【Paper】
Characteristics of Dioxins Removal by Coagulation and Sedimentation Process
Akihiro Toji* and Tetsuya Kusuda**
* Shinko Pantec CO., LTD
** Kyushu University
† Correspondence should be addressed to Akihiro Toji:
Shinko Pantec CO., LTD
（4-78 1-chome, Wakinohama-cho, Chuo-ku, Kobe, 651-0072 Japan）


Abstract
Removal characteristics of dioxins from leachate by a coagulation and sedimentation process are experimentally investigated.
Results of the experiments by dosing pentachlorobenzene（PCBZ）as a surrogate substance for the dioxins to tap water and to leachate showed that it was removed below its solubility and went down further with two and more times of coagulation and sedimentation treatment. Each of the PCDDs/PCDFs isomers was also removed below its solubility the same as PCBZ and the treated water met the latest effluent standards in concentration. These results were also confirmed at a commercial plant. At the commercial plant, 17.1pg-TEQ/L of the PCDDs/PCDFs in leachate was removed down to 1.42pg-TEQ/L in the effluent of the sedimentation tank.
The authors also proved that PCBZ behaves like the dioxins in the process of the coagulation and sedimentation and that the dioxins were removed under 10pg-TEQ/L which is equal to or less than the effluent standards.


Key words: leachate treatment, dioxins, coagulation, sedimentation, surrogate substance