Thesis (MSc (Microbiology))--University of Stellenbosch, 2010. / ENGLISH ABSTRACT: The relationship between various land management practices, soil properties and the soil microbial communities are complex and little is known about the effect of these interactions on plant productivity in agricultural systems. Although it would be advantageous to have a single organism or property that can be used as a measure of soil health, it may not be possible. Soil organisms which include both the microorganisms as well as soil fauna are subjected to the effect of their immediate environment. This microenvironment in turn is determined by the soil properties as well as above ground flora and their interactions. Most soil indicators interact with each other, and these interactions can modify or influence the soil properties. The complexities of the interactions between critical soil indicator values often preclude its practical use by land managers and policy makers. However, soil microbial communities (e.g. diversity and structural stability) may serve as a relative indicator of soil quality. These communities are sensitive to land management practices and changes in the microenvironment. The objective of this study was to gain an understanding of the complex relationships by investigating the effect of conventional, integrated and organic apple production systems on the physical, chemical and biological (particularly soil microbial diversity) properties of the soil. Automated Ribosomal Intergenic spacer analysis (ARISA) was used to characterise fungal (F-ARISA) and bacterial (B-ARISA) communities from soil samples obtained from an experimental apple orchard in Elgin, Grabouw. The intergenic spacer (ITS) region from the fungal rRNA operon was amplified using ITS4 and fluorescently FAM (6- carboxylfluorescein) labelled ITS5 primers. Similarly, the 16S-23S intergenic spacer region from the bacterial rRNA operon was amplified using ITSR and FAM-labelled ITSF primers. The sensitivity of the technique allowed us to discriminate between the soil microbial communities of the different treatments. From our results we observed significant increase (p < 0.05) in the fungal community diversity between the February and April samples, while the bacterial community diversity was consistent (p > 0.05). Also, treatments with mulch showed a significantly higher microbial diversity than the other treatments at a 5 % significance level. Fungal communities showed significant correlation with the potassium concentration in the soil, while bacterial communities depicted a significant correlation with the soil phosphorous concentration. Based on the results we concluded that different management practices have a significant effect on the soil microbial communities and that these communities are particularly sensitive to small changes in the environment. However, there is still a need to determine what the composition of the soil microbial communities are to be able to correlate our observations with soil health. / AFRIKAANSE OPSOMMING: Die verhouding tussen verskillende landboubestuurspraktyke, grondeienskappe en die mikrobiese gemeenskappe in grond is kompleks en weinig is bekend oor die uitwerking van hierdie interaksies op die produktiwiteit van landboustelsels. Alhoewel dit voordelig sou wees om ‘n enkele organisme of eienskap te kan hê wat die gesondheid van grond kan meet, sal dit dalk nie moontlik wees nie. Grondorganismes wat die mikroörganismes sowel as die grondfauna insluit, is onderworpe aan die invloed van hulle onmiddelike omgewings. Hierdie mikro-omgewings op hulle beurt word weer beïnvloed deur die grondeienskappe sowel as die die oppervlak flora en hulle wisselwerkinge. Meeste van die grondaanwysers toon ook wisselwerkinge met mekaar, en hierdie wisselwerkinge kan die grondeienskappe beïnvloed or selfs verander. Die kompleksiteit van die wisselwerkinge tussen kritiese grond aanwysers is meestal die rede waarom dit nie deur grondbestuurders en beleidsmakers gebruik word nie. Dit is ongeag die feit dat grond mikrobiese gemeenskappe (bv. diversiteit en stukturele stabiliteit) mag dien as ‘n relatiewe aanwyser van grondkwaliteit. Hierdie gemeenskappe is sensitief vir bestuurspraktyke en veranderinge in die mikro-omgewing. Die doel van die studie was om die