Discfiltration and ozonation for reduction of nutrients and organic micro-pollutants from wastewater – a pilot study

The combination of coagulation/flocculation and discfiltration with ozonation to reduce nutrients and organic micro-pollutants in secondary effluent was studied in pilot scale at Lundåkraverket wastewater treatment plant in Landskrona, Sweden. With a chemical dose of 4 gAl³⁺/m³ and 1.5 g/m³ cationic polymer as active material effluent water quality with regards to total phosphorous (Tot-P), suspended solids and turbidity were 0.03, 2 mg/l and 0.5 Nephelometric Turbidity Units (NTU) in average. The effluent water quality was similar whether ozonation with an applied ozone dose of 2–9 gO₃/m³ was performed prior to or after coagulation/flocculation/discfiltration. The results were corresponding to removal efficiencies for the coagulation/flocculation/discfiltration process of 94, 74 and 85% for Tot-P, suspended solids and turbidity, respectively. For organic micro-pollutants removal, it was found to be beneficial to perform coagulation/flocculation/discfiltration prior to ozonation as the ozone requirements were lowered for the dosing intervals applied. The removal was in the range of 38–98% depending on process configuration and ozone dose.