1,721,043 research outputs found
Nano and bio-based technologies for wastewater treatment: prediction and control tools for the dispersion of pollutants in the environment
No full textOver the past few decades the boom in the industrial sector has contributed to the release in the environment of pollutants that have no regulatory status and which may have significant impact on the health of animals and humans. These pollutants also refer as “emerging pollutants” are mostly aromatic compounds which derive from excretion of pharmaceutical, industrial effluents and municipal discharge. Some form of pollutions have also evolved, including the proliferation of acid mine drainage from oxidation or weathering of obsolete and unmanaged excavations around the world; this results mostly in the dispersion of inorganic pollutants in the environment at level surpassing the treatment capacity of conventional techniques. It is recurrent these days to find water treatment plants which no longer produce water that fits the purpose of domestic consumption based on newly established guidelines.
This situation has prompted water authorities and researchers to develop tools for proper prediction and control of the dispersion of pollutants in the environment to ensure that appropriate measures are taken to prevent the occurrence of outbreaks due to sudden load of these pollutants in the water system.
The chapters in this book cover a wide range of nano and bio-based techniques that have been designed for the real time detection of emerging contaminants in environmental water sources, geochemical models that are continuously improved for the prediction of inorganic contaminants migration from the mine solid wastes into ground and surface waters. Remediation strategies are also discussed and include effective techniques based on nanotechnology, advanced membrane filtration, oxidative and bio- degradation processes using various types of nanocatalysts, biocatalysts or supporting polymer matrices which are under advanced investigations for their implementation at large scale for the removal of recalcitrant pollutants from polluted water.
This book is divided is two sections, the first section covers the occurrence of emerging pollutants in environmental water while the second section covers state of the art research on the removal of emerging pollutants from water using sustainable technologies. A total of 13 chapters addressing various topics related to the two sections are essentially based on recent development in the respective field which could have a significant impact on the enhancement of the performance of wastewater treatment plants around the world and especially in developing countries where access to clean and safe water remains a daily challeng
Response of Bacterial Biosorbents to Chemical Treatment as Influenced by Cell Membrane Structure and Impact on the Adsorption Behaviour of Dyes
No full textThe impact of cell membrane structure and adsorption
capacity of dyes due to chemical treatment on
Gram-positive and Gram-negative bacteria was studied.
The adsorption was found to occur through a
chemisorption mechanism. The adsorption capacity of
treated bacteria was higher (68.49–161.29 mg/g) than
untreated bacteria (9.37–29.11 mg/g) during the removal
of methylene blue. Furthermore, the treatment
allowed bacteria to adsorb methyl orange, which was
not removed by untreated bacteria. The applied
chemical treatment is therefore influenced by the cell
membrane structure and could be considered to improve
the adsorption capacity of bacteria for the removal
of dyes from polluted wate
Susceptibility of Saccharomyces cerevisiae to inhibitors and impact on bioethanol production yield
Get PDFThere have been increasing concerns in developing countries over the competition between food and energy resulting from the production of bioethanol from edible biomass. Second generation lignocellulose feedstock is an attractive alternative, as bioethanol can be produced from non-edible materials. However, the pretreatment required for hydrolysis of lignocellulose into pentose and hexose sugars often results in the production of inhibitors likely to impede the activity of Saccharomyces cerevisiae during bioethanol production. This study aims to investigate the comparative inhibitory effects of acetic acid and vanillin on the viability of S. cerevisiae and the production yield of bioethanol. The fermentation broth was spiked with different concentrations of vanillin or acetic acid were and the bioethanol concentration were monitored over time and correlated with cell viability. The results showed that although S. cerevisiae was mostly susceptible by vanillin compared to acetic acid, the inhibitory effect of acetic acid on S cerevisiae had a more severe influence on the final bioethanol yield after 12 h (42.8% reduction) than vanillin (33.3%). The latter was ascribed to the simultaneous production of weak acids during the fermentation process. The viability test has shown that S. cerevisiae can adapt to the presence of inhibitors over 12 h and at lower concentrations (2 g/l vanillin and 4 g/l acetic acid) the effect of inhibitors on S. cerevisiae and ethanol production yield can be overcome by the adaptation of the yeasthttp://psrcentre.org/proceeding.php?page=2&mode=detail&catid=176&type=
