Ligy Philip

This paper describes the fluoride removal potential of a novel sorbent, magnesia-amended activated alumina (MAAA) from drinking water. MAAA, prepared by calcining magnesium hydroxide impregnated alumina at 450 °C has shown high fluoride sorption potential than activated alumina from drinking water. Batch sorption studies were performed as a function of contact time, pH, initial fluoride concentration, and adsorbent dose. Studies were also performed to understand the effect of various other co-existing ions present in real ground water samples. X-ray powder diffraction (XRD), scanning electron microscope (SEM), energy dispersive X-ray (EDAX) and a gas adsorption porosimetry analyses were used to characterize the physicochemical properties of MAAA. More than 95% removal of fluoride (10 mg l-1) was achieved within 3 h of contact time at neutral pH. Sorption of fluoride onto MAAA was found to be pH dependant and a decrease in sorption was observed at higher pHs. Among the kinetic models tested, pseudo-second-order model fitted the kinetic data well, suggesting the chemisorption mechanism. Among the various isotherm model tested, Sips model predicted the data well. The maximum sorption capacity of fluoride deduced from Sips equation was 10.12 mg g-1. Most of the co-existing ions studied have negligible effect on fluoride sorption by MAAA. However, higher concentrations of bicarbonate and sulfate have reduced the fluoride sorption capacity. © 2007 Elsevier B.V. All rights reserved.

A novel mixed bacterial culture was enriched from an endosulfan (6, 7, 8, 9, 10, 10 - hexachloro-1, 5, 5a, 6, 9, 9a-hexahydro-6, 9-methano-2, 3, 4-benzo (e) dioxathiepin-3-oxide) processing industrial surface soil. The cultures were successful in the degradation of aqueous phase endosulfan in both aerobic and anaerobic conditions. Using the cultures, endosulfan degradation in silty gravel with sand (GM) was examined via pilot scale reactor at an endosulfan concentration of 0.78 ± 0.01 mg g- 1 of soil, and optimized moisture content of 40 ± 1%. During operation, vertical spatial variability in endosulfan degradation was observed within the reactor. At the end of 56 days, maximum endosulfan degradation efficiency of 78 ± 0.2% and 86.91 ± 0.2% was observed in the top and bottom portion of the reactor, respectively. Both aerobic and anaerobic conditions were observed within the reactor. However, endosulfan degradation was predominant in anaerobic condition and the total protein concentration in the reactor was declined progressively down the soil depth. Throughout the study, no known intermediate metabolites of endosulfan reported by previous researchers were observed. Copyright © Taylor & Francis Group, LLC.

The high carcinogenic risk associated with chloroform (CF) consumption makes the development of on-site detection and removal technologies an important task. The role of nanomaterials (NMs)-based sensors and treatment methods is a promising option owing to their diverse structural and functional merits. In this line, the present review article is designed to highlight the recent development in the applications of NMs for sensing and eliminating aqueous CF. Numerous NMs, including metal oxides, carbon nanotubes, metal-organic frameworks, and graphitic structures, have been investigated as selective and sensitive (0.003–15.5 mg/L) sensors for CF. Likewise, to remove aqueous CF biochar, zerovalent iron, and silver nanoparticles have been explored as effective adsorbents (4.73−4.69х104mg/g) or reducing agents. Accordingly, selection criteria and performance evaluation of NMs with respect to structural advances (functional groups and polarity) and physiochemical property (hydrophobicity and volatility) of CF is provided. The limitations of the available methods, hindrances in upscaling, recommendations related to the use of non-toxic precursors, simple fabrication techniques, and regeneration possibilities are also discussed. Overall, the review summarizes the available sensing and treatment methods for the effective abatement of aqueous chloroform.

Sorption of three surfactants and personal care products in four types of commonly occurring Indian soils was extensively studied. The soils used in the study were red soil, clay soil, compost soil and sandy soil as classified by American Society for Testing and Materials (ASTM). The three surfactants used in the study were representative of cationic, non-ionic and anionic surfactant groups. The sorption of surfactants followed the descending order: sodium dodecyl sulphate (SDS) > trimethyl amine (TMA) > propylene glycol (PG). The maximum adsorption capacity (Qmax) was obtained in compost soil (28.6 mg/g for SDS; 9.4 mg/g for TMA and 4 mg/g for PG). The rate of adsorption was the maximum in compost soil followed by clay and red soils, and minimum for sandy soils. It is found that the Freundlich model fits the isotherm data better than the Langmuir model. Freundlich coefficient (Kf) increased as the organic content of soils increased. Desorption of target pollutants in tap water was 20–50% whereas acid desorbs 40–90% of target pollutants from soil matrix. It was also found that the adsorption and desorption were significantly affected by the presence of clay and organic matter. The results also indicate that surfactants and personal care products, especially TMA and PG, are highly mobile in sandy soil followed by red soil. Therefore, immobilization of target pollutants is most economical and effective in compost and clayey soils whereas for other type of soils the combination of physiochemical and biological process will be effective option for remediation.

