Please read the abstract in the section 00front of this document / Dissertation (MSc)--University of Pretoria, 2007. / Geography, Geoinformatics and Meteorology / MSc / Unrestricted

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M.Tech. (Architectural Technology) / The architectural intervention proposes an urban redevelopment along the mining belt of the city of Johannesburg through the treatment of acid mine drainage. The design research includes a network of selected sites located along the Johannesburgmining belt to address the problem of acid mine drainage,as well as to provide solutions for future urban environments. The main solutions to eradicate the acid mine water problem are infrastructural, which in most cases is associatedwith inhumane environments. A design question addressing the marriage between harsh infrast ructure and humane environments is therefore dealt with ,in an attempt to create a self-sustaining architecture in which infrastructure can have an integrative urban function for the future . The dissertation aims to achive a design intervention that will thread the traces of a mining century into this contemporary African city, through an architecture that will grow into the future of the ever-changing and continuously emergent Johannesburg.

Excessive release of metals and metalloids into the environment is a major global environmental concern and there is need for environmentally friendly and cost effective methods for their removal. The present study investigated the adsorptive removal of zinc, lead, copper and nickel ions from synthetic aqueous solutions and various metals from three acid mine drainage (AMD) sites using chicken eggshells. Process parameters including the initial metal concentration were evaluated and the optimum conditions obtained were pH 7, adsorbent dose of 7 g and contact time of 360 minutes (for the removal of 100ppm metal ions). Under these conditions the percentage adsorptions were; 97% for lead, 95% for copper, 94% for nickel and 80% for zinc. Aluminium, iron, potassium, nickel and zinc ions all had percentage adsorptions above 75% in AMD Sample 1. Potassium had a 98.78% adsorption while magnesium, strontium and zinc had 72.33; 68.75 and 53.07% adsorption respectively in Sample 2. Arsenic, chromium, copper, iron, antimony and tellurium ions were above 75% for Sample 3. The study demonstrated the efficacy of chicken eggshells and presents it as a viable low-cost adsorbent for bioremediation. / Environmental Science / M. Sc. (Environmental Science)

One of the most essential resources for life on our planet is water. A concern for water resource sustainability has shifted towards the sustainable development of clean water body resource (SWDF, 2009). Data for the Vaal River water chemistry is in abundance. However, research on the historic natural conditions influencing the inorganic water quality, is not as extensive. Inorganic data was obtained from the Department of Water Affairs, for the period 1972 to 2011, for identified monitoring stations along the Vaal River. Water quality was evaluated using various geochemical techniques to analyse the data. The results of the study indicate that the water chemistry of the Vaal River is controlled by: 1. Chemical weathering of siliceous sediment, intrusive igneous rocks and metamorphic rocks (Na+, K+, Mg2+, Ca2+ and (HCO3)-). 2. Anthropogenic influences increasing the sulphate (SO4) concentration There is no major increase in ion concentrations for the stations. However the concentrations of bicarbonate (HCO3)- and SO4 change as it progresses downstream from the first upstream station to the last downstream station. Based on the chemical characterisation, three groups have been identified. (1) Group 1 stations appear to suggest a higher influence in chemical weathering than the group 2 stations. (2) Group 2 stations appear to suggest a greater influence from SO4. (3) Group 3 stations appear to suggest an influence from both the bicarbonate and the SO4 influences. Geographically the chemical weathering is an indication of the three different groups with strong anthropogenic influences in the middle group. The water chemistry for the Vaal River is controlled by two processes, namely chemical weathering and anthropogenic influences. The prominent indication of the difference in these two influences can be seen between group 1 and group 2. A secondary conclusion indicates that a total dissolved solid (TDS) alone is not an accurate representation of anthropogenic influence (or poor water quality) on inorganic water quality of the Vaal River. The natural weathering or geological influences appears to play a more dominant role in certain sections or catchments with lower contributions from anthropogenic influences. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

