated that bacterial community contributed greatly to the ARGs profiles. Therefore, ARGs with their host bacteria revealed by network analysis were partially deposited on electrode substrates, and thus ARGs were effectively accumulated on electrodes. Function analysis of the bacterial community from PICRUSt predicted metagenomes revealed that closed circuit mode enhanced the abundances of the function genes of metabolic and the multiple ARGs, suggesting that closed circuit operation exhibited positive effects on metabolic process and ARG accumulation in CW-MFC system.

2.
Bioresour Technol ; 296: 122290, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31677404

RESUMO

Three-dimensional biofilm electrode reactors (3D-BERs) with high treatment efficiency were constructed to treat wastewater containing sulfadiazine (SDZ) and ciprofloxacin (CIP) coexposure with Zinc (Zn). The results showed that coexposure to target antibiotics and Zn increased the absolute and relative abundances of target antibiotic resistance genes (ARGs). Additionally, the target ARG abundances were higher on cathode of 3D-BER compared with ordinary anaerobic reactor while the abundances of total ARGs were decreased in the effluent. Meanwhile, redundancy analysis results revealed that the composition of bacteria carrying ARGs was greatly influenced in the cathode by the accumulation of Zn and antibiotic, which dominated the changes of ARG abundances. Additionally, ARGs with their host bacteria revealed by network analysis were partially deposited on electrode substrates when being removed from wastewater. Thus, 3D-BER exhibits capability of simultaneously eliminating antibiotic and Zn, and greatly reduces the risks of ARGs spread.


Assuntos
Antibacterianos , Ciprofloxacino , Bactérias , Biofilmes , Resistência Microbiana a Medicamentos , Eletrodos , Genes Bacterianos , Características de Residência , Sulfadiazina , Águas Residuárias , Zinco
3.
Bioresour Technol ; 296: 122352, 2020 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-31708385

RESUMO

The aim of this work was to study reverse solute flux (RSF) from osmotic membrane bioreactor (OMBR) and consequent solute buildup in the feed side. A polyelectrolyte (PAA-Na) served as a draw solute (DS) to minimize RSF in OMBRs. In addition, a bioelectrochemical system (BES) was employed to drive accumulated cations from the feed/anode side into the cathode compartment, subsequently achieving PAA-Na DS recovery with the aid of high catholyte pH. Compared to the 1 M NH4HCO3 DS, the 0.48 g mL-1 PAA-Na DS produced consistently stable water flux, enhanced water recovery and increased ammonium removal efficiency. Due to a dynamic balance between PAA removal and continuing RSF, the residual PAA concentration was 72 mg L-1 on the feed side (27.0% of TOC). These results demonstrate the advantages of integrating a PAA-Na DS with a BES to mitigate RSF and to support further development of OMBR technology.


Assuntos
Polieletrólitos , Purificação da Água , Reatores Biológicos , Membranas , Membranas Artificiais , Osmose
4.
Water Res ; 165: 114988, 2019 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-31442759

RESUMO

This study assessed the influence of substrate type on pollutants removal, antibiotic resistance gene (ARG) fate and bacterial community evolution in up-flow microbial fuel cell constructed wetlands (UCW-MFC) with graphite and Mn ore electrode substrates. Better COD removal and higher bacterial community diversity and electricity generation performance were achieved in Mn ore constructed UCW-MFC (Mn). However, the lower concentration of sulfadiazine (SDZ) and the total abundances of ARGs were obtained in the effluent in the graphite constructed UCW-MFC (s), which may be related to higher graphite adsorption and filter capacity. Notably, both reactors can remove more than 97.8% of ciprofloxacin. In addition, significant negative correlations were observed between SDZ, COD concentration, ARG abundances and bacterial a-diversity indices. The LEfse analysis revealed significantly different bacterial communities due to the substrate differences in the two reactors, and Geobacter, a typical model electro-active bacteria (EAB), was greatly enriched on the anode of UCW-MFC (Mn). In contrast, the relative abundance of methanogens (Methanosaeta) was inhibited. PICRUSt analysis results further demonstrated that the abundance of extracellular electron transfer related functional genes was increased, but the methanogen function genes and multiple antibiotic resistance genes in UCW-MFC (Mn) anode were reduced. Redundancy analyses indicated that substrate type, antibiotic accumulation and bacterial community were the main factors affecting ARGs. Moreover, the potential ARG hosts and the co-occurrence of ARGs and intI1 were revealed by network analysis.


