The flow of homogeneous fluids through porous media: analogies with other physical problems

Fluoride removal from water by adsorption—A review

Antibiotics, disinfectants and bacteria resistant to them have been detected in environmental compartments such as waste water, surface water, ground water, sediments and soils. Antibiotics are released into the environment after their use in medicine, veterinary medicine and their employment as growth promoters in animal husbandry, fish farming and other fields. There is increasing concern about the growing resistance of pathogenic bacteria in the environment, and their ecotoxic effects. Increasingly, antibiotic resistance is seen as an ecological problem. This includes both the ecology of resistance genes and that of the resistant bacteria themselves. Little is known about the effects of subinhibitory concentrations of antibiotics and disinfectants on environmental bacteria, especially with respect to resistance. According to the present state of our knowledge, the impact on the frequency of resistance transfer by antibacterials present in the environment is questionable. The input of resistant bacteria into the environment seems to be an important source of resistance in the environment. The possible impact of resistant bacteria on the environment is not yet known. Further research into these issues is warranted.

Resistance in the Environment

http://edge.rit.edu/content/P13418/public/Reference%20Documents/Fluoride%20Removal/Review%20of%20fluoride%20removal%20from%20drinking%20water.pdf

Review of fluoride removal from drinking water.

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Wastewater Engineering Treatment Disposal And Reuse

Soil organic carbon enrichment by addition of organic amendments (OAs) is a common agricultural and gardening practice. Such amendments can cause ambiguous environmental effects; it could enhance the sorption of pesticides by increasing soil organic carbon content, and on the contrary, dissolved organic matter (DOM) from OAs could facilitate their leaching. This study evaluated the influence of OAs, mixed waste compost, and dried goat organic manure on the sorption of organophosphates, dichlorvos, and chlorpyrifos. Soil (15 cm depth) was collected from an agricultural field and stored. Dissolved organic matter (DOM) extracted from the amendments and the amended soils was characterized by fluorescence spectroscopy and Fourier transform infrared spectroscopy (FT-IR). Initially, studies were carried out to evaluate the effect of DOM from organic amendments (OA-DOM) and dissolved humic acids (HAs) as model DOM on the sorption of selected pesticides. In the later part, OAs (2.5 and 5% w/w) were added to the soil, and sorption experiments were carried out using amended soil to understand the combined effects of insoluble and soluble organic carbon fraction. As dichlorvos sorption was found to be very low, desorption experiments were conducted only for chlorpyrifos using 0.01 M CaCl2 and DOM solutions. The spectroscopic characterization of OA-DOM revealed that it mainly contained large amounts of highly humified and aromatic material. OA-DOM and HAs had a similar effect on pesticide sorption leading to a slight but not significant increase in dichlorvos sorption while a substantial reduction in chlorpyrifos sorption was observed. Surface tension analysis highlighted that OA-DOM and HAs might have caused greater solubilization of chlorpyrifos, thus reducing sorption. Further, it also promoted greater desorption of adsorbed chlorpyrifos. These results seem to be related to the humified and aromatic nature of OA-DOM and HAs, determining the interactions between hydrophobic chlorpyrifos and DOM. On the contrary, the addition of OAs to soil promoted greater chlorpyrifos and dichlorvos sorption, but a clear correlation between increase in soil organic carbon and pesticide sorption could not be established. The study highlighted that the net effect of OA application was an increase in pesticide sorption that depended on the nature of DOM and pesticide properties. The interactions of hydrophobic chlorpyrifos with DOM can lead to a significant reduction in sorption to such an extent that the sorption in the presence of substantial DOM concentration can be less than the sorption without it.

Soil organic amendments: impacts on sorption of organophosphate pesticides on an alluvial soil

In-situ applications such as Microbial Enhanced Oil Recovery (MEOR) and remediation of contaminated sites demand production of biosurfactants in large quantities under oxygen limiting conditions. Few microorganisms have been isolated so far which can cater such need. In this paper, the characteristics of a biosurfactant produced under complete anaerobic conditions are presented. A novel biosurfactant producing microorganism, Pseudomonas sp ANBIOSURF-1 was isolated in our laboratory, from a microbial consortium enriched from municipal sewage sludge. The microorganism utilized vegetable oils and produced biosurfactant under complete anaerobic conditions. TLC tests revealed the presence of sugar and lipid as hydrophilic and hydrophobic moieties respectively. The biosurfactant synthesized under anaerobic condition thus belonged to class of glycolipids similar to that of rhamnolipids. The biosurfactant had a very low CMC value of 52 mg/l. The biosurfactant displayed good emulsifying activity over chlorinated solvents than the petroleum derivatives. The results suggest that Pseudomonas sp ANBIOSURF-1 could potentially be used for remediation of sites contaminated with chlorinated solvents through in-situ biosurfactant production.

Partial Characterization of Biosurfactant Produced under Anaerobic Conditions by Pseudomonas sp ANBIOSURF-1

This study demonstrates the use of disposed liquid crystal display (LCD) glass as a supporting matrix for the fabrication of a binder/linker free thin film graphene electrode. Graphene oxide (GO) was drop casted onto the LCD matrix and electrochemically reduced to form an ErGO–LCD electrode which was subsequently employed for the electro-Fenton oxidation of ciprofloxacin. Fourier transform infrared spectroscopy confirms the presence of (i) functional groups such as C═O, N–H, C≡N, and C–N on the LCD matrix, (ii) attachment of GO onto the LCD, and (iii) reduction of oxygen functionalities at the surface of the ErGO–LCD electrode. Raman and X-ray photoelectron spectroscopy were performed to examine the nature and chemical composition of the GO–LCD and ErGO–LCD electrodes. Cyclic voltammetry and electrochemical impedance spectroscopic studies revealed the enhancement of the oxidation–reduction properties and reduction of charge transfer resistance (Rct 17 Ω) in the presence of [Fe(CN)6]3–/4– redox species. El...

Green Approach To Produce a Graphene Thin Film on a Conductive LCD Matrix for the Oxidative Transformation of Ciprofloxacin

Process optimization for the recovery of oil from tank bottom sludge using microwave pyrolysis

Nitrate pollution in groundwater arising from wastewater and fertiliser application through vadose zone is a major problem and it causes a prime risk to groundwater-based drinking water supplies. In this study, a one-dimensional numerical model is developed to investigate the nitrogen species transport in unsaturated porous media along with mass transfer of oxygen from gaseous phase to aqueous phase. Further, the temperature-dependent nitrogen transformation rates, oxygen solubility in an aqueous phase from gaseous phase, and oxygen diffusion coefficient have been successfully incorporated. Results suggest that the temperature-dependent oxygen diffusion coefficient is significant in case of temperature variation between 30 and 45 °C, whereas the temperature-dependent oxygen solubility and transformation rate are found to be the critical parameters influencing the nitrogen species transport when the temperature variation is between 10 and 30 °C. In the temperature range between 30 and 45 °C, the model perf...

Indumathi M. Nambi

Papers

Soil organic amendments: impacts on sorption of organophosphate pesticides on an alluvial soil

Partial Characterization of Biosurfactant Produced under Anaerobic Conditions by Pseudomonas sp ANBIOSURF-1

Green Approach To Produce a Graphene Thin Film on a Conductive LCD Matrix for the Oxidative Transformation of Ciprofloxacin

Process optimization for the recovery of oil from tank bottom sludge using microwave pyrolysis

Numerical modelling on fate and transport of nitrate in an unsaturated system under non-isothermal condition