Treatment of industrial wastewater contaminated with recalcitrant metal working fluids by the photo-Fenton process as post-treatment for DAF

[Display omitted] Post-treatment of the industrial wastewater polluted by metalworking fluids (MWFs) was performed using the photo-Fenton process in following of the chemical addition-dissolved air flotation (CA-DAF) unit. Prior to this study, the CA-DAF was operated as full-scale by trial and error. For the photo-Fenton process as a pilot-scale batch reactor, initial pH value, FeSO4, and H2O2 concentrations were considered to study the effect of different operating conditions on chemical oxygen demand (COD) and total petroleum hydrocarbon (TPH) removals. This hybrid approach revealed removal efficiencies of 99.85% and 98.9% for COD and TPH in the optimized photo-Fenton process as pH 3, FeSO4: 100mg/l, and H2O2: 17.8g/l. The COD degradation results for the photo-Fenton system indicated that it could be well fit using a pseudo first-order kinetic model. By the GC–MS analysis of DAF and applied photo-Fenton effluents, a 73% removal rate of mono(2-ethylhexyl) phthalate was detected. It is likely favorable to increase the biodegradability. The cost analysis of this process for the consumed energy (6kWh) and chemicals (0.01818kg FeSO4 and 17.15kg H2O2) was estimated at approximately 26 $ per 1m3 of DAF effluent. Generally, these results imply that the CA-DAF unit followed by photo-Fenton is an effective and practical method for treating MWFs wastewater.