Tanning wastewater is difficult to be treated due to its high concentration of suspended solids (SS)

organic matters and chroma. In this work

an integrated process was proposed to treat the wastewater

which consisted of coagulation

anaerobic baffled reactor (ABR) and anoxic/aerobic-membrane bioreactor (A/O-MBR). The influences of coagulation conditions

ABR startup strategy and operation parameters (HRT

DO and temperature

etc.) on treatment effects were mainly investigated. The results showed that during the coagulation process (pH of 9.0-10.0 and PACl dosage of 350-450 mg·L-1)

the average removal rates of SS

chroma

total Cr and COD were 70.4%

73.9%

97.7% and 37.9%

respectively. Based on the strategy of stepped-loading

the ABR process startup was finished within 50 d

and after that a 68.2% of COD removal rate was achieved at the HRT of 20 h and temperature of 30℃. Through the optimizations of HRT (6 h) and DO (DO 2.0-3.0 mg·L-1) in the A/O-MBR the removal rates of COD and NH4-N were 67.7% and 81.3%

respectively. As a result

the final effluent quality well met the first class standard of DB 44/26-2001

demonstrating that the integrated process proposed in this paper was very promising to treat tanning wastewater.