Effects of ozone pre-treatment on diclofenac: intermediates, biodegradability and toxicity assessment.
Diclofenac (DCF), a common analgesic, anti-arthritic and anti-rheumatic drug, is one of the most frequently detected compounds in water. This study deals with the degradation of diclofenac in aqueous solution by ozonation. Biodegradability (BOD(5)/COD ratio and Zahn-Wellens test), acute ecotoxicity and inhibition of activated sludge activity were determined in ozonated and non-ozonated samples. Liquid chromatography coupled with time-of-flight mass spectrometry (LC/TOF-MS) was used to identify the intermediates formed in 1 h of ozonation. Eighteen intermediates were identified by these techniques and a tentative degradation pathway for DCF ozonation is proposed. Experimental results show that ozone is efficient at removing DCF: >99% removal (starting from an initial concentration of 0.68 mmol L(-1)) was achieved after 30 min of ozonation (corresponding to an absorbed ozone dose of 0.22 g L(-1), which is 4.58 mmol L(-1)). However, only 24% of the substrate was mineralized after 1 h of ozonation. The biodegradability, respiration inhibition in activated sludge and acute toxicity tests demonstrate that ozonation promotes a more biocompatible effluent of waters containing DCF.
Coelho
Alessandra D
AD
Programa de Engenharia Química - COPPE, UFRJ, CP 68502, 21941-972, Rio de Janeiro, Brazil.
Sans
Carmen
C
Agüera
Ana
A
Gómez
Maria José
MJ
Esplugas
Santiago
S
Dezotti
Márcia
M
D048908:Aliivibrio fischeri / Q000187:drug effects; D001673:Biodegradation, Environmental; D002853:Chromatography, Liquid; D004008:Diclofenac / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity; D007700:Kinetics; D013058:Mass Spectrometry; D010126:Ozone / Q000737:chemistry*; D023382:Toxicity Tests, Acute; D014874:Water Pollutants, Chemical / Q000737:chemistry* / Q000378:metabolism / Q000633:toxicity
D014874:Water Pollutants, Chemical; D004008:Diclofenac; D010126:Ozone