Water Science & Technology: Water Supply Vol 6 No 3 pp 9–16 © IWA Publishing 2006 doi:10.2166/ws.2006.705
Adsorption test of semi-volatile di-(2-ethylhexyl) phthalate in coagulation and flocculation processes with/without bubble in closed jar tester
Y. Thaveemaitree*, F. Nakajima**, H. Furumai* and S. Kunikane***
*Department of Urban Engineering, the University of Tokyo, 7-3-1 Hongo, Bunkyo, Tokyo, 113-8656, Japan (E-mail: yongyodt@env.t.u-tokyo.ac.jp; furumai@env.t.u-tokyo.ac.jp)
**Research Center for Advanced Science and Technology (RCAST), the University of Tokyo, 4-6-1 Komaba, Meguro, Tokyo, 153-8904, Japan (E-mail: nakajima@env.t.u-tokyo.ac.jp)
***Department of Water Supply Engineering, National Institute of Public Health, 2-3-6 Minami, Wako, Saitama, 351-0197, Japan (E-mail: kunikane@niph.go.jp)
ABSTRACT
Di-(2-ethylhexyl) phthalate (DEHP) is widely used and abundantly exists in the environment. Due to fresh water contamination, DEHP can enter drinking water treatment and be adsorbed on solid floc generated mostly from coagulation and flocculation processes. This study aimed to quantify the distribution of DEHP in liquid/solids (floating scum, suspended solids and settled sludge) after coagulation and flocculation processes with/without bubble. For this purpose, we developed a closed jar tester to prevent DEHP volatilization and contamination from the laboratory environment. According to DEHP adsorption results, the aluminium coagulant is an important factor for DEHP adsorption and the floating solid contained more DEHP than the settled solid. 60–72% of initial DEHP was found in solid under conditions with aluminium coagulant, whereas 3–5% of initial DEHP was found in solid under the condition without coagulant. When the bubble presented, DEHP concentration in the solids in the top and middle layers increased. The 55 minutes of operation time (coagulant, flocculation and settling processes) was not long enough to achieve the equilibrium of DEHP adsorption especially in the cases with coagulant.
Keywords: Adsorption; bubble; coagulation/flocculation; di-(2-ethylhexyl) phthalate; drinking water treatment
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