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

Abstract

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=460mL/h, H2C2O4 flowrate=2100mL/h, [Fe]0=150mg/L, pH=2.79, medium solar power=35.8Wh) 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 1386.8mg/L after 55 and 125min, 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 60Wh of accumulated energy due to the generation of hydroxyl radicals. However, solar power is unimportant at the end of the process (150Wh of accumulated energy), when the molecular reaction mechanism between H2O2 and the intermediates is predominant.The overall mineralization process (k=0.0096min−1) occurs due to the contributions of the photo-Fenton process (k=0.0044min−1) and the ferrioxalate photochemistry (k=0.003min−1). The synergism between both processes was 22.9% based on the first order rate constants for TOC removal.