Graduate Thesis Or Dissertation
 

Fungal growth responses to a photooxidized sodium ligninsulfonate

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https://ir.library.oregonstate.edu/concern/graduate_thesis_or_dissertations/736667877

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  • Sodium ligninsulfonate, a water soluble wide-range molecular weight polymeric by-product of the paper pulping industry, is added as waste effluent to water ways or burned, causing extreme pollution. The polymer is highly resistant to biodegradation. Therefore, modification of the structure to a more readily biodegradable form would be desirable, to be able to use this material for economic recovery, such as single cell protein (SCP), or other useful products. The ideal method of alteration would be one which did not in itself lead to other unwanted waste products such as would be inherent in a chemical process. In this study a sodium ligninsulfonate, Marasperse CB, was phototreated using a mercury-vapor ultraviolet lamp. Parameters studied during photolysis were oxygen effects, initial starting pH, temperature and wavelength ranges. Analytical methods included total carbon, thin layer chromatography, spectrophotometry, and fungal dry weight. The photolyzed ligninsulfonate was then used as a growth substrate for an Aspergillus isolated from soil enrichment. Definitive improvement of ligninsulfonate biological availability was demonstrated after photo-treatment of initial pH 3, 7 and 12 solutions. The response of the Aspergillus isolate was substantiated by assays of substrate carbon before and after growth, dry weights in relation to photolysis treatment time, and semiquantitative thin layer chromatography. The highest fungal yield came from the initial pH3 solution followed closely by the initial pH 12 solution. The pH 7 solution was approximately 50 percent of the former two. The greatest loss of carbon after growth occurred in the pH 3 and 12 solutions. Thin layer chromatography showed that during irradiation three new components were formed and three existing components increased in concentration as irradiation times increased. All of these components were reduced below detection limits after use of the solution as a growth medium. Carbon retention after irradiation was greatest in the initial pH 3 and 12 solutions as compared to the pH 7 solution. Photolysis occurred most efficiently in the pH 3 solution with regard to time, fungal yield, carbon loss after growth, and substrate utilization efficiency (fungal dry weight/carbon utilized). Wavelengths less than 210 nm allowed the most rapid modification with wavelengths greater than 280 nm causing essentially no short-term change. Photolysis of the ligninsulfonate was found to be temperature independent and oxygen dependent, showing a true primary photodecomposition mode. Photo-treatment of ligninsulfonate and definitive fungal growth response to the irradiated solution suggests that this treatment could be applied to improve biodegradation of other recalcitrant structures as well.
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file details RockhillRobertC1970.pdf 2017-08-17 Pubblico Scaricare