Assessment of Degree of Maturity of Compost Produced by Different Kitchen Waste Composting Methods

Kitchen waste in general has high water content with various plant required nutrients and organic matters but is non-toxic, and therefore, it is a good composting material. Three different composting methods were applied for experiments twice, which are mechanical aerobic composting, simple bucket composting, and fast composting processor, by using the same source of kitchen waste as the raw composting material. No significant difference was found between the compositions of the two kitchen waste samples. The major components of the two kitchen waste samples of this study were water content (averaged 72.7%), followed by combustible constituent (about 25.6%). The carbon-to-nitrogen (C/N) ratio was between 15 and 25. Since the operation and parameters of these three composting methods were different, the compositions of compost products were different. Among these three composting methods, compost produced by the simple bucket composting method had the highest water content (an average of 25%), while compost by the fast composting processor had the lowest (about 11%). For C/N ratio, compost produced by the fast composting processor had the highest C/N ratio (an average of 26), compost by the mechanical aerobic composting method the second (about 22), and compost by the bucket composting method the lowest (about 12). It is stipulated by the Council of Agriculture that for the miscellaneous types of compost, the C/N ratio should be between 10 and 20 to ensure that the compost has reached maturity. For the germination test, compost produced by the mechanical aerobic composting method had an average of 84%, compost by the fast composting processor had 81%, and compost by the bucket composting method had an average of 95%. Although all three methods can yield compost with a maturity level greater than the minimum requirement (80%), compost produced by the simple bucket method had better maturity. When comparing the three compost samples produced by different methods to the standards given by the Council of Agriculture, only the simple bucket compost qualified all the criteria.