A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage

 

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dc.contributor.advisor Ekama, George A
dc.contributor.advisor Ikumi, David
dc.contributor.author Harding, Theodor
dc.date.accessioned 2021-01-25T09:09:18Z
dc.date.available 2021-01-25T09:09:18Z
dc.date.issued 2020
dc.identifier.citation Harding, T. 2020. A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage. . ,Faculty of Engineering and the Built Environment ,Department of Civil Engineering. http://hdl.handle.net/11427/32660 en_ZA
dc.identifier.uri http://hdl.handle.net/11427/32660
dc.description.abstract This research study's the use of biological sulfate reduction technologies for the treatment of Sasol Secunda's coal-mine drainage (CMD) using Fischer-Tropsch Reaction Water (FTRW) as a cost-efficient carbon source. The research aims to develop a prototype dynamic model that describes this co-treatment of FTRW and CMD in both a continuously stirred tank reactor (CSTR) biological sulfate reduction (BSR) system and a BSR gas-lift (BSR-GL) integrated system. The BSR-GL system recovers elemental sulfur (S0 ) from the H2S produced and stripped from the BSR unit. Furthermore, this study aims to use the prototype model for a quantitative comparison of the CSTR-BSR and BSR-GL systems. Two bench-scale 5-litre CSTR-BSR and a 20-litre BSR-GL system were operated, under varying feed COD concentrations and hydraulic retention times (HRTs), to generate datasets for use in verification and a rudimentary validation of the prototype model. The BSR-GL integrated system includes 1) a 1-litre H2S gas reactive absorption (ABS) unit utilising an aqueous ferric solution for the recovery of elemental sulfur (S0 ) from sulfide and 2) ferrous biological oxidation reactor to regenerate ferric from the ferrous for re-supply to the ABS unit. The datasets generated in the experimental study allowed for the identification, mathematical modelling and reaction verification of 32 components that interact as reactants and products in 23 reactions observed in the two BSR systems. The prototype model is presented in a mass and charge balanced Gujer matrix that includes, i) 5 SRB mediated processes, ii) 2 liquid-gas mass transfer processes, iii) 3 processes describing the ABS and Fe2+ bio-oxidation units, iv) 4 processes describing sulfide and elemental sulfur oxidation and v) the S0 and poly-sulfide aqueous equilibrium and vi) 9 processes describing death regeneration and BPO hydrolysis. This prototype model was implemented in the DHI WEST® software for initial stage simulation trials. The experimental datasets allowed for the first-stage estimation of the best-fit reaction rate equations and the calibration of the kinetic parameters related to the 23 reactions, using MATLAB® curve fitting toolbox. A pre-processor that describe the pH and equilibrium chemistry of the components of the artificially prepared FTRW+CMD feed mixture batches under varying total concentrations have also been developed in this research. This was done to generated influent file to the DHI WEST® simulations that incorporated the dynamics related to the FTRW+CMD feed mixtures. The sulfate utilisation rate (gSO4 -2 .l-1 .d-1 ) of the GL-BSR and CSTR-BSR systems were compared to determine which system had the best sulfate removal. The results were found to be as follows; a. On comparison it was found that the sulfate substrate utilisation rate for the CSTR_BSR system is 39.28% of that of the BSR-GL_N2 system, where both systems were fed at feed mixture of COD of 2500mgCOD/l, where the COD:SO4 2- was 0.7, b. For the same systems fed a feed mixture of COD at 5000mgCOD/l (COD:SO4 2- = 0.7), the sulfate substrate utilisation rate for the CSTR_BSR system was found to be 17.86% less than that of the BSR_GLN2 system. c. Finally, it was also found that the substrate utilisation rate for the CSTR_BSR system was 30.06% less than that of the BSR_GLN2 system at Se of 4gCOD/l, for both systems fed substrate at 5000mgCOD/l. Thus, it can be concluded that the sulfate substrate utilisation rate for the BSR-GL system is higher than that of the CSTR_BSR system, for systems fed COD feed mixtures at 2.5 or 5gCOD/l where both systems have the same effluent substrate concentrations. However, the difference in the comparative substrate utilisation rate is less at higher feed substrate concentrations. This is the influence of substrate inhibition on the active SRB biomass, which increases with higher effluent substrate concentrations. Finally, this research found that the use of gas-lift reactor technologies is superior to CSTR technologies in the treatment of coal-mine drainage utilising biological sulfate reduction (BSR). The CSTR-BSR system, fed sulfate between 1.6 to 14gSO4 2- /l, produced effluent with high dissolved H2S concentrations, on average 285mgS/l and maximum at >600mgS/l. Releasing this effluent to the environment would be hazardous to aquatic and human health and corrosive to infrastructure. As such, the effluent from the CSTR-BSR system requires further treatment to stabilise the water for any use. The BSR-GL technology allows for the conversion of the H2S produced during BSR reactions to form elemental sulfur, which is a resource recovered from this process, thus complying to the circular economy aim of this study.
dc.subject Biological Sulfate Reduction
dc.subject Sulfide Oxidation
dc.subject Sulfur Oxidation
dc.subject H2S gas reactive absorption
dc.subject Ferrous biological Oxidation
dc.subject Resource Recovery
dc.title A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage
dc.type Doctoral Thesis
dc.date.updated 2021-01-25T09:01:27Z
dc.language.rfc3066 eng
dc.publisher.faculty Faculty of Engineering and the Built Environment
dc.publisher.department Department of Civil Engineering
dc.type.qualificationlevel Doctoral
dc.type.qualificationlevel PhD
