This study was carried out to evaluate the performance of Soil Aquifer Treatment
(SAT) under different loading regimes, using wastewater of much higher strength
than usually encountered in SAT systems, and also to investigate the removal of the
endocrine disruptors triclocarban (TCC), estrone (E1), 17¿-estradiol (E2) and 17¿-
ethinylestradiol (EE2). SAT was simulated in the laboratory using a series of soil
columns under saturated and unsaturated conditions.
Investigation of the removal of Chemical Oxygen Demand (COD), Biochemical
Oxygen Demand (BOD), Dissolved Organic Carbon (DOC), nitrogen and phosphate
in a 2 meter long saturated soil column under a combination of constant hydraulic
loading rates (HLRs) and variable COD concentrations as well as variable HLR
under constant COD showed that at fixed HLR, a decrease in the influent
concentrations of DOC, BOD, total nitrogen and phosphate improved their removal
efficiencies. It was found that COD mass loading applied as low COD wastewater
infiltrated over short residence times would provide better effluent quality than the
same mass applied as a COD with higher concentration at long residence times. On
the other hand relatively high concentrations coupled with long residence time gave
better removal efficiency for organic nitrogen. Phosphate removal though poor under
all experimental conditions, was better at low HLRs.
In 1 meter saturated and unsaturated soil columns, E2 was the most easily removed
estrogen, while EE2 was the least removed. Reducing the thickness of the
unsaturated zone had a negative impact on removal efficiencies of the estrogens
whereas increased DOC improved the removal in the saturated columns. Better
removal efficiencies were also obtained at lower HLRs and in the presence of silt
and clay.
Sorption and biodegradation were found to be responsible for TCC removal in a 300
mm long saturated soil column, the latter mechanism however being unsustainable.
TCC removal efficiency was dependent on the applied concentration and decreased
over time and increased with column depth. Within the duration of the experimental
run, TCC negatively impacted on treatment performance, possibly due to its
antibacterial property, as evidenced by a reduction in COD removals in the column.
COD in the 2 meter column under saturated conditions was modelled successfully
with the advection dispersion equation with coupled Monod kinetics. Empirical
models were also developed for the removal of TCC and EE2 under saturated and
unsaturated conditions respectively. The empirical models predicted the TCC and
EE2 removal profiles well. There is however the need for validation of the models
developed / Netherlands Organisation for International Cooperation in Higher Education (Nuffic) / The Appendix files for this thesis are unavailable online via Bradford Scholars.
| Identifer | oai:union.ndltd.org:BRADFORD/oai:bradscholars.brad.ac.uk:10454/5710 |
| Date | January 2011 |
| Creators | Essandoh, Helen M.K. |
| Contributors | Tizaoui, Chedly, Mohamed, Mostafa H.A. |
| Publisher | University of Bradford, School of Engineering, Design and Technology |
| Source Sets | Bradford Scholars |
| Language | English |
| Detected Language | English |
| Type | Thesis, doctoral, PhD |
| Rights | <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/"><img alt="Creative Commons License" style="border-width:0" src="http://i.creativecommons.org/l/by-nc-nd/3.0/88x31.png" /></a><br />The University of Bradford theses are licenced under a <a rel="license" href="http://creativecommons.org/licenses/by-nc-nd/3.0/">Creative Commons Licence</a>. |
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