Aki Yokoi*, Kimihito Futono*, Binle Lin*, Masaaki Hosomi*, and Akihiko Murakami*

* Dept. of Chemical Engineering, Faculty of Technology Tokyo University of Agri. and Tech.

+ Correspondence should be addressed to Aki Yokoi:
(2-24-16, Nakamachi, Koganei, Tokyo 184 Japan)

Abstract

It is difficult to treat film-processing wastewater (FW) only with a single process, because FW contains many refractory chemicals such as EDTA and CD-4s. Fenton's reagents (FR) are known to produce a hydroxyl radical, which is one of the strongest oxidizing agents when ferrous iron is present as a catalyst. It is expected that a chemical and biological treatment process will be promising as a FW treatment. In this study we carried on the experimental degradation of 20 refractory photo-chemicals (metol, etc.) contained in FW to evaluate the effect of the first Fenton process on the biodegradability of chemicals in a second biological process. We also conducted the experimental degradation of the same chemicals using the reverse process, i.e., the biological process followed by the Fenton process. The Fenton oxidation tests showed that the chemicals were degraded by 30% to 50% in dissolved organic carbon (DOC) . The consequent biodegradation test (for 100 hours) resulted in a DOC removal rate of over 90%. On the other hand, the overall DOC removal was rated at about 60% for all chemicals except for EDTA when tested in the reverse processes. This suggested that the refractory chemicals must have been converted into biodegradable substances by FR.

Key words: film-processing wastewater (FW), refractory chemicals, Fenton's reagents (FR), biological processes, biodegradability