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PW06 Life-Cycle Assessment
(PW074) Assessment tool for waste solvent treatment options in Swiss chemical industry.
Hungerbühler, K.1, Capello, C.1, Hellweg, S.1, 1 ETH Zurich, Zurich, Zurich, Switzerland
ABSTRACT- In chemical industry large amounts of waste solvent accrue annually. Mainly two different waste solvent treatment options are applied: (1) thermal treatment in special waste solvent incinerators and the cement industry and (2) solvent recovery. A generic inventory tool was developed to support decision making in the waste-solvent management of chemical industry. The incineration module of this tool calculates inventory data of solvent combustion as a function of the elemental waste solvent composition and technology used. The model for solvent recovery focuses on solvent distillation, which is the most important technology for solvent recovery. Input parameters that can be specified by the user comprise the waste solvent composition, solvent recovery rate, ancillary products, process specifications (e.g. reflux ratio), and the technology used for the treatment of the residues. If such process information is not available, default values including uncertainty ranges are provided. To determine these default values and uncertainty ranges, statistical methods were applied. In collaboration with Swiss chemical industry, we collected over 150 data for input and output variables from different solvent distillation processes. The statistical evaluation of these data provides empirical average, minimum, and maximum values. In order to calculate uncertainty ranges probability distribution for each parameter were statistically fitted. With increasing completeness of information from the user (e.g. used technology, yield, energy demand, etc) these uncertainty ranges decrease. The application of the model is illustrated in case studies on the comparison of incineration and solvent recovery. First results show that distillation is the environmentally preferable treatment option if solvents with complex petrochemical production are recovered. Incineration can be important if waste solvent mixtures have high enthalpy of combustion and little contamination with halogens.
Key words: waste solvent management, waste solvent treatment (incineration, distillation), generic inventory tool, LCA
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