Wong, Kin Shing Kinson. / Thesis submitted in: November 2007. / Thesis (M.Phil.)--Chinese University of Hong Kong, 2008. / Includes bibliographical references (leaves 145-158). / Abstracts in English and Chinese. / Acknowledgements --- p.i / Abstract --- p.ii / 摘要 --- p.v / Contents --- p.viii / List of figures --- p.xv / List of plates --- p.xx / List of tables --- p.xxi / Abbreviations --- p.xxiii / Chapter 1. --- Introduction --- p.1 / Chapter 1.1 --- Heavy metals --- p.1 / Chapter 1.1.1 --- Characteristics of heavy metals --- p.1 / Chapter 1.1.2 --- Heavy metal pollution in Hong Kong --- p.2 / Chapter 1.1.3 --- Common usage of heavy metals --- p.4 / Chapter 1.1.3.1 --- Copper --- p.4 / Chapter 1.1.3.2 --- Nickel --- p.4 / Chapter 1.1.3.3 --- Zinc --- p.5 / Chapter 1.1.4 --- Toxicity of heavy metals --- p.5 / Chapter 1.1.4.1 --- Copper --- p.6 / Chapter 1.1.4.2 --- Nickel --- p.7 / Chapter 1.1.4.3 --- Zinc --- p.7 / Chapter 1.1.5 --- Treatment techniques for metal ions --- p.8 / Chapter 1.1.5.1 --- Chemical precipitation --- p.9 / Chapter 1.1.5.2 --- Ion exchange --- p.10 / Chapter 1.1.5.3 --- Activated carbon adsorption --- p.10 / Chapter 1.2 --- Biosorption --- p.11 / Chapter 1.2.1 --- Definition of biosorption --- p.11 / Chapter 1.2.2 --- Mechanism --- p.12 / Chapter 1.2.3 --- Advantages of biosorption --- p.13 / Chapter 1.2.4 --- Selection of biosorbents --- p.15 / Chapter 1.3 --- Chitinous materials --- p.17 / Chapter 1.3.1 --- Background of chitin --- p.17 / Chapter 1.3.2 --- Structures of chitinous materials --- p.18 / Chapter 1.3.3 --- Sources of chitinous materials --- p.18 / Chapter 1.3.4 --- Application of chitinous materials --- p.20 / Chapter 1.3.5 --- Mechanism of metal ion adsorption by chitin --- p.22 / Chapter 1.4 --- Activated carbon --- p.25 / Chapter 1.4.1 --- Characteristics of activated carbon --- p.25 / Chapter 1.4.2 --- Applications of activated carbon --- p.26 / Chapter 1.4.3 --- Factors affecting adsorption ability of activated carbon --- p.27 / Chapter 1.4.4 --- Advantages and Disadvantages --- p.28 / Chapter 1.4.4.1 --- Advantages (Adsorption) --- p.28 / Chapter 1.4.4.2 --- Advantages (Regerneration) --- p.28 / Chapter 1.4.4.3 --- Disadvantages (Adsorption) --- p.28 / Chapter 1.4.4.4 --- Disadvantages (Regeneration) --- p.29 / Chapter 1.5 --- Cation exchange resin --- p.29 / Chapter 1.5.1 --- Usages of cation exchange resin --- p.29 / Chapter 1.5.2 --- Characteristics of cation exchange resin --- p.30 / Chapter 1.5.3 --- Disadvantages of using cation exchange resin --- p.30 / Chapter 1.6 --- Magnetite --- p.31 / Chapter 1.6.1 --- Reasons of using magnetite --- p.31 / Chapter 1.6.2 --- Characteristics of magnetite --- p.31 / Chapter 1.6.3 --- Immobilization by magnetite --- p.32 / Chapter 1.6.4 --- Advantages of using magnetite --- p.33 / Chapter 1.7 --- The biosorption experiment --- p.33 / Chapter 1.7.1 --- The batch biosorption experiment --- p.33 / Chapter 1.7.2 --- The adsorption isotherms --- p.34 / Chapter 1.7.2.1 --- The Langmuir adsorption isotherm --- p.34 / Chapter 1.7.2.2 --- The Freundlich adsorption isotherm --- p.36 / Chapter 2. --- Objectives --- p.38 / Chapter 3. --- Materials and methods --- p.39 / Chapter 3.1 --- Adsorbents --- p.39 / Chapter 3.1.1 --- Chitin A --- p.39 / Chapter 3.1.2 --- Pretreatment of chitin A --- p.39 / Chapter 3.1.3 --- Magnetite --- p.39 / Chapter 3.1.4 --- Activated carbon --- p.41 / Chapter 3.1.5 --- Cation exchange resin --- p.41 / Chapter 3.1.6 --- Pretreatment of cation exchange resin --- p.41 / Chapter 3.2 --- Chemicals --- p.43 / Chapter 3.2.1 --- Metal ion solution --- p.43 / Chapter 3.2.2 --- Buffer solution --- p.43 / Chapter 3.2.3 --- Standard solution --- p.43 / Chapter 3.3 --- Immobilization of chitin A by magnetite --- p.44 / Chapter 3.3.1 --- Effect of chitin A to magnetite ratio --- p.44 / Chapter 3.3.