Research on Sludge Toxicity Caused by DMF Biodegradation and Toxicity Spatial Distribution in Sludge Flocs
降解DMF引起污泥毒性及其毒性空间分布特性研究

The aerobic sequencing batch activated sludge system (SBR) was used to remove the toxic and refractory organic pollutant, N,N-dimethylformamide (DMF). The formation property and spatial distribution of the organic toxicity in sludge were studied. The operation parameters were controlled as follows: influent COD was about 300 mg·L-1, every DMF concentration phase lasted 30 d(40 mg·L-1, 80 mg·L-1, 120 mg·L-1), the SBR cycle lasted 12 h, and DO was 2.0-3.0 mg·L-1. The results showed that the sludge toxicity increased in the beginning and then decreased to a steady range at each DMF concentration phase; there was a positive correlation between the sludge toxicity and the initial DMF concentration; most of the sludge organic toxicity was caused by DMF biodegradation and existed in the inner extracellular polymeric substances (EPS) and intracellular section of sludge flocs.