One of the most essential resources for life on our planet is water. A concern for water resource sustainability has shifted towards the sustainable development of clean water body resource (SWDF, 2009). Data for the Vaal River water chemistry is in abundance. However, research on the historic natural conditions influencing the inorganic water quality, is not as extensive. Inorganic data was obtained from the Department of Water Affairs, for the period 1972 to 2011, for identified monitoring stations along the Vaal River. Water quality was evaluated using various geochemical techniques to analyse the data. The results of the study indicate that the water chemistry of the Vaal River is controlled by: 1. Chemical weathering of siliceous sediment, intrusive igneous rocks and metamorphic rocks (Na+, K+, Mg2+, Ca2+ and (HCO3)-). 2. Anthropogenic influences increasing the sulphate (SO4) concentration There is no major increase in ion concentrations for the stations. However the concentrations of bicarbonate (HCO3)- and SO4 change as it progresses downstream from the first upstream station to the last downstream station. Based on the chemical characterisation, three groups have been identified. (1) Group 1 stations appear to suggest a higher influence in chemical weathering than the group 2 stations. (2) Group 2 stations appear to suggest a greater influence from SO4. (3) Group 3 stations appear to suggest an influence from both the bicarbonate and the SO4 influences. Geographically the chemical weathering is an indication of the three different groups with strong anthropogenic influences in the middle group. The water chemistry for the Vaal River is controlled by two processes, namely chemical weathering and anthropogenic influences. The prominent indication of the difference in these two influences can be seen between group 1 and group 2. A secondary conclusion indicates that a total dissolved solid (TDS) alone is not an accurate representation of anthropogenic influence (or poor water quality) on inorganic water quality of the Vaal River. The natural weathering or geological influences appears to play a more dominant role in certain sections or catchments with lower contributions from anthropogenic influences. / MSc (Environmental Sciences), North-West University, Potchefstroom Campus, 2015

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: Acid mine drainage (AMD) is wastewater generated by mine and industrial activity with typically high heavy metal and sulphur content potentially resulting in toxic wastewater upon exposure to dissolved oxygen, water and micro-organisms. Due to the hazardous consequences of untreated AMD, treatment methods such as semi-passive biotic treatments, including constructive wetlands and microbial bioreactors were developed. Microbial bioreactors rely on suitable carbon sources such as ethanol, grasses and manure and the creation of anaerobic conditions for the reduction of sulphate, chemical oxidizable organic matter (COD) and to neutralise pH. Domestic wastewater sludge has also been identified as an economical and readily available carbon source that allows the treatment of both AMD and domestic wastewater. A synthetic medium simulating the COD and the biological degradable organic matter (BOD) of domestic wastewater sludge was formulated to exclude variations in the evaluation of domestic wastewater sludge as carbon source in the treatment of AMD. Firstly the BOD and COD of anaerobic domestic wastewater sludge was determined and used as parameters in the formulation of the synthetic medium. A ratio of 1:1 AMD: synthetic domestic wastewater sludge (SDWWS) was the optimum ratio in terms of sulphate and COD removal. Secondly, medical drip bags were used as anaerobic bioreactors to determine the microbial diversity in AMD treated with SDWWS using different variables. Data analyses from next generation sequencing showed that Chlorobium spp. dominated the 90 d pioneer trials at relative percentages of 68 % and 76 %. Transmission electron microscopy (TEM) images and the bright green colour of the liquid contents confirmed the data analyses. Sulphates and COD were removed at > 98 % and > 85 %, respectively. A shorter incubation time was investigated in the 30 d pioneer trial. Chlorobium spp. was dominant, followed by Magnetospirillum spp. and Ornithobacterium spp. The liquid