ingewikkelde verhoudings in die grondgemeenskappe te bestudeer en die uitwerking van konventionele, geïntegreerde en organiese appel produksie sisteme op die fisiese, chemiese en biologiese eienskappe (veral die grond mikrobiologiese diversiteit) te bepaal. Geoutomatiseerde Ribosomale Intergeniese Spasie Analise (ARISA) is gebruik om die fungus (F-ARISA) en bakteriese (B-ARISA) gemeenskappe van grondmonsters wat vanaf ‘n proef appelboord in Elgin (Grabouw) verkry is, te bepaal. Die intergeenspasie (ITS) area van die fungus rDNA operon is vermeerder deur die ITS4 en fluoresserende FAM (6-karboxylfluorescein) gemerkte ITS5 inleiers te gebruik. Soortgelyk is die 16S-23S intergeenspasie area van die bakteriese rDNA operon vermeerder deur ITSR en FAM-gemerkte ITSF inleiers te gebruik. Die sensitiwiteit van die tegniek laat ons toe om te onderskei tussen die grond mikrobiese gemeenskappe vanaf verskillende grondbehandelings. Vanuit die resultate kon ons aflei dat daar ‘n toename (p < 0.05) in die fungus gemeenskap diversiteit vanaf Februarie to April was terwyl die bakteriese gemeenskap ‘n konstante diversteit getoon het (p > 0.05). Behandelings met grondbedekking het ook ‘n beduidend hoër mikrobiese diversiteit getoon as ander behandelings. Fungus gemeenskappe het beduidende korrelasies getoon met kalium konsentrasies in die grond, terwyl bakteriese gemeenskappe ‘n beduidende korrelasie getoon het met grond fosfor konsentrasies. Gebaseer op die resultate kon ons aflei dat verskillende bestuurspraktyke ‘n uitwerking kan hê op die grond mikrobiese gemeenskappe en dat hierdie gemeenskappe sensitief is vir klein veranderinge in die omgewing. Dit sal egter nog nodig wees om die spesifieke samestelling van die grond mikrobiese gemeenskappe te bepaal voor ons hierdie waarnemings kan korreleer met grondgesondheid.

Thesis (MSc)--University of Stellenbosch, 2007. / ENGLISH ABSTRACT: The tolerance of Enterococcus mundtii ST4SA to stressful gastro-intestinal conditions in humans and animals is vital to its success as a probiotic. The need for new effective probiotics with stronger inhibitory (bacteriocin) activity has arisen due to the increasing number of antibiotic resistant pathogens. Enterococci are used in the fermentation of sausages and olives, cheese making and as probiotics. Their role as opportunistic pathogens in humans makes them a controversial probiotic (Moreno et al., 2005). Enterococci occur naturally in the gastro-intestinal tract which renders them intrinsic acid and bile resistance characteristics. E. mundtii ST4SA produces a 3950 Da broad-spectrum antibacterial peptide active against Gram-positive and Gram-negative bacteria, and viruses. The bacteria include Enterococcus faecalis, Streptococcus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae and Staphylococcus aureus. E. mundtii ST4SA inactivates the herpes simplex viruses HSV-1 (strain F) and HSV-2 (strain G), a measles virus (strain MV/BRAZIL/001/91, an attenuated strain of MV), and a polio virus (PV3, strain Sabin). This study focuses on the genetic stability of E. mundtii ST4SA genes when exposed to stress factors in the human and animal gastrointestinal tract. Based on results obtained by real-time PCR, the expression of genes encoding bacST4SA, RecA, GroES and 23S rRNA by E. mundtii ST4SA were not affected when the cells were exposed to acid, bile and pancreatic juice. This suggests that these genes of E. mundtii ST4SA will remain stable in the intestine. This could indicate that other genes of E. mundtii ST4SA could remain stable in the host. Further studies on the stability of genes encoding antibiotic resistance and virulence factors should be conducted to determine their stability and expression in the host in stress conditions. Concluded from this study, E. mundtii ST4SA is an excellent probiotic strain. / AFRIKAANSE OPSOMMING: Enterococcus mundtii ST4SA se weerstandsvermoë teen stresvolle gastrointestinale kondisies is essensieel vir die sukses van hierdie organisme as ‘n probiotikum. Die aanvraag vir nuwe, meer effektiewe probiotika met sterker inhibitoriese (bakteriosien) aktiwiteit is as gevolg van die toename in antibiotikum weerstandbiedende patogene. Enterococci word algemeen gebruik as probiotika, sowel as in die fermentasie van worse, olywe en kaas. Hulle