Comprehensive utilization method for wastewater in stevioside production

The invention discloses a comprehensive utilization method for wastewater in stevioside production, and belongs to the technical field of wastewater treatment. The comprehensive utilization method comprises the following steps: (1) collecting the wastewater in a stevioside production process, adding a flocculating agent till the pH value is 7.0 to 8.5, and performing slag-liquid separation after the flocculating agent settles down naturally, thus obtaining filtrate; (2) blasting the filtrate to form bubbles till no bubbles flow out, and collecting the bubbles to obtain bubble liquid; (3) extracting bubble-broken liquid, which is obtained by breaking bubbles in the bubble liquid, with water-saturated n-butyl alcohol to obtain an extracting solution, concentrating the extracting solution, and purifying the extracting solution through a silica gel column, thus obtaining a saponin concentrate; (4) treating the residual filtrate with a reverse osmosis membrane to obtain permeated liquid which can be directly used