Determination of stability of MBT-material

Mechanical-biological treatment (MBT) is - besides incineration - a common means of processing municipal solid waste (MSW) in order to stabilize the organic fraction before final disposal. Stabilization leads to a significantly reduced emission potential compared to fresh municipal solid waste, regarding both liquid and gaseous emissions. The definition of and the development of appropriate analytical tools for determination of the stability of MSW are topics of current interest in the European Union. Currently, stability is determined by sum parameters (i. e. total organic carbon (TOC), loss of ignition (LOI), dissolved organic carbon (DOC)) and biological reactivity. Whereas sum parameters do not necessarily characterize stability, biological tests are laborious and expensive. Infrared (IR) spectroscopy and thermal analysis (TA) provide comprehensive information on the chemical composition of solid waste samples. Results of preparatory investigations of MBT-material showed that different stages of organic matter degradation are reflected by characteristic changes in the IR-spectral and thermal pattern. Thus we assume that these methods - overcoming the drawbacks of the methods mentioned above - may represent rapid and reliable analytical tools for improved assessment of the actual emission potential of MBT-material. The main aim of the proposed project is the development of methodologies based on IR-spectral and thermal patterns for - Assessment of stability of mechanically-biologically treated municipal solid waste and - MBT-process control To achieve this a comprehensive investigation covering a wide range of diverse MBT-samples (all Austrian MBT- plants, as well as different seasons, input materials and levels of the process) is planned. Further to characterization with IR-spectroscopy and TA, conventional stability relevant parameters, including TOC, total nitrogen, DOC, respiration activity and gas generation will be determined to serve as reference. For interpretation of IR- spectroscopic and thermal analysis several statistical and chemometric approaches, including classification based on visual screening of spectra and thermograms, multivariate pattern recognition and classification methods, as well as multivariate calibration methods for prediction of biological parameters will be applied. Finally the different approaches will be compared and evaluated with regard to their feasibility for practical application.