Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnology, Durban Institute Of Technology, 2005 xxiii, 172 p. : ill. ; 30 cm / The provision of safe and sanitary water is a constitutional right and above all, a necessity of life. As a result of the rapid urbanisation and the past policies of apartheid, a large population of South Africa dwell in informal settlements, where there is very little hope of development, as the government does not possess the resources that are necessary for a full-scale sanitation programme. Therefore, on-site treatments have been considered to provide sanitation in these dense peri-urban areas. The anaerobic baffled reactor (ABR) is one such sanitation system. This reactor utilises the phenomenon of anaerobic digestion to degrade substrates. One of the major disadvantages of any anaerobic treatment processes is the extreme sensitivity of the bacterial communities, thus inducing slow recovery rates following toxic shocks. Therefore, an understanding of these microbial consortia is essential to effectively control, operate and optimise the anaerobic reactor. Fluorescence in situ hybridization, 4’,6-diamidino-2-phenylindole (DAPI) staining and DNA sequencing techniques were applied to determine the microbial consortium, as well as their reactions to daily operating conditions. With an understanding of these populations and their responses to perturbations within the system, it is possible to construct an anaerobic system that is successful in its treatment of domestic wastewater. In situ hybridizations were conducted for three operating periods, each characterised by specific flow rates. Results showed Eubacterial population dominance over the Archaeal population throughout both of the operating periods investigated. However, these cells cumulatively consisted of 50% of the total biomass fraction, as determined by DAPI staining. Group-probes utilised revealed a high concentration of fermentative acidogenic bacteria, which lead to a decrease in the pH values. It was noted that the ABR did not separate the acidogenic and methanogenic phases, as expected. Therefore, the decrease in pH further inhibited the proliferation of Archaeal acetoclastic methanogens, which were not present in the second operating period. DNA sequencing results revealed the occurrence of the hydrogenotrophic Methanobacterium and Methanococcus genera and confirmed the presence of Methanosarcina. Sequencing of the bacterial DNA confirmed the presence of the low G+ C Gram Positives (Streptococcus), the high G+C Gram Positives (Propionibacterium) and the sulfate reducing bacteria (Desulfovibrio vulgaris). However, justifications were highly subjective due to a lack of supportive analytical data, such as acetate, volatile fatty acids and methane concentrations. Despite this, findings served to add valuable information, providing details on the specific microbial groups associated with ABR treatment processes.

Thesis (M.Tech.: Biotechnology)-Dept. of Biotechnogy, Durban Institute of Technology, 2005 xvi, 85 leaves : ill. ; 31 cm / Atmospheric nitrogen pollution is on the increase and human activities are directly or indirectly responsible for the generation of the various nitrogen polluting compounds. This can lead to the two major problems of eutrophication and groundwater pollution. Therefore, the removal of nutrients such as nitrogen and phosphorus from wastewater is important. Nitrogen removal from wastewater is achieved by a combination of nitrification and denitrification. Thus, there is a need to identify and characterise heterotrophic denitrifying bacteria involved in denitrification in wastewater treatment systems. The aim of this study, therefore, was to characterise heterotrophic denitrifying bacteria through detailed biochemical and molecular analysis, to facilitate the understanding of their functional role in wastewater treatment systems. Drysdale (2001) isolated heterotrophic denitrifiers to obtain a culture collection of 179 isolates. This culture collection was used to screen for nitrate and nitrite reduction using the colorimetric biochemical nitrate reduction test. The isolates were thereafter Gram stained to assess their gram reaction, cellular and colonial morphology. Based on these results identical isolates were discarded and a culture collection of approximately 129 isolates remained. The genetic diversity of the culture collection was investigated by the analysis of polymerase chain reaction (PCR)-amplified 16S ribosomal DNA (rDNA) fragments on polyacrylamide gels using denaturing gradient gel electrophoresis (DGGE). Thus DNA fragments of the same length but different nucleotide sequences were effectively separated and microbial community profiles of eight predominant isolates were created. Batch experiments were conducted on these eight isolates, the results of which ultimately confirmed their characterisation and placed them into their four functional groups i.e. 3 isolates were incomplete denitrifiers, 2 isolates were true denitrifiers, 2 isolates were sequential denitrifiers and 1 isolate was an exclusive nitrite reducer.