dc.identifier.apacitation Harding, T. (2020). <i>A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage</i>. (). ,Faculty of Engineering and the Built Environment ,Department of Civil Engineering. Retrieved from http://hdl.handle.net/11427/32660 en_ZA
dc.identifier.chicagocitation Harding, Theodor. <i>"A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage."</i> ., ,Faculty of Engineering and the Built Environment ,Department of Civil Engineering, 2020. http://hdl.handle.net/11427/32660 en_ZA
dc.identifier.vancouvercitation Harding T. A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage. []. ,Faculty of Engineering and the Built Environment ,Department of Civil Engineering, 2020 [cited yyyy month dd]. Available from: http://hdl.handle.net/11427/32660 en_ZA
dc.identifier.ris TY - Doctoral Thesis AU - Harding, Theodor AB - This research study's the use of biological sulfate reduction technologies for the treatment of Sasol Secunda's coal-mine drainage (CMD) using Fischer-Tropsch Reaction Water (FTRW) as a cost-efficient carbon source. The research aims to develop a prototype dynamic model that describes this co-treatment of FTRW and CMD in both a continuously stirred tank reactor (CSTR) biological sulfate reduction (BSR) system and a BSR gas-lift (BSR-GL) integrated system. The BSR-GL system recovers elemental sulfur (S0 ) from the H2S produced and stripped from the BSR unit. Furthermore, this study aims to use the prototype model for a quantitative comparison of the CSTR-BSR and BSR-GL systems. Two bench-scale 5-litre CSTR-BSR and a 20-litre BSR-GL system were operated, under varying feed COD concentrations and hydraulic retention times (HRTs), to generate datasets for use in verification and a rudimentary validation of the prototype model. The BSR-GL integrated system includes 1) a 1-litre H2S gas reactive absorption (ABS) unit utilising an aqueous ferric solution for the recovery of elemental sulfur (S0 ) from sulfide and 2) ferrous biological oxidation reactor to regenerate ferric from the ferrous for re-supply to the ABS unit. The datasets generated in the experimental study allowed for the identification, mathematical modelling and reaction verification of 32 components that interact as reactants and products in 23 reactions observed in the two BSR systems. The prototype model is presented in a mass and charge balanced Gujer matrix that includes, i) 5 SRB mediated processes, ii) 2 liquid-gas mass transfer processes, iii) 3 processes describing the ABS and Fe2+ bio-oxidation units, iv) 4 processes describing sulfide and elemental sulfur oxidation and v) the S0 and poly-sulfide aqueous equilibrium and vi) 9 processes describing death regeneration and BPO hydrolysis. This prototype model was implemented in the DHI WEST® software for initial stage simulation trials. The experimental datasets allowed for the first-stage estimation of the best-fit reaction rate equations and the calibration of the kinetic parameters related to the 23 reactions, using MATLAB® curve fitting toolbox. A pre-processor that describe the pH and equilibrium chemistry of the components of the artificially prepared FTRW+CMD feed mixture batches under varying total concentrations have also been developed in this research. This was done to generated influent file to the DHI WEST® simulations that incorporated the dynamics related to the FTRW+CMD feed mixtures. The sulfate utilisation rate (gSO4 -2 .l-1 .d-1 ) of the GL-BSR and CSTR-BSR systems were compared to determine which system had the best sulfate removal. The results were found to be as follows; a. On comparison it was found that the sulfate substrate utilisation rate for the CSTR_BSR system is 39.28% of that of the BSR-GL_N2 system, where both systems were fed at feed mixture of COD of 2500mgCOD/l, where the COD:SO4 2- was 0.7, b. For the same systems fed a feed mixture of COD at 5000mgCOD/l (COD:SO4 2- = 0.7), the sulfate substrate utilisation rate for the CSTR_BSR system was found to be 17.86% less than that of the BSR_GLN2 system. c. Finally, it was also found that the substrate utilisation rate for the CSTR_BSR system was 30.06% less than that of the BSR_GLN2 system at Se of 4gCOD/l, for both systems fed substrate at 5000mgCOD/l. Thus, it can be concluded that the sulfate substrate utilisation rate for the BSR-GL system is higher than that of the CSTR_BSR system, for systems fed COD feed mixtures at 2.5 or 5gCOD/l where both systems have the same effluent substrate concentrations. However, the difference in the comparative substrate utilisation rate is less at higher feed substrate concentrations. This is the influence of substrate inhibition on the active SRB biomass, which increases with higher effluent substrate concentrations. Finally, this research found that the use of gas-lift reactor technologies is superior to CSTR technologies in the treatment of coal-mine drainage utilising biological sulfate reduction (BSR). The CSTR-BSR system, fed sulfate between 1.6 to 14gSO4 2- /l, produced effluent with high dissolved H2S concentrations, on average 285mgS/l and maximum at >600mgS/l. Releasing this effluent to the environment would be hazardous to aquatic and human health and corrosive to infrastructure. As such, the effluent from the CSTR-BSR system requires further treatment to stabilise the water for any use. The BSR-GL technology allows for the conversion of the H2S produced during BSR reactions to form elemental sulfur, which is a resource recovered from this process, thus complying to the circular economy aim of this study. DA - 2020 DB - OpenUCT DP - University of Cape Town KW - Biological Sulfate Reduction KW - Sulfide Oxidation KW - Sulfur Oxidation KW - H2S gas reactive absorption KW - Ferrous biological Oxidation KW - Resource Recovery LK - https://open.uct.ac.za PY - 2020 T1 - A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage TI - A prototype dynamic model for the co-treatment of a high strength simple-organic industrial effluent and coal-mine drainage UR - http://hdl.handle.net/11427/32660 ER - en_ZA


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