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.45 / Chapter 3.3.3 --- Effect of pH --- p.45 / Chapter 3.3.4 --- Effect of immobilization time --- p.46 / Chapter 3.3.5 --- Effect of temperature --- p.46 / Chapter 3.3.6 --- Effect of agitation rate --- p.46 / Chapter 3.3.7 --- Effect of salinity --- p.46 / Chapter 3.3.8 --- Mass production of magnetite-immobilized chitin A --- p.47 / Chapter 3.4 --- Batch adsorption experiment --- p.47 / Chapter 3.5 --- "Optimization of physicochemical condition on Cu2+，Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.48 / Chapter 3.5.1 --- Effect of equilibrium pH --- p.48 / Chapter 3.5.2 --- Effect of amount of adsorbent --- p.49 / Chapter 3.5.3 --- Effect of retention time --- p.49 / Chapter 3.5.4 --- Effect of agitation rate --- p.49 / Chapter 3.5.5 --- Effect of temperature --- p.50 / Chapter 3.5.6 --- Effect of initial metal ion concentration --- p.50 / Chapter 3.5.7 --- Adsorption isotherms --- p.50 / Chapter 3.5.8 --- Dimensionless separation factor --- p.52 / Chapter 3.5.9 --- Kinetic parameters of adsorption --- p.52 / Chapter 3.5.10 --- Thermodynamic parameters of adsorption --- p.53 / Chapter 3.6 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.54 / Chapter 3.6.1 --- Performances of various solutions on metal ion recovery --- p.54 / Chapter 3.6.2 --- Multiple adsorption and desorption cycles of metal ions --- p.55 / Chapter 3.7 --- Statistical analysis of data --- p.55 / Chapter 4. --- Results --- p.56 / Chapter 4.1 --- Immobilization of chitin A by magnetite --- p.56 / Chapter 4.1.1 --- Effect of chitin A to magnetite ratio --- p.56 / Chapter 4.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.59 / Chapter 4.1.3 --- Effect of pH --- p.59 / Chapter 4.1.4 --- Effect of immobilization time --- p.59 / Chapter 4.1.5 --- Effect of temperature --- p.59 / Chapter 4.1.6 --- Effect of agitation rate --- p.64 / Chapter 4.1.7 --- Effect of salinity --- p.64 / Chapter 4.1.8 --- Mass production of magnetite-immobilized chitin A --- p.64 / Chapter 4.2 --- Batch adsorption experiment --- p.67 / Chapter 4.2.1 --- Screening of adsorbents --- p.67 / Chapter 4.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.70 / Chapter 4.3.1 --- Effect of equilibrium pH --- p.70 / Chapter 4.3.2 --- Effect of amount of adsorbent --- p.74 / Chapter 4.3.3 --- Effect of retention time --- p.78 / Chapter 4.3.4 --- Effect of agitation rate --- p.82 / Chapter 4.3.5 --- Effect of temperature --- p.82 / Chapter 4.3.6 --- Effect of initial metal ion concentration --- p.86 / Chapter 4.3.7 --- Summary of optimized conditions for three metal ions --- p.87 / Chapter 4.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.87 / Chapter 4.3.9 --- Performance of reference adsorbents (AC and CER) --- p.87 / Chapter 4.3.10 --- Adsorption isotherms --- p.99 / Chapter 4.3.11 --- Dimensionless separation factor --- p.103 / Chapter 4.3.12 --- Kinetic parameters of adsorption --- p.106 / Chapter 4.3.13 --- Thermodynamic parameters of adsorption --- p.113 / Chapter 4.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.113 / Chapter 4.4.1 --- Performances of various solutions on metal ion recovery --- p.113 / Chapter 4.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.117 / Chapter 5. --- Discussions --- p.121 / Chapter 5.1 --- Immobilization of chitin A by magnetite --- p.121 / Chapter 5.1.1 --- Effect of chitin A to magnetite ratio --- p.121 / Chapter 5.1.2 --- Effect of amount of chitin A and magnetite in a fixed ratio --- p.121 / Chapter 5.1.3 --- Effect of pH --- p.122 / Chapter 5.1.4 --- Effect of immobilization time --- p.122 / Chapter 5.1.5 --- Effect of temperature --- p.122 / Chapter 5.1.6 --- Effect of agitation rate --- p.123 / Chapter 5.1.7 --- Effect of salinity --- p.123 / Chapter 5.2 --- Batch adsorption experiment --- p.123 / Chapter 5.2.1 --- Screening of adsorbents --- p.123 / Chapter 5.3 --- "Optimization of physicochemical condition on Cu2+, Ni2+ and Zn2+ adsorption by MCA, AC and CER" --- p.124 / Chapter 5.3.1 --- Effect of equilibrium pH --- p.125 / Chapter 5.3.2 --- Effect of amount of adsorbent --- p.126 / Chapter 5.3.3 --- Effect of retention time --- p.127 / Chapter 5.3.4 --- Effect of agitation rate --- p.128 / Chapter 5.3.5 --- Effect of temperature --- p.128 / Chapter 5.3.6 --- Effect of initial metal ion concentration --- p.129 / Chapter 5.3.7 --- Summary of optimized conditions for three metal ions --- p.130 / Chapter 5.3.8 --- Cost analysis of metal ion removal by three adsorbents --- p.132 / Chapter 5.3.9 --- Performance of reference adsorbents (AC and CER) --- p.133 / Chapter 5.3.10 --- Adsorption isotherms --- p.133 / Chapter 5.3.11 --- Dimensionless separation factor --- p.135 / Chapter 5.3.12 --- Kinetic parameters of adsorption --- p.136 / Chapter 5.3.13 --- Thermodynamic parameters of adsorption --- p.139 / Chapter 5.4 --- "Recovery of Cu2+, Ni2+ and Zn2+ from metal ion-laden MCA" --- p.140 / Chapter 5.4.1 --- Performances of various solutions on metal ion recovery --- p.140 / Chapter 5.4.2 --- Multiple adsorption and desorption cycles of metal ions --- p.141 / Chapter 6. --- Conclusions --- p.143 / Chapter 7. --- References --- p.145

A large fraction of the current cost of wastewater treatment is from the treatment and disposal of wastewater sludge. Improved design, energy efficiency, and performance of dewatering facilities could significantly decrease transport and disposal costs. Dewatering facilities are designed based on field experience, trial and error, pilot plant testing, and/or full scale testing. Design is generally time-consuming and expensive. A full-scale test typically consists_ of side-by-side operation of 4 to 5 full-scale dewatering units for several weeks to more than 6 months. Theoretical modeling of the physics of dewatering units such as the belt filter press, based on laboratory determined sludge properties, would better predict dewatering performance. This research developed a numerical computer model of the physics of gravity sedimentation. The model simulated the gravity sedimentation portion of the belt filter press. The model was developed from a physically-based numerical computer model of cake filtration by Wells (1990). As opposed to the cake filtration model, the inertial and gravity terms were retained in the gravity sedimentation model. Although in the cake filtration model, the inertial terms were shown to be negligible, according to Dixon, Souter, and Buchanan (1985), inertial effects in gravity sedimentation cannot generally be ignored. The region where inertia is important is the narrow interface between suspension and sediment. In the cake filtration model the gravity term was negligible due to the relatively large magnitude of the applied pressure; but in the gravity sedimentation model, since there was no applied pressure, it was necessary to consider the effect of gravity. _ Two final governing equations were developed - solid continuity and total momentum with continuity ("momentum"). ·The finite difference equations used a "space-staggered" mesh. The solid continuity equation was solved using an explicit formulation, with a forward difference in time and central difference in space. The "momentum" equation used a fully implicit formulation with a forward difference in time. The modeler could choose either a central difference or forward difference in space. Non-linear terms were linearized. Boundary Conditions and constitutive relationships were determined. Numerical errors in the numerical model were analyzed. The model was calibrated to known data and verified with additional data. The model was extremely sensitive to the constitutive relationships used, but relatively unaffected by the At or the use of central difference or forward difference for the spatial derivative term in the "momentum" equation. Correlations of the calibrated model to data with a low initial concentration show that the constitutive parameters approximate the data, but not very well. Model runs with low initial concentration required the addition of artificial viscosity to remain stable. The gravity term was always significant, whereas the inertial terms were many orders of magnitude less than gravity. However, the lower the initial concentration, the larger the inertial terms. In addition to the belt filter press, the model can also be applied to cake filtration and design of gravity sedimentation tanks as well.