rol as oppertunistiese patogene in mense veroorsaak kontroversie as gevolg van hul toenemende gebruik as probiotika. Enterococci is deel van die natuurlike mikroflora in die gastrointestinale weg van mense en diere. Dit verleen aan hierdie spesies ‘n natuurlike weerstandsvermoë teen maagsure, galsoute en pankreatiese afskeidings. E. mundtii ST4SA produseer ‘n 3950 Da wye spektrum anti-bakteriese peptied, aktief teen Gram positiewe en Gram negatiewe bakterieë sowel as virusse. Hierdie bakterieë sluit Enterococcus faecalis, Streptococcus spp., Pseudomonas aeruginosa, Klebsiella pneumoniae, Streptococcus pneumoniae en Staphylococcus aureus in. E. mundtii ST4SA inaktiveer die herpes simpleks virus HSV-1 en HSV-2, ‘n masels virus (MV/BRAZIL/001/91), en ‘n polio virus (PV3, stam Sabin). Hierdie studie fokus op die genetiese stabiliteit van E. mundtii ST4SA gene, wanneer hulle blootgestel word aan stress faktore in die mens en dier gastrointestinale weg. “Intydse” PKR data gebasseer op die uitdrukking van die bacST4SA, RecA, GroES en 23S rRNA gene in stresvolle kondisies dui aan dat E. mundtii ST4SA nie geaffekteer word wanneer die sel blootgestel word aan suur, gal en pankreatiese vloeistowwe nie. Hierdie resultate dui aan dat hierdie gene van E. mundtii ST4SA stabiel sal bly in die intestinale weg van die mens en dier. Dit kan aandui dat ander gene van E. mundtii ST4SA soos die wat kodeer vir virulensie faktore en antibiotikum se weerstandsvermoë stabiel mag bly in die gasheer. Verdere studies wat fokus op die stabiliteit van gene wat kodeer vir antibiotikum weerstandbiedendheid en virulensie faktore moet uitgevoer word om hulle stabiliteit en uitdrukking in die gasheer te bepaal. Bevindings van hierdie studie dui aan dat E. mundtii ST4SA goeie potensiaal het as ‘n probiotikum.

This study assessed the quality of the Umgeni River in Durban South Africa seasonally from March 2011 to January 2012, according to standard protocol. Water samples were collected from Inanda dam-U5, KrantzKloof Nature Reserve-U4, New Germany-U3, Reservoir Hills –U2 and River mouth – U1 areas of the Umgeni River. A two-step tangential flow filtration (TFF) process was setup for the concentration of viruses from water samples. Virus like particles (VLPs) was detected using electron microscopy. Canonical correspondence analysis (CCA) was used to statistically evaluate the data sets. All water samples had turbidity values which exceeded the South African water quality guideline value of 0.1 NTU for turbidity. Large seasonal variations in BOD5, COD and conductivity levels were observed. Chloride concentrations were extremely high at point U1 (19234 mg/ℓ) Cl during summer. Total heterotrophic bacterial (THB) population was highest at 13.67 x 106 cfu/100ml (U1 – summer). Enterococci (EC) concentrations were detected at points U1, U2, U3, and U4 during the autumn and spring period. pH, electrical conductivity, temperature, and turbidity positively correlated with the microbial communities, and were the key parameters responsible for water pollution according to CCA. Most water samples contained high populations of somatic (659 pfu/mℓ, U1 – summer) and F-RNA coliphages (550 pfu/mℓ, U2 – summer). VLPs were detected throughout all seasons, with point U1 (summer) having the highest population of 2086 VLP/mℓ. Several presumptive viruses including Adenoviridae, Picornaviridae, Poxviridae, and Reoviridae were detected based on their morphologies. Six cell culture lines were used to determine cytopathic effect (CPE) of the VLPs. VLP samples produced CPEs on the Vero, Hek 293, Hela and A549 cell lines. Integrated cell culture (ICC) - PCR confirmed the presence of infectious VLPs in the river water samples. Adenoviruses, Enteroviruses, rotaviruses and Hepatitis B viruses were detected and quantified in all water samples by nested PCR/RT-PCR and Real-Time PCR respectively, against positive control viruses. These results indicate the potential of viruses in the water samples especially from the lower catchment areas to infect the human hosts throughout the year. These observations have public health care implications and establish a need to monitor the viral population in addition to traditional water quality indicators. / Thesis (Ph.D.)-University of KwaZulu-Natal, Westville, 2013.

