In the lower portion, the temperature was found to be constant at a relatively high level throughout the composting process. The composition of the hog faeces changed significantly during the composting process, as shown in Table 3. The former is the energy source and the latter the nutrient source for rapid microbial activity. To realize this potentially high susceptibility to decomposition, there must be an ample supply of oxygen. Lowering of the moisture content by either drying or mixing in fresh faeces with the seed compost is effective for improving aeration within the heap.
Heat generated by active aerobic fermentation also effects evaporation.
The key to success in the continuous composting system is maintenance of a highly active aerobic fermentation. Once the microbial flora are contaminated with anaerobes, recycling does not operate smoothly. In the case of sewer water treatment, BOD proceeds from one phase to another. The first phase is said to take 14 days, which coincides with the period required for the aerobic fermentation in the system described. The main installations and expenses are shown in Table 4.