A total of 44 intermittent sand filter-septic systems, in five counties of Western Oregon, were sampled over a three-month period during the summer of 1995. The sand filter systems varied in age from 36 months up to 167 months (3 to 13.9 years). Liquid samples were taken from the septic tank and distribution box. In addition, soil samples were taken adjacent to the disposal trench and away from the disposal field area (control). All samples were analyzed for Total Kjeldahl Nitrogen (TKN) and nitrate and nitrite. Nitrite was not detected in any of the samples. The average removal of total nitrogen (TKN + nitrate) through the filter was found to be 43%. Nitrate was determined to be the dominant form of nitrogen in the sand filter effluent making up 94% of the total nitrogen. The age of the system was found not to be a predictor of the system's performance. Once the effluent entered the disposal field, little if any transformation of nitrogen occurred at an average depth of 30 inches (76.2 cm). / Graduation date: 1996

published_or_final_version / Civil Engineering / Master / Master of Philosophy

The influence of nitrogen (N) and phosphorus (P) limitation on pulp and paper mill activated sludge (AS) floc properties was studied using a bioreactor fed with synthetic Kraft mill effluent. The bioreactor and synthetic effluent were designed and shown to perform like the real mill system providing the AS, establishing the in vivo relevance of the results. Limitation of either N or P produced inadequate effluent biotreatment, shown by poor BOD5 and suspended solids removal, and by decreased biomass health, performance, and floc settling. Greatly enhanced poly-beta-hydroxybutyrate (PHB) (but not carbohydrate or extracellular polymeric substances [EPS]) synthesis was the common response of the floc microbial community to N limitation over many days. In contrast, P-limitation increased total carbohydrate and EPS, but not PHB. / N limitation, but not P limitation, caused the net floc surface charge to be much more negative, while P-limitation, but not N-limitation, increased the floc bound water content and surface hydrophobicity. Thus, in real pulp and paper mill AS systems, careful manipulation of N or P additions may be useful to optimize the key process of charged polymer-assisted AS dewatering.

Thesis (M.Tech.)-Department of Biotechnology, Durban University of Technology, 2006 xvi, 126 leaves / The microbial community present in a laboratory-scale modified Ludzack-Ettinger activated sludge system was investigated using a combination of novel molecular techniques. The parent system was investigated for a duration of one year and samples were taken at regular intervals to determine the profile and structure of the microbial community present within the anoxic and aerobic zones of the MLE system. The combination of molecular techniques included fluorescent in situ hybridisation (FISH) and denaturing gradient gel electrophoresis (DGGE). FISH was performed using oligonucleotide probes, which were complementary to conserved regions of the rRNA for the alpha, beta and gamma subclasses of the gram negative family Proteobacteria as well as a group-specific HGC oligonucleotide probe as a representative of the gram positive actinomycetes branch. The total eubacteria present was determined using the EUB oligonucleotide probes, EUB388, EUB388-II and EUB388-III. The DGGE analysis of PCR-amplified 16S rDNA gene segments was used to examine the microbial community profile in the anoxic and aerobic zones. The profile for each of the zones revealed a number of consistent bands throughout the duration of the laboratory-scale process. However, the profiles obtained suggested that a diverse microbial community existed within the aerobic and anoxic zones. The bands also indicated the presence of dominant and less dominant species of bacteria. Hybridisations obtained from the FISH analyses indicated that the alpha and gamma subclasses were predominant within the anoxic zone and the aerobic zone showed a dominance of the beta subclass of Proteobacteria. The steady state behaviour of the MLE system was confirmed with the results obtained from COD, TKN, nitrates and OUR analytical tests. COD and nitrogen mass balances were conducted to confirm the acceptance of the results obtained for each batch as an indication of the system performance for the MLE model. Nitrogen mass balances indicated an upset in the nitrogen levels for batches two and seven.