Effects of salinity on expression dewatering of waste activated sludge

This work evaluates filtration followed by consolidation characteristics of sodium chloride containing activated sludge. Experimental results indicate that contact time and salinity level affect the dewatering efficiency. Con sidering the consolidation stage, a critical salinity level (around 1-2% (w /w)) is observed at which the contribution of secondary consolidation stage reaches its minimum. Meanwhile the creeping among constituent aggregates b ecomes much easier than in the original sludge. In addition, double-layer c ompression/hydrophobic interactions and ion exchange partially account for the experimental results. (C) 1999 Academic Press.