Treatability of Surfactants in Wastewater from a Pharmaceutical Facility Using Chemical Oxidation and Advanced Oxidation Processes
Abstract:Peroxide and permanganate oxidation, ultrasound induced oxidation, ozonation, UV and UV+H2O2 oxidation processes are tested for removal of surfactants in a pharmaceutical process wastewater. The objective is to achieve total surfactant concentration in the effluent as less than 2 mg/L. Presence of H2O2 did not show any enhancement on ultrasound degradation of surfactants. However, presence of permanganate improved removal of surfactants under ultrasound irradiation. With 1 g/L permanganate, total surfactant was 75% removed, with concentration decreased to 2.1 mg/L after 3 hours of sonication. Ten (10) minutes of ozonation produce about 31% removal of total surfactant. After 20 min of ozonation, 22% of cationic surfactant was removed while 69% of non-ionic surfactant was removed, demonstrating that the cationic surfactant presented in this wastewater is more difficult to destroy than non-ionic surfactant with the ozonation. Surfactant concentration decreased to 3 mg/L (64% removal efficiency) within 1 hour of UV irradiation. Presence of H2O2 or permanganate enhanced UV degradation of surfactants significantly. The total surfactant concentration was decreased to 1.6 and 1.7 mg/L (81% and 80% removal efficiencies) in 30 min of UV irradiation in the presence of 100 mg/L H2O2 and 1 g/L permanganate, respectively. No obvious enhancement on surfactants removal was observed by increasing the H2O2 dosage from 100 mg/L to 1 g/L. UV flow through reactor with 50 mg/L H2O2 was selected as the optimized system for the treatment of the surfactant wastewater. The retention time was 30 minutes. The results showed that the effluent concentration of cationic surfactant was lower than 0.13 mg/L and that of non-ionic was 1.07 mg/L and 86% of total surfactant was destructed.
Separately and in parallel to the work discussed above studies were conducted by Parsons Corporation aimed toward removal of surfactants via Foam Fractionation. Using a 1 liter graduated cylinder, air pump, diffuser stone and 800 ml of biologically treated wastewater, tests were conducted at: 0.1; 1.0; 2.0; 4.0; 6.0; 9.0, and 12 liters/min. Optimum results indicated that at an air flow of 6 L/min (3.5 cm/s) >61% reduction of total surfactant was achieved from 2.74 mg/L to 1.05 mg/L. The surfactant removed was predominantly (83-84% of total surfactant) nonionic species and at 3.5 cm/s airflow the side stream (foam over) was only 6% (50ml) of the starting volume. The detailed results of this study are reported elsewhere.
Document Type: Research Article
Publication date: 2007-10-01
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