A new recycling hydrolytic-aerobic combined process was developed to treat the high concentration organic wastewater. Simulated wastewater containing 10 g·L^-1 starch with a CODcr value of 10000 mg·L^-1 wasused. At first, the hydrolytic degradation and aerobic degradation process were examined in two batch reactors, respectively. In the stand-alone hydrolytic process, starch in the wastewater almost disappeared after 11 h treatment, but CODCr remained as high as 5803mg·L^-1 after two days. In the aerobic process, the biodegradation rate of starch was much slower during the first 11 h than that in the hydrolytic process, although the CODCr removal efficiency reached 89.6% and more than 90% starch could be degraded after 37.5 h. To determine the interaction effects of the two processes, a series of hydrolytic-aerobic combinations were examined in details. Hydrolytic process played an important role in the whole recycle combination process as it could improve the biodegradability of the high concentration starch wastewater. However, from the other experiments, the negative effect of hydrolytic acidification was found in the hydrolytic-aerobic combination, which suggested that the aerobic microorganisms needed time to adapt themselves to the acidic environment. The effect of the degrading time, which was spent in the hydrolytic and aerobic unit, and the number of circulations, with which the wastewater went through the two units were investigated. It was found that a recycle combination of 6 h hydrolytic process with 12 h aerobic process was highly effective and potentially economical, in which the final removal efficiency of CODcr and efficiency of starch degradation reached 94.1% and 98.8%, respectively.
