The influence of factors on dewaterability of one-stage autothermal thermophilic aerobically digested sludges.

One-stage auto thermophilic aerobic digestion (ATAD) could achieve the same sludge stabilization efficiency as two- or multi-stage ATAD process does. However, the dewaterability of sludge might be affected through thermophilic digestion because of the release of intracellular substances under the thermophilic temperatures. This paper investigated which operation factors affect intracellular substances released in the liquid phase of sludge that lead to different extent of dewaterability. The results showed that optimal digestion time needs to be prolonged up to 480 h to avoid a deteriorated dewaterability phase. The deterioration in dewaterability of the sludge could be minimized at a retention time of 360 h (i.e., 15 days) under a digestion temperature of 65 °C. Specific capillary suction time (SCST) had quadratic correlations with SCOD, protein (PN) and polysaccharides (PS) in the liquid phase. The coefficient between SCST and the ratio of PN/PS had a value of 0.9764, indicating that the sludge dewaterability was significantly deteriorated by biopolymer of protein and polysaccharides in supernatant.