Thesis (D.Tech.: Biotechnology)-Dept. of Biotechnology, Durban University of Technology, 2008. xxiv, 322 leaves / Activated sludge models now in use worldwide for the design and operation of treatment systems use hypothetical concentrations of active organisms. In order to validate and calibrate model outputs, concentrations and activities of organisms responsible for nitrification and denitrification need to be reflected by actual measurements. This research has been initiated by the observation of an increasing gap of suitable techniques that exist in the direct measurement and separation of active biomass components, responsible for COD removal and denitrification.

Submitted in partial fulfillment of academic requirements for the degree of Masters of Technology: Department of Chemical Engineering, Durban University of Technology, 2009. / The primary objective of this project was to establish a screening protocol which could be used to access high strength/toxic effluent for toxicity and degradability prior to being disposed in wastewater treatment works. The serum bottle method (materials and method section) is simple, makes use of small glass vials (125 mℓ-volume were used in this research) which do not require any stirring nor feeding device or other engineered tool: a serum bottle is sealed immediately after all components are poured inside and thereafter conducted in a batch mode and occasionally shaken to ensure adequate homogenisation of the components. The only variables which are regularly measured are the volume of biogas produced and gas composition. The two assays, originally developed by Owen et al. (1979) to address the toxicity and the biodegradability have been combined in a single test called AAT, Anaerobic Activity Test, which enables one to assess simultaneously the inhibitory effect on the methanogenic biomass and the biodegradability of the test material as well as the ability of the biomass to adapt to the test material and therefore to overcome the initial inhibition. The screening protocol is illustrated in Annexure A. The protocol consists of a sequence of assays which employ the serum bottle methodology. A first step of the procedure is aimed at rapidly estimating whether the effluent is potentially toxic to the methanogenic biomass and in what concentration. The second step is a more extensive screening, aimed at precisely characterising the toxicity of the effluent, the extent of biodegradation that can be achieved, as well as at establishing whether a potential for adaptation of the biomass exists upon exposure. If the sample passes the screening stage, the same serum bottle method will be used to conduct a series of batch co-digestion experiments aimed at evaluating a convenient volumetric ratio between the test material and the readily biodegradable substrate. Finally, a laboratory-scale codigestion trial could simulate the full-scale process, thus enabling the selection of appropriate operating conditions for the start-up of the full-scale implementation. This the protocol has been used to assess the amenability to be anaerobically (co)digested of four industrial effluents, i.e. size and distillery effluents which are classified as high strength and scour and synthetic dye effluents classified as toxic. From the biodegradability and toxicity assays the following conclusions were drawn. The size and distillery effluent were found to be ii degradable at 32 g COD/ℓ and 16 g COD /ℓ concentrations respectively. Concentrations higher than these stipulated above were found inhibitory. Scour effluent was found to be recalcitrant at all concentration tested and synthetic dye was 100 % degradable at 0.12 g COD/ℓ and lower and highly inhibitory at concentration higher than 1.1 g COD/ℓ. Co-digestion experiment using serum bottle AAT method were undertaken between effluents i.e. size + distillery, size + scour, distillery + synthetic dye in an attempt to verify whether the digestion performance benefits from simultaneous presence of the two substrates. The volumetric ratios between the effluents were 1:1, 1:2, 2:1. The presence of two mixtures in the case of size and distillery had better methane production compared to individual substrate i.e. size or distillery separate. The mixture with volumetric flow rate ratio of 2:1 (size: distillery) was preferable in terms of process performance as it had highest COD removal compared to the other mixtures /ratios and individual substrates. The mixture of size and scour (2:1) had highest degradation percentage compared to other ratios but not high enough to qualify as degradable (less than 50 %). The mixture of distillery and synthetic dye had the same pattern with ratio of 2:1 giving the best COD conversion. The pattern than can be drawn from the degradability of mixtures is: the degradability of mixtures increase with the increasing amount of the most biodegradable compound/effluent in the mixture. Serum bottle results provided the detailed information regarding the safe operating parameters which should be used during the starting point for the larger scale investigation i.e. lab-scale investigations. The lab scale investigations were conducted primarily to validate screening and monitor how the digestion progresses and also to provide data for future project i.e. pilot plant investigation. Other effluents i.e. scour and synthetic dye and their co-digestion mixture were excluded from the lab-scale investigations since they were found to be non- biodegradable i.e. their COD conversion was less the 50 % in the screening protocol. Due to time constrains and other technical difficulties in the laboratory, the co-digestion of size and distillery mixture trials we not conducted on the laboratory scale. Laboratory-scale digestion trials showed that the best organic loading rate for distillery effluent in terms of reactor performance and stability was 1.0g COD/ℓ with efficiency of about 45 %, and for size was 2.0g COD/ℓ with an efficiency of 40 %. The efficiencies obtained in both effluents trials could be greatly improved by acclimation; however these results showed that the digestion of these effluents on the bigger scale is possible. / Water Research Commission

