engleski

Effect of intermittent stirring on composting performance in two different types of reactors

A pilot-scale composting of tobacco waste was conducted in two thermally insulated, forcefully aerated reactors to determine the effect of intermittent stirring on the composting performance. The first two experiments were carried out in a 240 dm3 packed bed reactor at airflow rate of 0.65 dm3 min-1 kgVSinitial-1 ; the first experiment was carried out without stirring (PBRNS) ; during the second experiment reactor was periodically opened and the substrate was manually stirred (PBRS). The third experiment was conducted in a 200 dm3 horizontal reactor with stirrers (HRS) at airflow rate of 0.38 dm3 min-1 kgVSinitial-1. Substrate was automatically agitated every 24 hours for 1 minute with the stirring rate of 6.3 rpm. During the composting in PBRNS there was a significant temperature distribution over the bed height. At the end of the processes in PBRNS, PBRS and HRS conversions of the volatile matter were 50.6% (at 38. day), 53.0% (at 28. day) and 51.1% (at 29. day), respectively, showing that stirring increases the degradation rate. Obtained temperature profiles and calculated reaction enthalpies showed that in PBRS there was a significant heat loss caused by periodic stirring of the composting mass while the reactor was opened. For that reason, although similar conversions of volatile matter obtained in PBRs and HRs, horizontal reactor with stirrers is recommended. Furthermore, process in HRS is easier to handle and consumption of electricity for stirring could be partly compensate with lower aeration rate.

composting; stirring; horizontal reactor; packed bed reactor

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