Large batch bench-scale dissolved air flotation system for simulating full-scale turbidity removal

• Published in: Environmental technology 2022-05, Vol.43 (12), p.1791-1804
• Main Authors: Gonzalez-Galvis, Juan Pablo, Narbaitz, Roberto M.
• Format: Article
• Language: English
• Subjects: Algae; Batch flotation; Climate adaptation; Climate change; DAF bench-scale tests; Diameters; Dissolved air flotation (DAF); Eutrophic environments; Eutrophication; Flocculation; Flotation; Global warming; Jar tests; natural organic matter removal; operating variable sensitivity; Organic matter; Rivers; Separation techniques; Turbidity; turbidity removal; Velocity gradient; Wastewater treatment; Water depth; Water treatment
• ISSN: 0959-3330; 1479-487X
• DOI: 10.1080/09593330.2020.1852317

One of the expected outcomes of global warming is increased algal and cyanobacterial blooms. Based on its ability to separate algal particles, dissolved air flotation (DAF) is considered as a climate change adaptation technology for water treatment. The feasibility of DAF treatment is often assessed using DAF jar tests; however, they are not particularly good at predicting a full-scale DAF system's turbidity removals. Therefore, our group has developed a more reliable larger-diameter/larger-volume batch apparatus (LB-DAF), which was optimized by comparison with a full-scale DAF plant treating a low turbidity, highly coloured river water (SUVA ∼ 4.3). The objective of this study was to verify that the LB-DAF was capable of simulating full-scale DAF systems treating two significantly different waters. One was water from a large eutrophic bay in Lake Ontario (SUVA ∼2.6) and the second was a river water (SUVA ∼3.5). The turbidity removals achieved by the full-scale DAF systems treating these waters were compared with those for the LB-DAF tests conducted using different flocculation velocity gradients, saturated water pressures, recycle ratios and water depth to diameter ratios. The LB-DAF tests are good predictors of the full-scale DAF turbidity removals, the average difference for the two waters tested were 2% and 6%. The LB-DAF natural organic matter (NOM) removals for both waters differed by less than 1% from that measured at the corresponding treatment plants. In addition, as in our previous LB-DAF study, varying the different LB-DAF operational variables did not have a significant impact on turbidity and NOM removals.