Techno-economic evaluation of ozone-oxidation for sludge reduction at the full-scale. Comparison between the application to the return activated sludge (RAS) and the sludge digestion unit

Ozone oxidation was applied to a fraction (30 %) of the return activated sludge (RAS) full-scale Wastewater Treatment Plant for reducing high production (20 t/week). The amount sent final disposal decreased by 50 % and 75 at 0.55 kgO3/h 0.80 dosage, respectively. When same ozonation system aerobic digestion (0.06, 0.50, 0.67 kgO3/h), reduction 27–77 %. A thorough economic analysis carried out considering overall quantity finally extracted from plant in presence absence ozonation, corresponding costs ozone operation costs. net cost saving calculated be 66.6 €/d 109.9 due two dosages, recycled unit, range 235–655 €/d, depending on percentage achieved. showed become economically convenient lower than that sustained Company. results obtained prove feasibility both locations WWTP: therefore, with respect other disintegration techniques, possesses technical advantage along versatility. Furthermore, it is also shown lowering dosages past experiences, since effectiveness still guaranteed.