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Investigations of the Effects of Biocide Dosing and Chemical Cleaning on the Organic Carbon Removal in an Integrated Ultrafiltration - Nanofiltration Desalination Pilot Plant

Membrane desalination has become one of the most important desalination technologies used in the world. It provides high water quality for numerous applications and it demonstrates excellent desalination efficiency. One of the most troubling drawbacks of membrane desalination is membrane fouling. It decreases the performance of the membranes and increases the energy requirement. Two of the most important causes of fouling are microbes and organic matter. Hence, to maintain an optimized desalination performance, routine inspection of microbial and organic contents of water is crucial for desalination plants.
In this study, water samples were obtained from different treatment points in an ultrafiltration (UF)/nanofiltration (NF) seawater desalination pilot plant. This was performed to better understand how the water quality changes along the desalination scheme. The effect of fouling control techniques, including Chemically Enhanced Backwash (CEB), Cleaning in Place (CIP), and the addition of a biocide (DBNPA) was studied. Different analytical tools were applied, including Bactiquant, Total Organic Carbon (TOC), Assimilable Organic Carbon (AOC), and Liquid Chromatography for Organic Carbon Detection (LC-OCD).
Out results showed that UF did not decrease TOC but it was sufficient in removing up to 99.7% of bacteria. Nanofiltration, removed up to 95% of TOC. However, NF permeate had a high increase in AOC as compared to the raw seawater sample. The LC-OCD results suggested that this might be due to the increased low molecular weight neutrals which were the most common organic species in the NF permeate.
The fouling control techniques showed various effects on the desalination efficiency. Daily CEB did not cause a reduction in TOC or bacteria but decreased AOC in the UF filtrate. The biocide addition resulted in an adequate membranes protection from fouling and it did not affect the investigated water parameters. When the dosing of biocide was stopped, the water quality parameters did not change, but the NF pressure drop increased rapidly, indicating fouling of this membrane. CIP did not show an impact on the organic and microbial contents of water, but it was efficient in restoring the operations back to acceptable pressure levels. These results indicated that the applied fouling protection techniques were beneficial in fouling control.

Identiferoai:union.ndltd.org:kaust.edu.sa/oai:repository.kaust.edu.sa:10754/626303
Date12 1900
CreatorsKhojah, Bayan
ContributorsLeiknes, TorOve, Biological and Environmental Sciences and Engineering (BESE) Division, Ghaffour, NorEddine, Moran, Xose Anxelu G., Moosa, Nasir
Source SetsKing Abdullah University of Science and Technology
LanguageEnglish
Detected LanguageEnglish
TypeThesis
Rights2018-12-06, At the time of archiving, the student author of this thesis opted to temporarily restrict access to it. The full text of this thesis became available to the public after the expiration of the embargo on 2018-12-06.

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