Improved mechanical removal of water from industrial or natural sludge - by addn. of complex hydrophilic and/or hydrophobic inorganic additive

摘要

The mechanical removal of water from industrial and natural sludges, contg. (mainly) microorganisms, using conventional techniques, e.g. filtration, centrifugation and pressing, is improved by adding to the sludge (a) less than 5 wt.%, or (b) more than 5 wt.% w.r.t. sludge dry matter, of a complex hydrophilic and/or hydrophobic inorganic additive with apparent density below 0.6 g/ml and grain size below 300 microns. In the case of (b), by recycling part of the de-watered and/or heated sludge into the untreated sludge at the end of the process, the amt. added is not more than 50% (0-30%), w.r.t. the initial sludge dry matter. The additive is hydrophilic and is a Na/Al silicate with at least 50% (at least 70%) of SiO2, or is hydrophobic and is phlogopite with at least 20% MgO or Na/Al silicate with at least 50% SiO2, with the polarity altered by a hydrophobising agent or addn. of a Si cpd. with Me gps. or an apolar cpd.. ADVANTAGE - The consistency of the sludge is improved, the rate of water removal is raised, and the efficiency of the process and the dry matter content of the sludge are an optimum. The sludge can be mechanically comminuted, granulated or powdered, and is more easily disposed of or burned.