DUSTINESS OF COMPOSTABLE WASTE - A METHODOLOGICAL APPROACH TO QUANTIFY THE POTENTIAL OF WASTE TO GENERATE AIRBORNE MICROORGANISMS AND ENDOTOXIN

The objective of the present study was to assess the effect of differe nt waste storage systems on the potential of the waste to emit airborn e dust, micro-organisms and endotoxin. Batches of 8.8 kg of compostabl e waste were incubated at 20 degrees C for periods of 1-2 weeks in thr ee 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) syst em (trash can in the kitchen, a container outside the house). The comp ostable waste was prepared in the laboratory using a standard recipe s imulating average kitchen waste in Denmark. Weight loss and temperatur e of the waste were recorded during the storage period. After incubati on, the volume of percolate was determined and the dustiness of the wa ste was measured in terms of the potential of the waste to emit bio-ae rosols in a rotating drum. Storage in the FA system resulted in high w eight 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 lo w weight loss (<3% per week), a temperature at ambient level and a vol ume of percolate less than 0.1 litre. Waste stored in the IA system wa s intermediate with a weight loss of 5-8% per week, a maximum temperat ure of 36 degrees C and a volume of percolate less than 1 litre. Dusti ness in terms of dust, endotoxin and micro-organisms was highly correl ated to weight loss of the waste. Storage of the waste in the FA syste m resulted in extremely high concentrations of airborne micro-organism s in the rotating drum compared to that seen after storage in the LA s ystem. The dustiness with respect to airborne Aspergillus fumigatus wa s at least a factor of 400 000 higher for FA waste compared to LA wast e. The present method of testing dustiness of waste is considered impo rtant for the design of waste collection equipment and may therefore, over time, contribute to an improved air quality for the workers engag ed in waste handling. (C) 1997 ISWA.