Treatment of electronic waste to recover metal values using thermal plasma coupled with acid leaching--a response surface modeling approach

The global crisis of the hazardous electronic waste (E-waste) is on the rise due to increasing usage and disposal of electronic devices. A process was developed to treat E-waste in an environmentally benign process. The process consisted of thermal plasma treatment followed by recovery of metal values through mineral acid leaching. In the thermal process, the E-waste was melted to recover the metal values as a metallic mixture. The metallic mixture was subjected to acid leaching in presence of depolarizer. The leached liquor mainly contained copper as the other elements like Al and Fe were mostly in alloy form as per the XRD and phase diagram studies. Response surface model was used to optimize the conditions for leaching. More than 90% leaching efficiency at room temperature was observed for Cu, Ni and Co with HCl as the solvent, whereas Fe and Al showed less than 40% efficiency.     

Effect of safe concentrations of some pesticides on thyroid in the freshwater murrel, Channa punctatus: a histopathological study

The effect of 'safe application rate (SAR)' concentrations of the insecticides fenitrothion 50% EC (an organophosphate) and carbofuran 3% G (a carbamate) on histopathological changes in the thyroid gland have been studied during chronic exposure for 120 days (mid-April to mid-August). The studies reveal significant declines in the diameters of the follicle and the colloid of the thyroid, but a significant increase in the height of the epithelium, following exposure to both fenitrothion or carbofuran. In the fenitrothion treatment, invasion by blood corpuscles into the follicular lumen, following breakdown of the epithelium, was also observed. The degeneration of the epithelium and the loss of colloid in the follicles suggest that the fenitrothion treatment is more severe than the carbofuran treatment.     

Impact of different doses of lead on internal organs of quails

Lead (Pb) is the most ancient poison known to man. In the present study, amount of accumulation of Pb in liver, kidney, ovary and testes of rain quail was studied using different doses of lead. Spectrophotometric analysis of heavy metal treated organs was carried out to determine the amount of metal accumulation in these organs. LD50 value was 4 ppm. Dose of lead was given in three ranges of low, medium and high. It was observed that testes (< or =6.8 x 10(-6)) mgkg(-1)day(-1) and ovary (< or =7.5 x 10(-6)) mgkg(-1)day(-1), accumulated low amount from different doses when given continuously for 21 days. In contrast to this, liver (< or =9.2 x 10(-6)) mgkg(-1)day(-1) and kidney (< or =9.3 x 10(-6)) mgkg(-1)day(-1) accumulated the maximum amount of metal when treated for the same number of days. This study is quite unique and astonishing as the period for intoxication is short (21 days) as compared to the long ones (91 days and above). Our results show that generally metal accumulation is highest in liver, while it is low in gonad.     

Heavy metal accumulation in lichens growing in north side of Lucknow city, India

Accumulation of Pb, Fe, Cr, Zn, Cd, Ni, Cu and Hg metals in six common lichen species growing on Mangifera indica trees in mango orchard surrounding the north side of the Lucknow city, were analyzed. The study revealed the higher concentration of Pb (3.3 - 15.6 microgg(-1)), Cr (25.6 - 137.5 microgg(-1)), Zn (49.4 - 219.7 microgg(-1)), Cu (10.2 - 66.6 microgg(-1)) and Fe (1748 - 19374 microgg(-1)).     

Occurrence of phthalic acid esters in Gomti River Sediment, India

Cadmium and lead are important environmental pollutants with high toxicity to animals and human. Soils, though have considerable metal immobilizing capability, can contaminate food chain via plants grown upon them when their built-up occurs to a large extent. Present experiment was carried out with the objective of quantifying the limits of Pb and Cd loading in soil for the purpose of preventing food chain contamination beyond background concentration levels. Two separate sets of pot experiment were carried out for these two heavy metals with graded levels of application doses of Pb at 0.4–150 mg/kg and Cd at 0.02–20 mg/kg to an acidic light textured alluvial soil. Spinach crop was grown for 50 days on these treated soils after a stabilization period of 2 months. Upper limit of background concentration levels (C _ul) of these metals were calculated through statistical approach from the heavy metals concentration values in leaves of spinach crop grown in farmers’ fields. Lead and Cd concentration limits in soil were calculated by dividing C _ul with uptake response slope obtained from the pot experiment. Cumulative loading limits (concentration limits in soil minus contents in uncontaminated soil) for the experimental soil were estimated to be 170 kg Pb/ha and 0.8 kg Cd/ha. Based on certain assumptions on application rate and computed cumulative loading limit values, maximum permissible Pb and Cd concentration values in municipal solid waste (MSW) compost were proposed as 170 mg Pb/kg and 0.8 mg Cd/kg, respectively. In view of these limiting values, about 56% and 47% of the MSW compost samples from different cities are found to contain Pb and Cd in the safe range.     