No abstract available. / Thesis (Ph.D.)-University of Natal, Pietermaritzburg, 2002.

Most waste generated in South Africa is sent to landfills for disposal, and although it is confined in specific areas, it can potentially affect both above and below ground water resources, impacting environmental and public health. This is particularly relevant in a country where water supplies are limited and groundwater resources are prone to pollution. The primary objective of this study was to assess the performance of an upflow packed-bed bioreactor purposedesigned for the treatment of leachates produced by landfills in the Durban Metropolitan Area (DMA). The effect of parameters such as the nature of the biofilm support matrix, aeration rate and recycle rate on the efficacy of the system were investigated. Another major aim of the project was to develop a low maintenance technology that could, nonetheless, bioremediate leachate effectively at minimum cost. This aspect of process design is a crucial factor in areas where there is a shortage of both funds and skilled labour. The glass 132 l packed-bed upflow bioreactor was evaluated by measuring its efficiency in terms of chemical oxygen demand (COD) and biological oxygen demand (BOD) reduction and ammonia removal. The bioreactor could be configured as a batch-type system, which was useful for comparing operating conditions; or as a continuous cascade system, which was used to assess its overall performance. Different biofilm support matrices viz. various grades of pine bark, plastic bioballs and ceramic noodles were evaluated in 22 l batch-type reactors. Leachates from five landfill sites were remediated during the course of the study, and only the leachate from Shongweni landfill, which had a remarkably low BOD:COD ratio (0.05), was intractable and could not be successfully treated; even in flask trials designed to test strategies such as augmentation of microflora and biostimulation. The other leachates investigated were from the Umlazi, Marianhill, Bisarsar Road (all general sites) and Bul-Bul Drive (a semi-hazardous site) landfills, all of which were remediated to some degree. Originally, leachate from the Umlazi landfill site was used, but it became unavailable when the site closed enforcing the use of other leachates for the remainder of the investigation. Leachates from Marianhill, Bisarsar Road and Bul-Bul Drive were treated simultaneously in duplicate operating the six-chambered bioreactor in the batchtype configuration. The highest COD removal efficiency (49 %) was obtained in the chambers treating the Bul-Bul Drive leachate, which was therefore used for further investigations. This leachate had the highest BOD:COD ratio and was therefore expected to be the most suited to biological remediation. The bioreactor performed best when plastic bioballs were used as biofilm support matrix with a relatively low level of aeration, although the uncomposted form of pine bark was used initially as the support matrix because it is inexpensive and readily available in South Africa. However, although satisfactory COD reduction (30 – 61 %) and ammonia removal (87 – 98 %) was achieved when the Umlazi leachate was treated, the possibility of compounds leaching out of the bark and affecting the quality of the treated leachate was a concern. Also, pine bark would be prone to mechanical degradation in a full scale operation. Of the other solid support matrices tested using the Bul-Bul leachate, COD removal efficiencies were superior with plastic bioballs (60 %) than with pine bark chips (29 %). The former therefore became the preferred biofilm support matrix. Aeration level did influence bioremediation of the Umlazi landfill leachate since those chambers aerated with an aquarium pump (0.05 – 0.1 litres air/litre leachate/min; 60 % COD removal) performed better than those aerated with a blower (0.6 -0.7 litres air/litre leachate/min; 42 % COD removal) and those that remained unaerated (44 % COD removal). Recycle rate did not significantly affect bioremediation, but the performance of the system was higher when operated in batch mode (up to 60 % influent COD removal), rather than in continuous flow-through (cascade) mode when only 37 % of the influent COD in the Bul-Bul leachate was removed. Under the latter conditions, most of the reduction occurred in the first four chambers and very little biodegradation occurred in the final two chambers. The cascade-mode will require some refinement to enhance the COD removal efficiencies achieved. However, it did eliminate 89 % of the BOD present in the raw leachate, producing a treated effluent with a consistent BOD:COD ratio of 0.05. The COD removal efficiencies achieved covered a wide range from a minimum of 23 % with Marianhill leachate to a maximum of 63 % with