Removal of diclofenac by conventional drinking water treatment processes and granular activated carbon filtration

• Published in: Chemosphere (Oxford) 2013-06, Vol.92 (2), p.184-191
• Main Authors: Rigobello, Eliane Sloboda, Dantas, Angela Di Bernardo, Di Bernardo, Luiz, Vieira, Eny Maria
• Format: Article
• Language: English
• Subjects: activated carbon; aluminum sulfate; Applied sciences; Byproducts; Charcoal; Chlorine; Chlorine - chemistry; Chlorine Compounds - chemistry; Chlorine dioxide; Chromatography, High Pressure Liquid - methods; coagulation; color; decarboxylation; Diclofenac; Diclofenac - chemistry; Diclofenac - isolation & purification; Disinfection; dissolved organic carbon; Drinking water and swimming-pool water. Desalination; Drinking water treatment; Exact sciences and technology; filters; filtration; Filtration - methods; flocculation; Granular activated carbon; Humic Substances; hydrogen; Hydroxylation; kaolin; oxidation; Oxidation-Reduction; Oxides - chemistry; Pollution; sand; solid phase extraction; Spectrometry, Mass, Electrospray Ionization; turbidity; Water Purification - methods; water treatment; Water treatment and pollution
• ISSN: 0045-6535; 1879-1298
• DOI: 10.1016/j.chemosphere.2013.03.010

•We evaluate the removal of diclofenac in conventional water treatment processes.•Aquatic humic substances were used in the water of this study.•The use of chlorine and chlorine dioxide as pre-oxidant were investigated.•Conventional treatment followed by activated carbon filtration was also studied.•Byproducts formed in the oxidation of diclofenac were identified by LC–MS/MS. This study was carried out to evaluate the efficiency of conventional drinking water treatment processes with and without pre-oxidation with chlorine and chlorine dioxide and the use of granular activated carbon (GAC) filtration for the removal of diclofenac (DCF). Water treatment was performed using the Jar test with filters on a lab scale, employing nonchlorinated artesian well water prepared with aquatic humic substances to yield 20HU true color, kaolin turbidity of 70 NTU and 1mgL−1 DCF. For the quantification of DCF in water samples, solid phase extraction and HPLC–DAD methods were developed and validated. There was no removal of DCF in coagulation with aluminum sulfate (3.47mgAlL−1 and pH=6.5), flocculation, sedimentation and sand filtration. In the treatment with pre-oxidation and disinfection, DCF was partially removed, but the concentration of dissolved organic carbon (DOC) was unchanged and byproducts of DCF were observed. Chlorine dioxide was more effective than chorine in oxidizing DCF. In conclusion, the identification of DCF and DOC in finished water indicated the incomplete elimination of DCF through conventional treatments. Nevertheless, conventional drinking water treatment followed by GAC filtration was effective in removing DCF (⩾99.7%). In the oxidation with chlorine, three byproducts were tentatively identified, corresponding to a hydroxylation, aromatic substitution of one hydrogen by chlorine and a decarboxylation/hydroxylation. Oxidation with chlorine dioxide resulted in only one byproduct (hydroxylation).