Basic Studies on Composting of Animal Wastes (2)

Limited Air Flow for Fermentation during Ventilation at Room Temperature and Effects of Property Reformers

Abstract

Composting experiments were performed with the compact experimental device which had been shown in our previous report.
Effects of waste properties and ventilating ratio on maximum temperatures of the materials and values of moisture losses were investigated. The results were as follows;
1. Carbonated husk was considered to be more suitable for the property reformer than sawdust which had been used generally, since it had a good effect on temperature rising of material and did not need such a sufficient treatment for decomposition of lignin as the sawdust needed.
2. Under the moisture content which was as high as that of raw manure, the fermentation resulted in wrong condition with property reformer whichever was chosen from the two (Fig. 1). It was confirmed that moisture content around 65% on wet basis was an upper limit for the effective composting when property reformer was used.
3. In the case of initial moisture content as high as that of raw manure, more than 15% property reformer to fecal wastes was needed in order to perform its function (Fig. 2). The result showed that considerable quantity of property reformer had to be mixed into fecal wastes in order to produce suitable waste condition to composting operation.
4. Experiments which were assumed that manure existed together with urine were performed. The results showed that mixing of urine gave a good effect on composting (Fig. 3 & 4).
5. The dry matter loss which brought about from fermentation had a considerable close correlation with the mean value of material temperature (Fig. 6). The material temperature which was equivalent to a result of thermo balance between fermentation and drying seemed to influence on decomposition rate of material ready to be resolved.
6. Condition for certain generation of high temperature was considered to be a range of ventilating ratio from 0.3 to 1.0l/min. per 1kg dry matter of mixed material, when maximum temperature of material was regarded as an important factor. While, the fermentation hardly occurred in ventilating ratio more than 5l/min. per 1kg dry matter.
7. Optimal ventilating ratio for decreasing moisture ranged from 1 to 3l/min, per 1kg dry matter. Regarding the result of former clause, ventilating ratio about 1.0l/min. per 1kg dry matter was considered to be optimal for rising temperature and decreasing moisture.