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Integrated spectral based monitoring, optimization and control of the combined ozonation and powdered activated carbon adsorption process to remove organic micropollutants from secondary effluent.

Authors :
Zhang T
Zheng L
Yang X
Demeestere K
Van Hulle SWH
Source :
Water research [Water Res] 2025 Jan 01; Vol. 268 (Pt A), pp. 122588. Date of Electronic Publication: 2024 Oct 09.
Publication Year :
2025

Abstract

In this study, an innovative approach for the integrated monitoring, optimization and control of the combined ozonation (O <subscript>3</subscript> ) and powdered activated carbon (PAC) adsorption process is introduced making use of spectral surrogates (UVA <subscript>254</subscript> and EEM-PARAFAC components). The combined O <subscript>3</subscript> -PAC process is designed to remove organic micropollutants (µP) from secondary effluent. Therefore, the removal of 6 µP with varying ozone reactivity was systematically studied in both O <subscript>3</subscript> and PAC as stand-alone systems and in the combined O <subscript>3</subscript> -PAC system. For the latter, adsorption experiments were performed with µP spiked into ozonated secondary effluent (sequential system) and with µP spiked into the initial secondary effluent before ozonation (integrated system). In accordance with Swiss standards, the goal was to achieve 80% atrazine removal (as a model O <subscript>3</subscript> recalcitrant compound) at optimized O <subscript>3</subscript> and PAC doses. An ozone dose ranging from 0.45 to 0.65 mg O <subscript>3</subscript> /mg DOC was more cost-effective in promoting subsequent PAC adsorption (less than 40%), particularly at low PAC doses (1-2 mg PAC/mg (initial (DOC))). The classical ideal adsorbed solution theory (IAST) model could not be used to predict the subsequent PAC dose after ozonation in the integrated system. Therefore, correlation models were established between (i) the reduction of spectral surrogates during both O <subscript>3</subscript> and PAC dosing and µP removal, (ii) the reduction of spectral surrogates during ozonation and the related PAC dose of the subsequent adsorption process and (iii) between the reduction of spectral surrogates during ozonation and the integrated process. Based on these correlation models, an online spectral control strategy was developed and implemented. Finally, the optimal dosing strategy for 80% atrazine removal was determined as 0.5 mg O <subscript>3</subscript> /mg DOC and 1.4 mg PAC/mg (initial) DOC.<br />Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.<br /> (Copyright © 2024 Elsevier Ltd. All rights reserved.)

Details

Language :
English
ISSN :
1879-2448
Volume :
268
Issue :
Pt A
Database :
MEDLINE
Journal :
Water research
Publication Type :
Academic Journal
Accession number :
39405627
Full Text :
https://doi.org/10.1016/j.watres.2024.122588