Changes in Main Parameters of Biological Stabilisation of Municipal Waste from a Full-Scale Mechanical-Biological Treatment (MBT) Installation

Poland's mixed municipal waste management system has been based on mechanical-biological treatment (MBT). One of the MBT processes is the biological stabilisation of fractions of less than 80 mm. The final product after biological stabilisation is a stabiliser that, once the conditions required by law are met, can be landfilled. The stabilizer must meet the following requirements: the loss of ignition (LOI) of the stabiliser is less than 35% DM, the organic carbon content is less than 20% DM and the AT₄ value (aerobic 4-day respiration test) value is less than 10 mgO₂/g DM. The study aimed to analyse the changes that occurred during the first 4 weeks of biological processing of the fraction of less than 80 mm of mixed municipal waste. The bioreactor feedstock consisted of 41.7% organic fraction (OF), the LOI was 32.3%, and the AT₄ value was 45.7 mgO₂/g DM. During biological processing, at 4 weeks, the loss of OF in the total weight of the waste was found to be 22.6%, the losses after roasting decreased by almost 90% and the value of AT₄ was 6.6 mgO₂/g DM. This means that the stabiliser already after 4 weeks, according to the law, could be sent to a landfill.