Comparison of dissolved air flotation and sedimentation for the treatment of two waters with low turbidity in Colombia

Abstract

The main objective of this research was to conduct a comparative study between dissolved air flotation (DAF) and conventional sedimentation (SED) for the treatment of a reservoir water (REW) and small stream water (STW) with low turbidity and low alkalinity in Colombia at the bench-scale level. The experiments were conducted at the bench-scale using a jar test apparatus. Aluminum sulfate was used as the coagulant. The experimental results showed that with an optimum coagulant dose of 30 mg/L as alum to treat REW and 10 mg/L as alum to treat STW; the percentage turbidity removal by DAF and SED were 88–85% and 84–86%; apparent color removal were 65–62% and 87%; and UV-254 nm removal as a surrogate measurement for the concentration of NOM were 74–73% and 64–69%, respectively. HIGHLIGHTS Comparison of two clarification processes in treating a reservoir and stream water for turbidity removal.; Comparison in removing natural organic matter by sedimentation and dissolved air flotation (DAF).; Advantages of DAF on sedimentation in treating two different low turbidity waters.; Impact of different flocculation times on DAF for turbidity removal.;

Keywords

• apparent color
• dissolved air flotation
• natural organic matter
• sedimentation
• turbidity