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1.
Environ Technol ; 38(4): 413-423, 2017 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-27283102

RESUMO

The accumulation of the nanowastes in the wastewater treatment plants has raised several concerns; therefore, it is an utmost priority to study the nanoparticle (NP) toxicity in such systems. In this work, the effect of TiO2 NPs on up-flow anaerobic sludge blanket (UASB) microflora and their photocatalytic effect on dewatered sludge were studied. We observed 99.98% removal of TiO2 NPs by sludge biomass within 24 h, though negligible toxicity was found up to 100 mg/L TiO2 concentration on extracellular polymeric substances (EPS), volatile fatty acid and biogas generation. The low toxicity corresponds to the agglomeration of TiO2 NPs in UASB sludge. Alterations in dewatered sludge biochemical composition and increase in cell damage were observed upon exposure to sunlight as evidenced by FTIR and fluorescent microscopy, respectively. Results suggest the negligible toxicity of TiO2 NPs on UASB biomass activity; however, once exposed to open environment and sunlight, they may exert detrimental effects.


Assuntos
Reatores Biológicos/microbiologia , Nanopartículas Metálicas/toxicidade , Titânio/toxicidade , Poluentes Químicos da Água/toxicidade , Biocombustíveis/análise , Biomassa , Biopolímeros/análise , Ácidos Graxos Voláteis/análise , Nanopartículas Metálicas/química , Nanopartículas Metálicas/efeitos da radiação , Esgotos/análise , Luz Solar , Titânio/química , Titânio/efeitos da radiação , Poluentes Químicos da Água/química , Poluentes Químicos da Água/efeitos da radiação
2.
Environ Sci Pollut Res Int ; 23(5): 4063-72, 2016 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-25824004

RESUMO

The continuous rise in production and applications of carbon nanotubes (CNTs) has grown a concern about their fate and toxicity in the environment. After use, these nanomaterials pass through sewage and accumulate in wastewater treatment plants. Since, such plants rely on biological degradation of wastes; their activity may decrease due to the presence of CNTs. This study investigated the effect of multiwalled carbon nanotubes (MWCNTs) on upflow anaerobic sludge blanket (UASB) microbial activity. The toxic effect on microbial viability, extracellular polymeric substances (EPS), volatile fatty acids (VFA), and biogas generation was determined. The reduction in a colony-forming unit (CFU) was 29 and 58 % in 1 and 100 mg/L test samples, respectively, as compared to control. The volatile fatty acids and biogas production was also found reduced. The scanning electron microscopy (SEM) and fluorescent microscopy images confirmed that the MWCNT mediated microbial cell damage. This damage caused the increase in EPS carbohydrate, protein, and DNA concentration. Fourier transform infrared (FTIR) spectroscopy results supported the alterations in sludge EPS due to MWCNT. Our observations offer a new insight to understand the nanotoxic effect of MWCNTs on UASB microflora in a complex environment system.


Assuntos
Consórcios Microbianos/efeitos dos fármacos , Nanotubos de Carbono/toxicidade , Esgotos/microbiologia , Poluentes Químicos da Água/toxicidade , Purificação da Água/métodos , Anaerobiose , Biocombustíveis/análise , Biopolímeros/análise , Reatores Biológicos/microbiologia , Microscopia Eletrônica de Varredura , Nanotubos de Carbono/química , Esgotos/química , Espectroscopia de Infravermelho com Transformada de Fourier , Propriedades de Superfície , Águas Residuárias/química , Águas Residuárias/microbiologia , Poluentes Químicos da Água/química
3.
Rev Environ Contam Toxicol ; 230: 83-110, 2014.
Artigo em Inglês | MEDLINE | ID: mdl-24609519

RESUMO

Nanotechnology offers unique attributes to various industrial and consumer sectors, and has become a topic of high interest to scientific communities across the world. Our society has greatly benefitted from nanotechnology already, in that many products with novel properties and wide applicability have been developed and commercialized. However, the increased production and use of nanomaterials have raised concerns about the environmental fate and toxicological implications of nanoparticles and nanomaterials. Research has revealed that various nanomaterials may be hazardous to living organisms. Among biota, plants are widely exposed to released nanomaterials and are sensitive to their effects. The accumulation of nannmaterials in the environment is a potential threat, not only because of potential damage to plants hut also because nanoparticles may enter the food chain. Although the literature that addresses the safety of nanoproducts is growing, little is known about the mechanisms by which these materials produce toxicity on natural species, including humans. In this paper, we have reviewed the literature relevant to what phytotoxic impact fabricated nanoparticles (e.g., carbon nanotubes, metallic and metal oxide nanoparticles, and certain other nanomaterials) have on plants. Nanoparticles produce several effects on plant physiology and morphology. Nanoparticles are known to affect root structure, seed germination, and cellular metabolism. Nanoparticles inhibit growth, induce oxidative stress, morphogenetic abnormalities and produce clastogenic disturbances in several plant species. The size, shape and surface coating of NPs play an important role in determining their level of toxicity. Of course, the dose, route of administration, type of dispersion media, and environmental exposure also contribute to how toxic nanoparticles are to plants. Currently, nanotoxicity studies are only in their initial phases of development and more research will be required to identify the actual threat nanoproducts pose to the plant system. To date, data show that there is a large variation in the phytotoxicity caused by different NPs. Moreover, the studies conducted thus far have mostly relied on microscopy to detect effects. Studies that incorporate measures and analyses undertaken with more modern tools are needed. Among new data that are most urgently needed on NPs is how fabricated NPs behave once released into the environment, and how exposure to them may affect plant resistance, metabolic pathways, and plant genetic responses. In this review, we have attempted to collect, present and summarize recent findings from the literature on nanoparticle toxicity in plants. To strengthen the analysis, we propose a scheme for accessing NP toxicity. We also recommend how the potential challenges presented by increased production and release of NPs should be addressed. It is our belief and recommendation that every nanomaterial-based product be subjected to appropriate toxicity and associated assessment before being commercialized.


Assuntos
Nanopartículas/química , Plantas/efeitos dos fármacos , Desenvolvimento Vegetal/efeitos dos fármacos , Fenômenos Fisiológicos Vegetais/efeitos dos fármacos , Plantas/anatomia & histologia
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