content changed to a dark brown colour. COD and sulphate concentrations were reduced by 60.8 % and 96 %, respectively, within 26 d, after which a plateau was reached. The effect of an established biofilm in the bioreactors showed that Chlorobium spp. also dominated approximately 62 %, in comparison to the 36 % in the 30 d pioneer trial. A sulphate and COD reduction of 96 % and 58 %, respectively, was obtained within 26 d and the liquid content was the same colour as in the 30 d pioneer trial. It is possible that brown Green sulphur bacteria were present. Therefore, although Chlorobium spp. was present at a higher percentage as in the 30 d pioneer trial, the removal of COD and sulphate was similar. During the 30 d trials a white precipitant formed at the top of the bioreactors, consisting primarily of sulphate and carbon that was also indicative of the presence of Chlorobium spp. Incubation at reduced temperature reduced sulphates by only 10 % and COD by 12 % after 17 d, followed by a plateau. Ornithobacterium spp. dominated in the first trial and Magnetospirillum spp. in the second trial. / AFRIKAANSE OPSOMMING: Suur mynwater (SMW) is afvalwater wat deur die myn- en industriële bedryf gegenereer word en bevat kenmerklik hoë konsentrasies swaar metale en swawel wat potensieel in toksiese afvalwater omskep kan word indien blootgestel aan opgelosde suurstof, water en mikro-organismes. Die skadelike gevolge wat blootstelling aan onbehandelde SMW mag hê, het gelei tot semi-passiewe behandelinge wat vleilande en mikrobiese bioreaktors insluit. Mikrobiese bioreaktore maak staat op n geskikte koolstofbron soos etanol, grasse en bemesting en die skep van ‘n anaerobiese omgewing vir die verwydering van sulfate en chemies oksideerbare organiese material (CSB), asook die neutralisering van pH. Huishoudelike afvalwaterslyk is ook uitgewys as ‘n ekonomies geskikte en algemeen beskikbare koolstofbron wat die behandeling van beide SMW en huishoudelike afvalwater toelaat. ‘n Sintetiese medium wat die CSB en biologies afbreekbare organiese materiaal (BSB) van huishoudelike afvalwater slyk naboots is geformuleer om die variasies in die evaluasie van huishoudelike afvalwater slyk as koolstofbron vir die behandeling van SMW, uit te sluit. Eerstens is die BSB en die CSB van huishoudelike afvalwater slyk bepaal en gebruik as n maatstaf vir die formulering van die sintetiese medium. ‘n Verhouding van 1:1 sintetiese huishoudelike afvalwater slyk (SDWWS) en SMW is optimaal ratio i.t.v. die verwydering van sulfate en CSB. Tweedens is mediese dripsakkies as anaerobiese bioreaktore gebruik om die mikrobiese diversiteit in SMW, wat met SDWWS behandel is, te bepaal deur verskeie veranderlikes te gebruik. Tweede generasie DNA-volgorde bepalingstegnieke is gebruik en data analises het gewys dat Chlorobium spp. die 90 d pionier toetslopie domineer met relatiewe persentasies van 68 % en 76 %. Transmissie elektron mikroskopie fotos en die helder groen kleur van die dripsakkies se vloeistof inhoud het die data analises bevestig. Die sulfate en CSB inhoud is onderskeidelik met > 98 % en > 85 % verminder. ‘n Korter behandelingstydperk is ondersoek met n 30 d pionier toetslopie. Chlorobium spp. was dominant, gevolg deur Magnetospirillum spp. en Ornithobacterium spp. Die vloeistof inhoud het na ‘n donker bruin kleur verander. Die CSB en sulfaat konsentrasies is met 60.8 % en 96 % onderskeidelik verminder na 26 dae waarna ‘n plato bereik is. Die effek van ‘n reeds bestaande biofilm in die bioreaktore het gewys dat Chlorobium spp. ook gedomineer het teen ‘n relatiewe persentasie van 62 % in vergelyking met die 36 % in die 30 d pionier toetslopie. ‘n Vermindering in sulfate en CSB van 96 % en 58 % is onderskeidelik is bereik binne 26 d en die vloeistofinhoud was dieselfde kleur as die bioreaktore in die 30 d pionier toetslopie. Dit is moontlik dat die bruin Groen swawel bakterieë teenwoordig was. Daarom, ondanks ‘n groter teenwoordigheid van die Chlorobium spp. teen ‘n relatiewe persentasie in vergelying met die 30 d pionier toetslopie, was die verwydering van CSB en sulfate soortgelyk. Tydens die 30 d toetslopies het ‘n wit neerslag aan die bokant van die bioreaktore gevorm wat hoofsaaklik uit sulfaat en koolstof bestaan het wat ook ‘n aanduiding van die teenwoordigheid van Chlorobium spp. is. ‘n Toetslopie wat by laer temperature uitgevoer is kon die sulfate en CSB met slegs 10 % en 12 % onderskeidelik verminder nadat ‘n plato na 17 d bereik is. Ornithobacterium spp. het die eerste toetslopie gedomineer waar Magnetospirillum spp. die tweede toetslopie gedomineer het.