Efficient removal of Pb(II) and Cd(II) from industrial mine water by a hierarchical MoS2/SH-MWCNT nanocomposite
Get PDFIn this study, we investigate the adsorption capability of molybdenum sulfide (MoS2)/thiol-functionalized multiwalled carbon nanotube (SH-MWCNT) nanocomposite for rapid and efficient removal of heavy metals [Pb(II) and Cd(II)] from industrial mine water. The MoS2/SH-MWCNT nanocomposite was synthesized by acid treatment and sulfurization of MWCNTs followed by a facile hydrothermal reaction technique using sodium molybdate and diethyldithiocarbamate as MoS2 precursors. Morphological and chemical features of the nanocomposite material were studied using various characterization techniques. Furthermore, the effects of adsorbent (MoS2/SH-MWCNT nanocomposite) concentration, contact time, initial concentration of heavy-metal ions, and reaction temperature were examined to determine the efficiency of the adsorption process in batch adsorption experiments. Kinetics and isotherm studies showed that the adsorption process followed pseudo-second-order and Freundlich adsorption isotherm models, respectively. Thermodynamic parameters calculated using van’t Hoff plots show the spontaneity and endothermic nature of adsorption. MoS2/SH-MWCNT nanocomposite demonstrates a high adsorption capacity for Pb(II) (90.0 mg g–1) and Cd(II) (66.6 mg g–1) following ion-exchange and electrostatic interactions. Metal–sulfur complex formation was identified as the key contributor for adsorption of heavy-metal ions followed by electrostatic interactions for multilayer adsorption. Transformation of adsorbent into PbMoO4–xSx and CdMoO4–xSx complex because of the adsorption process was confirmed by X-ray diffraction and scanning electron microscopy-energy-dispersive spectrometry. The spent adsorbent can further be used for photocatalytic and electrochemical applications; therefore, the generated secondary byproducts can also be employed for other purpose
Sediment microbial fuel cell for wastewater treatment: a new approach
No full textAbstract:
This chapter contains sections titled:
Introduction --
Fundamentals of SMFC and CW‐MFC --
Factors Affecting the Performance of SMFC and CW‐MFC --
Electricity Generation as a Function of Substrate Degradation --
Applications of SMFC and CW‐MFC --
Scaling Up of SMFC and CW‐MFC --
Conclusio
Achieving controllable MoS2 nanostructures with increased interlayer spacing for efficient removal of Pb(II) from aquatic systems
No full textThe development of new synthesis approaches for MoS2 is necessary to achieve controlled morphologies and unique physicochemical properties that can improve its efficiency in particular applications. Herein, a facile one-step hydrothermal route is proposed to prepare controllable MoS2 micro/nanostructures with an increased interlayer using sodium diethyldithiocarbamate trihydrate as the new S source at different pH values. To investigate the morphology, chemical composition, and structure of the MoS2 micro/nanostructures, various characterization techniques were used. The obtained microrods, microspheres, and microrods with hairlike structures (denoted as MoS2-N-H) were composed of MoS2 nanosheets with increased interlayer spacing (∼1.0 nm) and utilized for the removal of Pb(II) from aquatic systems. Among the structures, MoS2-N-H demonstrated the highest adsorption capacity (303.04 mg/g) for Pb(II) due to the existence of −S/–C/–N/–O-comprised functional groups on its surface, which led to strong Pb–S complexation and electrostatic attractions. The uptake of Pb(II) onto MoS2-N-H followed pseudo-second-order kinetics and Freundlich isotherm. To evaluate its practical applicability, the adsorbent was employed in real mine water analysis; it was found that MoS2-N-H could adsorb almost 100% of the Pb(II) ions in the presence of various coexisting ions. Additionally, after Pb(II) adsorption, MoS2-N-H was transformed into PbMoO4-xSx spindlelike nanostructures, which were further used for photodegradation of an antibiotic, viz., ciprofloxacin (CIP), to avoid secondary environment waste. Thus, this investigation provides an effective one-pot approach to fabricate controllable MoS2 micro/nanostructures with increased interlayer spacing for water treatment. The utility of these nanostructures in related supercapacitor/battery applications may also be envisaged because of their unique structural propertie
Selective adsorption of heavy and light metals by natural zeolites
Get PDFRecent studies have shown that zeolite can be applied through an ion-exchange process to remove metals from solutions. In this paper the potential of two zeolites to perform as sorbents for treatment of multi-metal system is investigated. Parameters such as initial metal concentration, contact time, zeolite type and affinity for heavy versus light metals are taken into consideration. All the samples were prepared and characterized by XRD, XRF and FTIR.
