Abstract: A two-phase anaerobic system composed of UBF acidification reactor with iron chip filter and UASB mechanization can treat medical wastewater from production of Zinc5-aminosalicylate (Zn5-ASA) of high concentration. The experiment results showed that when the HRT of the UBF and UASB was controlled at 5.95 h and 11.43 h respectively, the OLR of UBF and UASB reactors could COD highly reached 58.44 and 17.01 kg/(m³.d) respectively, and the total removal rate of COD and BOD₅ was about 90% and 95% respectively. From these results, this system has advantages of stable operation and high treatment efficiency. In the system, the iron chip filter of the UBF reactor can efficiently improve the bio-degradation of the wastewater by micro-electrolysis, and can save the regular adjusting alkali process. This system may open a new method for the treatment of organic wastewater difficult to degrade.