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Development and feasibility of an electrochemical-oxidation process for water disinfection
Thesis (MEng)--Stellenbosch University, 2018.
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| Language: | en_ZA |
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Stellenbosch : Stellenbosch University
2018
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| _version_ | 1867613818698334208 |
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| access_status_str | Open Access |
| author | De Wet, Leroi Johannes |
| author2 | Pillay, V. L. |
| author_browse | De Wet, Leroi Johannes Pillay, V. L. |
| author_facet | Pillay, V. L. De Wet, Leroi Johannes |
| author_sort | De Wet, Leroi Johannes |
| collection | Thesis |
| dc_rights_str_mv | Stellenbosch University |
| description | Thesis (MEng)--Stellenbosch University, 2018. |
| format | Thesis |
| id | oai:scholar.sun.ac.za:10019.1/103541 |
| institution | Stellenbosch University (South Africa) |
| language | en_ZA |
| last_indexed | 2026-06-10T12:42:11.774Z |
| license_str | Other — see source repository |
| provenance_str_mv | Harvested via OAI-PMH from SUNScholar — Stellenbosch University Repository |
| publishDate | 2018 |
| publishDateRange | 2018 |
| publishDateSort | 2018 |
| publisher | Stellenbosch : Stellenbosch University |
| publisherStr | Stellenbosch : Stellenbosch University |
| record_format | dspace |
| source_str | SUNScholar — Stellenbosch University Repository |
| spelling | oai:scholar.sun.ac.za:10019.1/103541 Development and feasibility of an electrochemical-oxidation process for water disinfection De Wet, Leroi Johannes Pillay, V. L. Stellenbosch University. Faculty of Engineering. Dept. of Process Engineering. Bromo-chloro-dimethyl-hydantoin Water quality management -- South Africa Disinfection and disinfectants Oxidation reduction reaction Metal ions as water disinfectants Ionization UCTD Thesis (MEng)--Stellenbosch University, 2018. ENGLISH SUMMARY: Quality of water supplies for potable use has deteriorated to such a state that point-of-use water disinfection has become a necessity. Historically, chlorine has been the most widely used disinfectant, but its shortcomings have led to the development of numerous alternative technologies over the last three decades. One of the emerging, but less understood technologies, are metal ions combined with an oxidising agent. Traditionally, chlorine disinfection has been controlled by measuring free chlorine residual and pH, but oxidation reduction potential (ORP) is emerging as an alternative indicator of the efficacy of disinfection. The objectives of the research were to (i) identify the contribution, if any, of metallic ions on the disinfection ability of bromo-chloro-dimethyl-hydantoin (BCDMH), (ii) investigate the feasibility of using metallic ions with BCDMH as a disinfectant on a typical potable water supply, (iii) evaluate ORP as an indicator of disinfection efficacy for a disinfection process that combines metallic ions with BCDMH. The feasibility investigated criteria such as efficiency, ease of implementation, financial implications and environmental implications, comparing the combined technology with the individual processes. A batch experimental setup was developed that treated a feed with a combination of metal ions and an oxidising agent. The feed consisted of tap water artificially contaminated with the bacterium Pseudomonas sp. strain CT07 at a concentration of between 0.5x107 and 2.0x107 cfu/ml. The drop plate method was used to determine disinfection by the reduction of bacterial concentrations to below detection limits. Copper, silver, and zinc ions were released by an ioniser and a BCDMH stock solution was used as oxidising agent. A fixed contact time of 5-minutes was used to keep findings relevant to point-of-use water disinfection. Experimental results were analysed using logistic regression. The logit model for combined treatment had a strong correlation with a Cox-Snell R2 of 0.516 and was significant with a p-value <0.001. The interaction coefficient (β12) was significant with a p-value of 0.036. The significant interaction coefficient showed that metal ions could improve the disinfecting ability of BCDMH at a short contact time of 5-minutes. The addition of metallic ions decreased the amount of BCDMH required to attain a certain probability for successful disinfection according to the probability model. The combined disinfection process is more efficient than the individual processes, can easily be implemented, and has environmental benefits over chlorine treatment. However, the combined technology is more expensive to operate than only BCDMH treatment. The addition of metal ions through ionisation can lead to a 25.67% reduction in BCDMH used, but it comes at an operating cost 2.5 times higher than treatment without metal ions. Final ORP values had no correlation with disinfection success. The change in ORP for the BCDMH treatment showed a significant relationship with treatment success with a p-value of 0.018. The relationship showed that a ΔORP of 164.35 mV should correspond to a 90% probability for successful treatment. However, the maximum experimental ΔORP was only 117 mV. The research showed that metal ions improve the disinfection efficiency of BCDMH. The technology has several advantages, but is not financially justifiable due to the increase in cost when compared to standard BCDMH treatment. The change in ORP was more closely related to