Raw Sewage Treatment by Coagulation/Flocculation and Ozonization

Coagulation/flocculation and ozonation are two treatment methods commonly used for effluents. Coagulation/flocculation destabilizes the charged particles in the medium, causing them to aggregate for subsequent separation through decantation or flotation. On the other hand, ozonation is an advanced oxidative treatment that can be employed for effluent polishing. This study aimed to evaluate the effectiveness of combining coagulation/flocculation and ozonation as an alternative treatment for raw sewage collected at the Curupy treatment station in Sinop, MT. The experiments were conducted in batches, involving seven doses of tannin-based coagulant (ranging from 0 to 300 mg L ^-1 ) with and without ozonation (for 40 minutes). Parameters such as pH, color, turbidity, UV absorbance (UV abs), chemical oxygen demand (COD), and biochemical oxygen demand (BOD) were measured before and after the treatments. The results demonstrated that the pH values remained relatively unaffected by the treatments. However, ozonation consistently led to superior removal rates compared to non-ozonation for color, turbidity, UV abs, COD, and BOD (with removal percentages of 86, 87, 74, 71, and 55% respectively, compared to 60%, 74, 49, 58, and 36% without ozonation. For color and turbidity, stabilization of removal rates occurred at coagulant dosages above 100-150 mg L ^-1 , regardless of ozone contact. Overall, the employed treatments ensured that the sewage met the required conditions for discharge into bodies of water and also made it suitable for potential reuse, thanks to the significant clarification of the effluent. The treatments effectively removed suspended and colloidal solids from the sewage as well as dissolved compounds.