Evaluating suitable model for the determination of binding affinity, the results showed that the pseudo second order kinetic model was adequate for such prediction. The binding affinity followed the order Co>Cu>Ca>Mg which was mainly correlated to the electronegativity of the metals. The FT-IR spectra revealed that the functional group –OH was mostly responsible for the binding of metals on the two zeolites.
The zeolites studied have shown preferential binding of heavy metals and can therefore be used to mitigate the level of such pollutant in multi-metal water syste
Comparative adaptation of B. subtilis and P. aeruginosa in diesel supplemented medium and impact on biodegradation potential
Get PDFThe degree of diesel blending is likely to influence its toxicity as well as the susceptibility and speed of biodegradation. It is therefore imperative to identify strains that can degrade diesel blend in record time, such as to minimize the impact on the environment. In this study the response of Bacillus subtilis and Pseudomonas aeruginosa to induced tolerance to diesel is comparatively analyzed and the implication on the biodegradation of blended diesel investigated using the gravimetric analysis method.
Results show that biodiesel promotes the degradation of diesel blend; however the induction of resistance affects differently the biodegradation potential of B. subtilis and P. aeruginosa. From two weeks to eight weeks induction time, there was increase of the biodegradation capabilities of B. subtilis, 213 % for B0, 24 % for B10 and 62 % for B50, while the biodegradation potential of P. aeruginosa decreased: 17% for B0, 60% for B10, 51% for B50.
The induction of tolerance to diesel could therefore be exploited to improve the biodegradation potential of B. subtilis, but further treatment will certainly be required for P. aeruginos
Bentonitc clay adsorption affinity for anionic and cationic dyes
No full textThe incidence of dye pollution in South Africa is quite alarming, requesting effective and affordable techniques to curb further degradation of the limited water resource. Adsorption is an attractive technique due to a better removal efficiency of contaminants. Bentonite also known as montmorillonite clay, has a very large surface area, suitable for adsorption; however the availability of binding sites on the clay is dependent on the geochemical transformation undergone during the genesis, making the geographical source of the clay an important parameter determining his adsorption potential. This consideration has motivated the need to test the adsorption potential of local bentonite clay for the removal of anionic and cationic dye from solution. The clay was characterized using XRD, XRF and FTIR. The adsorption affinity was tested using isotherm and kinetic models. According to the FTIR spectroscopy profile, dyes attached to the clay through interaction between the cetonyl group of the clay and the amines-primary and -secondary functional groups of methyl orange (MO) and methylene blue (MB) respectively. The adsorption capacity values obtained from the pseudo-second order kinetic model indicate that our bentonite clay has higher affinity for MB (qe = 147.06 mg/g) than MO (qe = 11.82 mg/g). It therefore ensues that our clay is suitable for the removal of MB from polluted water, but will require activation to improve the affinity for M
Mobility potential of metals in acid mine drainage occurring in the Highveld area of Mpumalanga Province in South Africa: implication of sediments and efflorescent crusts
No full textPrediction of the dispersion of pollutants from the acid mine drainage is an important step toward the development of remediation strategy and mitigation of environmental impact. Geochemical studies are often carried out to determine the speciation and mobility of metal pollutants in sediments and water. In the present study sequential leaching and humidity cell tests were carried out on the sediments from acid mine drainage (AMD) basin for the determination of the susceptibility of metal release. The X-ray diffraction (XRD) and Mössbauer analyses were carried on the efflorescent salts from the stream bank to determine the secondary minerals that could further contribute to AMD pollution impact; while speciation of metals in AMD solution was done using the geochemical model PHREEQC. The results show that metals such as Fe, Ni and U are bioavailable from the exchangeable fraction F1 of the sediments in the range of 1.1–81%; while secondary minerals contribute to higher release of Fe and SO42− in solution. The sediments studied were found to have a relatively higher acidity potential (36 and 73) versus a negligible neutralization potential. Species prediction of dissolved metals showed dominance of free metal ion species in water. Secondary minerals such as goethite and iron sulfate which have been reported to contribute to further acidification of water were found in the efflorescent crusts. The findings in this study therefore predict higher mobility and sustainable occurrence of metals in the effluent considered, prompting intervention for preservation of the environment and scarce water resource
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