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban Institute of Technology, 2005 xiv, 114 leaves : ill. 30 cm / The activated sludge process is the mostl used biological treatment process. Engineers and microbiologists are constantly seeking ways to improve process efficiency, which can be attributed to the increasing demand for fresh water supplies and proper environmental management. Since the inception of the activated sludge process, bulking and foaming have been major problems affecting its efficiency. Filamentous bacteria have been identified as the primary cause of bulking and foaming. Numerous attempts have been made to resolve this problem. Some of these attempts were effective as interim measures but failed as long term control strategies. The identification of filamentous bacteria and the study of their physiology have been hampered by the unreliability of conventional microbiological techniques. This is largely due to their morphological variations and inconsistent characteristics within different environments. To fully understand their role in promoting bulking and foaming, filamentous bacteria need to be characterized on a molecular level. The aim of this study was, therefore, to identify filamentous bacteria in pure culture with the purpose of validating these findings to the physiological traits of the pure cultures when they were isolated. Fourteen different filamentous cultures were used for this study. The cultures were identified using specific oligonucleotide probes via fluorescent in situ hybridisation and nucleotide sequencing. Prior to sequencing, an agarose gel and a denaturing gradient gel Electrophoresis profile were determined for each isolate. The various techniques were optimised specifically for the filamentous isolates. The isolates were identified as Gordonia amarae, Haliscomenobacter hydrossis, Acinetobacter sp./Type 1863, Type 021N, Thiothrix nivea, Sphaerotilus natans and Nocardioform organisms.

Thesis (MEng (Chemical Engineering))--Cape Peninsula University of Technology, 2018. / Advanced oxidation processes (AOPs) have gained considerable interest in the wastewater treatment industry. Low selectivity to organic pollutants and the high oxidation potentials provided by the free radicals produced from these processes are the root of this interest. Hydroxyl radical based AOPs seemed to dominate the field but recently sulphate radical based AOPs started to become more popular due to their even higher oxidation potential. The textile industry is known to be a considerable contributor to wastewater production. Many pollutants in this wastewater are organic pollutants which are very persistent to the more traditional treatment processes such as biological treatment and membrane filtration. Numerous studies have shown the potential and success of catalytic AOPs for the degradation of organic pollutants in wastewater. One such process is the use of a cobalt oxide nano-catalyst in conjunction with a peroxymonosulfate (PMS) oxidizer (Co3O4/PMS). The shortcoming with nano-catalysts however are the difficulty of recovering the catalyst in a slurry system or the effective immobilization of the catalyst in a continuous system. To address the issue of nano-catalyst immobilization, two different methods were used in the study to effectively immobilize the catalyst in a substrate. The methods were compared by utilizing the permeable reaction barriers in a continuous flow reactor. A bench scale reactor of 2.4 L/hr was designed and used to study the effect of PMS, catalyst mass and flow rate on the degradation efficiency and to determine the residence time and catalyst per PRB cross-sectional area ratio. A scale up rationale was formulated based on a constant residence time and the catalyst mass per PRB cross-sectional area ratio. Two design correlations were developed to predict the size of the permeable barrier and the catalyst mass required for the scale up PRB system. These parameters were used to design a reactor 30 times that of the bench scale reactor. In both reactors the optimum degradation occurred within 2 minutes indicating the success for catalyst immobilization and the development of a continuous reactor utilizing the Co3O4/PMS advanced oxidation technology.

