Wild bacteria inactivation in WWTP secondary effluents by solar photo-fenton at neutral pH in raceway pond reactors

For first time, the efficiency of raceway pond reactors for wastewater disinfection by solar photo- Fenton (50 mg H2O2/L and 20 mg Fe2+/L) at neutral pH has been shown in this study. Complete inactivation of wild total coliforms, E. coli and Enterococcus sp. in municipal wastewater treatment plant secondary effluents took place after 80 min. A comparison with a tubular reactor equipped with a compound parabolic collector (CPC) was carried out and disinfection times were the same for the CPC and RPR, the tubular one having a 5 cm tube diameter and the RPR was operated at 5 cm liquid depth. Both acute and chronic toxicity were evaluated before and after treatment in both reactors and their analysis showed no significant changes for the removal of either in the treated effluent in both reactors. Additionally, an economic assessment of the process in the RPR was also performed. Estimated total costs for a 400 m(3)/d scale solar photo-Fenton plant for disinfection (0.15 (sic)/m(3)) were in the range of reclaimed water rates.