Studies On Treatment Of Wastewater From The Process Of Extraction Diosgenin Of Dioscorea Zingiberensis

According to the characteristics of wastewater from the process of Dioscorea zingiberensis C. H. Wright which are of high concentration, high chroma and low pH, this paper studied pretreatment of wastewater by process of activated carbon absorption, photocatalysis oxidization and iron-carbon microelectrolysis- coagulation respectively. Effluent after pretreatment was treated further by UASB, and the paper studied on startup and operation of the process, comparison and analysis of results of three pretreatment methods.Above all, activated carbon was adopted to pretreat the wastewater. In the condition of pH 4.0, temperature in 25 ℃, removal efficiency of chroma was 95.61%, removal efficiency of COD was 51.72%. Regenerated by heating, removal efficiency of COD of effluent after pretreatment by activated carbon absorption was over 50%, removal efficiency of chroma was over 90%, and recycle efficiency of activated carbon was 94.40%. The value of BOD/COD of wastewater after treatment was 0.24, and lowered to the original wastewater. Photocatalysis oxidation was used for pretreating the wastewater. In the condition of pH 4.0, treatment time of 1.5 h, removal efficiency of COD was 68.72%, removal efficiency of chroma was 62.24% and the value of BOD/COD was 0.55. At last, to pretreat the wastewater adopted the method of iron carbon microelectrolysis–coagulation. In the condition of pH 4.0, HRT 40 min, removal efficiency of COD and chroma were 64.70% and 72.22%, respectively. The value of BOD/COD was 0.59.The acclimation of UASB reactor was completed successfully with organic loading rate of 5.0 kg COD/m3·day as influent after pretreatment by adopting a strategy of quick start-up in 60 days. During the course of operation of UASB system and in the condition of OLR 10~12 kgCOD/m3·d, removal efficiency of COD and chroma were both up to 95%, at the same time , operation of the reactor was steady. It was in the same state when OLR was improved to 15 kgCOD/m3·d, but the treatment efficiency of the reactor decreased; It was steady to avoid acidification as pH of effluent of the UASB reactor was in the range of 7.9~8.0.Specific methanogenic activity of granule sludge in UASB reactor was higher when organic loading rate was up to 10~12 kgCOD/m3·d, and activity of sludge of the system of UASB reactor was in the optimum situation. Wastewater after pretreatment by photocatalysis oxidation was disposed further by UASB reactor which operation was steady, and it acquires good effect. In the condition of organic loading rate was increased to 15 kgCOD/m3·d, removal efficiency of COD and chroma were 92.07% and 91.24% respectively, at one time the system of UASB reactor was steady. Wastewater after pretreatment by activated carbon absorption was disposed further by UASB reactor which operation was steady. Removal efficiency of COD and chroma were 84.62% and 87.50% respectively when organic loading rate was increased to 22.5 kgCOD/m3·d, and the system was steady.The combination of iron carbon microelectrolysis-coagulation with UASB was adopted to treat the wastewater from the process of Dioscorea zingiberensis. COD and chroma of the effluent which was treated by the combination were about 500 mg/L and 140~150 degree respectively, and pH was in the range of 7.9~8.0, removal efficiency of COD and chroma are 98.33% and 98.60% respectively.