A Time-Dependent System for Evaluating Groundwater Contamination Hazard Rating of Municipal Solid Waste Dumps

In developing countries, several old municipal solid waste dumps (unlined landfills) exist adjacent to large cities, releasing contaminants to the underlying aquifer, thus posing the hazard of groundwater contamination. These uncontrolled waste dumps need to be prioritized in terms of the groundwater contamination hazard posed by them, so that necessary control and remedial measures can be undertaken in a phased manner. This paper presents a time-dependent system for evaluating groundwater contamination hazard rating of municipal solid waste dumps. The system is based on source–pathway–receptor relationships and evaluates the relative value of hazard posed by a site over its entire leaching life, on a scale of 0–1,000. The system parameters have been selected based on literature and expert opinions. The Delphi technique is used to derive the relative importance weights of the system parameters. The proposed system is compared with six selected existing hazard rating systems. The comparison, made by way of score range analysis, shows that the proposed system exhibits a much wider range of hazard scores for various scenarios of site conditions, and hence the proposed system is more sensitive to varied site conditions. The application of different systems to six municipal solid waste dumps located in four cities of India shows that, whereas the existing systems individually produce clustered scores and return the same rank to more than one site, the proposed system produces significantly varying scores and return different ranks to different sites. This demonstrates that the proposed system improves decision making and makes a better basis for prioritization of municipal solid waste dumps for adopting control and remedial measures.     

Short-term accumulative signatures of heavy metals in river bed sediments in the industrial area, Tehran, Iran

In modern civilization, numerous anthropogenic activities release a variety of pollutants into the environment and with anomalous enrichment of heavy metals it causes surface and subsurface contamination. The aquatic sediments provide pertinent tools for the quality assessment of urban and industrial environments in large cities. The present study reveals short-term accumulative trends of heavy metals (Co, Cd, and Pb) in the sand and silt dominated riverbed sediments from Chitgar industrial area (Tehran, Iran) between the period of May 2007 and May 2008. Lead demonstrates highest concentration in residential areas, cadmium in and around industrial areas, whereas cobalt shows least variability. Geo-accumulation index implies moderately to highly polluted sediments with respect to Cd and Pb. With few exceptions, all three metals at different sampling stations display short-term increasing trends, independent of seasonal variability with urban and industrial distends along the river being the chief sources of contamination.     

Development and characterization of microwave composite cladding

The development of cladding through microwave radiation is recently explored and very few, initial studies were reported elsewhere. In order to explore more viability of process, (EWAC (Ni based) + 20% Cr₂₃C₆ powder) composite cladding has been developed on substrate austenitic stainless steel (SS-316). The experiments were conducted in domestic microwave oven and the clad of thickness, approximate 500 m has been developed by the exposure of microwave radiation at frequency 2.45 GHz for duration of 360 s. Typical clads cross sections of composite clads showed good metallurgical bonding with the substrate by partial dilution. The back scattered electron image of clad cross section showed the reinforced chromium carbide (Cr₂₃C₆) particles are uniformly distributed and well embedded in the Ni based matrix. The developed clad is free from visible solidification cracking and has significantly less porosity which is of the order of 0.90%. The XRD pattern of the developed clad showed the presence of FeNi₃, NiSi and Cr₂₃C₆ phases. The average Vicker's microhardness of developed clad was observed as 425 ± 140 Hv.     

Heat loss analysis: An approach toward the revival of parabolic dish type solar cooker

Present work investigates a noble approach toward the heat loss analysis of parabolic dish type solar cooker. Various experiments have been done on cooking pot to get the input parameter for calculation purposes. Cooking pot was kept at the focus of a parabolic dish type concentrator and repeated experiments have been done to measure solar radiation intensity (direct and Indirect) using a pyrometer, temperature at the focus of parabolic dish using a thermocouple and air velocity using hot wire anemometer to investigate the heat losses from the cooking pot. In the present article, a numerical approach has been performed to define the new parameter called performance index of the cooking pot which decides how the useful energy of working fluid inside the cooking pot approaches concentration ratio of the parabolic dish type solar cooker. The present analysis shows that the performance index varies from 15.45 to 17.66 and efficiency varies from 85.83% to 98.10% with the time of the day.     

Performance evaluation of Nahar oil–diesel blends in a single cylinder direct injection diesel engine

This study attempts to use plentiful available high oil content (67% of Nahar seed kernel) non-edible feedstock as a source for powering diesel engine. Various performance and emission characteristics of prepared Nahar oil–diesel blends (5%, 10%, 20%, 30%, and 40%) are analyzed in a single cylinder direct injection diesel engine at different load spectrum, in order to judge the optimum blend, which can be efficiently used in a diesel engine. 10% blending of Nahar oil with diesel fuel has shown a reduction in hydrocarbon and carbon monoxide emission by 8.64% and 8.34%, respectively. With the increase in blend concentration, the nitrogen oxide emission decreased considerably and smoke emission increased slightly. Further pressure crank angle and heat release rate analysis of 10% blending of Nahar oil with diesel confirms its smooth combustion inside the engine combustion chamber.     