disinfection success than to a single ORP value. A full concentration-contact time (CT) investigation would broaden the understanding of the interactions between metal ions, BCDMH, and pathogens. AFRIKAANSE OPSOMMING: Watergehalte van voorsiende water wat vir drink doeleindes gebruik word, het tot so ’n toestand verswak dat punt-van-gebruik waterdisinfeksie ’n noodsaaklikheid geword het. Histories, is kloor die mees gebruikte ontsmettingsmiddel, maar die tekortkominge daarvan het die afgelope drie dekades tot die ontwikkeling van talle alternatiewe tegnologieë gelei. Een van die opkomende, maar minder begrypte tegnologieë is die kombinasie van metaalione met ’n oksideringsagent. Tradisioneel is kloordisinfeksie beheer deur die vrye kloorresidu en die pH te meet, maar oksidasiereduksiepotensiaal (ORP) is besig om as ’n alternatiewe indikator van die doeltreffendheid van ontsmetting na vore te kom. Die doelwitte van die navorsing was om (i) die bydrae, indien enige, van metaalione op die ontsmettingsvermoë van broom-kloriedimethylhidantoïen (BCDMH) te identifiseer, (ii) die uitvoerbaarheid van die gebruik van metaalione met BCDMH as ’n ontsmettingsmiddel op ʼn tipiese drinkwaterbron te ondersoek, (iii) die ORP as ’n indikator van ontsmettingsdoeltreffendheid te evalueer vir ’n ontsmettingsproses wat metaalione met BCDMH kombineer. Die uitvoerbaarheidsondersoek het van kriteria soos doeltreffendheid, implementeringsgemak, finansiële implikasies en omgewingsimplikasies gebruik gemaak, en die vergelyk met die individuele prosesse. ’n Batch eksperimentele opstelling is ontwikkel wat ’n voer behandel het met ’n kombinasie metaalione en ’n oksideringsagent. Die voer het bestaan uit water wat kunsmatig besmet was met bakterie Pseudomonas sp. strain CT07 teen ’n konsentrasie van tussen 0.5x107 en 2.0x107 cfu/ml. Uitplating is gebruik om ontsmetting te bepaal deur die vermindering van bakteriese konsentrasies tot op ’n vlak onder die opsporingsgrense. Koper-, silwer- en sink-ione is deur ’n ioniseerder vrygelaat en ’n BCDMH voorraadoplossing is as oksideermiddel gebruik. ’n Vaste kontak tydperk van 5-minute is gebruik om die bevindings relevant te hou tot punt-van-gebruik waterdisinfeksie. Eksperimentele resultate was geanaliseer deur gebruik te maak van logistieke regressie. Die logit-model vir gekombineerde behandeling het ’n sterk korrelasie met ’n Cox-Snell R2 van 0.516 gehad wat beduidend was met ’n p-waarde <0.001. Die interaksie koëffisiënt (β12) was beduidend met ’n p-waarde van 0.036. Die beduidende interaksie koëffesiënt het getoon dat metaalione die ontsmettingsvermoë van BCDMH, vir ’n kort kontaktydperk van 5-minute, kan verbeter. Die byvoeging van metaalione verminder die hoeveelheid BCDMH wat benodig word om ’n sekere waarskynlikheid te bereik vir suksesvolle ontsmetting volgens die waarskynlikheidsmodel. Die gekombineerde ontsmettingsproses is meer doeltreffend, kan maklik implementeer word en dit het omgewingsvoordele oor die individuele prosesse. Maar, die gekombineerde tegnologie is duurder om te bedryf as slegs BCDMH-behandeling. Die byvoeging van metaalione deur ionisering kan lei tot ’n 25.67% vermindering in die gebruik van BCDMH, maar dit kom teen ’n bedryfskoste 2.5 keer meer as behandeling sonder metaalione. Finale ORP waardes het geen korrelasie met die ontsmettingssukses gehad nie. Die verandering in ORP vir die BCDMH behandeling het ’n beduidende verhouding getoon met behandelingsukses met ’n p-waarde van 0.018. Die verhouding het getoon dat ’n ΔORP van 164.35 mV ooreen behoort te stem met ’n 90% waarskynlikheid vir suksesvolle behandeling. Die maksimum eksperimentele ΔORP was egter slegs 117 mV. Die navorsing het getoon dat metaalione die onsmettingsdoeltreffendheid van BCDMH verbeter. Die tegnologie het verskeie voordele, maar dit is nie finansieel regverdigbaar nie as gevolg van die toename in koste teenoor standaard BCDMH behandeling. Die verandering in ORP was nouer verwant aan ontsmettingsukses as ’n enkele ORP-waarde. ’n Volledige koonsentrasie- kontak tyd (CT) ondersoek sal die begrip van die interaksies tussen metaalione, BCDMH en patogene verbreed. Masters 2018-02-26T09:40:01Z 2018-04-09T06:59:54Z 2018-02-26T09:40:01Z 2018-04-09T06:59:54Z 2018-03 Thesis http://hdl.handle.net/10019.1/103541 en_ZA Stellenbosch University xxiii, 206 pages ; illustrations application/pdf Stellenbosch : Stellenbosch University |
| spellingShingle | Bromo-chloro-dimethyl-hydantoin Water quality management -- South Africa Disinfection and disinfectants Oxidation reduction reaction Metal ions as water disinfectants Ionization UCTD De Wet, Leroi Johannes Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title | Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title_full | Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title_fullStr | Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title_full_unstemmed | Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title_short | Development and feasibility of an electrochemical-oxidation process for water disinfection |
| title_sort | development and feasibility of an electrochemical oxidation process for water disinfection |
| topic | Bromo-chloro-dimethyl-hydantoin Water quality management -- South Africa Disinfection and disinfectants Oxidation reduction reaction Metal ions as water disinfectants Ionization UCTD |
| url | http://hdl.handle.net/10019.1/103541 |
| work_keys_str_mv | AT dewetleroijohannes developmentandfeasibilityofanelectrochemicaloxidationprocessforwaterdisinfection |