Biosurfactant technology for remediation of cadmium and lead contaminated soils

This research focuses on column experiments conducted to evaluate the potential of environmentally compatible rhamnolipid biosurfactant produced by Pseudomonas aeruginosa strain BS2 to remove heavy metals (Cd and Pb) from artificially contaminated soil. Results have shown that di-rhamnolipid removes not only the leachable or available fraction of Cd and Pb but also the bound metals as compared to tap water which removed the mobile fraction only. Washing of contaminated soil with tap water revealed that approximately 2.7% of Cd and 9.8% of Pb in contaminated soil was in freely available or weakly bound forms whereas washing with rhamnolipid removed 92% of Cd and 88% of Pb after 36 h of leaching. This indicated that di-rhamnolipid selectively favours mobilization of metals in the order of Cd>Pb. Biosurfactant specificity observed towards specific metal will help in preferential elution of specific contaminant using di-rhamnolipid. It was further observed that pH of the leachates collected from heavy metal contaminated soil column treated with di-rhamnolipid solution was low (6.60-6.78) as compared to that of leachates from heavy metal contaminated soil column treated with tap water (pH 6.90-7.25), which showed high dissolution of metal species from the contaminated soil and effective leaching of metals with treatment with biosurfactant. The microbial population of the contaminated soil was increased after removal of metals by biosurfactant indicating the decrease of toxicity of metals to soil microflora. This study shows that biosurfactant technology can be an effective and nondestructive method for bioremediation of cadmium and lead contaminated soil.     

Environmental quality assessment studies of coal handling on peripheral land near Kanika siding, Basundhra-Garjanbahal area of MCL, Sundergarh, Orissa, India

Coal has been recognized as the most important source of energy generation in India. The present work was undertaken in order to assess the environmental impact of coal handling on peripheral land under near Kanika siding, Orissa, India. The data on suspended particulates in ambient air indicates an additional load of 50.5–108.7 μg/m³) to the ambient air due to coal loading which is equivalent to 50 × 365 to 108 × 365 kg/year. However, in the southern side (opposite to siding) covering the crop fields, the dust accumulation was maximum, i.e., 0.021 to 0.035 mg/cm² area in comparison to 0.001 to 0.021 in the eastern side and 0.001 to 0.029 in western side of the crop fields. The physical and chemical properties of soil was also assessed. The results reveal that the coal loading has definite negative impact on the peripheral land near the site.     

Two-layer channel flow involving a fluid with time-dependent viscosity

Environmental Fluid Mechanics - A pressure-driven two-layer channel flow of a Newtonian fluid with constant viscosity (top layer) and a fluid with a time-dependent viscosity (bottom layer) is...     

Water quality assessment of Majhiaon block of Garwa district in Jharkhand with special focus on fluoride analysis

Fluoride in groundwater is known to contaminate the water sources globally. Jharkhand, one of the states in the eastern part of India, is known to have excessive fluoride content in groundwater sources. The present work involves assessment of water quality with special reference to fluoride in Majhiaon block of Garwa district in Jharkhand. Iron, nitrate and arsenic were also tested for the water samples collected from site. Eight hundred forty samples were tested for fluoride on site using colourimetry method, and one tenth of the samples were brought to laboratory for iron, nitrate, arsenic and fluoride analysis. Results show that 402 samples were having fluoride above permissible limit. Iron and nitrate were found to be beyond permissible limits in 302 and 286 water samples, respectively. More than 50% of samples collected from school had fluoride levels above permissible limits. Arsenic was well within the limits. However, few samples shown were excessive of iron and nitrate.     

Assessing the potentials of Lemna minor in the treatment of domestic wastewater at pilot scale

Water crisis is one of the most serious problems faced by the world today. Phytoremediation is one of the serious efforts towards sustainability. Macrophyte-based wastewater treatment systems have several potential advantages compared with conventional treatment systems. Duckweeds (Lemna spp., Spirodela spp., Wolffia spp.) are small, green freshwater, free-floating aquatic plants. The primary objective of this work was to analyze the role of duckweeds in organic waste and nutrient removal from domestic wastewater being generated from hostels of Birla Institute of Technology, Mesra, Ranchi (India). Interesting results were obtained in which the BOD value reduced by 94.45% and the level of orthophosphate at the end of the work was found to be reduced by 79.39%. The duckweeds flourished well during the experimental period in the pH range of 7 to 8; it can be said that, other factors remaining favorable, the optimum pH for duckweed growth ranges from 7 to 8. Therefore, it can be concluded that this treatment can be successfully carried out on a large scale. Also, it is a low-cost solution to wastewater treatment problems and could satisfy the discharge standards.     