leachate from Bul-Bul Drive. These results are comparable with many of those reported by other authors treating landfill leachate. Up to 98 % of the ammonia was removed when the Umlazi leachate was treated. However, ammonia removal from the other leachates tested was erratic. Although the treated leachate from this system could not be released into the environment without further remediation, the reduction in concentration of pollutants would allow its return to the local water supply via a wastewater treatment plant. This was achieved without temperature and pH regulation or addition of extraneous nutrient sources. A cost-effective, low maintenance technology such as this one would be a useful tool for the treatment of effluents such as landfill leachate in countries like South Africa where although water conservation is urgently required, resources for highly sophisticated effluent remediation are often not readily available. / Thesis (Ph.D.)-University of KwaZulu-Natal, Pietermaritzburg, 2011.

The temporal fate of selected parameters, including redox potential; pH; phenol; nitrates; sulphates; copper and zinc, of a young synthetic acetogenic phase landfill leachate was assessed by perfusing a series of sequential soil (Hutton) microcosms (arrays) at two hydraulic loading rates (HLR). We chose HLRs that were representative of areas in South Africa with typically elevated rainfall (Pietermaritzburg – HLRh) and one with relatively low rainfall (Kimberley – HLRl). Preliminary phenol, copper, and zinc adsorption investigations on gamma radiation sterilized soil and unsterilized soil revealed superior adsorption rates for each compound in the unsterilized soil. This revealed the importance of the biological component of soil in phenol, copper, and zinc attenuation in soil. The results presented in this thesis suggest that the HLR of leachate into soil arrays contributes to significant differences in the fate of the landfill leachate parameters mentioned earlier. In addition, we assessed the temporal and spatial succession of bacterial community diversity in each of the soil arrays by polymerase chain reaction (PCR) and denaturing gradient gel electrophoresis (DGGE). Prior to this, we compared two soil DNA isolation techniques, the modified method of Duarte et al. (1998) (Bead Beat) and the commercial Mo-Bio UltraClean™ Soil DNA isolation kit (Kit). The DNA isolated by the Kit method was significantly superior regarding purity and absence of DNA fragmentation. However, the Bead Beat method produced a significantly higher yield per reaction before further purification with Wizard™ Clean-Up columns produced DNA extracts of similar purity at the cost of a significant reduction in DNA yield. The Kit method was chosen for future DNA isolation and PCR-DGGE based on the quality of the PCR amplicons generated from the Kit isolated DNA. PCR-DGGE was further optimized by comparing the efficiency and sensitivity of a silver stain against ethidium bromide. Silver stain generated DGGE gels with greater number of bands (species richness – S) and stronger band signal intensities. Captured DGGE fingerprints generated data that were subjected to the Shannon-Weaver Index (H’) and the associated Shannon-Weaver Evenness Index (EH) to measure the change in spatial and temporal bacterial diversity. There was a significant shift in S and H’ for both HLRs but a significant change in EH was only observed for HLRh. Furthermore, a temporal comparison of S and H’ between both HLRs revealed significant differences throughout the investigation. Canonical Correspondence Analysis (CCA) revealed spatial distribution of bacterial community diversity with depth. Effects of phenol concentration, redox potential, and pH of the effluent leachate on bacterial community diversity was tentatively assessed by three-dimensional graphical representation on PlotIT 3.2 software. Bacterial community diversity showed a decrease with elevated pH and phenol concentration along with decreasing redox potentials for both HLRs. While this study reveals the spatial and temporal dynamics of bacterial community diversity in situ, it provides important evidence with respect to: (i) the effects of rainfall / leaching rates (HLR) on spatial and temporal bacterial community succession; (ii) the importance of the biological component in natural attenuation; (iii) the ability of soil, previously unexposed to landfill leachate, to initiate natural attenuation of phenol and other leachate constituents; (iv) the capacity of PCRDGGE to fingerprint successional changes in bacterial community diversity, (v) and the potential to clone and sequence selected members of bacterial associations for future reference in environmental remediation strategies. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2008.

