Research On The Comprehensive Utilization Technology Of Dioscorea Zingiberensis C. H. Wright(DZW) Industrial Waste Residue

Diosgenin is an indispensable precursor for steroid hormone drugs. Traditional diosgenin extraction method caused high pollution and high production cost. Meanwhile, large amount of acid and organic solvent used in traditional extraction method makes the solid residues are difficult to treat. What’s more, another raw material for steroid hormone drugs named androstenedione began to draw people’s attention again. Thus, it is urgent to develop new diosgenin extraction method to solve solid waste pollution problem in diosgenin industry and reduce production cost to make diosgenin have a certain advantage in the alternative competition with androstenedione, based on the cleaner production technology of diosgenin, this study carried out detailed research on the comprehensive utilization of solid waste in diosgenin industry. The results were as follows:(1) Through the composition and structural characteristics analysis of the solid residue in diosgenin industry, a reasonable DZW solid residue degradation scheme was determined: first, remove the hemicellulose by dilute acid low pressure steam expansion(DALPSE) method, and then extract the lignin by organic solvent extraction method, finally the DZW solid residue after pretreatments was hydrolyzed by cellulase.(2) Through the degradation process optimization of hemicellulose in DZW solid residue using dilute acid low pressure steam expansion method, the optimal process conditions were obtained: dilute hydrochloric acid(2 mol/L), the solid-liquid ratio between DZW solid residue and dilute hydrochloric acid was 3:8(g/mL). Under this condition, the degradation efficiency of hemicellulose and cellulose was 94.71% and 45.61% respectively. It was proved that hemicellulose hydrolysate needs further detoxification processing through fermentation evaluation by Saccharomyces cerevisiae. Meanwhile, the X-ray diffraction(XRD) detection proved that dilute acid low pressure steam expansion treatment can reduce the crystallinity of cellulose in DZW solid residue.(3) Through the optimization of organic solvent extraction of lignin, the optimal extraction conditions were obtained: organic solvent was 1,4-butanediol, the solid-liquid ratio between DZW solid residue and organic solvent was 1:12(g/mL), reaction temperature 200℃, reaction time 2.0 h. Under this condition, the lignin extraction yield reached 73.65%. And the infrared spectrum analysis proved that the lignin extracted from DZW solid residue by this method is syringyl-lignin.(4) Through the optimization of enzymatic hydrolysis of cellulose in DZW solid residue after pretreatments, the optimal enzymatic hydrolysis conditions were obtained: substrate concentration 40 g/L, citric acid-sodium citrate buffer(pH 4.8, 0.1 mol/L), enzyme concentration 20 mg cellulase/g substrate, reaction temperature 50℃, rotation speed 125 rpm, reaction time 60 h. Under this condition, the degradation efficiency of cellulose reached 42.68%. It was proved that the enzymatic hydrolysate of cellulose can be used for bio-conversion via the evaluation by Saccharomyces cerevisiae. The comparison of cellulose degradation efficiency using DZW solid residues under different pretreatments and the observation of environmental scanning electron microscope demonstrated that the pretreatment methods adopted in this research can effectively remove the first degradation barrier of cellulose and improve the efficiency of cellulose degradation.To sum up, the comprehensive pretreatments combined with enzymatic hydrolysis of DZW solid residues adopted in this research could effectively degrade the DZW solid residue, and it is a promising method to be applied in diosgenin industry to effectively degrade the solid waste.