Treatment of bitumen post oxidative effluents by sulfate radicals based advanced oxidation processes (S-AOPs) under alkaline pH conditions

Sulfate radicals based Advanced Oxidation Processes (S-AOPs), namely Persulfate and peroxymonosulfate, were used for the treatment of post oxidative effluents from a production of petroleum bitumens under alkaline pH. Studies on the identification and monitoring of the volatile organic compounds (VOCs) along with COD, BOD and sulfide ions reduction were performed. Persulfate with a ratio between the oxygen from the oxidant and the COD in the effluents (rox) of 1.28 at 60 °C achieved 33% and 55% reduction of COD and BOD respectively. Peroxymonosulfate with a rox of 1.43 at 60 °C was the most effective S-AOP studied with 43% COD and BOD reduction. Sulfide ions were effectively oxidized in both technologies. Persulfate at lower rox 0.41 at 40 °C was the best process to treat VOCs. A detailed analysis of the effluents composition after treatment revealed VOCs by-product formation. Economical evaluation revealed that persulfate based processes were cheaper. Activation of PS and PMS by heat can occur but effectiveness of this method of activation is low. S-AOPs revealed to be effective as a pre-treatment method in terms of VOCs degradation. These studies also proved that a secondary treatment is mandatory for a cleaner production of petroleum bitumens.