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@PHDTHESIS{Sauter:994980,
author = {Sauter, Daniel},
othercontributors = {Wintgens, Thomas Josef and Jekel, Martin},
title = {{T}he role of biological post-treatment following ozonation
in advanced municipal wastewater treatment},
school = {Rheinisch-Westfälische Technische Hochschule Aachen},
type = {Dissertation},
address = {Aachen},
publisher = {RWTH Aachen University},
reportid = {RWTH-2024-09636},
pages = {1 Online-Ressource : Illustrationen},
year = {2024},
note = {Veröffentlicht auf dem Publikationsserver der RWTH Aachen
University; Dissertation, Rheinisch-Westfälische Technische
Hochschule Aachen, 2024},
abstract = {Numerous municipal wastewater treatment plants (WWTP) in
Europe have been, are, and will be upgraded with ozonation
for organic micropollutant abatement. It is consensus that
ozonation requires a biological post-treatment step to abate
potentially toxic oxidation products formed by the reaction
of ozone. Several different post-treatment processes have
already been applied and investigated at full-scale,
however, specific target parameters and design guidelines
are still missing. This long-term pilot study provides a
comprehensive treatment performance assessment of different
biological post-treatment options and, based on that
information, derives general recommendations for the
post-treatment design. The investigated deep-bed filters and
constructed wetlands (CW) efficiently removed the oxidation
by-products (OBP) N-nitrosodimethylamine (NDMA) and carbonyl
compounds. The latter were degraded more slowly than NDMA,
resulting in a decrease of removal efficiency at low empty
bed contact times (EBCT) of 5 min in the deep-bed filters.
The long EBCT in the CW are not limiting for the removal of
the investigated OBP. A dual-media filter with sand and
biological activated carbon (S/BAC) outperformed a
non-adsorptive sand / anthracite filter (S/A) regarding the
removal of bulk organics. Also, the S/BAC filter abated a
number of OMP even at high treated bed volumes of >50,000,
which was not observed in the S/A filter. Enhanced
phosphorus removal could be implemented in the deep-bed
filters with low efforts by inline coagulant dosing into the
influent and did not impair the function as biological
post-treatment. Based on inactivation experiments with
sodium azide, the OMP removal in BAC filtration could only
be attributed to biotransformation for valsartan. Analysis
of the filter media-attached biofilms revealed a
significantly higher amount of biomass per volume filter bed
in the BAC filter bed than in the anthracite filter bed,
explaining the discrepancy in the bulk organics removal and
potentially the removal of degradable OMP such as valsartan.
The dominant taxa in the microbial communities were found to
be similar and appeared at comparable relative abundances on
both filter materials. Among them, several have been
associated with OMP biotransformation, especially
ammonia-oxidising bacteria and archaea. The beta-diversities
of the microbial communities significantly differed between
the two filter media, however, these differences could not
be directly linked to the improved OMP removal in BAC
filters. Disinfection with ozone was particularly effective
for vegetative bacteria such as the bathing water quality
indicators Escherichia coli and enterococci. Post-treatment
with deep-bed filters and CW significantly improved the
disinfection result of ozonation, especially for parameters
that were less ozone-susceptible (somatic coliphages,
Clostridium perfringens). This demonstrated the
complementing effect of the different disinfection
mechanisms of ozonation (chemical) and filtration
(physical). Just as the conventional bacterial parameters,
ozonation effectively inactivated antibiotic resistant
bacteria (ARB). However, antibiotic resistance genes (ARG)
remained mostly unaffected by ozone and could only be
significantly removed during post-treatment. A selection
process of bacteria with ARG by ozonation was not observed.
A regrowth during biological post-treatment was found for
the parameters intact cell counts (flowcytometry) and
Pseudomonas aeruginosa. Based on the results of this pilot
study and the current knowledge from literature, a design
approach was proposed that provides guidance for the
selection and dimensioning of the biological post-treatment
process. Mandatory treatment goals (removal of biodegradable
oxidation by-products and toxicity) and site-specific
optional treatment goals (e.g. phosphorus removal) were
defined as the main criteria for the selection of a suitable
process. The dimensioning approach focuses on carbonyl
compounds as suitable representatives of biodegradable
oxidation by-products and assumes first-order kinetics for
their biodegradation. It enables to calculate EBCT as a
function of the targeted removal of carbonyl compounds. The
design approach was exemplarily applied to a real WWTP. BAC
filtration with additional coagulant dosing was selected as
the most suitable process for the site-specific treatment
requirements. To reach an overall removal of 80 $\%$ for a
set of selected carbonyl compounds, an EBCT of 16 min was
determined. This EBCT and the respective filter surface area
were approx. 20 $\%$ higher than calculated with a common
practice design approach that solely relies on a maximum
hydraulic loading rate of 15 m/h. The comparison
demonstrates that EBCT-based dimensioning approaches are
essential for ensuring an efficient removal of oxidation
by-products in biological post-treatment.},
cin = {314110},
ddc = {624},
cid = {$I:(DE-82)314110_20140620$},
typ = {PUB:(DE-HGF)11},
doi = {10.18154/RWTH-2024-09636},
url = {https://publications.rwth-aachen.de/record/994980},
}
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