M.G. Rasul

Influence of parameters on the heterogeneous photocatalytic degradation of pesticides and phenolic contaminants in wastewater: A short review

In recent years, the application of heterogeneous photocatalytic water purification processes has gained wide attention due to its effectiveness in degrading and mineralizing the recalcitrant organic compounds as well as the possibility of utilizing the solar UV and visible-light spectrum. This paper aims to review and summarize the recent works on the titanium dioxide (TiO(2)) photocatalytic oxidation of pesticides and phenolic compounds, predominant in storm and wastewater effluents. The effects of various operating parameters on the photocatalytic degradation of pesticides and phenols are discussed. Results reported here suggest that the photocatalytic degradation of organic compounds depends on the type and composition of the photocatalyst and, light intensity, initial substrate concentration, amount of catalyst, pH of the reaction medium, ionic components in water, solvent types, oxidizing agents/electron acceptors, catalyst application mode, and calcination temperature in the water environment. A substantial amount of research has focused on the enhancement of TiO(2) photocatalysis by modification with metal, non-metal and ion doping. Recent developments in TiO(2) photocatalysis for the degradation of various pesticides and phenols are also highlighted in this review. It is evident from the literature survey that photocatalysis has good potential to remove a variety of organic pollutants. However, there is still a need to determine the practical utility of this technique on a commercial scale.

Energy conservation in buildings: cogeneration and cogeneration coupled with thermal energy storage

Energy-conservation opportunity in an institutional building is studied through cogeneration with double-effect absorption chiller. Both, technical and economical feasibility is evaluated and presented. The typical electrical energy and cooling-load demand profiles of the buildings concerned are determined. Payback period, internal rate-of-return (IRR), net present value (NPV) and net profit of the Institute is determined through cash-flow analysis. Then, cogeneration coupling with thermal energy storage (TES) is studied and its technical and economical feasibility is evaluated and compared with that of cogeneration. On-site cogeneration with a double-effect absorption chiller provides a potential of at least 13% peak-demand reduction and about a 16% savings in energy consumption. It provides IRR greater than 21% but the saving potential is limited by the low demand of co-generated chilled water within the community of the Institution. Cogeneration coupling with thermal energy storage offers a simple and economically more attractive approach for maximizing the utilization of co-generated chilled-water and shows 23% reduction in peak demand and a 21% savings in energy consumption. It provides a higher IRR, greater than 25%.

Physical properties of bagasse

Bagasse is a by-product of sugar milling and important fuel resource for that industry. It is a fibrous, low density material with a very wide range of particle sizes and high moisture content. It is difficult to characterize properties of bagasse particles in the usual ways (i.e. by particle density, size, drag co-efficient, etc.). These properties are necessary to apply normal design procedures to, for example, pneumatic conveying, fluidization, drying, combustion, etc. In this paper techniques to determine some physical properties of the three major components of bagasse, namely pith, fibre and rind, are demonstrated. Average material properties may then be obtained based on the weight proportions of the components constituting the bagasse.

Segregation potential in binary gas fluidized beds

Some smoothly fluidized binary mixtures exhibit no tendency to segregate under a particular combination of solids and fluid volume fractions. In these cases the equilibrium mixture remains stable, even in the absence of mixing forces. The conditions corresponding to segregation potential free mixtures can be theoretically predicted from the physical properties of the system, and have been validated for liquid fluidized systems. This paper shows that the same approach may be applied to gas fluidized beds of fine particles. Experimental results of different binary mixtures in gas fluidized beds are reported to support the theory.

Fluidized bed combustion of Australian bagasse

The application of fluidized bed combustion (FBC) technology to energy generation from sugar cane bagasse has been prevented, amongst other reasons, by the difficulties associated with fluidizing this material. This difficulty arises because bagasse is often lightweight and of unusual morphology, and manifests itself by either matting-up within the bed (if there is not enough inert diluent) or by segregating out, usually floating to the surface (if the inert bed material is incorrectly chosen). So, the potential benefits of mixing inert solid and fuel, desirable for efficient combustion, is lost. For FBC to be viable, proper mixing of inert fluidizing solids and fuels are necessary. A model is presented in order to explain the mixing and segregation behaviour of binary particles in fluidized beds. The conditions corresponding to equilibrium mixtures can be theoretically predicted from the physical properties of the system. Experimental observations in a gas fluidized bed are shown to support the theory. Fluidized binary mixtures exhibit no tendency to segregate under a particular combination of solids and fluid volume fractions. In these cases, the mixture remains stable, even in the absence of mixing forces. The application of the theory to bagasse combustion in fluidized bed is discussed.

