FLOTATION PROCESS APPLIED TO SECONDARY SL UDGE EXTRACTION - PILOT PROJECTS AND TECHNICAL AND ECONOMIC-EVALUATION

Flotation tests with dissolved ail were carried out to separate solids from the liquid in an aerated lagoon effluent and in the mixed liquor from an activated sludge biological treatment. in all conditions stud ied, flotation allowed efficient removal of solids even in sludge bulk ing situations with a minimum quantity of flocculant. These tests, com bined with previous biological treatment test results, have led to the design of an industrial-scale system and to the completion of a finan cial and engineering analysis.