| heal.abstract |
A reliable method for monitoring the composting process evolution and assessing compost stability is a key factor for successful composting. Respirometric methods are commonly used, but they usually measure the activity at one specific temperature. In this study the objective was to determine simultaneously the respiration activity, in terms of oxygen uptake rate, at a number of different temperatures. The ""thermogradient respirometer"" developed consists of a solid aluminum cylinder (1.5 m long, 155 mm diameter), in which a controlled and stable temperature gradient was achieved by attaching an electrically heated plate to one end and a cooling system to the other. The respiration rate of samples obtained from a 0.6 m3 pilot scale bioreactor, where olive mill wastewater was cocomposted with extracted olive press-cake, was determined at eight different temperatures, from 20 to 66°C. The thermogradient respirometer revealed more information about the history and the origin of the samples than respirometry at one temperature, and proved to be a very sensitive instrument for process monitoring, as it could identify shifts of microbial populations in the composting mass. |
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