Microbial activities during composting of pulp and paper-mill primary solids

In this study, bench-scale aerobic reactors were used to monitor microbial activities and determine the degradability of pulp and paper-mill primary solids. Over the 43-day composting period, the level of microorganisms detected increased four-fold. However, based on amounts of CO2 produced, the increase expected was 19-fold, suggesting lysis of some cells in the population. The composition of the microbial population, determined through species identification by the BIOLOG(R) method, and by spot plating, changed throughout the composting process with Cellulomonas spp. not appearing until day 22. Chemical analyses suggested a fall of 33% in the cellulose content, but no other statistically significant chemical changes were observed.