The goal of this study was to evaluate the feasibility of using advanced coagulation with
Fe(VI) in coagulation-flocculation-sedimentation/ flotation systems for the pretreatment
of SWRO desalination plants during algal bloom events.
Algal organic matter (AOM) material extracted from marine diatom species (Chaetoceros
affinis) was added to Red Sea water to mimic algal bloom conditions. Low dosage of
Fe(VI) (<1 mg Fe/L) was very effective at improving feed water quality containing AOM
(algal bloom conditions). Based on results from both a bench-scale DAF unit and Jar
testing unit, 0.75 mg Fe/L of Fe (VI) proved to be effective at improving the raw water
quality which is comparable to the performance of 1 and 3 mg Fe/L of Fe (III). The
removal efficiency for both testing units with the use of Fe(VI) was up to 100% for algae
, 99.99% for ATP, 99% for biopolymers and 70 % for DOC. The improvement in Fe(VI)
performance is related to the simultaneous action of Fe(VI) as oxidant, disinfectant and
coagulant.
The performance of Fe(VI) coagulant was also evaluated with the use of coagulant aids
(clays). The overall turbidity, DOC, biopolymers and algal cells removal was improved
via using Fe(VI) and clays at very low dose. Generally, it was found that for the same
pretreatment performance achieved, a much lower Fe(VI) dose was required compared to
Fe (III), which make it important to study of cost effectiveness for using Fe(VI) instead
of Fe(III) and estimate cost savings during algal bloom conditions.
A detailed cost comparative study was conducted for Fe(III) vs. Fe(VI) coagulation
process based on the removal efficiency. The use of Fe(VI) reduced the total pretreatment
cost by 77% and sludge disposal cost by > 88% compared to the use of Fe(III) in the
pretreatment process. The use of Fe(VI) reduces the operational and maintenance cost in
SWRO desalination plant by 7% and the production cost by 4%. This study proved that
the use of Fe(VI) during high turgidity and algal bloom conditions helped providing high
raw water quality to the RO process with lower chemicals and operations cost as well as
low chlorine and iron residuals.
| Identifer | oai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/668172 |
| Date | 02 1900 |
| Creators | Alshahri, Abdullah |
| Contributors | Ghaffour, NorEddine, Biological and Environmental Sciences and Engineering (BESE) Division, Saikaly, Pascal, Pinnau, Ingo, Missimer, Thomas |
| Source Sets | King Abdullah University of Science and Technology |
| Language | English |
| Detected Language | English |
| Type | Dissertation |
| Rights | 2021-03-21, At the time of archiving, the student author of this dissertation opted to temporarily restrict access to it. The full text of this dissertation became available to the public after the expiration of the embargo on 2021-03-21. |
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