A novel clean bio-pulping process for rice straw based on aerobic fermentation coupled with mechanical refining

In this study, the effect of aerobic fermentation pretreatment on bio-mechanical pulping of rice straw was investigated with compound bacterial agents (2 geobacillus sp, 1 parageobacillus sp and 4 thermos sp). The microbial community, chemical composition, surface morphology, crystal index and other parameters were monitored at various time intervals during the aerobic fermentation process. The chemical constituents of rice straw (mainly cellulose, hemicellulose and lignin) were partly degraded and dissolved in the fermentation process, leading to increased surface roughness and crystallinity index. The bio-mechanical pulping process was optimized in terms of Canadian freeness standard (CSF), specific energy consumption (SEC), water retention value (WRV), pulping yield, and physical properties of the resultant pulp. Under the optimal process conditions, the fermentation pre-treatment resulted in about 54% energy saving, 13% WRV improvement, and 81% increase in tensile strength at a given pulp freeness.