Assuntos
Fontes de Energia Bioelétrica , Grafite , Antibacterianos , Bactérias , Eletrodos , Águas Residuárias , Áreas Alagadas
5.
Bioresour Technol ; 281: 188-194, 2019 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-30822639

RESUMO

The aim of this work was to study sulfadiazine (SDZ) biodegradation efficiency, antibiotic resistance genes (ARGs) development and shift of microbial communities under conditions of limited methanogens activity in Microbial fuel cells (MFCs). The results indicated that the removal performance of SDZ was decreased with the suppression of methanogens in both MFCs and open-circuit controls. The relative abundances of ARGs were even enhanced by the inhibition of methanogens. The biodegradation mechanism of SDZ was obtained, in which SDZ was initially divided into aniline and pyrimidin-2ylsulfamic acid, then converted into small molecules. Geobacter was found as the dominant microorganism, indicating its potential to degrade SDZ in the MFCs. These findings suggest there is a trade-off between electricity production and SDZ removal and ARG development by the mean of methanogen inhibition in MFCs.


Assuntos
Antibacterianos/farmacologia , Fontes de Energia Bioelétrica , Farmacorresistência Bacteriana , Geobacter/metabolismo , Sulfadiazina/metabolismo , Eletricidade , Geobacter/efeitos dos fármacos , Metano/metabolismo
6.
Chemosphere ; 217: 599-608, 2019 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-30445405

RESUMO

This study aims to demonstrate that an up-flow microbial fuel cell-coupled constructed wetland (UCW-MFC) can effectively treat synthetic wastewater that contains a high concentration of pharmaceutical and personal care products (PPCPs, 10 mg L-1 level), such as ibuprofen (IBP) and bisphenol A (BPA). A significant decline in chemical oxygen demand (COD) and ammonia nitrogen (NH4+-N) removal was observed when BPA was added, which indicated that BPA was more toxic to bacteria. The closed circuit operation of UCW-MFC performed better than the open circuit mode for COD and NH4+-N removal. Similarly, the removal rates of IBP and BPA were increased by 9.3% and 18%, respectively, compared with the open circuit mode. The majority of PPCPs were removed from the bottom and anode layer, which accounted for 63.2-78.7% of the total removal. The main degradation products were identified. The removal rates of IBP and BPA decreased by 14.6% and 23.7% due to a reduction in the hydraulic detention times (HRTs) from 16 h to 4 h, respectively. Electricity generation performance, including voltage and maximum power density, initially increased and then declined with a decrease in the HRT. Additionally, both the current circuit operation mode and the HRT have an impact on the bacterial community diversity of the anode according to the results of high-throughput sequencing. The possible bacterial groups involved in PPCP degradation were identified. In summary, UCW-MFC is suitable for enabling the simultaneous removal of IBP and BPA and successful electricity production.


Assuntos
Compostos Benzidrílicos/química , Ibuprofeno/química , Microbiota , Fenóis/química , Purificação da Água/métodos , Áreas Alagadas , Bactérias/metabolismo , Fontes de Energia Bioelétrica/microbiologia , Análise da Demanda Biológica de Oxigênio , Eletricidade , Águas Residuárias/química
7.
Ecotoxicol Environ Saf ; 162: 376-382, 2018 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-30015182

