Effect of Moisture Content and Air Frow Rate on High-rate Composting of Cattle Manure

Abstract

This study was initiated to investigate the effect of initial moisture content and air flow rate on high-rate composting of cattle manure at its early stage. A two-way layout statistical design was used for the experiment. The mean composting temperature of which influence of open air was eliminated was used as a criterion of aerobic decomposition of cattle manure. The following results were obtained through this study.
1. As the result of an analysis of variance, the contribution ratios of air flow rate, moisture content and their interaction for average composting temperatures were 48, 21 and 19 percent respectively.
2. During the initial phase of composting, the optimum aeration rate was 120 liters/min/m³ and the optimum moisture content was from 60 to 65 percent wet basis. In the case of this combination mean composting temperature of which influence of open air was eliminated was from 30 to 45°C at 1 percent level of significance. For the given set of conditions, the thermophilic temperature reached 73 to 76°C at the middle part of the composting mixture.
3. Moisture content and dried material weight of composting had little changes for each 48 hours incubation period. These results would be useful criteria for the design of windrow composting plant and applicable on small farms that must meet more strict environmental criteria.