Abstract
This paper describes the application of ozone treatment for liming float wastewater. Oxidation of both sulphide and organic compounds is investigated and applied on a highly concentrated alkali effluent. The ozonation proves to be efficient for the total oxidation of sulphides (S2-, HS-...) present in this effluent. The present study shows that 3.5 g of ozone are necessary to oxidize 1 g of sulphide. COD removal effectiveness by ozone alone is evaluated to 16% when the effluent is treated at its initial pH ( pH = 12.9) and biochemical oxygen demand (BOD5/COD) ratio of effluent, ozonated for 2 h, increases from 0.22 to 0.36 indicating that the effluent becomes biodegradable. Ozonation effectiveness strongly depends on pH. A high COD reduction (55%) is reached at optimal pH = 8. The addition of hydrogen peroxide, as an oxidant, enhances the efficiency of the ozone treatment. The COD removal increases from 16% with O-3 alone to 64%, after 1 h of ozonation with hydrogen peroxide dose of 8 mL per liter of liming float wastewater.