Fenton and photo-Fenton processes integrated with submerged ultrafiltration for the treatment of pulp and paper industry wastewater

Abstract

Excessive amounts of wastewater produced by the paper industry, often containing a wide range of toxic and recalcitrant pollutants based on raw materials used, should be subjected to efficient treatment processes before discharging to the environment. This experimental work examined hybrid Fenton and photo-Fenton enhanced (UVC254 and UVA365) UF system performances in treating raw wastewater from pulp and paper industry by membrane oxidation reactor (MOR). By response surface analyses of Taguchi experimental design, the systems were compared onto hybrid efficiencies, in settings optimized for maximal responses with minimum chemical needs, regarding the performance metrics of TOC and COD removal efficiencies and UF water flux. Organics were removed slightly better than Fenton in both photo-Fenton, and H2O2 and Fe2+ spends per TOC were accomplished as more efficient than anticipated in every MOR system. Optimal TOC-COD removals were found as 64.0–74.9% by 85.2 L/m2h at Fenton system, and as 66.5–76.1% by 138.1 L/m2h at UVA-Fenton, while 69.7–82.1% by 90.0 L/m2h at UVC-Fenton with the lowest chemical spending. Hybrid MORs studied were at desirable operational costs of 2.11, 4.15 and 3.13 $/kg removed COD in Fenton, UVA-Fenton and UVC-Fenton systems, respectively, corresponding to the demineralisation costs of 0.0075–0.0143 $/g TOC removed. This study revealed that by synergistic MOR performances, effluents, after pH adjustment, are directly dischargeable in sewage infrastructure ending with complete treatment. In a near future, such innovative approaches towards industrial wastewater treatments, at less resource demands, will unambiguously gain importance, as pressures to reuse wastewater increase and discharge limits become stricter.