Development and demonstration of a cleaner process to produce diosgenin from Dioscorea zingiberensis based on physical separation

A new, cleaner process to produce diosgenin (CAS number 512-04-9) from Dioscorea zingiberensis with much less pollutant generation has been developed based on physical separation. A demonstration factory with an annual production capacity of 200 t of diosgenin has been built in Shanyang County, Shaanxi Province, China. The new process employs several new techniques including separation and refinement of starch, reuse of acid and mechanical washing of acid hydrolyzate. Through the application of a series of cleaner techniques, the water consumption was reduced by 66.2%, the wastewater generation was reduced by 63.3%, the acid consumption was reduced by 81.1%, the residual acid in the wastewater was reduced by 93.4% and the chemical oxygen demand production was reduced by 43.7%. The overall economic benefit increased RMB 38,087 Yuan (USD 6046) per t of diosgenin. Based on the new process, the wastewater can be treated to meet the national discharge standard using a common wastewater treatment technology.