The presence of heavy metal ions in waste streams is one of the most pervasive environmental issues of present times. A rotating biological contactor (RBC) was used to investigate the potential capacity of microbial biofilms in remediation of the metal ion species from a mixed metal contaminated effluent solution containing Cr+3 , Pb+2 and Cu+2 , each at a concentration of 200 mg r1 • In the first part of this study the effectiveness of various support materials for the development of microbial biofilms capable of removing heavy metals from a synthetic effluent was investigated. EDX analysis showed that none of the support matrices investigated, viz. gravel, polyester batting and sand, adsorbed metal ions on their surfaces; hence, metal adsorption was due purely to microbial activities. The biofilms attached more firmly and uniformly to polyester batting than to gravel and sand. The characteristics of polyester batting which made it a superior support matrix were its surface roughness and porous hydrophilic nature, which provided a larger surface area for the adhesion of microorganisms and attraction of nutrients during the biofilm development process. The selective accumulation of metal ion specIes by various microbial populations grown as biofilm using polyester batting as support matrix in separate compartments of a single-stage RBC bioreactor was examined. Lead ions were readily accumulated by almost all the microbial biofilms tested. Fungus-dominated biofilms selectively accumulated chromium ions whereas biofilms comprising mainly bacteria more readily accumulated copper ions from the mixed metal contaminated effluent solution. However, where interactions between the bacterial and fungal components were encouraged the mechanical stability of the biofilms was enhanced so that large amounts of all three metal ion species were removed by this biofilm. The combined effect of a series of bench-scale columns containing liquid humic acid and a three stage RBC bioreactor on the removal of metal ion species from a mixed metal contaminated effluent was investigated. After seven days of treatment the combined system had removed approximately 99% of the Cr+3, 98% of the Pb+2 and 90% of the Cu+2 ions from the mixed metal contaminated synthetic effluent. Complexation of the metal ions with humic acid was the predominant factor accounting for approximately 68-86% Cr+3 , 70-86% Pb+2 and 53-73% Cu+2 removal levels within the columns. A large proportion of the remaining Cr+3 and Pb+2, but not of the Cu+2, was removed in compartment 1 of the RBC. This suggested that the presence of the former two metals in solution might have reduced the removal of the Cu+2 ions from the system. The removal of substantially large amounts of the competing ions chromium and lead during the initial stages of the treatment process meant that copper was successfully taken up in the second and third RBC compartments. Hence, the economy of the treatment process was improved as larger quantities of the metal ions were removed in a shorter period of time than was possible when using the individual treatments (humic acid-metal complexation and biofilm adsorption) separately. More than 75%,92% and 86% of the adsorbed Cr+3 , Pb+2 and Cu+2 ions, respectively, were recovered from the three RBC bioreactor compartments following repeated washing of the biofilms with 0.1 M HCI. This relatively easy desorption suggested that the metal ions were simply adsorbed onto the surfaces of the biofilm cells rather than being taken into the cytoplasm of the cells. / Thesis (M.Sc.)-University of KwaZulu-Natal, Pietermaritzburg, 2004.