Macrofungi have long been investigated for various scientific purposes including their food and medicinal characteristics. Their role in aerobiology as a fraction of the primary biological aerosol particles (PBAPs), however, has been poorly studied. In this study, we present a source of macrofungi with two different but interdependent objectives: (i) to characterize the macrofungi from a tropical dry evergreen biome in southern India using advanced molecular techniques to enrich the database from this region, and (ii) to assess whether identified species of macrofungi are a potential source of atmospheric PBAPs. From the DNA analysis, we report the diversity of the terrestrial macrofungi from a tropical dry evergreen biome robustly supported by the statistical analyses for diversity conclusions. A total of 113 macrofungal species belonging to 54 genera and 23 families were recorded, with Basidiomycota and Ascomycota constituting 96% and 4% of the species, respectively. The highest species richness was found in the family Agaricaceae (25.3%) followed by Polyporaceae (15.3%) and Marasmiaceae (10.8%). The difference in the distribution of commonly observed macrofungal families over this location was compared with other locations in India (Karnataka, Kerala, Maharashtra, and West Bengal) using two statistical tests. The distributions of the terrestrial macrofungi were distinctly different in each ecosystem. We further attempted to demonstrate the potential role of terrestrial macrofungi as a source of PBAPs in ambient air. In our opinion, the findings from this ecosystem of India will enhance our understanding of the distribution, diversity, ecology, and biological prospects of terrestrial macrofungi as well as their potential to contribute to airborne fungal aerosols.

Well-known purification technologies built for arsenic (As) removal from drinking water are not sustainable, either being unaffordable or inefficient in the elimination of traces of As. In our experiments, we observed that carbonate ion can counteract the effects of As exposure as it efficiently prevented As-induced cytotoxicity on epithelial cell lines of the small intestine (IEC-6). The cotreatment of IEC-6 cells with 40 ppm of carbonates and As (≥3 ppm) showed substantial remissions in the As-induced cytotoxicity and increased the viability from 50% to 75%. The production of intracellular reactive oxygen species (ROS) and cellular acidification were also reduced in this process (pH increase from 5 to 6.5). Thus, the present study suggests that the cytoprotective effect of carbonate can involve multiple pathways, such as reduction of extracellular/intracellular acidosis, H2O2 decomposition, balancing mitochondrial potential, and immobilization of As. We show that As-contaminated drinking water enriched with carbonates up to 40 ppm has a reduced toxic effect on cells in comparison to that of an As-alone sample. Therefore, carbonates can act as an adjunct in addition to the prevailing approaches to tackle mass poisoning by As. We believe that this study is initial evidence for developing an alternative method to tackle the prevailing mass environmental poisoning by As, using locally available, affordable, safe, and sustainable solutions.

In the present study, fate of carbofuran in anaerobic environments and the adverse effects of carbofuran on conventional anaerobic systems were evaluated. Carbofuran degradation studies were carried out in batch reactors with varying carbofuran concentrations of 0 to 270.73 mg/L corresponding to a sludge-loading rate (SLR) of 2.12 × 10-6 to 3.83 × 10-3 g of carbofuran/g of volatile suspended solids (VSS)/d. Carbofuran concentration was reduced to undetectable levels at the end of 8 and 13 days in the batch reactors operated with a SLR of 2.12 × 10-6 and 3.33 × 10-5 g of carbofuran/g of VSS/d, respectively. Performances of two anaerobic reactors i.e. upflow anaerobic sludge blanket (UASB) and modified UASB (with tube settlers) were evaluated in the presence and absence of carbofuran using synthetic wastewater. In the absence of carbofuran, the soluble chemical oxygen demand (COD) removal efficiency in the conventional UASB reactor at 8 h and 6 h hydraulic retention time (HRT) was nearly 88% and 76%, respectively, whereas in modified UASB reactor it was increased to 90% at 8 h HRT and 78% at 6 h HRT. When 28 mg/L (SLR of 1.19 × 10-2 g of carbofuran/g of VSS/d) of carbofuran was introduced in the reactors, the COD removal efficiency was reduced to 41% and 44% in conventional and modified UASB reactors respectively. However, the reactor could maintain around 80% COD removal efficiency at a carbofuran concentration of 7.84 mg/L (SLR of 3.64 × 10-3 g of carbofuran/g of VSS/d). The reactor efficiency was also measured in terms of specific acetoclastic methanogenic activity (SMA). The toxic effect of carbofuran was reversible to a certain extent. Carbofuran removal efficiency in the conventional UASB reactor at carbofuran concentrations of 7, 13 and 28 mg/L were 40 ± 3%, 27 ± 3%, and 11 ± 3%, respectively. In modified UASB reactor, carbofuran removal efficiency was almost uniform at 7 and 13 mg/L but it was reduced nearly by 56% at 28 mg/L. The major metabolite of carbofuran i.e. 3-keto carbofuran was found in all the reactors. © Taylor & Francis Group, LLC.

