An Advanced Experimental Composting Reactor for Systematic Simulation Studies

An advanced experimental composting reactor was constructed for systematic simulation studies of the effects of oxygen levels and temperature on carbon and nitrogen turnover in the composting process. The reactor was thermally insulated and equipped with a fan to mix the compost gases in order to eliminate possible gradients in temperature and gas composition. It was also equipped for independent control of oxygen level and temperature in the compost matrix. The control of oxygen content in the compost gas was such that 95% of the readings of the oxygen level were in the interval 16-01 ± 0-26% during an initial experiment. In the same experiment, 95% of the temperature readings were in the interval 54-6 ± 0-5°C. The volume of the reactor was approximately 200 l to allow for taking samples for analysis during prolonged experiments. The system was equipped for continuous monitoring of gas flow and emissions of the gases CO2, NH3 and N2O from the reactor. The water content in the compost matrix was controlled by adding water and mixing the material once a day to compensate for moisture losses due to drying as an effect of heat production and aeration. The regulation of water content was less precise than regulation of temperature and oxygen content and the average water content in the reactor varied within the interval 57.5-70.5%, It was concluded that the performance of the reactor was satisfactory for future systematic experiments.