Organic micropollutants (OMPs) oxidation by ozone: Effect of activated carbon on toxicity abatement

• Published in: The Science of the total environment 2017-07, Vol.590-591, p.430-439
• Main Authors: Rozas, Oscar, Baeza, Carolina, Núñez, Katherine, Rossner, Alfred, Urrutia, Roberto, Mansilla, Héctor D.
• Format: Article
• Language: English
• Subjects: Activated carbon; Advanced oxidation process; Daphnia magna; Emerging contaminants; Organic micropollutants; Ozone
• ISSN: 0048-9697; 1879-1026
• DOI: 10.1016/j.scitotenv.2016.12.120

Oxidation and removal of organic micropollutants (OMPs) on ultrapure (UPW) and natural water (NW) by ozone (O3) and ozone/powdered activated carbon (O3/PAC) have been studied. The OMPs atrazine (ATZ, herbicide), carbamazepine (CBZ, anticonvulsant), diclofenac (DCL, anti-inflammatory) and triclosan (TCS, antimicrobial) are incorporated continuously and uncontrolled on water treatment systems (e.g., drinking water treatment plants, wastewater treatment plants). Batch experiments on ultrapure and natural water showed that ATZ treated with O3 and O3/PAC has the slowest transformation rate (>90% at 30min reaction) while CBZ, DCL and TCS were oxidized very fast (>90% at ~5min). The radical scavenger tert-Butyl alcohol (TBA) was used to evaluate the contribution of HO on the OMPs oxidation. TBA, a hydrophilic compound with low adsorbability, was used as a strong HO scavenger to assess the role of the OH radical in the oxidation of the OMPs studied. ATZ oxidation was mainly driven by OH radicals. On the contrary, CBZ, DCL and TCS were removed by direct reaction with ozone. Infrared analysis (FTIR) showed changes in the PAC surface functional groups of the carbon exposed to ozone, decreasing its basic properties. The acute toxicity assays of the OMPs mixture dissolved in UPW performed with D. magna was significantly reduced by ozonation. The addition of PAC to the ozonation process, strongly improved the acute toxicity removal. Short chain mono- and di-carboxylic acids were identified as some of the oxidation intermediates formed during ozone treatment. [Display omitted] •O3 and O3/PAC are a good alternative for OMPs treatment.•Carboxylic acids were identified as degradation product.•The simultaneous treatment of ozone and PAC enhances TOC removal.•OMPs oxidation with O3 reduces the overall toxicity.•PAC addition to the ozonation treatment enhances toxicity removal evaluated by D. magna Bioassays.