Submitted in fulfillment of the academic requirements for the degree of Master of Technology in Engineering: Chemical Engineering, Durban University of Technology. Durban. South Africa, 2015. / The textile industry consumes large volumes of water and in turn produces substantial quantities of polluted effluents. Approximately 30% of reactive dyes used during the textile processing remain unfixed on fibres and are responsible for the colouration in effluents. Various conventional methods are being used to treat textile effluent. However, the disadvantage of these methods is that total colour removal is not achieved and chemical by-products are introduced from the use of chemicals. The water quality produced therefore does not meet the requirement for textile reuse. Membrane based processes provide interesting possibilities of separating hydrolysed dye stuff and dyeing auxiliaries, thereby reducing colouration and COD content. They can be employed to treat reactive dye bath effluent to recover the salts and water for the purpose of reuse. This study aimed at integrating membrane processes into the reactive dye bath of a textile industry. The objectives were to determine the quality of permeate produced in terms of removal of organics, ascertain its reusability for dyeing, investigate the production rate in terms of permeate fluxes and finally to investigate the cleanability and flux recovery of the membranes. Three effluent samples were chosen for this study based on the dyeing recipe; Light shade, Medium shade and Dark shade. Ultrafiltration (UF) and Nanofiltration (NF) membrane processes were employed to treat the reactive dye bath effluents to recover the salts and water. Investigations were conducted firstly with UF as a pre-treatment to NF. Secondly, evaluations were carried out on the performance of two types of NF membranes (SR90 and NF90) in terms of permeate quality and fluxes for the investigated samples. The effect of cleaning on membrane performance was done. A reusability test was carried out on the permeate samples for dyeing. It was found that the use of UF as a pre-treatment yielded an increase in permeate of 5–25% of the NF fluxes and 90% in organics reduction for all treated samples, hence increasing the water recovery. High rejection of ˃90% by NF90 for COD, TOC and colour were obtained for all the treated samples. SR90 rejection was 80–90% for colour and ˃90% for COD and TOC. Salt recovery for NF90 was 60–90% and for SR90 was 40–50%. The reusability tests carried out showed that permeate recycled from NF90 can be used for any section in the textile industry including the most critical such as dyeing on light shades, while that from SR90 can be used for dyeing dark shades only. It was then concluded that membrane based processes can be integrated into the dye bath of the textile process for the purpose of reuse, thereby saving on the cost of chemicals (salts), reducing fresh water usage and reducing the extent of final effluent treatment.

