Enhancing sludge thickening in continuous treatment using polymeric bubbles with cationic polymer P2900 and...

Sludge thickening is a fundamental stage of treatment. This study investigated the application, in continuous treatment, of polymeric bubbles produced with cationic polymer P2900 and cocamidopropyl betaine (CAPB), a zwitterionic surfactant. The proposed reagent combination aims to form aerated flakes, solid waste structures, and rapidly rising air bubbles, ideal for treatments in compact units. Using this combination, it was possible to achieve a total solids concentration of 45% with the modified bubbles and 25% with the conventional water treatment. This level of thickening occurred under the following operating conditions: initial total solids (TS) concentration of 10 g L^-1, a flow rate of 5 L min^-1, saturation pressure (psat) of 3 atm, and polymer dosage of 10 mg (gTS)^-1. The suggested mechanism of action involves the adhesion of P2900 molecules to CAPB at the air/water interface, forming a lining on the bubble surface. Additionally, polymerized species form due to the residual aluminum (Al) in the sludge, which would occur during flocculation in the helical tubular flocculator (HTF), adsorbing the micelles and bubbles of CAPB. The critical micellar concentration (CMC) of CAPB was 0.26 mmol L^-1. Polymeric bubble technology can provide an efficient and cost-effective approach to sludge thickening in continuous treatment.