Removal of Aldehydes in Exhaust Gas with Sodium Sulfite Solution

Abstract

Aldehydes in exhaust gas from dryers or apparatuses of the Zimmermann processes in night soil treatment plants can be removed by the addition reaction with sodium sulfite. The selection of anti-oxidant for Na₂SO₃ solution and the condition for aldehyde absorption were investigated in this paper. The following results were obtained. Glycerol is the most effective anti-oxidant. The optimum condition for aldehyde absorption at room temperature is specified as follows: superficial gas velocity; 1.0-1.7m/s, liquid/gas ratio: 2l/m³ (or larger), pH of the absorptive solution: around 7, Na₂SO₃ concentration: 5×10-2mol/l for 250 ppm aldehyde content (1×10-1mol/l for actual gas). Under this condition, exhaust gas for the Zimmermann process could be removed almost completely.