Thesis (MSc)--Stellenbosch University, 2015. / ENGLISH ABSTRACT: The Okiep copper district in the north-western corner of South Africa is a region that has been mined for over 150 years. Most mining operations have ceased, but years of mining has left the area scattered with abandoned mining sites. Acids (as used in ore processing) together with acid mine drainage generated from tailings exposure, collectively referred to as AMD hereafter, are a contamination risk to water resources and the biodiversity of this arid area. This study focused on an abandoned copper processing pond located close to the town of Nababeep. The leaching pond is unlined and has been excavated in the shallow colluvial soils. The natural soils of the area are shallow (60 cm) (WRB – Arenosol; SA – Oakleaf). Formations of corroded granite-gneiss boulders are an indication of the corrosiveness of the AMD collecting in the pond. The AMD was collected from the pond in the dry season at its most concentrated form and the AMD had exceptionally high concentrations of Al (26.9 g/l), Fe (42.9 g/l), Mg (20.5 g/l), Cu (3.8 g/l) and Mn (3.4 g/l). Melanterite (FeSO4·7H2O), a soluble ferrous compound, was found to play an important role in the immediate release of Fe and sulfates. The pristine soils have a sandy texture (2–5.2 %clay). The minerals detected in the clay phase include illite, kaolinite, montmorillonite and quarts. Pristine soils show some degree of contamination with low pH (4.38–4.77) and high Cu and sulfate contents. Soils located in the processing pond, which have been exposed to AMD for an extended period of time, showed poorly crystalline phases to be present (indicated by a broadening of the XRD peaks for clay minerals). Saturation indices (SI) were determined for saturated paste extracts of the pond soils and the obtained SI values support the notion of dissolution of silicate clays, as the obtained SI values ranged between –1.3 and –11.77 for illite and –4.76 to 0.58 for kaolinite. Jarosite, a new phase, formed in the contaminated soil and is a sink for K. Long term weathering experiments of pristine soils exposed to AMD indicated that clay minerals are significantly weathered and altered, which was identified by observing the broadening of the clay XRD peaks. Fourier transform infrared (FTIR) spectra were generated by scanning clay samples of the weathered soil. Amorphous phases were confirmed by structured water bands with wavenumber values of 3700 and 3300 cm−1 for acid treated soil. Micrographs showed a more amorphous and corroded morphology in the acid treated soil. Metal retention experiments were conducted by exposing the pristine soil to AMD repeatedly. Iron was the predominant metal attenuated in the soil. Metals such as Al, Mn, Na, K, Ca and Co were released by the soil into solution. Removal of Si is associated with the dissolution of clay minerals. The pristine soil shows limited capacity to neutralize acidity and low capacity to retain metals when leached with AMD. Metals were predominantly extracted in the water soluble phase of the long term weathering treatments. Aluminium was the most mobile fraction, being extracted predominantly from the water soluble fraction (2035 mg/kg). Exchangeable and acid soluble fractions did not retain significant quantities of metals. In the soil from the processing pond, the reducible