Thesis (PhD (Food Science))--University of Stellenbosch, 2006. / High-rate anaerobic bioreactors are used for the treatment of various wastewaters, of which the upflow anaerobic sludge blanket (UASB) bioreactor has the widest application, especially in the food and beverage industries. In an UASB bioreactor sludge develops in a particular granular or flocculent form and the success of the anaerobic process relies on the formation of active and settable granules. These granules are formed by self-aggregation of bacteria that can be divided into different trophic groups that are responsible for the metabolic breakdown of organic substrates. The successful performance of a bioreactor is influenced by the composition of the substrate which subsequently may have an impact on the microbial consortium present in the UASB granules. In order to determine if a change in the structure of the non-methanogenic microbial community takes place, UASB brewery granules were subjected to the sudden addition of different carbon sources at different concentrations. A shift in the microbial community did occur when the granules were subjected to lactate medium (5 g.l-1). No changes in the microbial community were observed when the granules were stressed with glucose medium as carbon source, regardless of an increase in the glucose concentration. In order to better understand the effect that different wastewaters may have on the microbial consortium present in different UASB granules, the polymerase chain reaction (PCR) based denaturing gradient gel electrophoresis (DGGE) technique and sequence analysis were used to fingerprint and identify the Bacteria and Archaea present in either, winery, brewery, distillery or peach-lye canning UASB granules. Each granule type showed distinct PCR-based DGGE fingerprints with unique bands, while other bands were found to be present in all the granules regardless of the wastewater being treated. Bacillus, Pseudomonas, Bacteroides, Enterococcus, Alcaligenes, Clostridium, Shewanella, Microbacterium, Leuconostoc, Sulfurospirillum, Acidaminococcus, Vibrio, Aeromonas, Nitrospira, Synergistes, Rhodococcus, Rhodocyclus, Syntrophobacter and uncultured bacteria were identified, representing different acidogenic, acetogenic and homoacetogenic Bacteria.Different methanogenic bacteria such as Methanosaeta, Methanosarcina, Methanobacterium and uncultured bacteria belonging to the group Archaea were also fingerprinted and identified from different UASB granules. In both these studies a DGGE marker was constructed that may be used to assist in the identification of bacteria. The DGGE marker can also be used to monitor the presence of bacteria over a time period during anaerobic digestion. Bioaugmentation or the enrichment of granules results in tailor-made granules that may be used for the treatment of specific wastewaters. One of the most important contributions to the maintenance and enhancement of UASB granule formation is the inclusion of suitable microbes in the granule structure. Enterobacter sakazakii was isolated from raw winery wastewater and was found to produce sufficient amounts of desired fatty acids. This bacteria was, therefore, incorporated into batch cultured granular sludge. In order to identify and monitor the presence of the incorporated E. sakazakii in the tailor-made granules, 16S rRNA gene sequence primers and PCR conditions were developed. The use of molecular techniques such as PCR-based DGGE and sequence analysis proved to be successful methods to fingerprint and identify the microbial consortium present in the different UASB granules.

Thesis (MEng (Civil Engineering))--University of Stellenbosch, 1983. / 129 leaves printed on single pages, preliminary pages and numbered pages 1-1 – 12.5. Includes bibliography, list of abbreviations and list of figures. / Digitized at 300 dpi black and white PDF format (OCR), using KODAK i 1220 PLUS scanner. / ENGLISH ABSTRACT: The remedy of a bulking sludge was investigated by the principle of selection of microorganisms. Selection of microorganisms in activated sludge was achieved by putting a selection compartment, with a high substrate concentration, ahead of the main aeration basin. The initial results in the experiments indicated selection of microorganisms and a reduction of SVI, but complete selection of microorganisms could not be obtained. / AFRIKAANSE OPSOMMING: Die herstel van 'n uitdyende slyk is deur die beginsel van selektering van mikroorganismes ondersoek. Selektering van mikroorganismes in geaktiveerde slyk is toegepas deur n seleksie kompartement met 'n hoë substraatkonsentrasie, voor die groot belugtingsbak te plaas. Die aanvanklike resultate wat verkry is, het selektering van mikroorganismes en 'n verlaging in die SVI getoon, maar volledige selektering van mikroorganismes kon nie verkry word nie.

published_or_final_version / Civil Engineering / Doctoral / Doctor of Philosophy

published_or_final_version / Environmental Management / Master / Master of Science in Environmental Management

Antibiotic resistance profiles of fecal coliform isolated from unchlorinated and chlorinated secondary effluent were determined. Of 332 fecal coliforms isolated from chlorinated effluent a mean of 48% were multiply antibiotic resistant. In contrast, of 347 fecal coliforms isolated from unchlorinated effluent a mean of 29% were multiply antibiotic resistant. Resistance to ampicillin, cephalothin, and carbenicillin were significantly higher in the former than the latter. Randomly selected isolates survived and/or grew in sterile and unsterile effluent retaining resistance patterns for 40 days. Resistance factors were transferred in laboratory medium at frequencies from 0 to 1.2 x 10⁻² (number of recombinants/number of recipients) and in sterile neutralized tertiary effluent at frequencies from 0 to 1.0 x 10⁻⁴. Resuscitative techniques were necessary for optimal recovery of fecal coliforms from effluent using selective media. Antibiotic resistance patterns of fecal coliforms isolated from unchlorinated and chlorinated effluent was not associated with chlorine or heavy metal resistance. Multiply antibiotic resistant fecal coliforms from chlorinated effluent were significantly less sensitive to lytic phage than multiply antibiotic sensitive fecal coliforms from unchlorinated effluent (p < .05). Using group discriminate analysis of data, phage typing techniques were shown to be a potential tool for tracing fecal contamination of groundwater.