Drawing the Materials Balance for an MBT cycle from Routine Process Measures in a Plant located in Venice

Abstract

An observation term was carried on in an MBT plant owned and run by a public Company to treat MSW left by separate collection. All observations and measurements were made without interfering with the ordinary operation rules, in order to assess the efficiency of one process cycle for a given batch of waste. Analytical data came from both a) process instruments and b) physical analysis of a batch of waste entering / exiting from a selected bio-cell. From the process mass losses (about 37% – including moisture evaporation – in that single process cycle) the theoretical amounts of water and carbon dioxide produced by biodegradation were calculated. A verification of the results was tried through a thermal balance, comparing the energy released by degradation with the energy losses from the bio-cell. The results showed a fair agreement, within 80%; what appeared critical is the knowledge of the chemical composition of fermentable waste (taken as cellulose as first attempt) and the actual amount of heat developed by biological oxidation.