Spouted bed combustion of wood charcoal: performance comparison of three different designs

The combustion efficiency of a conventional spouted bed reactor with a central spout inlet is compared with two alternative reactors having different spout inlet arrangements. For one of the designs, air was introduced into a square duct column through a rectangular slit across the whole cross-section of the column, while in the other the air was introduced into a cylindrical column through a circular slit. Column cross-sectional area and air inlet area for all the reactors were approximately the same. The highest gas-solid contacting and lowest carbon monoxide (CO) emission was achieved in the design with circular slit air inlet while the lowest gas-solid contacting and highest CO emission was observed in the design with rectangular slit air inlet.

Environmental pollution generated from process industries in Bangladesh

The sources of environmental pollution in process industries in Bangladesh are discussed. Total pollution load into environment (i.e., into air, water and land) generated from process industries is determined and presented using industrial pollution projection system (IPPS) developed by the World Bank. Most polluting industries in Bangladesh are identified and ranked. The projection of this pollution load for year 2011–2012 is estimated and discussed. It was found that the food industry was the worst air polluter, whereas pulp and paper was the worst water polluter, and tanneries and leather industries were worst polluter of toxic chemicals. Industrial pollution control measures are recommended.

Segregation in binary and ternary liquid fluidized beds

The mechanism underlying segregation in liquid fluidized beds is investigated in this paper, A binary fluidized bed system not at a stable equilibrium condition. is modelled in the literature as forming a mixed part-corresponding to stable mixture-at the bottom of the bed and a pure layer of excess components always floating on the mixed part. On the basis of this model: (0 comprehensive criteria for binary particles of any type to mix/segregate, and (ii) mixing, segregation regime map in terms of size ratio and density ratio of the particles for a given fluidizing medium, are established in this work. Therefore, knowing the properties of given particles, a second type of particles can be chosen in order to avoid or to promote segregation according to the particular process requirements. The model is then advanced for multicomponent fluidized beds and validated against experimental results observed for ternary fluidized beds

Study on Australian energy policy, socio-economic, and environment issues

This article deals with the Australian total energy consumption related to economic growth and carbon dioxide (CO2) emission in which total energy consumption is sub-divided into renewable and non-renewable energy consumption. The aim of this study is to determine the nexus between all energy elements with gross domestic product and CO2 emission using the Cobb-Douglas equation. The study is based on the Australian panel data over the period from 1976–1977 to 2012–2013. Vector error correction model and generalized method of moments were used to estimate the variables for the relationship between energy variables. The proposed model shows good agreement with the data available on the bioenergy production and consumption in Organization for Economic Co-operation and Development countries. In this model, oil price, oil consumption, carbon tax, renewable energy technology, population growth, urbanization, etc., have been considered as model variables or governing factors. The results show the bidirectional re...

Longitudinal heavy haul train simulations and energy analysis for typical Australian track routes

Computer simulations are utilised to study the energy used by heavy haul trains and the amount of energy that can be generated from dynamic braking of these trains; these studies allow the potential for the application of hybrid locomotives to be evaluated. An in-house written software package is used to perform simulations on the energy balance between energy usage and the energy generated from dynamic braking for heavy haul operations on two typical track routes in Australia. The simulation results show that the energy generated from dynamic braking can contribute up to 30% of the energy used in locomotive traction. Detailed analyses show that the locomotives can operate at an average power that is much less than full power, and an energy hybridisation potential factor is defined, with the maximum factor reaching a value of 63%. This factor indicates the considerable potential for using hybrid locomotive traction in heavy haul applications.