Solar-photo-Fenton treatment of wastewater from the beverage industry: Intensification with ferrioxalate

• Beverage industry wastewater mineralized by solar photo-Fenton/ferrioxalate process.
• Under optimal conditions, 70.6% of TOC was removed in 55 min and 96.6% in 125 min.
• The process also removes completely the toxicity, COD and 99.8% of BOD-5.
• This process considerably reduces the time of a biological treatment.
• Synergism of photo-Fenton process and ferrioxalate photochemistry is 22.9%.

The mineralization of industrial wastewater from beverage industries during a solar photo-Fenton enhanced process mediated by ferrioxalate complexes was evaluated as an alternative to reduce the total treatment time required for conventional anaerobic digestion procedures in a compound parabolic collector (CPC) pilot plant. Under selected conditions (H2O2 flowrate = 460 mL/h, H2C2O4 flowrate = 2100 mL/h, [Fe]0 = 150 mg/L, pH = 2.79, medium solar power = 35.8 Wh) and continuous operation, 70.6% and 96.6% of the total organic carbon (TOC) was removed from industrial effluent with an initial TOC concentration of 1386.8 mg/L after 55 and 125 min, respectively. In addition, this process completely removed the toxicity and COD and removed 99.8% of the BOD-5.First, the physico-chemical pre-treatment of raw wastewater was performed based on sedimentation to remove suspended solids and reduce the turbidity by 91%.The effects of the variables were studied during two different irradiation periods. Solar power is the main factor that influences mineralization during the first 60 Wh of accumulated energy due to the generation of hydroxyl radicals. However, solar power is unimportant at the end of the process (150 Wh of accumulated energy), when the molecular reaction mechanism between H2O2 and the intermediates is predominant.The overall mineralization process (k = 0.0096 min−1) occurs due to the contributions of the photo-Fenton process (k = 0.0044 min−1) and the ferrioxalate photochemistry (k = 0.003 min−1). The synergism between both processes was 22.9% based on the first order rate constants for TOC removal.