Combining ``chimie douce'' and green principles for the developing world: Improving industrial viability of photocatalytic water remediation

We highlight the need for a comprehensive, multi-disciplinary approach for the development of cost-effective water remediation methods. Combining ``chimie douce'' and green chemical principles seems essential for making these technologies economically viable and socially relevant (especially in the developing world). A comprehensive approach to water remediation will take into account issues such as nanotoxicity, chemical yield, cost, and ease of deployment in reactors. By considering technological challenges that lie ahead, we will attempt to identify directions that are likely to make photocatalytic water remediation a more global technology than it currently is. (C) 2013 Elsevier Ltd. All rights reserved

Biological sulfate reduction of a sulfate-rich industrial waste liquor using sulfate reducing bacteria

An industrial waste liquor having high sulfate concentrations was subjected to biological treatment using the sulfate-reducing bacteria (SRB) Desulfovibrio desulfuricans. Toxicity levels of different sulfate, cobalt and nickel concentrations toward growth of the SRB with respect to biological sulfate reduction kinetics was initially established. Optimum sulfate concentration to promote SRB growth amounted to 0.8 - 1 g/L. The strain of D. desulfuricans used in this study initially tolerated up to 4 -5 g/L of sulfate or 50 mg/L of cobalt and nickel, while its tolerance could be further enhanced through adaptation by serial subculturing in the presence of increasing concentrations of sulfate, cobalt and nickel. From the waste liquor, more than 70% of sulfate and 95% of cobalt and nickel could be precipitated as sulfides, using a preadapted strain of D. desulfuricans. Probable mechanisms involving biological sulfide precipitation and metal adsorption onto precipitates and bacterial cells are discussed.

Embodied energy assessment of building materials in India using process and input-output analysis

Growing demand for urban built spaces has resulted in unprecedented exponential rise in production and consumption of building materials in construction. Production of materials requires significant energy and contributes to pollution and green house gas (GHG) emissions. Efforts aimed at reducing energy consumption and pollution involved with the production of materials fundamentally requires their quantification. Embodied energy (EE) of building materials comprises the total energy expenditure involved in the material production including all upstream processes such as raw material extraction and transportation. The current paper deals with EE of a few common building materials consumed in bulk in Indian construction industry. These values have been assessed based on actual industrial survey data. Current studies on EE of building materials lack agreement primarily with regard to method of assessment and energy supply assumptions (whether expressed in terms of end use energy or primary energy). The current paper examines the suitability of two basic methods; process analysis and input-output method and identifies process analysis as appropriate for EE assessment in the Indian context. A comparison of EE values of building materials in terms of the two energy supply assumptions has also been carried out to investigate the associated discrepancy. The results revealed significant difference in EE of materials whose production involves significant electrical energy expenditure relative to thermal energy use. (C) 2014 Elsevier B.V. All rights reserved.

Biodiesel Exhaust Treatment with Dielectric Barrier Discharges Coupled with Industrial Waste Byproducts

Biodiesel run engines are gaining popularity since the last few years as a viable alternative to conventional petro-diesel based engines. In biodiesel exhaust the content of volatile organic compounds, oil mist, and mass of particulate matter is considerably lower. However, the concentration of oxides of nitrogen (NOx) is relatively higher. In this paper the biodiesel exhaust from a stationary engine is treated under controlled laboratory conditions for removal of NOx using dielectric barrier discharge plasma in cascade with adsorbents prepared from abundantly available industrial waste byproducts like red mud and copper slag. Results were compared with gamma-alumina, a commercial adsorbent. Two different dielectric barrier discharge (DBD) reactors were tested for their effectiveness under Repetitive pulses /AC energization. NOx removal as high as 80% was achieved with pulse energized reactors when cascaded with red mud as adsorbent.

Embodied and operational energy of urban residential buildings in India

Globally, buildings consume nearly half of the total energy produced, and consequently responsible for a large share of CO2 emissions. A building's life cycle energy (LCE) comprises its embodied energy (EE) and operational energy (OE). The building design, prevalent climatic conditions and occupant behaviour primarily determines its LCE. Thus, for the identification of appropriate emission-reduction strategies, studies into building LCE are crucial. While OE reflects the energy utilized in operating a, EE comprises the initial capital energy involved in its construction (material and burden associated with material consumption in buildings. Assessment of EE and OE in buildings is crucial towards identifying appropriate design and operational strategies for reduction of the building's life cycle energy. This paper discusses EE and OE assessment of a few residential buildings in different climatic locations in India. The study shows that share of OE and EE in LCE greatly depends upon the types of materials used in construction and extent of space conditioning adopted. In some cases EE can exceed life cycle OE. Buildings with reinforced concrete frame and monolithic reinforced concrete walls have very high EE. (C) 2015 Elsevier B.V. All rights reserved.