RESUMO

A previous study revealed that the electrolytic stimulation process in bio-electrochemical reactors (BER) can accelerate growth of sulfadiazine (SDZ) antibiotic resistant bacteria (ARB) in nutrient broth medium. However, the influence of different medium nutrient richness on the fate of ARB and the relative abundance of their corresponding antibiotic resistance genes (ARGs) in this process is unknown. Specifically, it is not clear if the fate of ARB in minimal nutrition simulated wastewater is the same as in nutrient broth under electrolytic stimulation. Therefore, in this study, nutrient broth medium and the simulated wastewater were compared to identify differences in the relative abundance of Klebsiella michiganensis LH-2 ARGs in response to the electrolytic stimulation process, as well as the fate of the strain in simulated wastewater. Lower biomass, specific growth rates and viable bacterial counts were obtained in response to the application of increasing current to simulated wastewater medium. Furthermore, the percentage of ARB lethality, which was reflected by flow cytometry analysis, increased with current in the medium. A significant positive correlation of sul genes and intI gene relative abundance versus current was also observed in nutrient broth. However, a significant negative correlation was observed in simulated wastewater because of the higher metabolic burden, which may have led to decreased ARB viability. Further investigation showed that the decrease in ARGs abundance was responsible for decreased strain tolerance to SDZ in simulated wastewater. These results reveal that minimal nutrition simulated wastewater may reduce ARB and ARGs propagation in BER.


Assuntos
Resistência Microbiana a Medicamentos/genética , Klebsiella/efeitos dos fármacos , Águas Residuárias/microbiologia , Bactérias/efeitos dos fármacos , Reatores Biológicos , Farmacorresistência Bacteriana/genética , Eletrólise/métodos , Genes Bacterianos , Klebsiella/genética , Purificação da Água/métodos
8.
Sci Total Environ ; 637-638: 295-305, 2018 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-29751310

RESUMO

A continuous flow microbial fuel cell constructed wetland (MFC-CW) coupled with a biofilm electrode reactor (BER) system was constructed to remove sulfamethoxazole (SMX). The BER unit powered by the stacked MFC-CWs was used as a pretreatment unit, and effluent flowed into the MFC-CW for further degradation. The experimental results indicated that the removal rate of 2 or 4 mg/L SMX in a BER unit was nearly 90%, and the total removal rate in the coupled system was over 99%. As the hydraulic retention time (HRT) was reduced from 16 h to 4 h, the SMX removal rate in the BER decreased from 75% to 48%. However, the total removal rate in the coupled system was still over 97%. The maximum SMX removal rate in the MFC-CW, which accounted for 42%-55% of the total removal, was obtained in the anode layer. In addition, the relative abundances of sul genes detected in the systems were in the order of sulI > sulII > sulIII, and significant positive correlations of sul gene copy numbers versus SMX concentration and 16S rRNA gene copy numbers were observed. Furthermore, significant negative correlations were identified between sul genes, 16S rRNA gene copy numbers, and HRT. The abundances of the sul genes in the effluent of the MFC-CW were lower than the abundances observed in the BER effluent. High-throughput sequencing revealed that the microbial community diversity of the BER was affected by running time, power supply forms and HRT. Bio-electricity from the MFC-CW may reduce microbial community diversity and contribute to reduction of the antibiotic resistance gene (ARG) abundance in the BER. Taken together, the BER-MFC-CW coupled system is a potential tool to treat wastewater containing SMX and attenuate corresponding ARG abundance.


Assuntos
Biofilmes , Eletrodos , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Fontes de Energia Bioelétrica , RNA Ribossômico 16S , Sulfametoxazol
9.
Chemosphere ; 203: 434-441, 2018 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-29635154

RESUMO

The intensive use of antibiotics results in their continuous release into the environment and the subsequent widespread dissemination of antibiotic resistance genes (ARGs), thus posing potential risks for public health. Although vertical up-flow constructed wetlands (VUF-CWs) have been widely used to treat wastewater in remote or rural regions, few studies have assessed the potential risks of ARG dissemination when VUF-CWs are applied to treat wastewaters containing antibiotics. In this study, the removal performance of two typical antibiotics (sulfamethoxazole (SMX) and tetracycline (TC)) and the fate of ARGs were evaluated in three lab-scale VUF-CWs. The results indicated that high removal efficiencies (>98%) could be achieved for both SMX and TC. However, the exposure of antibiotics resulted in harboring abundant ARGs (mainly sul- and tet-related genes), even with increasing abundances with operation time. The abundances of ARGs had a positive correlation with the accumulation of SMX and TC in different layers of VUF-CWs, where the tet and sul genes have the highest abundance in the bottom layer due to the highest antibiotic exposure concentration. Positive correlations were observed between the abundance of tet gene and antibiotic concentration in effluent. Although the effluent had lower abundances of the ARGs than that in the wetland media, the occurrence of ARGs in effluent might still pose risk for public health. Further studies are required to explore effective control strategies to eliminate ARGs from VUF-CWs.


