Exhaust gas cleaning in which solvent is sepd. from washing fluid - has separate stages to separate activated sludge and solvent from washing fluid at absorption tower

摘要

To clean exhaust gas, charged with biologically degradable matter and esp. impurities which are dissolved with difficulty in water, it is passed through an absorption tower to be washed by a fluid with an activated sludge and a high boiling solvent in a circuit to absorb the impurities. In an initial stage, the activated sludge is sepd. from the mixt. of solvent and washing fluid. The solvent is sepd. from the washing fluid in a separate second state. Pref., the activated sludge is sepd. from the mixt. of solvent and washing fluid in a separator or centrifuge, and the solvent is sepd. from the washing fluid by membrane filtration, esp. micro- or ultra-filtration. At least part of the activated sludge is returned to the cleaning circuit, and the sepd. solvent is wholly or partially returned to the cleaning circuit. The sepn. of the solvent and the washing fluid is continuous or intermittent. ADVANTAGE - The sepd. water or purified water, is free of matter and esp. activated sludge or solvent, and requires no further treatment or disposal.