Effect of chaotic mixing on enhanced biological growth and implications for wastewater treatment: A test case with Saccharomyces cerevisiae

• Published in: Journal of hazardous materials 2006-08, Vol.136 (1), p.130-136
• Main Authors: Bagtzoglou, Amvrossios C., Assaf-Anid, Nada, Chevray, Rene
• Format: Article
• Language: English
• Subjects: Applied sciences; Cell Proliferation; Chaotic advection; Chemical engineering; Exact sciences and technology; General purification processes; General treatment and storage processes; Hydrodynamics of contact apparatus; Mixing; Pollution; Reactors; Saccharomyces cerevisiae; Saccharomyces cerevisiae - cytology; Saccharomyces cerevisiae - metabolism; Waste Disposal, Fluid - instrumentation; Waste Disposal, Fluid - methods; Wastes; Wastewater treatment; Wastewaters; Water treatment and pollution
• ISSN: 0304-3894; 1873-3336
• DOI: 10.1016/j.jhazmat.2005.11.039

Mixing patterns and modes have a great influence on the efficiency of biological treatment systems. A series of laboratory experiments was conducted with a controlled, small-scale analog of a pilot wastewater aeration tank, consisting of two eccentrically placed cylinders. By controlling the rotation direction and speed of the two cylinders, it has been possible to develop chaotic flow fields in the space between the walls of the cylinders. Our experiments utilized Saccharomyces cerevisiae as the biological oxidation organism and air bubbles as the mixing agent supplied by a large fine pore diffuser to the cells in their exponential growth phase. The effect of various mixing patterns on cell growth was studied at different cylinder eccentricities, rotation directions and speeds. It was found that chaotic advection flow patterns: (a) enhanced growth, and (b) sped up the onset of maximal growth of the organism by 15–18% and 14–20%, respectively.