Improving water security and sanitation in rural areas: comparative evaluation of TiO₂ and photo-Fenton processes for rural wastewater treatment and reuse

Wastewater treatment and reuse are essential for addressing water shortages and promoting sustainable water security and sanitation development, particularly in rural areas. This paper aims to compare the performance of various oxidation processes, including UV/photo-Fenton, solar photo-Fenton, solar photocatalysis using TiO₂, and UV/TiO₂, for treating rural wastewater using response surface methodology (RSM). The effects of several factors on the photocatalytic treatment performance in terms of reducing organic pollutants and disinfecting wastewater were evaluated using Plackett–Burman and Box–Behnken experimental designs. The outcomes indicate that pH is a crucial factor for enhancing photocatalytic treatment efficiency. By optimizing the photocatalytic treatment conditions, the Fenton process achieved the highest removal efficiencies for different pollutants. Specifically, at a pH of 3, a concentration of 1.678 mg/L of the reagent Fe²⁺ was sufficient to reduce COD, TOC, and turbidity by 44.88, 55, and 97.21%, respectively, within just 1 h. Interestingly, the optimized conditions led to significant removal of ammonium (69.74%). Bacteriological analyses further demonstrated reductions in total germs and E. coli and the absence of streptococci. The effect of phytotoxicity on lettuce seed growth was evaluated in terms of the germination index (GI). The treated wastewater showed no phytotoxic effects and achieved a GI above 99%. The findings highlight the effectiveness of the Fenton process as a viable treatment alternative for enhancing effluent quality and increasing the potential for the agricultural reuse of effluent as fertilizer.