The importance of the volume ratio of bound water to dry solids in considering the solid liquid separation characteristics of sludges
The excess activated sludge is very difficult to filter, but its solid liquid separation characteristics can be improved by freezing and thawing process. In this paper, the centrifugal and the gravitational settling experiments were done by using unfrozen and frozen activated sludges. The volume ratios (Φ w) of bound water to dry solids in unfrozen and frozen sludge were 13 and 5, respectively. Therefore, it is found that the bound water in excess activated sludge can be decreased by freezing and thawing process. The equation for the average solid compressive pressure ((ps)av) in the sediment zone was derived, based on the general equation for the local compression characteristics of a solid-liquid mixture. Also, the relationship between (ps)av and the average porosity ((ε )av) in the sediment zone (1-(ε )av = E (ps)av ? , E and ? ; constants ) was confirmed by the centrifugal and the gravitational settling experiments. The order of (ε )av was unfrozen sample ? Fast frozen sample ? Slow frozen sample. This order was consistent with the order of the average specific filtration resistance obtained from the constant pressure filtration experiments.
K. Kawasaki A. Matsuda
Bunkyo-cho, Matsuyama, Ehime 790-8577, JAPAN Department of Applied Chemistry, Ehime University
国际会议
第四届中日化工学术研讨会(The 4th Joint China/Japan Chemical Engineering Symposium)(CJCES)
成都
英文
2007-12-19（万方平台首次上网日期，不代表论文的发表时间）