Study On The Reclamation Of Wastewater From Diosgenin Production Of Dioscorea Zingiberensis C.H.Wright And The Technology Of Pollution-free Production Of Diosgenin

The wastewater from diosgenin production of Dioscorea Zingiberensis C.H. Wright was of great acidity, high organic matter concentration and carbohydrates produced in the process of amylum hydrolysis. The rivers which the wastewater poured into directly without any treatment from the diosgenin factories were polluted seriously, which had been a hard nut to crack of the healthy development of the industry. In this paper, the way of comprehensive utilization of the wastewater was studied to make it reclaimed and reduce pollution. Meanwhile, the technology of pollution-free production of diosgenin, amylum separation technology, was also discussed.Objectives: Study the technology routes to the reclamation of diosgenin wastewater and the pollution-free production of diosgenin to reduce pollution and equalize the cost of treatment and solve the environmental problem caused by diosgenin wastewater. Methods: The first batch wastewater, which was the most polluted and consisted of the highest organic matter concentration, was used to produce industrial alcohol. The conditions of fermentation process was optimized and the fermentation scale was enlarged. The new way of pollution-free production of diosgenin, amylum separation technology, and its effect on diosgenin yield, amylum yield and acid demand were also analyzed. Results: 1. One yeast strain which could grow well and produce alcohol in wastewater had been screened out after domestication and selection. The optimum technological parameters of wastewater pretreatment and fermentation process were found out and reached the pilot-scale experiment's level. The results showed that the output of the 85% industrial alcohol of45L wastewater was 1600mL. According to national standard GB394-93, the industrial alcohol conformed to criterion of acceptability on the whole. The economic benefit was obvious which could be a new pocketbook for wastewater further treatment. After alcoholic fermentation, removal percentage of CODcr, BOD5, chroma and reducing sugar was 70%, 61%, 71% and 87% respectively. Organic matter content in wastewater reduced sharply and water quality was improved markedly. The value of BOD/COD reached 0.40 - 0.42 showing the increased biodegradability of wastewater. 2. A new way that araylum in Dioscorea Zingiberensis C.H.Wright was separated ahead of hydrolysis and diosgenin extracting was attained and had many advantages contrasted to the traditional production route: the by-product amylum was obtained and amylum yield reached 30.2%, diosgenin yield increased by about 10.68% and acid demand decreased by about 15%;the quantity and the organic matter content of the diosgenin wastewater reduced largely which could lighten the stress of wastewater treatment obviously. Conclusions: By means of comprehensive utilization of diosgenin wastewater to produce industrial alcohol, not only the wastewater pollution to environment could be reduced, but also the aim at balancing the cost of the wastewater further treatment and even at gaining economic profit could be achieved. In addition, it was easy for most of diosgenin factories of small scale to accept because of its simpleness and feasibility. Compared with the traditional method, the new way had many strongpoints and was a tendency of diosgenin industry to develop. Both of the technology routes had obvious economic and social benefits.