Treatment of washrack wastewater with water recycling by advanced flocculation–column flotation

• Published in: Desalination and water treatment Vol. 8; no. 1-3; pp. 146 - 153
• Main Authors: Rubio, Jorge, Zaneti, Rafael Newton
• Format: Journal Article
• Language: English
• Published: L'Aquila Elsevier Inc 01-08-2009; Desalination Publications
• Subjects: Aerated flocs; Applied sciences; Drinking water and swimming-pool water. Desalination; Exact sciences and technology; Flocculation; Flotation; Pollution; Water reuse; Water treatment and pollution; Aerated flocs; Flotation; Flocculation; Water reuse; Bus; Energy consumption; Motor vehicle; Operating conditions; Waste water; Solid liquid separation; Flocculation reagent; Physicochemical purification; Road traffic; Recycling
• ISSN: 1944-3986; 1944-3994; 1944-3986
• DOI: 10.5004/dwt.2009.679

A new technique for flocculation and flotation (aerated flocs), called flocculation–column flotation (FCF) was evaluated for the treatment of vehicle (bus) washrack wastewater and water reuse. The system is composed of a compact flocculation–flotation unit, utilizing an in-line flocculator device, a centrifugal multiphase pump which generates microbubbles (Sauter mean diameter, 75 μm), and a column flotation for solid/liquid separation. Design and operating parameters were studied and the efficiency of the FCF was evaluated based on the chemical and physio-chemical quality of the treated water. A tannin derivative was employed as a flocculant and aerated flocs (0.8–1.6mm diameter; 45–150 m h-1 rise rates) were rapidly formed (10 s, residence time). Due to the rapid formation of these very light flocs, the FCF system was able to handle a high hydraulic-load capacity (>18 mh-1), using a reduced foot print (compact unit), and reduced energy consumption. The data shows that this rapid FCF system appears to have a high potential to treat oily (or non-oily) voluminous wastewater at high flow-rates.