Levels of ATP in different organic wastes under composting conditions

Background: the concentration of ATP in selected samples from the composting process of several organic wastes (municipal solid wastes, wastewater sludge, animal by-products and cow manure) has been determined in order to characterize the aerobic biological activity of such wastes. Results: the values obtained ranged from 0 (in old stable compost from cow manure) to 0.07 μ mol ATP/g dry matter in thermophilic samples of municipal solid wastes composting. In general, it was found that ATP levels were in agreement with the stage of the composting process (initial stage, thermophilic period and maturation). On the other hand, ATP concentration correlated well (p<0.05) with the overall respiration activity during a whole composting process of municipal solid waste at full scale. Conclusion: ATP concentration can be used to determine the biological activity of organic solid wastes in different stages of their biological treatment and to predict compost stability prior to soil application

Effect of inoculation dosing on the composting of source-selected organic fraction of municipal solid wastes

The effects of a commercial inoculum (MicroGest 10X, Brookside Agra L.C.) on the field-scale composting of the source-selected organic fraction of municipal solid wastes (OFMSW) have been studied by following routine parameters of the composting process (temperature, oxygen content and moisture) and biologically-related tests such as the respirometric index and the maturity grade. The inoculum was added to composting piles of OFMSW at different levels: control (no added inoculum), treatment A (10⁵ CFU g⁻¹ of OFMSW), treatment B (10⁶ CFU g⁻¹ of OFMSW) and treatment C (10⁷ CFU g⁻¹ of OFMSW). The inoculum selected produced a significant acceleration of the composting process with high levels of biological activity in the thermophilic phase. In terms of the acceleration of composting and economy the optimal treatment was B, which produced a reduction of approximately half of the total composting time. Treatment C did not improve significantly the results obtained with treatment B, whereas treatment A has little effect on the composting of OFMSW when compared with the control experiment. Respirometric index (determined at 55 °C) and maturity grade appeared to be the most reliable tests to follow the biological activity of the composting of OFMSW. On the other hand, routine parameters such as temperature, oxygen content and moisture showed no significant differences among the different inoculation levels tested in the composting process