Domestication And Process Optimization Of Flora Ethanol Fermentation Of Paper Mill Sludge

Paper mill sludge is a kind of solid waste produced in the process of wastewater treatment by paper-making enterprises, simple landfill, incineration or discharges directly without any treatment will not only easily make secondary pollution to the environment, but also make a resource waste. There is large amounts of fiber material in paper mill sludge, which can be used as the biomass raw material to ferment and produce fuel ethanol, possessing preferable value of resource utilization.This article based on that aims of achieving the resource utilization of paper mill sludge and optimizing the technology for biomass in paper mill sludge conversion to ethanol, researches in the domestication of fermented bacteria and the cellulase produced by fermentation with Tichoderma Reesei Rut C-30 have been done, also the mixed bacteria simultaneous saccharification and fermentation conversion to ethanol and the fermentation of pentose and hexose have been experimented.The content of holocellulose in paper mill sludge that produced by disposing of APMP papermaking wastewater with biological activated sludge has achieved 47.9%. Through using different concentration gradient paper mill sludge hydrolyzate to domesticated fermentation strain. The OD value of Saccharomyces cerevisiae and Escherichia coli increased respectively from 2.226 and 1.978 to 2.493 and 2.187, respectively increased about 12.0% and 10.6%, the data showed those microorganism has fairly adapted the growing environment of paper mill sludge fermentation, the strains tolerance towards fermentation have been obtained.The simultaneous saccharification and fermentation has been experimented with Tichoderma Reesei Rut C-30, Saccharomyces cerevisiae and Escherichia coli respectively as cellulase-producing strains and ethanol-fermented strains. The optimum fermented-condition at 5% substrate has been obtained by the single factor and the orthogonal experiments. fermented temperature 38℃,cellulase loading of 25 FPU/g substrate, inoculation size of 6%, E.coli koll and Saccharomyces cerevisiae ratio of 1:1 (cell dry weight, initial concentration of 1.0 g/L and 0.33 g/L) conditions.Under this optimum technology conditions, the yield of ethanol production per gram of paper sludge utilized was 0.115g/g, which corresponds to 42.31% of the theoretical yield. Analyzing the experiment of monosaccharide composition in paper mill sludge hydrolyzate by paper chromatography, the result demonstrated that more xylose and glucose exists in hydrolyzate, and also a little arabinose and mannose. The experiment to fermente glucose and xylose with mixed microorganism in mixture showed that the utilization of total reducing sugars in process of fermentation has reached 90.8%, the utilization of glucose is higher than xylose, and in the process glucose is firstly used to ferment. The fermentation result of paper mill sludge hydrolyzate with mixed microorganism demonstrated:ethanol-fermentation ranges in 24h, the highest yield of ethanol is 5.67g/L, the ethanol conversion rate achieved 63.06% of the theoretical yield.Analysis of infrared spectroscopy demonstrated that the intense degradation of cellulose and hemicellulose is the most remarkable change after hydrolysis and fermentation of paper mill sludge, The polysaccharide characteristic peaks of infrared spectrum of the original sludge is stronger than polysaccharide hydrolysis and fermentation. Analysis of scanning electron microscopy showed that cellulose is degraded highly apparent after hydrolyzing paper mill sludge, the fiber of fermentation residue is degraded completely basically in most way.