Assuntos
Antibacterianos/análise , Resistência Microbiana a Medicamentos/genética , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Áreas Alagadas , Genes Bacterianos , Sulfametoxazol/análise , Tetraciclina/análise , Águas Residuárias/análise , Poluentes Químicos da Água/análise
10.
Ecotoxicol Environ Saf ; 151: 272-278, 2018 Apr 30.
Artigo em Inglês | MEDLINE | ID: mdl-29407560

RESUMO

Few studies have been performed on both the potential and the risks of biofilm-electrode reactors (BERs) with regard to the removal of antibiotics. This study used 33 BERs to investigate the removal rate and degradation pathway of sulfadiazine (SDZ). Furthermore, the effects of additional electrons on sul genes and microbial community composition were examined. The study found that rapid elimination rates of 20mg/L SDZ were observed during the first 3h with different DC voltage rates. Even high concentrations (160mg/L) could be rapidly removed after 24h of system operation. Pyrimidin-2ylsulfamic acid and aniline were noted to be principal products, and an SDZ degradation mechanism was proposed. The study identified 41 species of microorganism; based on bacterial community divergence caused by voltage, and six samples were grouped into four clusters. The relative abundances of sul genes from biofilm were in the following order: sulII >sulIII >sulI >sulA. The sulI, sulII, and sulA genes were enhanced with electrical stimulation in the cathode layer. It is noteworthy that sul genes were not detected in the effluent after 24h of operation.


Assuntos
Bactérias/genética , Biofilmes , Reatores Biológicos/microbiologia , Genes Bacterianos , Sulfadiazina/metabolismo , Eletrodos
11.
Bioresour Technol ; 256: 224-231, 2018 May.
Artigo em Inglês | MEDLINE | ID: mdl-29453048

RESUMO

The aim of this work was to study sulfamethoxazole (SMX) removal efficiency and fate of corresponding sul genes in a stacked microbial fuel cell-constructed wetland coupled biofilm electrode reactor system (MFC-CW-BER). Findings showed that two stacked MFC-CWs could provide a relatively stable electricity supply to support the biofilm for SMX removal. Excellent SMX removal (>99.29%) was obtained in the BER-MFC-CW. Compared with the 2000 µg L-1 SMX influent, the relative abundance of the sul genes in biofilm media and effluent was enhanced with continuously high concentrations of SMX (4000 µg L-1). The relative abundances of sul genes in biofilm media and effluent increased as the hydraulic retention time decreased. However, there was no obvious variation in the relative abundance of sul genes in the effluent from MFC-CWs. No effect could be observe of the direct voltage and bioelectricity on the relative abundance of the sul genes in the BER.


Assuntos
Fontes de Energia Bioelétrica , Sulfametoxazol , Biofilmes , Eletrodos , Águas Residuárias , Áreas Alagadas
12.
Chemosphere ; 196: 251-259, 2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29306197

RESUMO

The fate of antibiotic-resistant bacteria (ARB) and associated antibiotic-resistant gene (ARG) expression under electrolytic stimulation in bio-electrochemical reactors (BERs) was unknown. In this study, sulfadiazine resistant bacteria (Klebsiella spp.), which were isolated from a BER, were subjected to constant direct current (DC) stimulation in a simulated BER. With an increase of the current from 7 to 28 mA, it was found that lactic dehydrogenase (LDH) showed a 1.03-, 1.21-, 1.34-, and 1.46-fold value compared with the control at 48 h, indicating that the cell membrane permeability had increased. Since the adenosine triphosphate (ATP) concentration increased with the current, the specific growth rate of Klebsiella spp. increased (R = 0.98). The viable count of Klebsiella spp. reached a maximum at 19 mA and then decreased. The percentage of ARB lethality, which was reflected by flow cytometry analysis, increased from 18% (7 mA) to 37.8% (28 mA) at 48 h. Reactive oxygen species (ROS) produced from the electrolysis of water were greater with the increasing current (R = 0.94), which may be responsible for the high lethality rate of Klebsiella spp.. Scanning electronic microscope results showed that electrolytic stimulation changed the cell surface morphology with some cell disruption. An upregulation of sulII and int1 expression was observed. A significant correlation between int1 and the current (R = 0.97) were observed. Taken together, BERs possess potential risks in accelerating ARB multiplication and promoting ARG expression.


