Removal of Pharmaceutical and Endocrine Disrupting Chemicals by Sequential Photochemical and Biological Oxidation Processes.

UV/H2O2;antimicrobial activity;hydroxyl radical;pharmaceuticals;photolysis;biochemically active compounds

Baeza, Ana Carolina ; Detlef Knappe, Committee Chair,Francis L. de los Reyes, Committee Member,Joel Ducoste , Committee Member,David Ollis , Committee Member,Baeza, Ana Carolina ; Detlef Knappe ; Committee Chair ; Francis L. de los Reyes ; Committee Member ; Joel Ducoste ; Committee Member ; David Ollis ; Committee Member

University:North Carolina State University

关键词: UV/H2O2;    antimicrobial activity;    hydroxyl radical;    pharmaceuticals;    photolysis;    biochemically active compounds;   

Others  :  https://repository.lib.ncsu.edu/bitstream/handle/1840.16/5524/etd.pdf?sequence=1&isAllowed=y

美国|英语

来源: null

【 摘 要 】

The presence of biochemically active compounds (BACs) such as endocrinedisrupting chemicals (EDCs) and antimicrobial compounds in the aquatic environmentis an issue of great concern. For example, EDCs can cause gender bending in aquaticlife, and antimicrobial compounds may lead to the evolution of antimicrobial resistantbacteria. The principal objective of this research was to quantify the effectiveness ofcombining UV/H2O2 and biological oxidation processes for the mineralization ofBACs that commonly occur at trace levels in municipal wastewater and in drinkingwater sources.Initially, the photolysis and UV/H2O2 photooxidation rates of six BACs [theantimicrobial compounds sulfamethoxazole (SMX), sulfamethazine (SMZ),sulfadiazine (SDZ), and trimethoprim (TMP), the EDC bisphenol-A (BPA), and theanalgesic diclofenac (DCL)] were determined. Experiments were conducted inultrapure water, lake water (Lake Wheeler, NC) and wastewater treatment planteffluent (North Cary Water Reclamation Facility, Cary, NC). Photolysis and UV/H2O2oxidation rates of BACs were quantified with a quasi-collimated beam (QCB)apparatus equipped with low pressure UV lamps, and the effects of the followingfactors on the BAC oxidation rates were evaluated: (1) pH, (2) H2O2 concentration,and (3) presence/absence of background organic matter. With the QCB apparatus,parameters such as quantum yields and second order rate constants describing thereaction between hydroxyl radicals and BACs were determined. With these parametersthe level of BAC transformation at different UV fluences and H2O2 concentrationswas predicted. For example, at treatment conditions used at a full-scale UV/H2O2 plantin the Netherlands (UV fluence = 540 mJ cm-2, H2O2 dose = 6 mg L-1), the followingBAC transformation percentages would be obtained in NC lake water: ∼98% forDCL, ∼79% for SMX, ∼60% for SMZ, ∼51% for SDZ, ∼43% for TMP, and ∼46% forBPA. In wastewater treatment plant effluent, predicted BAC transformationpercentages were lower at the same treatment conditions because hydroxyl radicalscavengers were present at higher concentrations.Apart from determining parent compound removal rates in UV photolysis andUV/H2O2 photooxidation processes, antimicrobial activity removal was quantified byconducting growth inhibition assays. Using the Enterobacteriaceae organism E. coliATCC® 25922, growth inhibition assay data showed that the antimicrobial activity inphotochemically treated water samples was principally a result of the parentcompound concentration that remained upon treatment. Therefore, no measurableantimicrobial activity was exerted by the photolysis and UV/H2O2 oxidation productsof the studied sulfonamides and TMP. These results were consistently obtained for thedifferent background water matrices and solution pH values that were studied.Finally, the mineralization potential of three 14C-labeled BACs (sulfadiazine,bisphenol-A, and diclofenac) after UV/H2O2 treatment was examined with aconsortium of lake water bacteria and with bacteria associated with lake sediments.Upon UV/H2O2 oxidation, mineralization of 14C-labeled BAC oxidation intermediatesby lake water bacteria was extremely slow (<1.1% for SDZ, <0.8% for BPA and<0.8% for DCL in 30 days). The use of lake sediments enhanced the biodegradationrate of sulfadiazine and its UV/H2O2 oxidation intermediates, but mineralization rateswere still slow (1.1% for SDZ and 5.2% for SDZ UV/H2O2 oxidation intermediatesafter 30 days).Overall, the results of this research suggest that the UV/H2O2 process is able toremove BAC parent compounds and, for antibiotics, antimicrobial activity; however,oxidation intermediates may be persistent in the environment. Additional studiesshould be performed to determine the effects of these intermediates on aquatic life andtheir toxicological importance in the context of direct or indirect potable water reuse.