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Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics

Phosphorus (P) is an essential nutrient which supports growth and life. A need has developed to recycle P due it being a finite mined resource. At present, most P is lost due to runoff or wastewater (WW) effluent and ending up in rivers and oceans. In order to recycle P and other nutrients, Wastewat...

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Main Author: Du Toit, Johan
Other Authors: Ikumi, David S
Format: Thesis
Language:English
Published: Department of Civil Engineering 2022
Subjects:
Civil Engineering
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access_status_str Open Access
author Du Toit, Johan
author2 Ikumi, David S
author_browse Du Toit, Johan
Ikumi, David S
author_facet Ikumi, David S
Du Toit, Johan
author_sort Du Toit, Johan
collection Thesis
description Phosphorus (P) is an essential nutrient which supports growth and life. A need has developed to recycle P due it being a finite mined resource. At present, most P is lost due to runoff or wastewater (WW) effluent and ending up in rivers and oceans. In order to recycle P and other nutrients, Wastewater Treatment Plants (WWTPs) will need to be converted to Water and Resource Recovery Facilities (WRRFs). However, for WRRFs to be feasible, a better understanding of the current models predicting the fate of P and other material components in place are required. The objective of this study is to utilise augmented batch tests to determine the characteristics of the Waste Activated Sludge (WAS) containing Polyphosphate Accumulating Organisms (PAOs) from a full-scale WWTP as input variables in the Steady State (SS) Anaerobic Digestion (AD) model to ensure accurate prediction of AD performance. The experimental setup used in this research consisted of two completely mixed laboratory scale (20 litres volume, mesophilic 36 ̊C) Anaerobic Digesters (ADrs). The ADrs were operated at SS for 15 day and 32-day Solid Retention Times (SRT) and were fed WAS from a full-scale treatment plant which consisted of a Membrane Bioreactor (MBR) Nitrification-Denitrification (ND) Biological Excess Phosphorus Removal (BEPR) Activated Sludge (AS) system. Two different methods ((i) a novel approach by Maake & Ikumi, (2021) and (ii) the method used by Harding, (2009)) were compared in determining the saturation kinetic rates and the WAS characteristics as input variables for the SS AD models. It was determined that the novel approach by Maake & Ikumi, (2021) was very reliable in determining Chemical Oxygen Demand (COD) removal, Free and Saline Ammonia (FSA), system effluent pH and total alkalinity. With respect to the Ortho-Phosphates (OP), the parent system from where the WAS is sourced, had a long SRT. This resulted in a low predicted PAO count and Poly-Phosphate (PP) content, which resulted in low amounts of Organically bound Phosphate (OrgP) being released into the Anaerobic Digester Liquor (ADL), which equated to an underprediction of OP. Due to the low PP content found in the WAS fed to the ADrs, the ADL was not fully saturated, resulting in no struvite precipitation taking place. This was accurately modelled for both Maake & Ikumi, (2021) and Ikumi, Harding & Ekama, (2013) modelling scenarios.
format Thesis
id oai:open.uct.ac.za:11427/35718
institution University of Cape Town (South Africa)
language eng
last_indexed 2026-06-10T12:33:08.525Z
license_str Not specified — see source repository
provenance_str_mv Harvested via OAI-PMH from UCTD — University of Cape Town Open Access Repository
publishDate 2022
publishDateRange 2022
publishDateSort 2022
publisher Department of Civil Engineering
publisherStr Department of Civil Engineering
record_format dspace
source_str UCTD — University of Cape Town Open Access Repository
spelling oai:open.uct.ac.za:11427/35718 Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics Du Toit, Johan Ikumi, David S Civil Engineering Phosphorus (P) is an essential nutrient which supports growth and life. A need has developed to recycle P due it being a finite mined resource. At present, most P is lost due to runoff or wastewater (WW) effluent and ending up in rivers and oceans. In order to recycle P and other nutrients, Wastewater Treatment Plants (WWTPs) will need to be converted to Water and Resource Recovery Facilities (WRRFs). However, for WRRFs to be feasible, a better understanding of the current models predicting the fate of P and other material components in place are required. The objective of this study is to utilise augmented batch tests to determine the characteristics of the Waste Activated Sludge (WAS) containing Polyphosphate Accumulating Organisms (PAOs) from a full-scale WWTP as input variables in the Steady State (SS) Anaerobic Digestion (AD) model to ensure accurate prediction of AD performance. The experimental setup used in this research consisted of two completely mixed laboratory scale (20 litres volume, mesophilic 36 ̊C) Anaerobic Digesters (ADrs). The ADrs were operated at SS for 15 day and 32-day Solid Retention Times (SRT) and were fed WAS from a full-scale treatment plant which consisted of a Membrane Bioreactor (MBR) Nitrification-Denitrification (ND) Biological Excess Phosphorus Removal (BEPR) Activated Sludge (AS) system. Two different methods ((i) a novel approach by Maake & Ikumi, (2021) and (ii) the method used by Harding, (2009)) were compared in determining the saturation kinetic rates and the WAS characteristics as input variables for the SS AD models. It was determined that the novel approach by Maake & Ikumi, (2021) was very reliable in determining Chemical Oxygen Demand (COD) removal, Free and Saline Ammonia (FSA), system effluent pH and total alkalinity. With respect to the Ortho-Phosphates (OP), the parent system from where the WAS is sourced, had a long SRT. This resulted in a low predicted PAO count and Poly-Phosphate (PP) content, which resulted in low amounts of Organically bound Phosphate (OrgP) being released into the Anaerobic Digester Liquor (ADL), which equated to an underprediction of OP. Due to the low PP content found in the WAS fed to the ADrs, the ADL was not fully saturated, resulting in no struvite precipitation taking place. This was accurately modelled for both Maake & Ikumi, (2021) and Ikumi, Harding & Ekama, (2013) modelling scenarios. 2022-02-18T06:17:19Z 2022-02-18T06:17:19Z 2021 2022-02-10T09:14:29Z Master Thesis Masters MSc http://hdl.handle.net/11427/35718 eng application/pdf Department of Civil Engineering Faculty of Engineering and the Built Environment
spellingShingle Civil Engineering
Du Toit, Johan
Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
thesis_degree_str Master's
title Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
title_full Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
title_fullStr Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
title_full_unstemmed Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
title_short Anaerobic Digestion Steady State model parameter estimation for determination of waste activated sludge characteristics
title_sort anaerobic digestion steady state model parameter estimation for determination of waste activated sludge characteristics
topic Civil Engineering
url http://hdl.handle.net/11427/35718
work_keys_str_mv AT dutoitjohan anaerobicdigestionsteadystatemodelparameterestimationfordeterminationofwasteactivatedsludgecharacteristics

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