The influence of biomass temperature on biostabilization–biodrying of municipal solid waste

Abstract

A laboratory study was carried out to obtain data on the influence of biomass temperature on biostabilization–biodrying of municipal solid waste (initial moisture content of 410 g kg wet weight (w.w.) −1). Three trials were carried out at three different biomass temperatures, obtained by airflow rate control ( A=70 °C, B=60 °C and C=45 °C). Biodegradation and biodrying were inversely correlated: fast biodrying produced low biological stability and vice versa. The product obtained from process A was characterized by the highest degradation coefficient (166 g kg TS 0 −1; TS 0 −1 = initial total solid content) and lowest water loss (409 g kg W 0 −1; W 0 = initial water content). Due to the high reduction of easily degradable volatile solid content and preservation of water, process A produced the highest biological stability (dynamic respiration index, DRI=141 mg O 2 kg VS −1; VS = volatile solids) but the lowest energy content (EC = 10,351 kJ kg w.w. −1). Conversely, process C which showed the highest water elimination (667 g kg W 0 −1), and lowest degradation rate (18 g kg TS 0 −1 ) was optimal for refuse-derived fuel (RDF) production having the highest energy content (EC = 14,056 kJ kg w.w. −1). Nevertheless, the low biological stability reached, due to preservation of degradable volatile solids, at the end of the process (DRI = 1055 mg O 2 kg VS −1 ), indicated that the RDF should be used immediately, without storage. Trial B showed substantial agreement between low moisture content (losses of 665 g kg W 0 −1), high energy content (EC = 13,558 kJ kg w.w. −1) and good biological stability (DRI = 166 mg O 2 kg VS −1 ), so that, in this case, the product could be used immediately for RDF or stored with minimum pollutant impact (odors, leaches and biogas production).