1997 Volume 8 Issue 7 Pages 303-310
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 (3 to 6 times) 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 touna 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 -1.0 kg-N/m3/d and 11.6- 3.7 d, 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 0.39-0.78 kg-N/m3/d (HRT= 4.9-2.4 d) ) .
