Cheese wastewater treatment through combined coagulation-flocculation and photo-Fenton-like advanced oxidation processes for reuse in irrigation: effect of operational parameters and phytotoxicity assessment

Abstract

The present study aims to investigate the e ciency of a combined cheese wastewater treatment approach involving coagulation with ferric chloride coupled with a Photo-Fenton-like oxidation process for potential reuse in irrigation. Laboratory-scale tests were conducted, examining the in uence of various operational parameters on the treatment process. Speci cally, the effects of initial wastewater pH, coagulant dosage, decantation time for the coagulation process, and initial pH, chemical oxygen demand (COD) concentration, Fe 3+ and H 2 O 2 dosages for Photo-Fenton-like oxidation were studied. Coagulation was found effective at natural pH of 6 and showed a highest removal e ciency in terms of COD (50.6%), biological oxygen demand BOD 5 (42.1%), turbidity (99.3%), and least sludge volume generation (11.8% v/v) for an optimum coagulant dose of 400 mg Fe 3+ L -1 and 8 hours of decantation time. Thereafter, the sequential treatment of cheese wastewater based on coagulation as a pre-treatment process and then Photo-Fenton-like oxidation (Fe 3+ /H 2 O 2 /UVA-300W), enhanced the removal of COD, BOD 5 and total organic carbon (TOC) to 91.2%, 91.4% and 97.5%, respectively using the optimized conditions (pH = 3;and 24 hours of irradiation time). Furthermore, the phytotoxicity of treated cheese wastewater was evaluated by seed germination and root elongation tests using lentil seeds as bioindicators. The experimental results showed that the combined process allowed a signi cant phytotoxicity reduction. The obtained outcome was encouraging and supports the possible use of the treated cheese wastewater as an additional water source for agricultural irrigation, helping to reduce the existing de cit and conserve water resources.