ABSTRACT
Aims: The final screening of fungal isolates aimed at applications based tertiary screening i.e. deinking of mixed office waste paper and saccharification of pearl millet stover and cellulases from selected fungal isolates were characterized. Study Design: An experimental study. Methodology: Samples from soil, compost and decaying wood were collected from different habitats and were screened based on growth over CMC-agar medium (primary screening), zone ratios and enzyme activities (secondary screening) and applications such as bio-deinking of mixed office paper and saccharification of pearl millet stover (tertiary screening). Results: 134 fungal isolates were selected during primary screening based on their growth. In secondary screening, fungal strains showing zone ratio of 3.0 or more were selected for application based tertiary screening. Two fungal isolates AKB-24 and AKB-25 were selected based on their applications in deinking of mixed office waste and saccharification of pearl millet stover after tertiary screening. Fungal isolates AKB-25 and AKB-24 were identified as Aspergillus nidulans and Penicillium sp. Optimum pH for FPase, endoglucanase, and glucosidase activities were 5.0 for both the fungal strains. Cellulases from A. nidulans AKB-25 were found moderately thermo-stable with optimum endoglucanase activity at 65ºC and optimal FPase and β-glucosidase activities at 60ºC. The maximal endoglucanase, FPase and β-glucosidase activities were observed at 55ºC for fungal strain Penicillium sp. AKB-24. Cellulases from both fungal strains were found stable up to 48 h at 50ºC. Conclusion: Aspergillus nidulans AKB-25 and Penicillium sp. AKB-24 were selected based on an extensive screening and enzymes from both fungal strains were found effective in bio-deinking of mixed office waste paper. Enzyme from Aspergillus nidulans AKB-25 was also found effective in saccharification of pearl millet stover.
ABSTRACT
Aims: The study aims at mitigating pulp kappa number before bleaching to minimize pollution load. Study Design: An experimental study. Methodology: The various parameters of direct fungal (Coprinellus disseminatus MLK01) treatment (F-stage) of unbleached kraft pulp of Anthocephalus cadamba were optimized and compared with the results of enzymatically pre-bleaching. Finally, the pulp was bleached by EQP three-stage and XECEHH six stages bleaching sequences. Results: Direct fungal treatment (F-stage) delignified the Anthocephalus cadamba kraft pulp more selectively with Coprinellus disseminatus MLK01 compared to xylanase prebleached pulp from the same fungus and oxygen delignification. F-stage mitigated the unbleached pulp kappa number by 55.0% and improved brightness and viscosity by 17.3 and 7.63% respectively. Kappa number reduction and brightness improvement were 22.1 and 6.3% more in F-stage compared to XE-stage. The kappa number and pulp brightness of oxygen delignified were 0.9 and 5.2% less compared to F-stage. The viscosity of oxygen delignified pulp reduced drastically due to alkaline peeling reactions compared to XE-stage (‒26.86%) and F-stage (‒27.09%). The brightness and viscosity of XECEHH bleached pulp were 80.1% and 7.4 cps at a chlorine demand of 4.3% while FEQP bleached pulp produced brightness of 79.7% and viscosity 8.2 cps. COD and colour values in effluent generated during FEQP bleaching were 53.29% and 54.36% less compared to CEHH bleaching.