Removal of Organic Micropollutants from a Municipal Wastewater Secondary Effluent

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Removal of Organic Micropollutants from a Municipal Wastewater Secondary Effluent

Removal of Organic Micropollutants from a Municipal Wastewater Secondary Effluent by UVA-LED Photocatalytic Ozonation

By Ana M. Chávez, Ana R. Ribeiro, Nuno F. F. Moreira, Adrián M. T. Silva, Ana Rey, Pedro M. Álvarez and Fernando J. Beltrán

Abstract:

Numerous contaminants of emerging concern (CECs) have been found in different water bodies. Directive 2013/39/EU and Decision 2018/840/EU are consequently being implemented in the field of water policies. Twelve CECs (e.g., isoproturon, ciprofloxacin, and clarithromycin are among those listed) were detected in a municipal wastewater secondary effluent by means of solid phase extraction and ultra-high-performance liquid chromatography with tandem mass spectrometry (SPE-UHPLC-MS/MS). Different advanced oxidation processes (AOPs), based on the combination of ozone, UVA-LED and powdered TiO2, were investigated for their removal in a semi-batch operation.

In addition, TiO2-coated glass rings (P25R) were characterized with different techniques (SEM, WDXRF) and used for continuous mode operation in a packed bed reactor (PBR). Among the AOPs studied, ozone-based processes were found to be more efficient than heterogeneous photocatalysis. A kinetic study was performed showing that direct ozonation is the main oxidation pathway for CEC removal. Ozone was successfully decomposed in combination with UVA-LED and P25R, resulting in an apparent rate constant of 3.2 × 10−2 s−1 higher than in the O3/LED system (1.0 × 10−3 s−1) or with ozone alone (8.6 × 10−5 s−1). Hydroxyl radical reaction could prevail over direct ozone reaction for the most refractory compounds (e.g., isoproturon). 

Keywords : municipal wastewater secondary effluent; contaminants of emerging concern; ozonation; light emitting diodes; TiO2-coated glass rings

Catalysts 2019, 9(5), 472; DOI: 10.3390/catal9050472 

(This article belongs to the Special Issue Photocatalysis Science and Engineering in Europe)

Source: MDPI

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