Submitted in fulfillment of the degree of Master of Applied Science: Biotechnology, Durban University of Technology, Durban, South Africa, 2017. / Domestic wastewater contains a high nutrient load, primarily in the form of Carbon (C), Nitrogen (N), and Phosphorous (P) compounds. If left untreated, these nutrients can cause eutrophication in receiving environments. Biological wastewater treatment utilizes a suspension of microorganisms that metabolize this excess nutrient load. Nitrogen removal in these systems are due to the synergistic processes of nitrification and denitrification, each of which requires its own set of operating parameters and controlling microbial groups. An alternative N-removal pathway termed the anammox process allows for total N-removal in a single step under anoxic conditions. This process, mediated by the anammox bacterial group, requires no organic carbon, produces negligible greenhouse gases and requires almost 50 % less energy than the conventional process, making it a promising new technology for efficient and cost-effective N-removal. In this study, a sequencing batch reactor (SBR) was established for the autotrophic removal of N-rich wastewater through an anammox-centric bacterial consortia. The key microbial members of this consortia were characterized and quantified over time using molecular methods and next generation sequencing to determine if the operational conditions had any effect on the seed inoculum population composition. Additionally, local South African wastewater treatment plants were screened for the presence of anammox bacteria through 16S rRNA amplification and enrichment in different reactor types. A 3 L bench scale SBR was inoculated with active biomass (~ 5 % (v/v)) sourced from a parent anammox enrichment reactor, and maintained at a temperature of 35 °C ± 1 °C. The reactor was fed with a synthetic wastewater medium containing no organic C, minimal dissolved oxygen (< 0.5 mg/L), and N in the form of ammonium and nitrite in the ratio of 1:1.3. The reactor was operated for a period of 366 days and the effluent ammonium, nitrite and nitrate were measured during this period. The hydraulic retention time was controlled at 4.55 days from Day 1 to Day 250, and thereafter shortened to 1.52 days from Day 251 to Day 360 due to an increased nitrogen removal rate (NRR). During Phase I of operation (Day 1 to Day 150), the reactor performance gradually increased up to an NRR of ~160 mg N/day. During Phase II (Day 151 to Day 250), the overall reactor performance decreased with the NRR decreasing to ~90 mg N/day, while Phase III (Day 251 to Day 366) displayed a gradual recovery of NRR back to the reactor optimum of ~160 mg N/day. The accumulation of nitrate in the effluent during the latter parts of Phase II and Phase III, coupled with oxygen ingress (~2.1 mg/L) in the same period, indicated that it was not the anammox pathway that was dominating N-removal within the reactor, but more likely the second half of the nitrification pathway mediated by the nitrite oxidizing bacteria (NOB). This was further confirmed through molecular analysis, which indicated that the bacterial population had shifted significantly over the course of reactor operation. Quantitative PCR methods displayed a decrease in all the key N-removing population groups from Day 1 to Day 140, and a marginal increase in anammox and aerobic ammonia oxidizing bacteria from Day 140 – Day 260. From Day 300 onwards, NOB had started dominating the system, simultaneously suppressing the growth of other N-removing bacterial groups. Despite this, the NRR peaked during this period, indicating an alternative mechanism for ammonia removal within the reactor system. A total population analysis using NGS was also performed, which corroborated the QPCR results and displayed a population shift away from anammox bacteria towards predominantly NOB and members of the phylum Chloroflexi. The proliferation of aerobic NOB and Chloroflexi, and the suppression of anammox bacteria, indicated that DO ingress was indeed the primary cause of the population shift within the reactor. Despite this population shift, N-removal within the reactor remained high. New pathways have recently emerged which implicate these two groups as potential N oxidizers, with specific NOB groups showing the ability for oxidation of ammonia through the comammox process, and members of the Phylum Chloroflexi being capable of nitrite reduction. This could imply that an alternate pathway was responsible for the majority of N-removal within the system, in addition to the anammox and conventional nitrification pathways. Additionally, in an attempt to detect a local anammox reservoir, eleven wastewater systems from around South Africa were screened for the presence of anammox bacteria. Through direct and nested PCR-based screening, anammox bacteria was not detectable in any of the activated sludge samples tested. Based on the operating conditions of the source wastewater systems, a subset of three sludge samples were selected for further enrichment. After 60-110 days of enrichment in multiple reactor configurations, only one reactor sample tested positive for the presence of anammox bacteria. Although this result indicates that anammox bacteria might not be ubiquitous within every biological wastewater system, it is more likely that anammox bacteria might only be present at undetectable levels, and that an extended enrichment prior to screening is necessary for a true representation of anammox bacterial prevalence in an environmental sample. / M

Ph.D. (Biochemistry) / Please refer to full text to view abstract