Dustiness of compostable waste: A methodological approach to quantify the potential of waste to generate airborne micro-organisms and endotoxin

The objective of the present study was to assess the effect of different waste storage systems on the potential of the waste to emit airborne dust, micro-organisms and endotoxin. Batches of 8.8 kg of compostable waste were incubated at 20 degrees C for periods of 1-2 weeks in three different storage systems: a system with relatively free access of air (FA) to the waste (paper bags in the kitchen, paper sacks outside the house), a system with low access (LA) of air (plastic bags in the kitchen, a container outside the house), and an intermediate (IA) system (trash can in the kitchen, a container outside the house). The compostable waste was prepared in the laboratory using a standard recipe simulating average kitchen waste in Denmark. Weight loss and temperature of the waste were recorded during the storage period. After incubation, the volume of percolate was determined and the dustiness of the waste was measured in terms of the potential of the waste to emit bio-aerosols in a rotating drum. Storage in the FA system resulted in high weight loss of the waste (15-25% per week), a maximum temperature of 45 degrees C and no percolate was observed. The LA system resulted in low weight loss (<3% per week), a temperature at ambient level and a volume of percolate less than 0.1 litre. Waste stored in the IA system was intermediate with a weight loss of 5-8% per week, a maximum temperature of 36 degrees C and a volume of percolate less than 1 litre. Dustiness in terms of dust, endotoxin and micro-organisms was highly correlated to weight loss of the waste. Storage of the waste in the FA system resulted in extremely high concentrations of airborne micro-organisms in the rotating drum compared to that seen after storage in the LA system. The dustiness with respect to airborne Aspergillus fumigatus was at least a factor of 400 000 higher for FA waste compared to LA waste. The present method of testing dustiness of waste is considered important for the design of waste collection equipment and may therefore, over time, contribute to an improved air quality for the workers engaged in waste handling. (C) 1997 ISWA.