Pollution

The contact process preferably used vanadium pentaoxide as catalyst to increase the rate of reaction of producing sulphuric acid. Sulfuric acid plants regularly require catalyst replacement in order to cope with process improvements. The spent catalyst considered as hazardous solid waste and cannot be discarded untreated owing to presence of high amount of vanadium and other associated metal. Because of significant environment implications of spent catalyst wastes it is imperative to recover valuable metals present in them. The recovery of precious materials or metals from waste will not only help in mitigating environment problem due to metal pollution but also improve the economy of the country. The purpose of this research work is to develop method to recover vanadium from spent V2O5 catalyst. The detailed study of extraction, separation and recovery of vanadium from leached spent catalyst solution of composition; V, 3.6% ; Al,2.1%; Fe, 1.3 Ti, 0.8 and less than 1 % of Cr and Pb is reported in this paper. Cyanex 272 (bis (2, 4, 4-trimethylpentyl) phosphinic acid) has been explored for the recovery of vanadium from spent V2O5 catalyst. The effects of different parameters like, pH, solvent concentration, organic to aqueous ratio etc were optimised for the complete extraction and recovery of vanadium. The proposed procedure gives high purity vanadium with almost a quantitative yield (~99%) and of course free from closely associated metals. The extractants could be reused up to ten cycles with no significant change in the extraction capability.

The kinetics of nickel leaching from lateritic Chromite overburden (COB) by organic (Oxalic) acid has been investigated. In this context, the effects of oxalic acid concentration and temperature upon the rate of nickel extraction from COB were evaluated. The leaching kinetics study was also performed for nickel extraction from thermally pre-treated COB, since nickel extraction was improved by the thermal pre-treatment of the COB. Well established shrinking core models were applied to study the kinetics of nickel extraction from raw and pre-treated COB. The experimental outcomes evident that, rates of nickel extraction from raw as well as the pre-treated COB were controlled by diffusion controlled shrinking core rate kinetics model. Further, apparent activation energies for extraction of nickel from raw and pre-treated COB were estimated to be 14.31 kJ/mol and 14.56 kJ/mol respectively.

The concentrations of the toxic elements As, Cd, Hg, Sb and V in well and borehole water, samples from the Bibiani mining area in the Western Region of Ghana have been measured using instrumental neutron activation analysis (INAA) following irradiation with thermal neutrons and counting with a conventional counting system. This study was conducted to assess the impact of mining activities on the ground water resources of the Bibiani mining area. The concentrations of the elements measured in the rainy season water samples were in the ranges: As, 0.04 – 6.08 mg/L; Hg, 1.63 – 2.05 mg/L; Sb, 0,52 – 0.96 mg/L and V, 0.06 – 0.62 mg/L. The concentrations of Cd were below 0.01 mg/L (i.e. the detection limit) in all the rainy season samples. In the dry season samples, the concentration ranges of the various elements were: As, 0.67 – 4.71 mg/L; Cd, 0.35 – 2.80 mg/L; Hg, 0.30 – 4.93 mg/L; Sb, 0.08 – 0.70 mg/L and V, 0.07 – 0.52 mg/L. In the rainy season, the concentrations of As in 54% of the samples, Hg in 31% of the samples, and Sb in 23% of the samples were above their respective World Health Organization (WHO) limits whereas in the dry season water samples, the concentration of As in 31% of the samples, Cd in 62% of the samples, Hg in 23% of the samples and Sb in 15% of the samples were above their respective WHO limits. The pH values of all the water samples ranging from 3.90 to 5.93 pH units fell below the lower limit of the range 6.5 – 8.5, the WHO (1985) pH range for good quality drinking water. Therefore it could be concluded on this grounds that the wells and boreholes studied in Bibiani mining area were polluted hence not suitable for human consumption.

Ground water is increasingly being sought as a source of drinking water due to the scarcity, non-availability and bacteriological pollution of surface water. This paper deals in the physico-chemical characteristics of the ground water samples of tube wells of ten villages in Sardarsahar Tahsil (Churu) of Rajasthan State. The different parameters determined are pH, TDS, fluoride, chloride, total alkalinity and total hardness. It has been observed that all values are higher compared to APHA (American public Health Association), AWWA (American water work Association) and WPCF (1975). Other parameters were found within desirable limits. The high value of these parameters may have health implications, so, this ground water is not good for health and therefore, needs attention.