Assuntos
Reatores Biológicos/microbiologia , Farmacorresistência Bacteriana/genética , Klebsiella/metabolismo , Antibacterianos , Humanos , Klebsiella/genética
13.
Bioresour Technol ; 244(Pt 1): 345-352, 2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28780269

RESUMO

The removal rate and degradation pathway of Sulfamethoxazole (SMX) in bioelectrochemical system (BES) and the elimination dynamics of SMX in a BES driven by stacked constructed wetland-coupled microbial fuel cells (CW-MFCs) were investigated. The results found that SMX (30mgL-1) was rapidly degraded in the BES, and the SMX removal kinetics was simulated well by a first-order kinetic model (R2>0.93). Low current had no effect on the degradation products but enhanced the SMX removal rate. Biotransformation was the main pathway for the SMX elimination in the BES. The CW-MFCs supplied adequate and stable electricity (0.84-1.01V) to support the BES for rapid SMX degradation without additional energy inputs. The relative abundance of Methanosarcina (18.7%) and VadinCA11 (3.1%) increased with an increase in voltage up to 1.2V. However, the opposite was observed for Methanosaeta and Methanomassiliicoccus. The current in the BES influenced the methanogenic communities.


Assuntos
Fontes de Energia Bioelétrica , Sulfametoxazol , Biotransformação , Eletricidade , Áreas Alagadas
14.
Chemosphere ; 178: 548-555, 2017 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-28351013

RESUMO

Microbial fuel cell-coupled constructed wetlands (CW-MFCs) use electrochemical, biological, and ecological functions to treat wastewater. However, few studies have investigated the risks of antibiotic resistance genes (ARGs) when using such systems to remove antibiotics. Therefore, three CW-MFCs were designed to assess the dynamics of ARGs in filler biofilm and effluent over 5000 h of operation. The experimental results indicated that relatively high steady voltages of 605.8 mV, 613.7 mV, and 541.4 mV were obtained at total influent antibiotic concentrations of 400, 1,000, and 1600 µg L-1, respectively. The 16S rRNA gene level in the cathode layer was higher than those in the anode and two middle layers, but the opposite trend was observed for the sul and tet genes. The relative abundance of the three tested sul genes were in the order sulI > sulII > sulIII, and those of the five tet genes were in the order tetA > tetC > tetW > tetO > tetQ. The levels of sul and tet genes in the media biofilm showed an increase over the treatment period. The effluent water had relatively low abundances of sul and tet genes compared with the filler biofilm. No increases were observed for most ARGs over the treatment period, and no significant correlations were observed between the ARGs and 16S rRNA gene copy numbers, except for sulI and tetW in the effluent. However, significant correlations were observed among most of the ARG copy numbers.


Assuntos
Antibacterianos/efeitos adversos , Fontes de Energia Bioelétrica/efeitos adversos , Resistência Microbiana a Medicamentos/genética , Recuperação e Remediação Ambiental/métodos , Poluição da Água/efeitos adversos , Antibacterianos/isolamento & purificação , Biofilmes , Dosagem de Genes , RNA Ribossômico 16S/genética , Águas Residuárias/microbiologia , Áreas Alagadas
15.
Chemosphere ; 164: 113-119, 2016 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-27580265

