Degradation of Procion Red H-E7B reactive dye by coupling a photo-Fenton system with a sequencing batch reactor.

A bench-scale study combining photo-Fenton reaction with an aerobic sequencing batch reactor (SBR) to degrade a commercial homo-bireactive dye (Procion Red H-E7B, 250mgl(-1)) was investigated. The photo-Fenton process was applied as a pre-treatment, avoiding complete mineralisation, just to obtain a bio-compatible water able to be treated by means of the SBR in a second step. In this sense, different Fenton reagent concentrations were assessed by following dye solution biodegradability enhancement (BOD(5)/COD), as well as the toxicity (EC(50)), DOC, colour (Abs(543.5)) and H(2)O(2) evolution with photo-Fenton irradiation time. Obtained pre-treated solutions were biologically oxidized in a SBR containing non-acclimated activated sludge. Different hydraulic retention time (HRT) in the bioreactor were tested to attain the maximum organic load removal efficiency. Best results were obtained with 60min of 10mgl(-1) Fe(II) and 125mgl(-1) H(2)O(2) photo-Fenton pre-treatment and 1 day HRT in SBR.