Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors

The primary aim of this research was to develop a variety of methods for the specific characterisation of soluble microbial products (SMPs) that are produced during substrate metabolism or cell lysis and degradation in anaerobic treatment. In biological wastewater treatment processes, the analysis o...

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Main Author: Le, Chencheng
Other Authors: David Campbell Stuckey
Format: Theses and Dissertations
Language:English
Published: 2018
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Online Access:http://hdl.handle.net/10356/73164
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Institution: Nanyang Technological University
Language: English
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spelling sg-ntu-dr.10356-731642023-03-03T19:16:12Z Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors Le, Chencheng David Campbell Stuckey Liu Yu School of Civil and Environmental Engineering Nanyang Environment and Water Research Institute DRNTU::Engineering::Environmental engineering::Water treatment The primary aim of this research was to develop a variety of methods for the specific characterisation of soluble microbial products (SMPs) that are produced during substrate metabolism or cell lysis and degradation in anaerobic treatment. In biological wastewater treatment processes, the analysis of metabolic compounds that are produced during the process is critical to monitoring the performance of system; these soluble products directly affect process efficiency (removal of oxidizable compounds) and quality of the effluent after treatment, and are also one of the major causes of fouling in membrane bioreactors. However, analysing them is challenging due to their inherently dilute nature (sub ppm level) and heterogeneity. In this PhD project, the chemical composition of SMPs produced during the anaerobic condition will be identified and quantified using both sophisticated analytical instruments, e.g. GC-MS, and conventional chemical analyses. Firstly, an analytical methodology for low molecular weight SMPs (<580 Da) in wastewater treatment systems was established using a combination of solid phase extraction (SPE) and liquid-liquid extraction (LLE), which was optimized and enabled the maximum number of compounds to be identified. Next, conventional colorimetric measurements of carbohydrates and proteinaceous materials generated from anaerobic bioreactor were critically evaluated. These result highlighted the severe limitations of these dated assays, and the need for exercising care when interpreting results, particularly where complex heterogeneous wastewater is concerned. Then protocols for the characterisation of free amino acids using HPLC, and for elucidating the monomeric structure of loosely bound exopolysaccharides (EPS) using GC-MS were developed in order to gain greater insights into the biological transformations occurring in anaerobic digestion (AD), and the SMPs produced. Finally, all these optimized methods were employed to comprehensively assess the impact of different carbohydrate substrates (glucose, fructose and sucrose) and nitrogen sources (urea and NH4Cl) on the production and composition of SMPs during AD. This study revealed that these macronutrients could strongly influenced many measures of wastewater quality, and the results clearly demonstrated that well-characterized nutritional conditions ensure a cooperative bacterial symbiosis converting complex organic matter to biogas effectively. All the findings in this project provide fresh and useful insights into an area that is under researched, and often overlooked by engineers studying overall engineered wastewater treatment systems. Doctor of Philosophy (CEE) 2018-01-08T06:27:02Z 2018-01-08T06:27:02Z 2018 Thesis Le, C. (2018). Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors. Doctoral thesis, Nanyang Technological University, Singapore. http://hdl.handle.net/10356/73164 10.32657/10356/73164 en 185 p. application/pdf
institution Nanyang Technological University
building NTU Library
continent Asia
country Singapore
Singapore
content_provider NTU Library
collection DR-NTU
language English
topic DRNTU::Engineering::Environmental engineering::Water treatment
spellingShingle DRNTU::Engineering::Environmental engineering::Water treatment
Le, Chencheng
Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
description The primary aim of this research was to develop a variety of methods for the specific characterisation of soluble microbial products (SMPs) that are produced during substrate metabolism or cell lysis and degradation in anaerobic treatment. In biological wastewater treatment processes, the analysis of metabolic compounds that are produced during the process is critical to monitoring the performance of system; these soluble products directly affect process efficiency (removal of oxidizable compounds) and quality of the effluent after treatment, and are also one of the major causes of fouling in membrane bioreactors. However, analysing them is challenging due to their inherently dilute nature (sub ppm level) and heterogeneity. In this PhD project, the chemical composition of SMPs produced during the anaerobic condition will be identified and quantified using both sophisticated analytical instruments, e.g. GC-MS, and conventional chemical analyses. Firstly, an analytical methodology for low molecular weight SMPs (<580 Da) in wastewater treatment systems was established using a combination of solid phase extraction (SPE) and liquid-liquid extraction (LLE), which was optimized and enabled the maximum number of compounds to be identified. Next, conventional colorimetric measurements of carbohydrates and proteinaceous materials generated from anaerobic bioreactor were critically evaluated. These result highlighted the severe limitations of these dated assays, and the need for exercising care when interpreting results, particularly where complex heterogeneous wastewater is concerned. Then protocols for the characterisation of free amino acids using HPLC, and for elucidating the monomeric structure of loosely bound exopolysaccharides (EPS) using GC-MS were developed in order to gain greater insights into the biological transformations occurring in anaerobic digestion (AD), and the SMPs produced. Finally, all these optimized methods were employed to comprehensively assess the impact of different carbohydrate substrates (glucose, fructose and sucrose) and nitrogen sources (urea and NH4Cl) on the production and composition of SMPs during AD. This study revealed that these macronutrients could strongly influenced many measures of wastewater quality, and the results clearly demonstrated that well-characterized nutritional conditions ensure a cooperative bacterial symbiosis converting complex organic matter to biogas effectively. All the findings in this project provide fresh and useful insights into an area that is under researched, and often overlooked by engineers studying overall engineered wastewater treatment systems.
author2 David Campbell Stuckey
author_facet David Campbell Stuckey
Le, Chencheng
format Theses and Dissertations
author Le, Chencheng
author_sort Le, Chencheng
title Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
title_short Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
title_full Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
title_fullStr Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
title_full_unstemmed Characterisation of soluble microbial products (SMPs) in anaerobic bioreactors
title_sort characterisation of soluble microbial products (smps) in anaerobic bioreactors
publishDate 2018
url http://hdl.handle.net/10356/73164
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