Variations in single scattering albedo and Angstrom absorption exponent during different seasons at Delhi,India

Simultaneous measurements of aerosol absorption and scattering coefficients for the PM_2.5 aerosols particles were done at Delhi during April 2008–March 2009 to estimate the aerosol single scattering albedo (SSA) and the Angstrom absorption exponents at the surface. The annual average SSA at 0.55 μm was found to be 0.70 ± 0.07 with only slight variations during the four seasons, summer (0.63 ± 0.06), monsoon (0.69 ± 0.07), winter (0.74 ± 0.03) and spring (0.72 ± 0.04). However, large variations in average absorption and scattering coefficients were seen during these four seasons. The average absorption coefficients during summer, monsoon, winter and spring were found to be 62.47 ± 21.27, 50.95 ± 43.61, 189.65 ± 85.94 and 90.65 ± 33.06 Mm^?1 respectively. The corresponding scattering coefficients were 110.46 ± 36.15, 95.34 ± 49.46, 565.59 ± 274.59 and 236.56 ± 96.25 Mm^?1. The Angstrom absorption exponent (α_σ(abs)) remained close to unity throughout the year averaging at 1.02 ± 0.08, 1.02 ± 0.10, 1.04 ± 0.11, and 1.03 ± 0.05 during summer, monsoon, winter and spring seasons respectively, strongly indicating that the absorption at Delhi aerosol is mainly due to the abundance of black carbon of fossil fuel origin.     

Studies on process optimization of biodiesel production from waste cooking and palm oil

This work investigated the optimisation of biodiesel production from waste cooking oil (WCO) and palm oil using a two-step transesterification process for WCO and base catalysed transesterification for palm oil. Transesterification reactions were carried out to investigate the effects of prepared catalyst CaO, methanol/WCO and methanol/palm oil ratio and temperature on the yield of biodiesel. A series of experiments were conducted to determine the best conditions for biodiesel production, using methanol/oil ratio between 4:1 and 11:1 and contact time varying between 2 and 4 h. Biodiesel yield of around 90 and 70% was obtained for palm and waste cooking oil at the methanol/oil ratios of 6:1 and 8:1 at temperature of 60 °C for reaction time of 4 h using prepared CaO as catalyst. The physicochemical properties of palm and WCO biodiesel were carried out using standard methods, while the fatty acid profile was determined using gas chromatography. The investigation concludes that biodiesel obtained from palm and waste cooking oil was within the specified limit.     

Quantitative determination of gibberellins by high performance liquid chromatography from various gibberellins producing Fusarium strains

High performance liquid chromatographic (HPLC) method was developed for analysis of seven gibberellins, i.e., GA₃, GA₄, GA₇, GA₃ methyl ester, GA₇ methyl ester 3,13 diacetate, GA₇ methyl ester, and fusaric acid, using an isocratic system. Method was used for estimation of gibberellins from different Fusarium strains. Gibberellins were extracted from 28 strains of Fusarium, out of which six strains of Fusarium were isolated from soil of different parts of India and 22 strains were procured from the Indian Type Culture Collection, Indian Agricultural Research Institute, New Delhi. Extracts were analyzed for qualitative and quantitative estimation of gibberellins by thin layer chromatography and HPLC, respectively. On the basis of quantitative analysis of produced gibberellins by HPLC, they were categorized as low, moderate, and high gibberellin producing strain. For the first time, Fusarium solani was also reported as high GA₃ producing strain.     

Decomposition effects on the mass burning rate of organic peroxide pool fires

The mass burning rate of pool fires of organic peroxides do not vary appreciably with the pool size as have been observed for the hydrocarbons. Instead the decomposition temperature largely controls the same. The dependence of mass burning rate on the decomposition temperatures namely self-accelerating decomposition temperature (SADT) and extrapolated onset temperature measured by differential scanning calorimetry (DSC) for organic peroxide pool fires are identified and correlations are developed.