Treatment of simulated Reactive Yellow 22 (azo) dye effluents using Spirogyra species

The potential of commonly available green algae belonging to Spirogyra species was investigated as viable biomaterials for biological treatment of simulated synthetic azo dye (Reactive Yellow 22) effluents. The results obtained from the batch experiments revealed the ability of the algal species in removing the dye colour and was dependent both on the dye concentration and algal biomass. Maximum dye colour removal was observed on the third day for all the system conditions. Monitoring of ORP values helped to understand the overlying biochemical mechanism of algal-dye system. Based upon the results, the dye-algal treatment mechanism was attributed to biosorption (sorption of dye molecules over the surface of algal cells), bioconversion (diffusion of dye molecules into the algal cells and subsequent conversion) and biocoagulation (coagulation of dye molecules present in the aqueous phase onto the biopolymers released as metabolic intermediates during metabolic conversion of dye and subsequent settlement).     

Planning limestone resources for the Indian steel industry

Most of the two billion tonnes of limestone consumed annually is used either as the basic raw material in the manufacture of cement or as flux input in the metallurgical industries. Of the total flux, 90% is used by the steel industry. The cement industry needs limestone in a finely pulverized form, whereas the steel industry uses it in lump form, with the lumps not less than 12 mm in size. The exploitation of limestone as flux for the steel industry must be scientifically planned. This article covers the methodology of planning, incorporating the study of the detailed status of the resource inventory, demand for limestone, exploration of new deposits, and calculating and manipulating the costs of production, transport and development of each project to match the demand pattern of steel plants. A computer was used for the optimization of supplies and their selection on planning horizons.     

The legacy of Bhopal: The impact over the last 20 years and future direction

Chemical process safety was not a major public concern prior to 1984. As far as chemical hazards were concerned, public fears focused on disease (cancer) and environmental degradation. Even a series of major process incident tragedies did not translate into widespread public concerns about major incidents in chemical plants that might disastrously affect the public. This situation changed completely after the December 1984 disaster at the Union Carbide plant in Bhopal. Not only was the public's confidence in the chemical industry shaken, the chemical industry itself questioned whether its provisions for protection against major incidents were adequate.

The recognition of the need for technical advances and implementation of management systems led to a number of initiatives by various stakeholders throughout the world. Governments and local authorities throughout the world initiated regulatory regimes. Has all that has resulted from the legacy of Bhopal reduced the frequency and severity of incidents? How can we answer this question? As we move into more and more globalization and other complexities what are the challenges we must address? According to the authors, some of these challenges are widespread dissemination and sharing of lessons learned, risk migration because of globalization, changing workforce, and breakthroughs in emerging areas in process safety.     

GIS-based hazard and vulnerability assessment of a torrential watershed

Environment, Development and Sustainability - Torrents are ephemeral streams which usually carry heavy bedload and flash flows. The frequent changes in its course caused by meandering and migration...     

Are environmental conditions responsible for animal-plant carcinogen interaction? A study relating to enzootic bovine haematuria

Summary Enzootic bovine haematuria (EBH) is a disease of cattle characterised by intermittent presence of blood in their urine and tumours of mixed origin in the urinary bladder. No consensus exists on the etiology of the disease, though bracken fern (Pteridium aquilinum) and/or papilloma virus have been implicated. There are areas where the malady is absent but the putative incrementing factor(s) are present. This raised the possibility of investigations into the interplay of environmental factors which might be conducive to the possible exposures to carcinogens in some regions. A comparative study of areas where the disease is prevalent (enzootic), and where it is absent (nonenzootic), to determine the type of vegetation (including ferns), the grazing patterns, the animal husbandry practices and the agroclimatic conditions in animal-plant interaction, is presented. Most of the ferns are common to both enzootic and nonenzootic areas. Bracken fern, a known source of carcinogens is present in both enzootic and nonenzootic areas. Ferns, with the exception of Athyrium spp. are not acceptable to the cattle when offered, being smelt and rejected. Ferns are not used as bedding material in the enzootic area studied.The authors conclude that different environmental conditions and animal husbandry practices may result in the cattle in the enzootic areas being exposed to carcinogenic brackens and other ferns at a time when there is a shortage of other alternative feedstuffs.Drs Dawra, Sharma and Krishna work at the Palampur Regional Station of the Indian Veterinary Research Institute. Correspondence should be addressed to Dr Rajinder K. Dawra.     

Contaminants in drinking water and its mitigation using suitable adsorbents: an overview

Various options are applicable for the removal of water pollutants included reverse osmosis, ion exchange, coagulation, co-precipitation, catalytic reduction, herbal filtration, electrodialysis and adsorption. This paper deals with the sorption phenomena for the removal of pollutants from drinking water. Attempts have been made to use low cost sorbents developed by pretreatment/activation/impregnation with alkalis, acids, iron oxide, manganese dioxide, ferric chloride, alum, lime, aluminum salts with natural products/indigenous minerals viz. activated alumina, activated carbon, groundnut husk, saw dust, chemically coated sand, fly ash, zeolites, clay minerals and other plant products. Application of Freundich and Langmuir isotherms were used to assess the adsorption capacity. Equilibrium isotherms were determined at optimum temperature and pH to characterize the sorption process. Statistical parameters such as mass transfer coefficients, multiple regression analysis were applied to establish the mechanism. It is suggested that the characterization of suitable, and exhausted sorbent through the application of fourier transformed infrared spectroscopy (FTIR), X-ray diffraction (XRD), X-ray fluorescence (XRF) is essential to establish its surface bonding. Scope for safety evaluation and risk assessment to human and biosphere may provide the guideline and predication to the regulatory agencies for its sustainable use and safe disposal The ecotoxicological assessment of the leachates and low cost removal technology are discussed in this paper.     

Influence of human-induced disturbance on benthic microbial metabolism in the Pichavaram mangroves,Vellar–Coleroon estuarine complex,India

Large areas of mangroves in India are heavily disturbed by cattle grazing, hypersalinity, and other human-induced impacts. In two disturbed Avicennia marina forests and two undisturbed A. marina and Rhizophora apiculata forests in the Pichavaram mangroves of the Vellar–Coleroon estuarine complex, southeast India, we measured the rates and pathways of microbial decomposition of soil organic matter to determine if human impact is altering biogeochemical activity within these stands. Rates of total carbon oxidation (T_COX) were higher in the undisturbed A. marina forest (mean 199 mol C m^–2 year^–1) than in the two impacted stands (43 and 79 mol C m^–2 year^–1); rates of total carbon oxidation in the R. apiculata forest averaged 75 mol C m^–2 year^–1. Sulphate reduction (range 21–319 mmol S m^–2 day^–1) was the major decomposition pathway (65–85% of T_COX), except at the most disturbed forest (30% of T_COX). Rates of sulphate reduction at all sites peaked in sub-surface soils to a depth of about 1 m, leading to little carbon burial (3–5% of total C input). There was some evidence of measurable iron and manganese reduction in association with tree roots. Rates of microbial activity were rapid in comparison with rates measured in other mangrove soils, reflecting high rates of phytoplankton production and organic matter retention in this lagoon. Human-induced disturbance creates a sharp zonation of dry, hypersaline soil overlying less saline, wetter soil, suppressing surface microbial and root growth. We conclude that this vertical alteration of soil characteristics and biogeochemistry shifts the cycling of nutrients between trees and microbes to a disequilibrium state, partly explaining why mangroves are stunted in these declining forests.Communicated by G. F. Humphrey, Sydney