Abstract
In this paper, we describe the issues regarding nonylpheol formation in the activated sludge process. In this research, a lad-scale experiment simulating a conventional activated sludge process was conducted for 160 days where hydraulic retention time was set at I day, solid retention time varied from 10 to 15 days and the dissolved oxygen (DO) level in the aeration section was controlled below 0.5mg·l-1. Nonylphenol ethoxylates (NPnEOs) (n=3 to 14) solution (200mg·l-1) were fed as a single organic substance. NPnEOs were degraded in the aeration section, but a large amount of NPnEOs (n=1-4) and NP accumulated in the activated sludge. However, nonylphenol formation was not observed in the batch biodegradation experiments under either saturated DO conditions or anaerobic conditions. It indicates that the reduction rate of short-chain NPnEOs and the formation rate of NP were strongly dependent upon the DO condition.
