Biofouling control of industrial seawater cooling towers

Handle URI:
http://hdl.handle.net/10754/626169
Title:
Biofouling control of industrial seawater cooling towers
Authors:
Albloushi, Mohammed ( 0000-0001-5973-0428 )
Abstract:
The use of seawater in cooling towers for industrial applications has much merit in the Gulf Cooperation Council countries due to the scarcity and availability of fresh water. Seawater make-up in cooling towers is deemed the most feasible because of its unlimited supply in coastal areas. Such latent-heat removal with seawater in cooling towers is several folds more efficient than sensible heat extraction via heat exchangers. Operational challenges such as scaling, corrosion, and biofouling are a major challenge in conventional cooling towers, where the latter is also a major issue in seawater cooling towers. Biofouling can significantly hamper the efficiency of cooling towers. The most popular methods used in cooling treatment to control biofouling are disinfection by chlorination. However, the disadvantages of chlorination are formation of harmful disinfection byproducts in the presence of high organic loading and safety concerns in the storage of chlorine gas. In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities. Test results of GAC bio-filter showed that around 70 % removal of total organic carbon in the seawater feed was achieved and was effective in keeping the microbial growth to a minimum. The measured results from this study enable designers of seawater cooling towers to manage the biofouling problems when such cooling towers are extrapolated to a pilot scale.
Advisors:
Leiknes, TorOve ( 0000-0003-4046-5622 )
Committee Member:
Ng, Kim Choon ( 0000-0003-3930-4127 ) ; Gojobori, Takashi ( 0000-0001-7850-1743 ) ; Amy, Gary
KAUST Department:
Biological and Environmental Sciences and Engineering (BESE) Division
Program:
Environmental Science and Engineering
Issue Date:
Nov-2017
Type:
Dissertation
Appears in Collections:
Dissertations

Full metadata record

DC FieldValue Language
dc.contributor.advisorLeiknes, TorOveen
dc.contributor.authorAlbloushi, Mohammeden
dc.date.accessioned2017-11-15T11:56:21Z-
dc.date.available2017-11-15T11:56:21Z-
dc.date.issued2017-11-
dc.identifier.urihttp://hdl.handle.net/10754/626169-
dc.description.abstractThe use of seawater in cooling towers for industrial applications has much merit in the Gulf Cooperation Council countries due to the scarcity and availability of fresh water. Seawater make-up in cooling towers is deemed the most feasible because of its unlimited supply in coastal areas. Such latent-heat removal with seawater in cooling towers is several folds more efficient than sensible heat extraction via heat exchangers. Operational challenges such as scaling, corrosion, and biofouling are a major challenge in conventional cooling towers, where the latter is also a major issue in seawater cooling towers. Biofouling can significantly hamper the efficiency of cooling towers. The most popular methods used in cooling treatment to control biofouling are disinfection by chlorination. However, the disadvantages of chlorination are formation of harmful disinfection byproducts in the presence of high organic loading and safety concerns in the storage of chlorine gas. In this study, the research focuses on biofouling control in seawater cooling towers by investigating two different approaches. The first strategy addresses the use of alternative oxidants (i.e. ozone micro-bubbles and chlorine dioxide) in treatment of cooling towers. The second strategy investigates removing nutrients in seawater using granular activated carbon filter column and ultrafiltration to prevent the growth of microorganisms. Laboratory bench-scale tests in terms of temperature, cycle of concentration, dosage, etc. indicated that, at lower oxidant dosages (total residual oxidant (TRO) equivalent = 0.1 mg/l Cl2), chlorine dioxide had a better disinfection effect than chlorine and ozone. The performance of oxidizing biocides at pilot scale, operating at assorted conditions, showed that for the disinfectants tested, ozone could remove 95 % bioactivity of total number of bacteria and algae followed by chlorine dioxide at 85%, while conventional chlorine dosing only gave 60% reduction in bioactivities. Test results of GAC bio-filter showed that around 70 % removal of total organic carbon in the seawater feed was achieved and was effective in keeping the microbial growth to a minimum. The measured results from this study enable designers of seawater cooling towers to manage the biofouling problems when such cooling towers are extrapolated to a pilot scale.en
dc.language.isoenen
dc.subjectCooling Toweren
dc.subjectOxidantsen
dc.subjectBiofoulingen
dc.subjectOrganic carbonen
dc.subjectGACen
dc.titleBiofouling control of industrial seawater cooling towersen
dc.typeDissertationen
dc.contributor.departmentBiological and Environmental Sciences and Engineering (BESE) Divisionen
thesis.degree.grantorKing Abdullah University of Science and Technologyen
dc.contributor.committeememberNg, Kim Choonen
dc.contributor.committeememberGojobori, Takashien
dc.contributor.committeememberAmy, Garyen
thesis.degree.disciplineEnvironmental Science and Engineeringen
thesis.degree.nameDoctor of Philosophyen
dc.person.id117766en
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