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Byline: Rajesh Kumar Singh, H.R. Murty, S.K. Gupta, A.K. Dikshit Environmental issues in steel industry are so numerous, complex and interconnected that an ad hoc approach to problem solving is no longer considered effective. The growing pressure from all stakeholders forces steel companies to incorporate the environmental responsibility in all activities. Consequent to evolution of various environment management tools for supporting and improving environmental performance of the industry, steel companies have focused their attention towards integration of environmental strategy in their overall management system. This paper deals with an Integrated Approach to Environmental Management of the steel industry, which shall ensure a continuous improvement in environmental performance in order to increase competitiveness in the future steel market. In this paper, a business model is being suggested for integration of environment in overall management system. Based on the above model, a framework has been designed for implementation of Integrated Environmental Management Systems (IEMS) in steel industry. IEMS aims at 'the Greening of the industry' which shall integrate Pollution Prevention (P2), Life Cycle Assessment (LCA), Environment Management Information System (EMIS), green supply chain, environment performance evaluation, environmental accounting and other environmental management tools to EMS according to ISO 14001 requirements. This approach shall allow the steel companies to find and implement profitable and powerful measures that avoid waste generation; reduce environmental pollution; improve consumption of natural resources and go beyond legal compliance.

Byline: Sudhakar Yedla, A.K. Dikshit Endosulfan is among the most widely used pesticides in developing countries and other parts of the world and has been found to contaminate various parts of the environment, including drinking water sources. In an earlier study to find a suitable adsorbent to remove endosulfan, wood charcoal was found to give promising results. In the present study, the process controlling the rate of endosulfan sorption onto wood charcoal and the mechanism of removal were examined using various methodologies. Both film and pore diffusion coefficients were determined, and the linearity of the rate constants of adsorption with initial endosulfan concentrations revealed the process to be controlled by film diffusion. This was supported by the linear fit of the rate constants with the inverse of the diameter of adsorbent particles and the change in adsorption rates with agitation speed. Multiple interruption tests also revealed that endosulfan sorption onto wood charcoal is controlled by film diffusion. The increase in reaction rate constant with temperature and isosteric heat of adsorption in the range of -2.655 to 5.185 kcal/mol implied that the endosulfan removal process was endothermic in nature. The activation energy of 2.33 kcal/mol, which was less than 12 kcal/mol, revealed that the removal mechanism could be attributed to physisorption with a major contribution of van der Waals and electrostatic forces.

Byline: Sudhakar Yedla, A.K. Dikshit With the increasing use of pesticides in modern agriculture, increased evidence of their disastrous effects on the environment has been noticed. Pesticides applied in various modes and places contaminate various parts of the environment, including groundwater sources. As pesticide problems are greater in the rural areas, the authors have developed a successful low-cost technology for rural areas with wood charcoal treated with nitric acid. As pesticides are classified as hazardous waste, the sludge resulting from their treatment has to be disposed off safely. This paper describes the removal of pesticides at a higher concentration of 24 mg/l, using a mixed culture of aerobic bacteria, and also a study of the inhibiting action of endosulfan on bacterial cells. It was found that bacteria without acclimatisation could remove 89.7% of endosulfan, and with prior acclimatisation the efficiency was 96%. It was found that removal in the initial phase is because of the hydrophobic nature of endosulfan and its affinity to sediments. The adsorbed endosulfan subsequently undergoes biotransformation, which has been confirmed by monitoring endosulfan concentrations in the bacterial sludge. Transformation was found to be significant in the acclimatised culture system. The fluctuation in bacterial performance was greater at lower concentrations of endosulfan, and overall inhibition was greater at higher concentrations.

Byline: Debabrata Mazumder, A.K. Dikshit Wastewater treatment by the hybrid reactor system has become wide-spread as it provides advantages of both the suspended and attached growth phase at the same time. It may be used to treat some rate-limiting substrate, priority pollutants, volatile organic compounds etc. as well as for nitrification. This versatile nature of hybrid reactor demands for a detailed investigation on the mechanism, mode of operation, different applications and major configurations available. The present article is devoted to explore these issues with respect to previous background and successive development in this area. Apart from the laboratory and pilot-scale study, some industrial applications have been overviewed to understand the performance of hybrid reactor in the concerned field. The approach of modelling for the hybrid reactor system is also demonstrated with the hypothetical data set. A comprehensive details about major hybrid processes is presented along with their schematic diagrams. The review on hybrid process revealed that it would be economic for upgradation of existing activated sludge system, ensuring carbonaceous oxidation and nitrification in a single reactor and treatment of slowly bio-degradable substances also.

Byline: Sameer Sharma, S.V. Barai, A.K. Dikshit In recent years, urban air pollution has emerged as an acute problem because of its negative effect on health and living conditions. Regional air quality problems, in general, are linked to violations of specified air quality standards. The current study aims to find neural network based air quality predictors, which can work with a limited number of datasets and are robust enough to handle data with noise and errors. A number of available variations of neural network models, such as the Recurrent Network Model (RNM), the Change Point Detection Model with RNM (CPDM), the Sequential Network Construction Model (SNCM), the Self Organising Feature Model (SOFM), and the Moving Window Model (MWM), were implemented using MATLAB software for predicting air quality. Developed models were run to simulate and forecast based on the annual average data for 15 years from 1985 to 1999 for seven parameters, viz. VOC, NOx, CO, SO2, PM10, PM2.5 and NH3 for one county of California, USA. The models were fitted with first nine years of data to predict data for remaining six years. The models, in general, could predict air quality patterns with modest accuracy. However, the SOFM model performed extremely well in comparison with the other models for predicting long-term (annual) data.