Darvill Wastewater Works (DWWW) receives and treats both domestic and industrial wastewater from the city of Pietermaritzburg, in KwaZulu-Natal. Sludge from the wastewater treatment is sprayed onto surrounding lands, causing odour and fly problems. The plant also discharges treated effluent into the Msunduzi River, compromising water quality. This study uses several economic valuation techniques to estimate the value of the benefits of improving air and water quality to overcome these problems caused by DWWW. The benefits. are then compared with the costs of upgrading DWWW to see whether or not upgrading DWWW to improve air and water quality would be worthwhile. The Contingent Valuation Method (CVM) was used to elicit people's willingness to pay (WTP) for improvements in air quality due to the elimination of odours and flies caused by sludge deposited by DWWW. The WTP estimates reflect individual's preferences for improvements in air quality. The stated WTP amounts were positively related to household income, but negatively related to the age and gender of the respondent and the number of dependants in the household. The mean monthly WTP for the surveyed households is higher for those that are closer to the pollution source (R23.00 and R29.00 for Zones land 2) and less for those further away (RI4.00 for Zone 3). Sobantu residential area had the lowest mean monthly WTP (R18.00), followed by Lincoln Meade (R27.00) and Hayfields (R54.00). This is expected, as Sobantu has relatively high levels of unemployment and lower household incomes. Strategic, hypothetical and free rider bias may have led to the unexpected signs of some estimated regression coefficients in linear regression models used to estimate WTP. The mean WTP was estimated as R307.20 per annum per household, and when this is aggregated over the total population in the residential areas impacted by odours and flies (37192 households), the benefits of eliminating odours and flies are estimated as R11 425 382.00 per annum. A hedonic price method was used to quantify the decline in property values as a result of odours and flies caused by sludge deposited by DWWW. Properties experienced a R6650.08 decline in selling price if the distance from them to DWWW is decreased by one kilometre. Properties that are closer to DWWW were worth RI5 953.90 less than those further away from DWWW. Aggregating these values over all estimated impacted households in the study, gives an estimated benefit of improving air quality of R28 480 518.00 per annum. The impact of water pollution was quantified by estimating the revenue (R3 744 975.00) that would be lost by Pietermaritzburg if the Duzi Canoe Marathon were to be cancelled due to incidences of diarrheoa reported during the race. A cost of illness procedure was adopted to quantify the effect of water pollution on the health of communities that use the Msunduzi River as a source of potable water supply. A value of R1 243 372.50 was estimated as the annual cost of water-related illnesses in these rural areas. This value represents the costs of the river pollution to those communities. Both of these exercises indicated that improving water quality of the Msunduzi River would be beneficial to society. The effect of nutrient enrichment of the Msunduzi River was quantified by estimating the cost of removing water hyacinth from the Inanda Dam, treatment cost at Wiggins water treatment works and the value of recreation at Mahlabathini Park (Inanda Dam). The annual cost of removing water hyacinth was estimated from the direct costs of chemicals and labour as R47 202.15. The increased treatment costs at Wiggins attributable to DWWW were estimated as R1 104 999.20 and R956 924.15 per annum for removal of algae, and tastes and odours, respectively. The value of R706.90 per annum was estimated as the consumer surplus accruing to recreationists, and, therefore, the value of recreation at Mahlabathini Park to an individual. These annual benefits, when aggregated over the total study population (296 590) were over two hundred million rands (R209 659 470.00). The estimated total benefits (R256 662 840.00) of eliminating odours and flies and effluent problems were compared to the actual costs of two alternative methods of upgrading DWWW using cost-benefit analysis. These alternatives were co-disposal option (R170 473 320) and a land disposal option (R168 809377). Benefit-cost ratios of 1.51 and 1.52 suggest that from society's standpoint, it would be beneficial to upgrade the plant in order to eliminate its adverse environmental impacts. The study results have important implications for policy makers, both the DWWW management and the Pietermaritzburg-TLC municipality. At present DWWW is operating beyond its design capacity, and this problem, together with the poor status of Pietermaritzburg's reticulation system, causes overflow of untreated or compromised final effluent into the Msunduzi River during rainy seasons. These problems also impact on the efficient operation of the plant as the sludge is not properly digested before being sprayed onto surrounding land. Thus to prevent further environmental degradation, a fundamental basis of the National Environmental Management Act, DWWW would need to address these issues. Upgrading DWWW would be a short-term solution if the problems with the storm-runoff into the plant is not addressed. / Thesis (M.Sc.)-University of Natal, Pietermaritzburg, 2002.