Worapon Kiatkittipong

Life cycle assessment of bagasse waste management options.

Bagasse is mostly utilized for steam and power production for domestic sugar mills. There have been a number of alternatives that could well be applied to manage bagasse, such as pulp production, conversion to biogas and electricity production. The selection of proper alternatives depends significantly on the appropriateness of the technology both from the technical and the environmental points of view. This work proposes a simple model based on the application of life cycle assessment (LCA) to evaluate the environmental impacts of various alternatives for dealing with bagasse waste. The environmental aspects of concern included global warming potential, acidification potential, eutrophication potential and photochemical oxidant creation. Four waste management scenarios for bagasse were evaluated: landfilling with utilization of landfill gas, anaerobic digestion with biogas production, incineration for power generation, and pulp production. In landfills, environmental impacts depended significantly on the biogas collection efficiency, whereas incineration of bagasse to electricity in the power plant showed better environmental performance than that of conventional low biogas collection efficiency landfills. Anaerobic digestion of bagasse in a control biogas reactor was superior to the other two energy generation options in all environmental aspects. Although the use of bagasse in pulp mills created relatively high environmental burdens, the results from the LCA revealed that other stages of the life cycle produced relatively small impacts and that this option might be the most environmentally benign alternative.

Simulation of pervaporation membrane reactors for liquid phase synthesis of ethyl tert-butyl ether from tert-butyl alcohol and ethanol

Abstract The synthesis of ethyl tert -butyl ether (ETBE) from a liquid phase reaction between ethanol (EtOH) ethyl and tert -butyl alcohol (TBA) in pervaporation membrane reactors (PVMRs) is discussed in this paper. Three modes of PVMR operation; semi-batch reactor (SBR), continuous stirred tank reactor (CSTR) and plug flow reactor (PFR) were modeled using kinetic parameters of the synthesis over β-zeolite and permeability data for a polyvinyl alcohol (PVA) membrane from our previous work. Good agreement between experimental and simulation results for the SBR mode was obtained. The study focused on comparing PVMR performances between two modes of continuous flow operation for various operating parameters, i.e. ratio of catalyst weight to total molar feed rate ( φ ), ratio of membrane area to catalyst weight ( δ ), operating temperature and feed composition. It was found that the CSTR mode shows superior performance to the PFR mode only within some ranges of operating conditions. To obtain high ETBE yields, it is best to operate the PVMRs at low temperature with a high ratio of membrane area to catalyst weight ( δ ) and with the feed ratio of EtOH and TBA at the stoichiometric value or slightly higher.