RESUMO

Three-dimensional biofilm-electrode reactors (3D-BERs), which possess a large effective area to drive the reductive degradation of contaminants, have recently attracted attention for wastewater treatment. There have been few studies of the potential and risks of the application of this system on the removal of antibiotics. Here four 3D-BERs were designed to initially assess the potential for electrical stimulation to remove sulfamethoxazole (SMX), tetracycline (TC) and chemical oxygen demand, and to study the fate of the corresponding antibiotic resistance genes. The results indicated that the 3D-BER could significantly reduce antibiotic concentrations in wastewater, achieving removal rates of 88.9-93.5% and 89.3-95.6% for SMX and TC, respectively. The concentrations of target genes (sulI, sulII, sulIII, tetA, tetC, tetO, tetQ, and tetW) in a granular-activated carbon (GAC) cathode were higher than those in a GAC anode in the 3D-BR (reactor with biological sludge and no voltage) and 3D-BER. An obvious increasing trend in the relative abundances of all target genes was observed in the GAC. A low current density could not increase the development of sul and tet genes in the 3D-BER. The total resistance was in the following order: 3D-BER > 3D-BR > 3D-ER (reactor with 0.8 V and without biological sludge). In addition, the dehydrogenase activity of the microorganisms in the 3D-BER was significantly higher than in the 3D-BR (p < 0.05). High-throughput sequencing revealed that the microbial communities and relative abundance at the phyla level were affected by current stimulation.


Assuntos
Anti-Infecciosos/química , Biofilmes , Resistência Microbiana a Medicamentos/genética , Microbiota/genética , Sulfametoxazol/química , Tetraciclina/química , Eliminação de Resíduos Líquidos/métodos , Antibacterianos/química , Reatores Biológicos , Técnicas Eletroquímicas , Oxirredutases/metabolismo , Resistência a Tetraciclina/genética
16.
Bioresour Technol ; 189: 87-93, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25864035

RESUMO

In this study, the soil microbial fuel cells (MFCs) were constructed in the topsoil contaminated with toxic refractory organic pesticide, hexachlorobenzene (HCB). The performance of electricity generation and HCB degradation in the soil-MFCs were investigated. The HCB degradation pathway was analyzed based on the determination of degradation products and intermediates. Experimental results showed that the HCB removal efficiencies in the three groups (soil MFCs group, open circuit control group and no adding anaerobic sludge blank group) were 71.15%, 52.49% and 38.92%, respectively. The highest detected power density was 77.5 mW/m(2) at the external resistance of 1000 Ω. HCB was degraded via the reductive dechlorination pathway in the soil MFC under anaerobic condition. The existence of the anode promoted electrogenic bacteria to provide more electrons to increase the metabolic reactions rates of anaerobic bacteria was the main way which could promote the removal efficiencies of HCB in soil MFC.


Assuntos
Fontes de Energia Bioelétrica , Eletricidade , Compostos Orgânicos/isolamento & purificação , Praguicidas/isolamento & purificação , Microbiologia do Solo , Biodegradação Ambiental , Poluição Ambiental , Hexaclorobenzeno/isolamento & purificação , Praguicidas/toxicidade
17.
Biosens Bioelectron ; 68: 135-141, 2015 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-25562740

RESUMO

Microbial fuel cells (MFCs) have got tremendous attention for their capability to enhance the degradation of some recalcitrant pollutants and simultaneous electricity production. A microbial fuel cell coupled constructed wetland (CW-MFC) is a new device to treat the wastewater and produce energy which has more wastewater treatment volume and more easily to maintenance than others MFCs. The studies on the performance of CW-MFCs are necessary. In this work, the effects of hydraulic residence time (HRT), reactive brilliant red X-3B (ABRX3) proportion and COD concentration on the electricity production of CW-MFC and the degradation characteristics of ABRX3 were investigated. The decolorization rate and the electricity production increased to a peak before slowing down with the elongation of HRT. The highest decolorization rate and electricity production were obtained when HRT was 3 days. The ABRX3 proportion (calculated as COD) in the wastewater played an important role in decolorization and electricity production, which may influence the distribution of electrons in the system. The power density of CW-MFC and the decolorization rate decreased concomitantly with an increasing ABRX3 proportion. The COD concentration influenced the CW-MFC performance slightly. The highest decolorization rate and power density reached 95.6% and 0.852 W/m(3), respectively, when the COD concentration was 300 mg/L while the ABRX3 proportion was 30%. The coulombic efficiency of the CW-MFC depended on glucose and ABRX3 proportions in the wastewater. ABRX3 acquired more electrons than the anode. Further investigations are needed to optimize CW-MFC performance and explain the mechanism of biorefractory compounds degradation and electron motion in CW-MFCs.


