Degradation Of Selected Pharmaceuticals In Urine And Wastewater By Advanced Oxidation Processes

Pharmaceuticals have been frequently detected in natural environment and wastewater treatment plants.Due to their adverse effect to aquatic ecosystem,numerous studies have been reported focusing on pharmaceutical removal.Advanced oxidation processes?AOPs?are attractive and promising technologies to destruct organic pollutants.Hydroxyl radical?·OH?-and sulfate radical?SO₄·^-?-based AOPs have been widely applied and proved to be effective in eliminating pharmaceuticals.Source-separated urine contains higher concentration of pharmaceuticals,which becomes an alternative matrix to remove pharmaceutical effectively while recovering nutrients.This study investigated the degradation of trimethoprim?TMP?,sulfamethoxazole?SMX?and its major human metabolite N4-acetyl-sulfamethoxazole?acetyl-SMX?in synthetic human urine by UV,UV/H₂O₂ and UV/PDS.The kinetic simulation was also performed.The results showed that direct photolysis rate of SMX was higher than that of acetyl-SMX,and far higher than that of TMP.All the three compounds reacted fast with ·OH and SO₄·^-with high reactivity.However,degradation of the target compounds in synthetic fresh urine was highly inhibited due to the decrease of ·OH and SO₄·^-concentrations.In synthetic hydrolyzed urine,degradation was inhibited to different extent for each compound.The presence of chloride did not impact the removal rates of the compounds,but decreased the concentration of SO₄·^-while increase ·OH concentration in UV/PDS process.Carbonate radical?CO3·-?,generated from the reactions between bicarbonate and ·OH and SO₄·^-,became the major reactive species in synthetic hydrolyzed urine.CO3·-degraded SMX and TMP,but reacted slowly with acetyl-SMX.Ammonia reacted with ·OH and SO₄·^-to generate reactive nitrogen species that could react appreciably only with SMX.Transformation product identification was performed for SMX and TMP by different reactive species.Reaction with ·OH generated products with largest variance due to its low selectivity.SO₄·^-and CO3·-reacted with aromatic compounds by electron transfer,thus produced similar major products.The main reactive species deduced from the product presence in synthetic urine solution were supported by the simulation results of corresponding contributing reactive species.No antimicrobial property was detected for transformation products of either TMP or SMX against a tested strain identified as a poly-phosphate accumulating organism.Acute toxicity applying luminescent bacterium Vibrio Qinghaiensis indicated 20%-40% higher inhibitory effect of TMP and SMX after treatment.In addition,higher eco-toxicity of specific transformation product was estimated.Applying the same method,kinetic simulation of degradation of eight sulfonamides in synthetic wastewater by UV,UV/H₂O₂ and UV/PDS was performed in this study.The simulation results fitted the observed results satisfactorily.Electric energy per order of UV/H₂O₂ and UV/PDS processes was calculated.Meanwhile,an energy-cost evaluation was also conducted to optimize the efficiency of UV/H₂O₂ and UV/PDS by changing UV intensity and oxidant dose.