Improvement of domestic wastewater primary sedimentation through ozonation

The use of ozone as an aid for flocculation-coagulation of domestic wastewaters has been studied. Jar tests of ozonated and non-ozonated wastewater at different coagulant (hydrated aluminum and ferrous sulfate salts) and flocculant (calcium hydroxide and A-201 polyelectrolyte) doses have been conducted to obtain optimum floc size. Settling experiments have then been carried out to follow changes of total COD conversion and surface area of a primary settling tank needed to reach a given percentage particle separation. The results show that the use of preozonati- on provides beneficial results to both improve COD conversion and reduce the sedimentation surface area.