Supercritical water oxidation of recalcitrant organic pollutants present in retentates from RO desalination of secondary effluents

Yaron Aviezer*, Liat Birnhack, Ori Lahav*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

Abstract

This work focuses on applying supercritical water oxidation (SCWO) for eliminating residues of
pharmaceutical, endocrine-disruptor and pesticide species from the reject of reverse-osmosis-treated
secondary municipal wastewater. SCWO, a well-known treatment method for organic sludge and
highly concentrated wastewaters, has not yet been investigated with reverse osmosis (RO) retentates
of municipal secondary effluents. The results shown here, focusing on batch SCWO of municipal
effluent RO retentate spiked with emerging pollutants, demonstrate the potential of utilizing this
single advanced-oxidation generic treatment to fully-mineralize the vast variety of organic species
encountered in municipal wastewater effluents, while at the same time lowering its total organic
carbon concentration by up to 99%. The chosen model pollutants (carbamazepine and 17β-Estradiol
both in synthetic solution and within a real effluent RO retentate matrix) and the effluent’s background organic matter, started to degrade already at subcritical conditions, however near-complete
mineralization of the full matrix (including transformation products) was invariably attained only at fully-established supercritical conditions (450°C–540°C). The extreme hydrothermal oxidation conditions applied in this work allowed for simultaneous oxidation of target molecules and background organic species throughout the applied temperature range, while the phenomenon known as “radicals scavenging” by the background organic matter, was not observed. A new technique is
introduced in this work for controlling the pressure within semi-batch SCWO experiments.
Original languageEnglish
JournalDesalination and Water Treatment
DOIs
StatePublished - 1 Jan 2020

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