| Shan Yang County is seated in source protection area of "water from South to North". During these years, Zingiberpofficinale planting and diosgenin producing industry have developed rapidly. But, diosgenin producing wastewater is belong to organic wastewater of high density, that is has low acidity, that its component is complex, that is contains much ramification, which its color is dark and biodegradability isn't good. On account of Shan Yang County lies to the upper reaches of river, wastewater discharged by diosgenin producing enterprises has polluted water quality of lower reaches. Therefore, diosgenin producing enterprises are commanded to stop operating. So, it's necessary for diosgenin producing enterprises to reduce the discharge of wastewater and lighten pollution to lower reaches.The thesis brings up a scheme that wastewater discharged by diosgenin producing enterprises is reused to the process of diosgenin producing process. And analyzes its technological necessity and practicability. It finds that present treatment can't satisfy the command of discharge standard of Shan Yang County, while the reuse of wastewater can realize the zero-discharge and have no influence on product. So the reuse scheme is necessary and practicable. Besides, the thesis also evaluates the economic benefits by reuse scheme. Through comparison the cost of present and reuse treatment, it shows that reuse scheme not only can save more money than present method, but also can bring income indirectly for enterprises and government. So the reuse scheme has good economic benefits. Finally, the thesis also analyzes the society benefits brought by reuse scheme. It discovers that diosgenin producing enterprises can operate again as no discharge wastewater to river, which promotes the stability of Shan Yang County and development near Shan Yang County. Therefore, the reuse scheme can make diosgenin be produced again so realize indirectly society benefits.
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