Stability and Removal of Dexamethasone Sodium Phosphate from Wastewater Using Different Techniques

Stability and removal of dexamethasone sodium phosphate (DSP) from wastewater produced at Al-Quds University Campus were investigated. Kinetic studies in both pure water and wastewater coming from secondary treatment (activated sludge) demonstrated that the antiinflammatory DSP underwent degradation to its hydrolytic derivative, simply named dexamethasone, in both media. The first order hydrolysis rate of DSP in activated sludge at 25°C (3.80×10-6 s-1) was about 12-fold greater than in pure water (3.25×10-7 s-1). The overall performance of the wastewater treatment plant (WWTP) installed in the University Campus was also assessed showing that 90% of spiked DSP was removed together with its newly identified metabolites. In order to check for different tools to be used instead of ultra-filtration membranes, the effectiveness of adsorption and filtration by micelle-clay preparation for removing DSP was ascertained in comparison with activated charcoal. Batch adsorption in aqueous suspensions of the micelle-clay composite and activated carbon was well described by Langmuir isotherm showing the best results for micelle-clay material. Besides, filtration of DSP water solutions by columns filled in with a mixture of sand and micelle-clay complex showed complete removal of the drug at concentration higher than sand/activated-charcoal filled filters.