There is an urgent need for the development of inexpensive, but reliable and efficient photocatalyst which can work under solar radiation for drinking water application. Hence the treatment options to be tried out for drinking water contaminated with pesticides and their formulation products should be cost effective and affordable. In this study, we developed a cheap and efficient photocatalyst and continuous photoreactor for the removal of pesticides from drinking water under solar radiation. Continuous photodegradation experiments were carried out with synthetically prepared commercial grade methyl parathion (Folidon 50% E.C.), dichlorvos (DDVP 70% E.C.), and analytical grade lindane. Photodegradation of mixed pesticide was carried out using both Degussa P-25 TiO 2 and N-doped TiO 2 with identical mass concentrations (50μg/L) of all the three pesticides under UV, visible and solar radiation. Continuous reactor was operated for more than 24h (6h each on 4days) for mixed pesticide degradation. N-doped TiO 2 showed 100% degradation for all the three pesticide under solar radiation. Photodegradation of mixed pesticide showed methyl parathion, dichlorvos and lindane were degrading simultaneously. However, the rate of reaction was completely different from single pesticide degradation. N-doped TiO 2 showed higher photocatalytic activity under solar radiation compared to UV and visible light. GC-MS analysis of mixed pesticide degradation showed more than 16 peaks in the middle of the reaction. Among these peaks, three intermediates such as hexachloro-benzene and para-nitrophenol and dichlorovinyl-O-methyl phosphate were identified in the middle of the reaction. However, at the end of the reaction (reactor outlet) none of the intermediates were observed. © 2012 Elsevier Ltd.

Studies were conducted on a mixture of pollutants commonly found in coke oven wastewater (CWW) to evaluate the biodegradation of various pollutants under anaerobic, aerobic, and anoxic conditions. The removal of the pollutants was monitored during individual bioreactor operation and using a combination of bioreactors operating in anaerobic–aerobic–anoxic sequence. While studying the performance of individual reactors, it was observed that cyanide removal (83.3 %) was predominant in the aerobic bioreactor, while much of the chemical oxygen demand (COD) (69 %) was consumed in the anoxic bioreactor. With the addition of cyanide, the COD removal efficiency was affected in all the bioreactors, and several intermediates were detected. While treating synthetic CWW using the combined bioreactor system, the overall COD removal efficiency was 86.79 % at an OLR of 2.4 g COD/L/day and an HRT of 96 h. The removal efficiency of 3,5-xylenol and cyanide, with inlet concentration of 150 and 10 mg/L, was found to be 91.8 and 93.6 % respectively. It was found that the impact of xylenol on the performance of the bioreactors was less than cyanide toxicity. Molecular analysis using T-RFLP revealed the dominance of strictly aerobic, mesophilic proteobacterium, Bosea minatitlanensis, in the aerobic bioreactor. The anoxic bioreactor was dominant with Rhodococcus pyridinivorans, known for its remarkable aromatic decomposing activity, while an unclassified Myxococcales bacterium was identified as the predominant bacterial species in the anaerobic bioreactor.

A widespread occurrence of pharmaceuticals and personal care products (PPCPs) is reported in all the environmental matrices. Thus, the present study investigated the prevalence of these emerging contaminants in the wastewater from Vichoor village, Tamil Nadu, India. Among the 14 investigated PPCPs, caffeine (CAF), triclosan (TCS), bisphenol A (BPA), and diethyl phthalate (DEP) were the most frequently detected compounds in the concentration range of 5 ng/L to 250.14 µg/L. A seasonal variation (p < 0.05) in the concentration of selected PPCPs was observed, except for BPA, DEP, and carbamazepine (CBZ), due to the difference in the consumption pattern among the households of the community. The fate of selected pollutants was investigated in each component of vertical flow constructed wetland (VFCW). The overall removal efficiencies of COD, ammonia, phosphate, and pathogens were more than 93.34 ± 1.94%, 85.25 ± 1.51, 79.81 ± 1.15%, and 99.9 ± 0.81%, respectively. Also, VFCW exhibited substantial removal of the selected pollutants in the range of 81–97.7%. Microbial degradation (74.9–93.8%) followed by sorption over the substrate materials (0.54–12.56%) seem to be the predominant mechanism for the removal of target PPCPs. The environmental risk assessment witnessed that PPCPs concentration in the treated effluent contributed lower risk to human and aquatic organisms.