[Water distribution and dewatering performance of the hydrothermal conditioned sludge].
Water distribution within sludge is an effective means of characterizing its ability to dewater. The bound water content and water bond strength in hydrothermal treated sludge were investigated based on differential scanning calorimetry (DSC), and sludges were dewatered by expression tests. Hydrothermal treatment of sludge resulted in a decrease of bound water content from 3.6 g/g dry solid to lower than 1.0 g/g. The lowest bound water content was 0.592 g/g at 170 degrees C and 90 min. The results indicated that the hydrothermal treatment of the sludge changed the bound water into free water which could be mostly removed during the mechanical dewatering performance, and improved the dewater ability of sludge. The residual free water in the dewatered cake was basically keeping unchanged about 10% depending on the dewatering operation system error. The thermodynamic interpretation showed that the water bond strength in the dewatered cake was at the same level, and it was about 65 kJ/kg, which determined the dewatering process. There was a reduction of water content in dewatered cake from 80% to 50% with hydrothermal conditioning at 170 degrees C.
Department of Environmental Science and Engineering, Tsinghua University, Beijing 100084, China. xr02@mails.tsinghua.edu.cn
Rui
R
Xun
Wei
W
Wang
Wei
W
Qiao
D055598:Chemical Phenomena; D005374:Filtration; D006358:Hot Temperature; D012722:Sewage / Q000737:chemistry*; D014865:Waste Disposal, Fluid / Q000379:methods*; D014867:Water / Q000032:analysis*
D012722:Sewage; D014867:Water