Identification and analysis of polyaromatic hydrocarbons (PAHs)—biodegrading bacterial strains from refinery soil of India

Polyaromatic hydrocarbons (PAHs) utilizing bacteria were isolated from soils of seven sites of Mathura refinery, India. Twenty-six bacterial strains with different morphotypes were isolated. These strains were acclimatized to utilize a mixture of four polycyclic aromatic hydrocarbons, i.e., anthracene, fluorene, phenanthrene, and pyrene, each at 50 mg/L concentration as sole carbon source. Out of total isolates, 15 potent isolates were subjected to 16S rDNA sequencing and identified as a member of diverse genera, i.e., Bacillus, Acinetobacter, Stenotrophomonas, Alcaligenes, Lysinibacillus, Brevibacterium, Serratia, and Streptomyces. Consortium of four promising isolates (Acinetobacter, Brevibacterium, Serratia, and Streptomyces) were also investigated for bioremediation of PAH mixture. This consortium was proved to be efficient PAH degrader resulting in 40–70 % degradation of PAH within 7 days. Results of this study indicated that these genera may play an active role in bioremediation of PAHs.     

Influence of burning of fireworks on particle size distribution of PM<Subscript>10</Subscript> and associated Barium at Nagpur

Influence of burning of fireworks on particle size distribution of PM₁₀ and associated barium (Ba) were studied at a congested residential cum commercial area of Nagpur city, India. Sampling was carried out by cascade impactor having 50% cut-off aerodynamic diameters of <10, 9, 5.8, 4.7, 3.3, 2.1, 1.1, 0.7, and <0.4 μm, 2 days before diwali, during diwali, celebrations of marriage functions, and New Year’s Eve. Noticeably, increased levels of PM₁₀ and Ba were observed during diwali as compared to days before diwali and other activities. PM₁₀ levels were increased by four to nine times whereas Ba levels were increased by eight to 20 times higher in alveolar region, when compared with the levels observed before diwali. Probability of deposition of Ba mass in alveolar region varied between 14 and 27 ng/h with higher deposition when the burning of fireworks activity was lower near the site. Trimodal distribution of Ba was observed on the first 2 days of diwali at 0.4–2.1, 2.1–4.7, and 4.7 to less than PM₁₀ micrometer range. While on the third day, it appeared bimodal with 70% contribution in coarse fraction whereas on the fourth day, distribution appeared unimodal with 66% contribution in alveolar region (<0.4–1.1 μm). Distribution of Ba varied with respect to particle size, in accordance with the intensity of the fireworks used on different days and distance between the burning of firecrackers from the monitoring site.     

Association between environmental exposure to p,p′-DDE and lindane and semen quality

Scientific concern exists about the toxic effect of dichlorodiphenyldichloroethylene (p, p′-DDE) and lindane on male infertility, and the mechanism underlying male reproductive toxicity of this pesticide remains unanswered. We investigated not only the possible association between the chlorinated pesticide levels and semen quality in nonoccupationally exposed men, but also the probable mode of action using mitochondrial membrane potential (MMP), reactive oxygen species (ROS), lipid peroxidation (LPO), and sperm chromatin structure assay (SCSA). A study in 278 men (21–40 years old) who visited Obstetrics and Gynecology Department, KGMU, Lucknow, for semen analysis was conducted. We performed semen analysis according to the WHO guidelines, while p, p′-DDE and lindane analysis was done by the GLC and LPO by the spectrophotometer, and the sperm mitochondrial status, ROS, and SCSA with the flow cytometer. The questionnaire data showed no significant difference in the demographic characteristics between the two groups, i.e., trying to conceive >1 year and proven fertility. However, a significant difference in the concentration of p, p′-DDE and lindane was observed between the groups. When the subjects were divided among four categories by quartile of exposure, the subjects in the highest quartile showed low sperm motility as compared to the subjects in the lowest quartile. Pearson’s correlation showed a significant negative correlation between semen p, p′-DDE, lindane level, and sperm quality and positive association with the number of cells with depolarized mitochondria, elevation in ROS production and LPO, and DNA fragmentation index (DFI). The findings are suggestive that these toxicants might cause a decline in semen quality, and these effects might be ROS, LPO, and mitochondrial dysfunction mediated.     

Assessing Spatial Occurrence of Ground Level Ozone around Coal Mining Areas of Chandrapur District, Maharashtra, India

Stratospheric input and photochemical ozone formation in the troposphere are the two main sources determining the ozone levels in the surface layer of the atmosphere. Because of the importance of ozone in controlling the atmospheric chemistry and its decisive role in the heat balance of atmosphere, leading to climate change, the examination of its formation and destruction are of great interest. This study characterized the distribution of Ground level Ozone (GLO) in Chandrapur district is lying between 19°25′N to 20°45′N and 78°50′E to 80°10′E. Continuous ozone analyzer was used to quantify GLO at thirteen locations fixed by Global Positioning System (GPS) during the winter of 2005–2006. The daily GLO at all the locations ranged between 6.4 and 24.8 ppbv with an average and standard deviation of 14.9 ± 6.5 ppbv. The maximum and minimum concentration occurs during 1300–1600 h and 0300–0500 h may be due to high solar radiation facilitating photochemical production of O₃ and downward mixing from the overlying air mass and in situ destruction of ozone by deposition and/or the reaction between O₃ and NO. GIS based spatial distribution of GLO in Chandrapur district is indicates that the central core of the district and southern sites experienced elevated levels of GLO relative to the northern and western areas. The sites near by Chandrapur city are particularly affected by elevated GLO. The average variation of GLO with temperature shows a significant correlation of r = 0.55 indicating a direct relationship between GLO and temperature. Similarly an attempt has been made to compare the GLO monitored data in Chandrapur district with the reported values for other locations in Indian cities. This generated database helps regulatory agencies to identify locations where the natural resources and human health could be at risk.