Efficient solid waste composting by improved degradation of cellulose

Abstract

This work was undertaken to understand the degradation of cellulose in composting of food waste and paper mixture, and to find any correlations between the nitrogen behavior and cellulose degradation. The effects of operating parameters including C/N ratio, seed compost inoculation, temperature on the cellulose degradation were investigated intensity in laboratory scale experiment observing the changes of cellulolytic population, cellulase activity, cellulose content as well as general composting reaction throughout the composting process. Furthermore, the dominant cellulolytic microorganisms were isolated and identified. The C/N ratio of 14.0 significantly influenced the degradation of cellulose. The cellulose was degraded in maturing stage concurrent with peak cellulose activity, temperature rise, and sub-peak of $CO_2$ evolution rate. This retardation might be ascribed to the high content of ammonia resulted from the low C/N ratio as well as the abundance of easily degradable organic matters. However, the cellulose contained in waste paper fraction was degraded from the start of composting in C/N ratios of 20.4 and 29.9, indicating that this range of C/N ratio might be appropriate for the cellulose degradation. The seed inoculation was effective in promoting the degradation of cellulose at the early thermophilic stage, because a sufficient amount of cellulolytic population was supplied with the inoculation of seed compost at 25% on dry weigh base. As the seed inoculation increased, the cellulose activity was a high initially and rised rapidly to the maximum. Neverthless, the efficacy of seed inoculation seemed to be confined to the initial degradation of cellulose and early evolution of cellulase activity. The temperature was found to be a factor determining the degradation of cellulose. The high temperature above 60 ℃ gave rise to significant ammonification at the thermophilic period and influenced the start of cellulase activity and cellulose degradatio...