Byline: Debabrata Mazumder, A.K. Dikshit The deep-shaft activated sludge process is a unique modification of the activated sludge system. The main objective of this system is to increase the amount of dissolved oxygen available for biological activity. This can be achieved by increasing the rate of oxygen transfer from the gas phase to the liquid phase. The deep-shaft configuration increases the partial pressure of oxygen, thereby causing a high saturation concentration in the reactor. In the deep-shaft process, owing to high oxygen availability, a higher organic loading can be accommodated with a comparatively low air supply. This reduces the energy and area requirements and lowers the overall cost of treatment. This technology has been successfully applied for the high-rate treatment of strongly polluted wastewater, as well as for the treatment of wastewater containing toxic or slowly biodegradable pollutants. This paper presents different applications of the deep-shaft activated sludge process, along with their relative performances.

For the removal of 2,4-D (2,4-dichloro-phenoxy-acetic acid) and atrazine (2-chloro-4-ethyalamino-6-isopropylamino-s-traiazine) from water environment, batch studies were performed to study the kinetics of 2,4-D and atrazine sorption by rubber granules. Experiments were conducted at various initial concentrations of 7.5 mg/L, 4 mg/L, and 0.5 mg/L of 2,4-D and atrazine with 18 g/L sorbent dose. The equilibrium time was found to be 120 minutes for both 2,4-D and atrazine. The regression analysis for the experimental data showed that the rapid stage zone of kinetics profiles followed a first order reversible kinetics for all initial concentrations of sorbate. The various thermodynamic properties such as enthalpy and entropy activation values (ΔH and ΔS) also show that the sorption is spontaneous. This article will provide information toward understanding the sorption phenomena of 2, 4-D and atrazine on waste tyre rubber granules. It also is valuable to us in finding out the rate constant of sorption of 2,4-D and atrazine. [ABSTRACT FROM AUTHOR]

From this study it was evident that outer peristaltic parts of waste tire granules gave the highest removal. Film and pore diffusions are the major factors controlling rates of sorption from solution by porous adsorbents. For sorption of 2,4‐D on waste tire rubber granules, the sorption rate coefficient of second‐order kinetic equation was utilized indirectly to determine the rate‐limiting step. The diffusion coefficient lies in the scale of 10 -8 cm 2 /s, and the pore diffusion coefficient is in the range of 10 -9 –10 -10 cm 2 /s. So both film and pore diffusion are rate limiting. Considering external mass transfer from fluid to particle, using the effect of initial concentration, and using the effect of adsorbent size, no conclusion was reached regarding rate‐controlling steps. It is apparent from the study that external mass transfer (film diffusion) as well as intra‐particle diffusion (pore diffusion) play significant roles in the sorption process for 2,4‐D removal from water onto rubber granules. [ABSTRACT FROM AUTHOR]

Waste pickers and collectors constitute the bottom layer of waste recycling in the metropolis of Delhi. Pickers collect waste just by picking them up from public places such as garbage dumps and streets, whereas collectors purchase waste from waste producers such as households and shops for sale to higher-level waste traders. Most pickers have incomes below the poverty line set by the Planning Commission of India, whereas the majority of collectors earn marginally higher than the poverty-line income. The poverty of pickers is not transitory, but chronic as they have no connection to enter the community of collectors and higher-level waste traders within which the community mechanism works effectively to reduce risk and transaction costs. Despite their low economic and social status, pickers and collectors are making important contributions to society. It is found that pickers and collectors are adding more value than their own income to waste producers' income and to the saving of the city government's expenditure for disposing waste. Increased public support not only for social services, but also production services and infrastructure can be justified not only for the purposes of reducing poverty but also for furthering their positive contribution to society. [ABSTRACT FROM AUTHOR]

In this study, the effects of size of adsorbent, temperature, pH of solution, ionic strength, presence of inorganic substances such as calcium ion, magnesium ions, chloride ions, fertilizers and presence of organic substances such as dissolved organic mater, surfactant, other herbicides on sorption of 2,4-D and atrazine onto rubber granules were investigated. The removal efficiency was more for fine adsorbent particles. Temperature played an important role in sorption process. Temperature effect was endothermic for 2,4-D and exothermic for atrazine, respectively. The removals were maximum at pH 4 for 2,4-D and at pH 6 for atrazine. The presence of other herbicide (butachlor) reduced sorption capacity of rubber granules by ∼ 10% for both 2,4-D and atrazine. All other factors had insignificant effect on sorption capacity. The mathematical expressions were developed for predicting the overall percentage removal of 2,4-D and atrazine on the basis of major four controlling factors viz. adsorbent size, temperature, pH and presence of other herbicide. [ABSTRACT FROM AUTHOR]

Evaluates the performance of a fixed bed adsorber column to remove endosulfan, an organochlorine pesticide from the water environment using wood charcoal as an adsorbent. Use of the bed depth-service time approach for the design of the adsorber; Maximum desorption rate; Bed efficiency based on total capacity; Rate of transfer of sorbate.

Management of Endosulfan contaminated eluent (24 mg/1) resulting from a treatment process to remove Endosulfan from water with wood charcoal, was attempted using various methods viz. volatilisation, hydrolysis and sorption by viable cell bacteria with and without acclimatisation. Volatilisation failed in giving better result, as Endosulfan was not considerably volatile. It could achieve a removal efficiency of 1.4-2%. Hydrolysis resulted in 28.4% and 17.9% removal of Endosulfan in acidic and alkaline media, respectively. Viable cell bacteria (aerobic) without prior acclimatization showed efficiency of 89.7% and after prior acclimatisation showed 96% removal efficiency. Sorption by the acclimatized biomass was found a suitable method for the removal of Endosulfan at a concentration of 24 mg/l. [ABSTRACT FROM AUTHOR]