Sven Nimmermark

Physical and chemical processes in baled waste fuel, with emphasis on gaseous emissions.

Over a period of seven months, the temperature and the emissions from six cylindrical and two rectangular stored bales containing waste for later use as fuel were measured. The bales were kept at two different ranges of temperatures: 30-35°C and 20-25°C respectively. It was found that only the rectangular bales showed significant production of CO2. The increase of emission for one of the rectangular bales kept at 30-35°C, was 0.246% vol. CO2 per day for a 2-week period, after which there was a decrease of CO2 concentrations at a rate of 0.0224% vol. during a 32-week period. The other rectangular bale kept at 20-25°C, exhibited a similar trend. However, the increase of CO2 concentrations was less at a rate of 0.0259% vol. per day during a 8-week period, after which the CO2 emission decreased at a rate of 0.0224% vol. per day during a 25-week period. All the bales exhibited aerobic decomposition in the sampling point. However on measuring the leachate concentrations, it was evident that the bales were actually in the equivalent acid-generating phase of a young landfill. The temperature inside the bales did not increase higher than the ambient air temperature.

Physical, Chemical and Biological Processes for Optimizing Decentralized Composting

On-site composting of nonpolluted organic wastes avoids costs and energy for transportation since the volume to be transported can be reduced to about 20% of the original. This paper describes the aerobic processes in a small-scale composting reactor, and evaluates how these processes can be optimized. The optimized composting process has a relatively short turnover time for organic matter; at the same time the temperature of about 60°C decreases the problems with pathogens and weeds in the mature compost. The compost produced has a high nutritional value, with high concentrations of especially nitrogen, potassium and phosphorus, while the contamination by heavy metals and other toxic substances are very low.