The Effect of Low Initial C:N Ratio during Composting of Rice Straw Ash with Food Waste in Evaluating the Compost Quality

Abstract

The physicochemical and biological changes was examined during composting of rice straw ash with food waste in order to assess the effectiveness as stability and maturity of compost at low initial C:N ratio of 20 with three different aeration rates of 0.4, 0.6, 0.8 L/min.kg. The rice straw was burned at 300°C temperature to produced rice straw ash before being used to compost with a food waste. A laboratory-scale of bin composter reactor in a cone-shape was used during the composting process. The composting mixture with aeration rates of 0.6L/min.kg maintained the temperature exceeding 55°C for three days to meet the requirement of pathogen destruction compared to the composting mixture with aeration rate 0.4L/min.kg and 0.8L/min.kg. The final C:N ratio for composting mixture with aeration rates 0.4, 0.6 and 0.8L/min.kg was 11. The pH values and moisture content obtained for all composting mixture was in a range of 7-8 and 40-70%. However, the final germination index in all composting mixture was never over 80%.