Observations and prediction of recovered quality of desalinated seawater in the strategic ASR project in Liwa, Abu Dhabi

Observations and prediction of recovered quality of desalinated seawater in the strategic ASR project in Liwa, Abu Dhabi

Stuyfzand, Pieter Jan (TU Delft Geo-engineering; KWR Water Cycle Research Institute)
Smidt, Ebel (Waterfocus; SG Consultancy and Mediation Ltd)
Gerardus Zuurbier, Koen (KWR Water Cycle Research Institute)
Hartog, Niels (KWR Water Cycle Research Institute; Universiteit Utrecht)
Dawoud, Mohamed A. (Environment Agency Abu Dhabi)

2017

To be able to overcome water shortages, Abu Dhabi Emirate started an Aquifer Storage and Recovery (ASR) project with desalinated seawater (DSW) as source water near Liwa. It is the largest DSW-ASR project in the world (stored volume ~10 Mm³/year), and should recover potable water for direct use. DSW is infiltrated into a desert dune sand aquifer using "sand-covered gravel-bed" recharge basins. In this study, we evaluate the hydrogeological and hydrogeochemical stratification of the (sub)oxic target aquifer, and water quality changes of DSW during trial infiltration runs. We predict water quality changes of DSW after 824 d of infiltration, during 90 d of intensive recovery (67% recovered) without storage (scenario A), as well as after 10 years of storage (scenario B, with significant bubble drift). Monitoring of preceding trials revealed a lack of redox reactions; little carbonate dissolution and Ca/Na exchange; much SiO₂ dissolution; a strong mobilization of natural AsO₄ ^3-, B, Ba, F, CrO₄ ^2-, Mo, Sr and V from the (sub)oxic aquifer; and immobilization of PO₄, Al, Cu, Fe and Ni from DSW. The Easy-Leacher model was applied in forward and reverse mode including lateral bubble drift, to predict water quality of the recovered water. We show that hydrogeochemical modeling of a complex ASR-system can be relatively easy and straightforward, if aquifer reactivity is low and redox reactions can be ignored. The pilot observations and modeling results demonstrate that in scenario A recovered water quality still complies with Abu Dhabi's drinking water standards (even up to 85% recovery). For scenario B, however, the recovery efficiency declines to 60% after which various drinking water standards are exceeded, especially the one for chromium.

Abu Dhabi
Aquifer Storage and Recovery (ASR)
Break-through curve
Chromate
Desalinated seawater
Hydrochemistry
Recovery efficiency
Trace elements
Transport modeling

http://resolver.tudelft.nl/uuid:c3b16068-ce7b-4107-a126-fb0af39b3f15

https://doi.org/10.3390/w9030177

2073-4441

Water, 9 (3)

Institutional Repository

journal article

© 2017 Pieter Jan Stuyfzand, Ebel Smidt, Koen Gerardus Zuurbier, Niels Hartog, Mohamed A. Dawoud