Degradation patterns of organic material in batch and fed-batch composting operations

Abstract

Using dog food as a model organic waste for composting raw materials, the degradation patterns of organic materials in dog food during batch and fed-batch operations were compared. The degradation pattern of the organic materials was con firmed by continuously measuring the quantity of CO ₂ evolu tion during the composting process. The CO₂ evolution rate in the batch operation peaked at 30 h, then gradually decreased, whereas the rate in the fed-batch operation peaked daily every time the dog food was added. In the fed-batch operation, the conversion of carbon and the population den sity of bacteria dropped when new dog food was added, but quickly recovered. While the conversion of carbon fluctuated from day to day by a few percent, on average, approximately 80% of the carbon added had been converted by around the 8th day of composting of the fed-batch operation.