Assuntos
Compostos Azo/química , Fontes de Energia Bioelétrica , Técnicas Biossensoriais , Naftalenossulfonatos/química , Biodegradação Ambiental , Eletricidade , Águas Residuárias/química , Águas Residuárias/microbiologia
18.
J Hazard Mater ; 283: 186-92, 2015.
Artigo em Inglês | MEDLINE | ID: mdl-25278156

RESUMO

This paper examined the feasibility of agricultural wastes used as solid carbon sources and the effect of determined agricultural wastes on improving denitrification. Eight agricultural wastes were evaluated in MBR tests to find out their carbon release capacity, denitrification potential, leaching elements and surface properties. The results showed that retinervus luffae fructus, wheat straw, corncob and rice straw had higher carbon release capacity with COD of 13.17-21.07 mg g(-1)day(-1), BOD5 of 3.33-7.33 mg g(-1)day(-1) and respirable carbon of 8.64-10.71 mg g(-1)day(-1). Correspondingly, they displayed a good denitrification potential of 105.3-140.1mg NO3(-)-Ng(-1). Rice straw, retinervus luffae fructus and corncob were then applied in MBRs. These three agricultural wastes were found to be effective in enhancing the denitrification process, where the TN removal increased from 43.44% (control MBR) to 82.34, 68.92 and 62.97%, respectively.


Assuntos
Biofilmes , Reatores Biológicos , Carbono , Purificação da Água/métodos , Agricultura , Biodegradação Ambiental , Nitratos , Nitrogênio , Águas Residuárias/química
19.
Bioresour Technol ; 144: 165-71, 2013 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-23867535

RESUMO

A microbial fuel cell coupled constructed wetland (planted with Ipomoea aquatica) system (planted CW-MFC) was used for azo dye decolorization. Electricity was simultaneously produced during the co-metabolism process of glucose and azo dye. A non-planted and an open-circuit system were established as reference to study the roles of plants and electrodes in azo dye decolorization and electricity production processes, respectively. The results indicated that plants grown in cathode enhanced the cathode potential and slightly promoted dye decolorization efficiency. The electrodes promoted the dye decolorization efficiency in the anode. The planted CW-MFC system achieved the highest decolorization rate of about 91.24% and a voltage output of about 610 mV. The connection of external circuit promoted the growth of electrogenic bacteria Geobacter sulfurreducens and Beta Proteobacteria, and inhibited the growth of Archaea in anode.


Assuntos
Compostos Azo/isolamento & purificação , Fontes de Energia Bioelétrica , Biocombustíveis/análise , Corantes/isolamento & purificação , Eletricidade , Áreas Alagadas , Archaea/metabolismo , Bactérias/metabolismo , Biodegradação Ambiental , Biocombustíveis/microbiologia , Análise da Demanda Biológica de Oxigênio , Cor , Eletrodos , Oxirredução , Oxigênio/análise , Águas Residuárias/química , Águas Residuárias/microbiologia , Purificação da Água
20.
Bioresour Technol ; 102(20): 9490-6, 2011 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-21865035

RESUMO

The effect of polymeric ferric chloride (PFC) addition on phosphorus removal and membrane fouling were investigated in an anoxic/oxic submerged membrane bioreactor. The total phosphorus concentration in effluent averaged at 0.26 mg/L with PFC addition of 10-15 mg/L, while the rate of membrane fouling increased 1.6 times over the control MBR (without PFC addition). Three-dimensional excitation-emission matrix fluorescence spectroscopy and Gel Filtration Chromatography analysis indicated that soluble microbial byproduct-like materials and large molecules (M(W)>100 kDa) were one of the main contributors of biofouling. Fourier transform infrared spectrum confirmed that the major components of the cake layer were proteins and polysaccharides materials. Scanning electron microscopy demonstrated that membrane surfaces were covered with compact gel layer formed by organic substances and Energy Dispersive X-ray analysis indicated that ferric metals were the most important inorganic pollutants. Consequently, soluble organic substances and dose of PFC should be controlled to minimize membrane fouling.


Assuntos
Membranas Artificiais , Fósforo/isolamento & purificação , Cromatografia em Gel , Microscopia Eletrônica de Varredura , Espectrometria de Fluorescência , Espectroscopia de Infravermelho com Transformada de Fourier
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA