Treatment of oil spill by sorption technique using fatty acid grafted sawdust

Treatment of oil spills remains a challenge to environmental scientists and technologists. Among all the existing techniques used for oil treatment, sorption is a popular technique because it is cheap, simple and effective. Among the various sorbents used, sawdust appears to be the most attractive material in terms of cost, versatility and abundance. In the present work, the efficacy of surface modification of sawdust by fatty acids (oleic acid, stearic acid and decanoic acid) and vegetable oils (castor oil or mustard oil) is demonstrated. Sorption of seawater contaminated with crude oil and also weathered oil was greatly enhanced by the surface modification. The results show that oleic acid grafted sawdust (OGSD) has the best sorption capacity for crude oil as well as weathered oil.     

Assessment of biomass and lipid productivity and biodiesel quality of an indigenous microalga Chlorella sorokiniana MIC-G5

Generation of biodiesel from microalgae has been extensively investigated; however, its quality is often not suitable for use as fuel. Our investigation involved the evaluation of biodiesel quality using a native isolate Chlorella sorokiniana MIC-G5, as specified by American Society for Testing and Materials (ASTM), after transesterification of lipids with methanol, in the presence of sodium methoxide. Total quantity of lipids extracted from dry biomass, of approximately 410–450 mg g^?1 was characterized using FTIR and ¹H NMR. After transesterification, the total saturated and unsaturated fatty acid methyl esters (FAMEs) were 43% and 57%, respectively. The major FAMEs present in the biodiesel were methyl palmitate (C16:0), methyl oleate (C18:1), and methyl linoleate (C18:2), and the ¹H NMR spectra matched with criteria prescribed for high-quality biodiesel. The biodiesel exhibited a density of 0.873 g cm^–3, viscosity of 3.418 mm² s^?1, cetane number (CN) of 57.85, high heating value (HHV) of 40.25, iodine value of 71.823 g I₂ 100 g^?1, degree of unsaturation (DU) of 58%, and a cold filter plugging point (CFPP) of –5.22°C. Critical fuel parameters, including oxidation stability, CN, HHV, iodine value, flash point, cloud point, pour point, density, and viscosity were in accordance with the methyl ester composition and structural configuration. Hence, C. sorokiniana can be a promising feedstock for biodiesel generation.     

Role of magnetite and humic acid in radionuclide migration in the environment

Sorption of ¹³⁷Cs, ⁹⁰Sr, ¹⁵⁴Eu and ¹⁴¹Ce by magnetite has been studied at varying pH (4 to 11) in the presence and absence of humic acid. The sorption studies have also been carried out at varying ionic strength (0.01 to 0.2 M NaClO₄) and humic acid concentration (2 to 20 mg/L). Percentage sorption of ¹³⁷Cs and ⁹⁰Sr was found to be pH dependent, with the sorption increasing with increasing pH of the suspension. At any pH, the percentage sorption of ⁹⁰Sr was higher than that of ¹³⁷Cs. The results have been explained in terms of the electrostatic interaction between the positively charged metal ions and the surface charge of the magnetite which becomes increasingly negative with increasing pH. On the other hand, ¹⁵⁴Eu and ¹⁴¹Ce were found to be strongly sorbed by the magnetite at all pH values, with the sorption being independent of pH. The strong sorption of trivalent and tetravalent metal ions suggests the role of complexation reactions during sorption, apart from the electrostatic interactions. However, in the case of ¹⁴¹Ce surface precipitation of Ce(III) formed by reduction of Ce(IV) in the presence of magnetite cannot be ruled out. Presence of humic acid (2 mg/L) was found to have negligible effect on sorption of all metal ions.     

In-situ monitoring of chromium cytotoxicity in sugarcane

The potential of in-situ monitoring of cytotoxic effects of chromium through root-tip assay was studied in a sugarcane cultivar CoLk 8102 (Saccharum spp. hybrid). Sugarcane setts supplied with graded concentrations of chromium (VI), exhibited a reduction of 85.92 and 95.10 % in mean root length at 40 and 80 ppm Cr dosages along with 61.25 and 82.50% reduction in mean root number/node respectively. Mitotic index of root tip cells of treated setts declined and the frequency of aberrant mitotic phases increased pari passu to the increasing chromium concentration. To compare and quantify the effect of graded chromium dosages on frequency of chromosome aberrations vis-à-vis inhibition of mitotic activity, a 'Decretion factor' (D.F.) has been used for the first time. The value of DF increased with the increase in the chromium dosages. The increase in chromosome aberration frequency was low at low chromium dosages (1 or 2 ppm), but the high Cr dosages (40 and 80 ppm), induced sharp reduction in mitotic efficiency of root system along with anomalies in the process of cell division and induced chromosome aberrations in sugarcane root meristem, which in turn affected the over all plant growth.     

Study of fluoride content in groundwater of Nawa Tehsil in Nagaur, Rajasthan

There is a severe fluoride problem in Nawa tehsil of Nagaur district. Villagers are suffering from dental fluorosis and skeletal fluorosis. So an extensive geochemical study of 27 villages of eastern, south-eastern and southern zone of Nawa tehsil was done. Total 46 ground water samples were collected and analyzed for various physicochemical parameters as well as fluoride content. The ground water samples collected in clean polyethylene plastic containers were analyzed for pH, electrical conductivity, total dissolved salts, calcium, magnesium, total hardness, chloride and alkalinity. The fluoride concentration in the three different zones ranged from 0.64 to 14.62 mg l(-1) where 13.04% samples were found within permissible limit while 86.96% had fluoride beyond permissible limit (> 1.5 mg l(-1)). It was found that among the three different zones south-eastern zone was under serious fluoride contamination where fluoride concentration ranged between 1.10 to 14.62 mg l(-1). In the eastern zone fluoride concentration was recorded from 1.52 to 5.13 mg l(-1) whereas in the southern zone it was found between 0.64 to 3.63 mg l(-1).     

Some notes on the population dynamics of the monogenean gill parasite Gastrocotyle indica

The fish Caranx kalla of different size groups (2 to 18 cm body length) is present during various calender months of the year off the Madras coast (S. India). C. kalla displays a definite progressive shift in growth during successive months; the fish grows from 2 cm (September) to about 18 cm (August) over a period of 12 months. The highest (47%) or lowest (11%) incidence of a monogenean gill parasite Gastrocotyle indica has been observed in the C. kalla size groups 2.0 to 3.9 cm or 16.0 to 17.9 cm; however, the maximum specific density of 10.9 parasite/infested fish was observed in the size group 14.0 to 15.9 cm. Small fish (2.0 to 3.9 cm) carry only larvae (58/100 fish); larger hosts (4.0 to 5.9 cm) larvae (45/100 fish) and juveniles (8/100 fish); individuals of the 6.0 to 15.9 cm size group harbour larval, juvenile and adult stages of G. indica. Fishes of more than 16 cm carry only adult parasites. The level of parasitization is higher on the male hosts (30% incidence; 5 parasites/infested male) than on the females (25% incidence; 4 parasites/infested female). The highest incidences of larval, juvenile and adult G. indica occur in September, February, and May, respectively; the parasite seems to live for 1 year. The host requires a period of about 8 months to acquire immunity against infestation by G. indica or copepod parasites.     

Performance and modeling studies of rotating biological contactor for treatment of vegetable oil wastewater

This study focuses on a lab-scale rotating biological contactor (RBC) treating vegetable oil wastewater with high BOD and COD. The fabricated RBC was checked for efficiency in degrading polluted wastewater under different operating conditions. The maximum removal efficiencies for BOD and COD were 95.75% and 89%, respectively. This high removal percentage was obtained with 30% submergence of 10 discs rotating at 8 rpm. For the first time, bio-kinetic models were applied to the experimental results for vegetable oil wastewater. The best fit was obtained with the modified Stover-Kincannon and Grau model. The saturation constant (K_s) values were 1.872 and 3.024 g/L/d for BOD and COD, respectively, for the modified Stover-Kincannon and Grau model. For the Grau second-order model, the saturation constant was 1.416 and 3.744 g/L/d for BOD and COD, respectively. The predicted effluent BOD and COD values of the modified Stover–Kincannon model fitted almost exactly with the experimental values. This clearly predicts that this model can be best used to predict effluent BOD and COD concentration in a Rotating Biological contactor treating vegetable oil wastewater. The kinetic parameters determined in this study can be used to improve the design and operation of continuous mode RBC systems.     

Zinc and copper induced changes in physiological characteristics of Vigna mungo (L.)

The effect of deleterious concentration of zinc and copper provided either individually or in combination in the nutrient media was investigated in order to assess the effect of metal interaction in Vigna mungo (L.). Both metals showed negative effect and led to a marked decrease in seed germination (20%), seedling growth (91.7%) and nitrate reductase activity (85.7%) with the increase in metal concentrations. The present study also emphasizes on the response of catalase and peroxidase enzyme under zinc and copper stress. Both antioxidant enzymes exhibited an increasing trend under different treatment conditions but it was reverse at highly toxic metal concentration. The results showed active involvement of peroxidase enzyme in regulating oxidative stress rather than catalase enzyme, as the specific activity of peroxidase enzyme got increased by 8.94% under the combined metals stress whereas catalase activity got declined by 60.97% in comparison to control due to excessive stress. The combined effect of copper and zinc metal was more pronounced in comparison to their individual effects.     

Dental fluorosis—a case study from Nawa tehsil in Nagaur district,Rajasthan (India)

A study was carried out in Nawa tehsil of Nagaur district to assess the prevalence of dental fluorosis and its crippling effect due to ingestion and prolonged exposure of fluoride over a long period of time. During the survey of the study area, high concentration of fluoride (14.62 ppm) has been recorded. The presence of fluoride in quantities in excess of limits is a serious matter of concern from a public health point of view. Due to higher fluoride level in groundwater, several cases of dental fluorosis have appeared at alarming rate in the study area. The children’s teeth are damaged and are characterized by black and brown stains as well as cracking and pitting of the teeth have been observed. In the study area, 93.12% population suffered from dental fluorosis, and it was more prevalent in men (94.90%) than in women (90.00%). Dental fluorosis was also examined according to different grades. Out of the total 72 afflicted, in the 4–16-year age group, 41.46% were suffering from Grade I, Grade II was more prevalent in 33.85% of the 17–28-year age group and similarly Grade II was more prevalent in 39.13% of the 29–40-year age group. In the age group of above 40 years, grade III and grade IV were more prevalent. Thus, in the higher age group, the prevalence and severity of fluorosis is almost certainly due to longer exposure to fluoride. The major risk factor consistently identified for dental fluorosis was the consumption of fluoridated drinks and fluoride supplements. Ingestion of calcium, vitamin D and vitamin C is effective in protection from fluoride toxicity to certain extent.