Optimizing Micropollutant Removal by Ozonation; Interference of Effluent Organic Matter Fractions

Abstract

Ozonation for micropollutant removal from wastewater treatment plant effluent is energy and costintensive because of competition between background organic matter and micropollutants. This study aims to elucidate the interference of different organic matter fractions during the ozonation of micropollutants. Wastewater treatment plant effluent was fractionated using membranes and XAD-8 resin. All membrane and resin fractions were spiked with 18 micropollutants (2 µg/L) and ozonated with 0.25, 0.5 and 1 g O 3 /g TOC. Results show that these fractions differ in their interference with the ozonation of micropollutants. Interference was lower in the smallest size fraction (<1 kDa) than in all other fractions for micropollutants with low and medium ozone reactivity. The hydrophobic neutrals and hydrophilics resin factions showed a high interference for ozonation of micropollutants with medium and high ozone reactivity, respectively. The four parameters that were analyzed (specific UV absorbance at 254 nm, fluorescence, chemical oxygen demand and nitrite) could not elucidate the differences in micropollutant removal. Still, we conclude that understanding the type of organic matter present in the matrix, is essential to optimize micropollutant ozonation and other tertiary micropollutant removal treatments.

The BO3 process for removal of micropollutants from wastewater treatment plant effluent : exploring the synergies between biological treatment and ozonation

“…The size fractions did not show a significant difference in their interference with MP ozonation (Figure 4.4). This result is different from our previous study where the smallest size fraction (F4) showed a lower interference than the other fractions [177]. The reason for this difference could be a change in the used membranes, resulting in different pressure and cross-flow velocity conditions (section 0).…”

“…Membrane fractionation was performed based on van Gijn et al [177] with an updated method (section 0). A Mexplorer test unit (NX Filtration BV, the Netherlands), and three hollow fiber membranes (Pentair, USA) with molecular weight cut-off of 150 kDa, 10 kDa, and 1 kDa were used to separate EfOM into four size ranges: 0.45 µm -150 kDa (F1), 100-10 kDa (F2), between 10 and 1 kDa (F3) and smaller than 1 kDa (F4).…”

“…Resin fractionation was based on van Gijn et al [177] and Imai et al [103] with minor modifications, i.e. doubling the starting volumes to increase OM concentrations in the final fractions (section 0).…”

“…In addition, the effect of resin fractions on by-product formation [78], and the effect of ozone on the fraction compositions has been studied [100]. Van Gijn et al [177] showed that size and resin based fractions show differences in interference during MP ozonation. Still, the variations of these fractions in different effluents and the reasons why these fractions interfere differently are unclear.…”

Performance Efficiency of Conventional Treatment Plants and Constructed Wetlands towards Reduction of Antibiotic Resistance

“…Moreover, while considering the role of tertiary treatment in the removal of ARGs, their dose of application (O 3 , UV and chlorine), contact time with the wastewater and wastewater characteristics play a significant role [ 4 , 65 , 156 ]. Additionally, investigations have reported that there are times when O 3 is relatively less effective than the other two disinfection methods, as O 3 gets generally consumed by the organic matter in the effluent [ 157 ]. When coupled with UV treatment, chlorination is reported to be modestly effective for the removal of ARG, integrons that are associated with horizontal gene transfer, and 16s rRNA genes that serve as a marker for bacterial cells [ 158 ].…”