A performance-based tabular approach for joint systematic improvement of risk control and resilience applied to telecommunication grid,gas network,and ultrasound localization system

Environment Systems and Decisions - Organizational and technical approaches have proven successful in increasing the performance and preventing risks at socio-technical systems at all scales....     

Cloning and expression of α-amylase in E. coli: genesis of a superior biocatalyst for substrate-specific MFC

One of the most practical approaches for establishing a successful microbial fuel cell (MFC) is to fasten the oxidation rate of the substrate by the microorganisms to get quick paced electron transfer between microbes and electrode. A genetically modified Escherichiacoli, overexpressing α-amylase, is constructed and applied as biocatalyst in MFC using starch as substrate. The results are compared with nonrecombinant, native E.coli. The results show better performance for the MFC containing the recombinant strain demonstrated by higher power density (PD), lower resistance, and significant electrochemical activity. Maximum PD has been recorded as 279.04 mW m^?2 compared to 120.33 Mw m^?2 for the MFC operated with nonrecombinant E.coli. The impedance results also suggest the effectiveness of the recombinant strain by lowering the internal resistance by more than half order as compared to the nonrecombinant one. These results affirm that the engineered strain can be used as a superior biocatalyst in contrast to the native strain and by using the technique of genetic alteration; gene of interest can be inserted based on the substrate to be treated. So, this work gives a useful insight for accomplishing successful MFC operation with the use of bacterial stains engineered at the molecular level.     

Experimental investigation of solar still with opaque north triangular face

Developing a compact, simple, and productive solar still is a main challenge. This paper describes a simple modification of the solar still that significantly enhances its productivity. A laboratory scale of modified single effect double slope glass solar still with the opaque triangular north wall has been developed and tested for enhancement of productivity in sunny days of the summer season in the month of April. The experiments on still have been carried out under three levels of water depths from 1 to 3 cm and compared it with the performance of conventional still of double slope single effect solar still of the same size. It is clear from the observations that opaque type still gave maximum distillate of 1793 ml at 1 cm depth of water while conventional still could produce only 1519 ml for the same depth of water. Also, for 2 and 3 cm depth of water, the opaque type still found to be more productive than conventional double slope solar still. As the former produced 1532 and 1464 ml while the latter produced 1328 and 1235 ml, for 2 and 3 cm depth of water, respectively.     

Effect of different design aspects of pipe for earth air tunnel heat exchanger system: A state of art

Earth air tunnel heat exchanger (EATHE) is a promising passive technique to provide thermal comfort condition in buildings. EATHE system uses undisturbed temperature of the ground for heating/cooling of air. Despite the several advantages, this technique has not become much popular owing to its high capital cost (mainly pipe cost and trench excavation cost) and large land area requirements. The primary objective of this study is to present a comprehensive review of different EATHE pipe layouts, pipe properties and positioning of the pipe with their advantages and limitations. It is observed that the ring pipe layout is the most cost-effective pipe-layout for small size EATHE system because it saves excavation cost by using a trench of the existing foundation of the building. However, Grid pipe-layout is an ideal layout for a large size EATHE system. Multi-layer pipe layouts should be used to reduce the land area requirement significantly. Moreover, EATHE system can be installed beneath the building (under building foot-print) to eliminate extra land area requirement for the installation of EATHE system. This review article shows that the Initial capital cost and land area requirement for the EATHE system can be substantially reduced by using appropriate pipe layout. It can be concluded that if EATHE system is installed with proper design strategies, it will be a clean and cost-effective method for building heating/cooling with significant power savings.     

Production,engine performance,combustion, emission characteristics and economic feasibility of biodiesel from waste cooking oil: A review

The depletion of fossil fuel reserves and increasing demands for diesel are considered to be important triggers for many of the initiatives that have been taken to search for possible sources for the production of biodiesel from materials available within the country. It is possible to produce biodiesel from waste/used cooking oils (WCO) that is comparable in quality to that of fresh vegetable oil. Not only does reuse of WCO, which can otherwise harm human health, reduce the burden on the government of treating oily wastewater, disposing of the waste, and maintaining public sewers, it also significantly lowers the production cost of biodiesel. In the process of frying, oil undergoes many reactions, leading to the formation of a number of undesirable compounds, such as polymers, free fatty acids, and many other chemicals. This poses challenges in the transesterification of WCO. This article covers different techniques in the production of biodiesel from WCO. It also compares combustion, emissions, and engine performance characteristics of biodiesel from WCO as well as factors affecting biodiesel production from WCO and its economic feasibility.