Prediction of temperature and thermal inertia effect in the maturation stage and stockpiling of a large composting mass

Abstract

A macroscopic non-steady state energy balance was developed and solved for a composting pile of source-selected organic fraction of municipal solid waste during the maturation stage (13500 kg of compost). Simulated temperature profiles correlated well with temperature experimental data (ranging from 50 to 70ºC) obtained during the maturation process for more than 50 days at full scale. Thermal inertia effect usually found in composting plants and associated to the stockpiling of large composting masses could be predicted by means of this simplified energy balance, which takes into account terms of convective, conductive and radiation heat dissipation. Heat losses in a large composting mass are not significant due to the similar temperatures found at the surroundings and at the surface of the pile (ranging from 15 to 40ºC). In contrast, thermophilic temperature in the core of the pile was maintained during the whole maturation process. Heat generation was estimated with the static respiration index, a parameter which is typically used to monitor the biological activity and stability of composting processes. In this study, the static respiration index is presented as a parameter to estimate the metabolic heat that can be generated according to the biodegradable organic matter content of a compost sample, which can be useful in predicting the temperature of the composting process.

Optimal bulking agent particle size and usage for heat retention and disinfection in domestic wastewater sludge composting

“…However, recent results obtained in the industrial composting of municipal solid wastes have shown that the utilization of large particles of bulking agent used to prevent a loss of porosity in large composting masses does not have a significant effect on the material heat retention. In these organic wastes, the temperature is maintained for long periods given the properties of compost as a heat insulator (Barrena et al, 2006).…”

Respirometric screening of several types of manure and mixtures intended for composting

“…For mixture 3 no differences in the biological activity were observed through the process. The measurement of biological activity is of special relevance in full scale facilities, where the temperature is maintained in the thermophilic range because of the limited heat transfer (Barrena et al, 2006b), even when biological activity has diminished. Differences were observed in the evolution of interstitial oxygen content of the studied materials.…”

Phospholipid fatty acid analysis to monitor the co-composting process of olive oil mill wastes and organic household refuse

“…Indeed, during waste composting the high temperatures reached strongly affect the microbial growth and biodegradation kinetics [9]. The high values are directly influenced by the mode and frequency of aeration [10][11][12] as well as the compost's insulating properties [13].…”