Nitrate and nitrite are naturally occurring ions that are ubiquitous in the environment. Both are products of the oxidation of nitrogen ( which comprises roughly 78% of the atmosphere) by micro-organisms in plants, soil or water and to a lesser extent by electrical discharges such as lightening. After a period of time, the nitrates seep into the water table. This is a concern primarily for those whose household water source is a well rather than their city. Nitrates can cause cancer in humans, when consumed over a period of time. The objective of this study is investigation and determination of nitrate, nitrite and other physico-chemical parameters of Southern Bijapur district. 30 samples of water were analysed for pH, TGS, Total hardness, alkalinity, nitrate and nitrites. The southern part of Bijapur district had more than the maximum acceptable concentration (MAC) for nitrate in drinking water. It was concluded that nitrate contents in drinking water was found to be 8.0 to 392 mg/L.

Airborne beta activity measurements have been carried out on the site of the Ghana Atomic Energy Commission (GAEC). The GAEC is a nuclear institution in Ghana that is involved in the application of nuclear techniques in research, radioisotope production and utilization, operation of a research reactor and processing of radioactive waste. Ludlum model 333-2 air beta monitor was used to conduct the measurements. Monthly averages of gross beta activities ranged from 1.2 to 3.0 mBq/m3. The gross beta activities measured were found to be due mainly to decay products of natural radioisotopes. Monthly total suspended particulate mass concentrations ranged from 22 to 110 µg/m3. Gross beta activities and particulate mass concentrations partially correlated. Based on these results, it could be stated that present ambient airborne radioactivity has minimal radiological consequences on the environment and inhabitants of the study area. Mass concentration levels would however need to be regulated.

The hydrobiology of Andrott Island, Lakshadweep was investigated during November 2011 to May 2012 period. Estimation of salinity, temperature, dissolved oxygen, pH, nutrients, hardness, primary productivity, phytoplankton and zooplankton communities were carried out. Among the factors mentioned above nutrient levels were significantly less in the Andrott Sea. Altogether nine species of phytoplankton and ten groups of zooplankton were identified during the present study. The filamentous algae Trichodesmium sp., diatoms such as Pleurosigma, Navicula, Skeletonema, Thalassiosira, Coscinodiscus and Nitzschia; dinoflagellates such as Dinophysis and Ceratium contributed to the phytoplankton community. Significant fauna composed of Foraminiferans, Rotifers, Polychaete larvae, Isopods, Ostracods, Crustacean larvae, Copepods, Mysids, Gastropod larvae and fish larvae.

Life Cycle Assessment was successfully carried out on activated carbons produced from milk bush kernel shell (MB), flamboyant pod back (FB) and rice husk (RH) in order to determine their environmental burden and to assess the potential health impacts. The analysis covered the whole processes involved in producing activated carbon from the raw agricultural wastes. In this work the carbonaceous part of the agricultural wastes were carefully obtained, washed, with distilled water, dried in the oven, to remove moisture before being carbonized at 300 - 6000C. The carbonized chars were further activated with H3PO4, dried in the oven, washed with distilled water and NaHCO3 to remove any residual acid and finally dried in the oven. The solid pollutants generated in the production of activated carbon from MB, FB and RH ranged from 40.21 to 41.65%, 36.31 to 36.92%, and 15.34 to 21.55%, respectively, while the air pollutants generated in the production ranged from 11.85 to 12.15%, 11.83 to 11.94%, and 18.39 to 19.12%, respectively. Similarly, the liquid pollutants generated in the production activated carbon from MB, FB and RH ranged from 46.50 to 46.88%, 51.25 to 51.75%, 60.06 to 64.82%, respectively. Generally the order of the waste generated in the process was liquid > solid > air pollutants except for rice husk which produced more air pollutants than solid pollutants. The analysis of the solid pollutants showed that they can be recycled as fuel, thus leaving little quantity of solid wastes after process. Similarly the air and liquid pollutants generated were well contained within the acceptable environmental practice.

This study investigated contributions of industrial wastewater on quality of receiving urban rivers and streams in Dar es Salaam City, Tanzania, to establish their contamination levels and assess risks to human health and ecology. Water and sediment samples from 21 locations were analyzed for physicochemical parameters, nutrients and toxic metals. Pollution status was evaluated by contamination indices and comparison with benchmarks. Results showed high levels of dissolved solids, nutrients and toxic metals in water and significant levels of contamination in sediments. Poorly treated industrial effluents contributed in contaminating the receiving rivers; however significant levels of contamination were found to originate from other upstream sources as well. These findings indicate high risk to human health and the environment.