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

* Tokyo Tanabe Pharmaceutical Company
** Department of Chemical Engineering, Tokyo University of Agriculture and Technology

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

Abstract

This paper describes a highly efficient chemical/biological treatment process for photo-processing waste (PW) . This process has "demonstrated" treatment efficiencies of 96% for total organic carbon (TOC) and chemical oxygen demand (COD), 99% for total nitrogen (T-N), and 98% for total phosphate (T-P) . The process involves the initial treatment of raw PW by peroxide oxidation, followed by dilution (3to6times) and an aerobic biological activated carbon (BAC) treatment. The waste stream is then subjected to biological denitrification using an up-flow anaerobic sludge blanket (UASB) system. By taking advantage of Fe2+, S2O32-, and SO32- contained in PW, the Fenton reaction was found to act instantly upon peroxide oxidation without adding Fe2+ or adjusting pH levels. Results showed that the oxidation process sharply decreased TOC and COD to 40% and 20%, respectively, while simultaneously improving the biodegradation of refractory compounds. Moreover, by neutralizing the peroxide oxidation solution, 98% of the waste's T-P was removed. In the aerobic BAC system, where the load of ammonium nitrogen and the hydraulic retention time (HRT) were fixed respectively to 0.09-1.0kg-N/m3/d and 11.6-3.7d, the ammonium nitrogen was nitrified and organic compounds underwent degradation. As a result, the ammonium nitrogen was completely nitrified to nitrate or nitrite, and then denitrified to nitrogen via a biological denitrification process in which the denitrification rate was 99% (operating at the load of 0.39-0.78kg-N/m3/d (HRT=4.9-2.4d) ) .

Key words: photo-processing waste, peroxide oxidation, refractory compounds, aerobic biological activated carbon (BAC), biological denitrification.