The ozonation of extremely polluted petrochemical wastewater: Effect of catalysts, initial pH, volumetric flow rate and concentration of ozone on oxidation rate
Journal Title: Journal of Biodiversity and Environmental Sciences (JBES) - Year 2015, Vol 6, Issue 1
Abstract
Ozonation of an extremely polluted petrochemical wastewater from styrene and propylene oxide production and the influence of different factors on the treatment efficiency were investigated. The treatment efficiency was the highest under alkaline conditions and with the use of catalysts. Optimal values of ozone concentration and volumetric flow rate of the ozone-oxygen mixture were 20 mg L–1 and 400 L (L × h)–1, respectively. The use of H2O2 (0.075 wt%) as a catalyst allowed the maximum COD conversion (93%) and acetophenone removal (98%) to be achieved after 60 min. In the meantime, at an optimal concentration of MnSO4.5H2O (0.1 wt%), the treatment efficiency in terms of COD and acetophenone removal increased up to 85% and 84%, respectively. Acetophenone was completely removed from the wastewater when the ozonation time was increased to 90 min, using H2O2 or MnSO4.5H2O as a catalyst, while phenol, styrene, and ethylbenzene were entirely removed after 60 min. During the ozonation process an abnormal increase in pH appeared due to •OH-radical formation. This interesting phenomenon resulted in the possibility of increasing the treatment efficiency by lengthening the time during which the maximum pH as well as the maximum quantity of •OH-radicals were observed.
Authors and Affiliations
Quyen Ngo, Linh Dao, Evgeniy Grigoriev, Alexandr Petukhov
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