Abstract:A new 2 900 m3 IC anaerobic reactor had been built by an OCC papermaking company, and the anaerobic granular sludge from the same kind of wastewater was introduced. After starting up for 21 d, the IC anaerobic reactor reached the design loading and could treat OCC wastewater for 15 000 m3/d with total CODCr for 50 000 kg/d. The CODCr removal rate was 72%~86%, and the VFA of reactor outlet water remained 30~110 mg/L, indicating the new IC anaerobic reactor can improve efficiency in a short time.