fraction had a high concentration of reducible Fe (21175 mg/kg) and Si (3070 mg/kg). The reducible fraction also had the highest concentration of Cr (15.85 mg/kg), Cu (41.53 mg/kg), Pb (8.0 mg/kg) and Zn (10.65 mg/kg) compared to the other fractions of this soil. For the control experiment, the concentration of Cu (77.3 mg/kg), Pb (10.8 mg/kg) and Zn (24.1 mg/kg) were higher than contaminated soil yet lower for Cr (6.05 mg/kg). From these experiments, it can be concluded that the pristine soils studied have a limited ability to retain heavy metals in the non-bioavailable fraction, and, due to the nature of AMD, they are not effective in retaining metals sufficiently. The findings of this study suggest that the capacity of these pristine soils to buffer pH and retain metals is greatly limited. This could be as a result of (1) the low clay content, (2) the low concentration of secondary carbonates and (3) the low pH of the soil. The leaching of AMD from the pond is thus not regulated by the soils and poses a risk for nearby water resources. / AFRIKAANSE OPSOMMING: Die Okiep Koper Distrik, geleë in die noord-westelike hoek van Suid-Afrika, is ‘n streek waar mynbou al vir meer as 150 jaar plaasvind. Die meeste mynbou aktiwiteite is gestaak, maar jare van mynbou het die streek nagelaat met verskeie verlate mynbouterreine. Sure, wat in die prosessering van erts gebruik word, en suurmynwater wat gegenereer word uit die mynuitskot (gesamentlik verwys na as suurmynwater) is ‘n besoedelingsrisiko vir waterbronne en biodiversiteit in hierdie dorre area. Die studie fokus op ‘n verlate koper prosesserings aanleg naby die dorpie Nababeep. Die logingsdam is nie geseël nie en is uitgegrawe in vlak, kolluviale grond. Die natuurlike gronde van hierdie area is vlak (60 cm) (WRB – Arenosol; SA – Oakleaf). Formasies van weggevrete graniet-gneis rotse in die opgaardam is ‘n aanduiding van die bytende potensiaal van hierdie suurmynwater. Suurmynwater was versamel in die dam gedurendie die droë seisoen in die mees gekonsentreerde vorm. Die suurmynwater het besonderse hoë konsentrasies van Al (26.9 g/l), Fe (42.9 g/l), Mg (20.5 g/l), Cu (3.8 g/l) en Mn (3.4 g/l). Melanteriet (FeSO4·7H2O) is ‘n ysterhoudende verbinding en, alhoewel dit oplosbaar is, speel dit ‘n belangrike rol in die onmiddelike vrylating van Fe en sulfate. Die onversteurde grond het ‘n sand tekstuur (2–5.2 % klei). Die minerale wat in die klei fraksie ge-identifiseer is sluit illiet, kaoliniet, montmorilloniet en kwarts in. Die ongerepte gronde dui egter op ‘n mate van besoedeling deurdat dit ‘n lae pH (4.38–4.77) enhoë Cu en sulfaat inhoud het. Die grond wat geleë is naby die prosesseringsaanleg en ook blootgestel is aan suurmynwater vir ‘n verlengde tyd, dui daarop dat swak kristallyne fases teenwoordig is in die grond. Dit word bevestig deur ‘n verbreding van die XRD pieke van kleiminerale. Versadiging indekse (VI), wat bepaal is in versadigde grondekstraksies van die damgrond, ondersteun die oplossing van die silikaatkleie en word gereflekteer deur VI waardes wissel tussen –1.3 en –11.77 vir illiet en –4.76 tot 0.58 vir kaoliniet. Jarosiet is ‘n nuwe fase wat gevorm het in die besoedelde grond en is ‘n sink vir K. Langtermyn verweringseksperimente wat gedoen is deur die onversteurde grond bloot te stel aan suurmynwater wys beduidende verwering en verandering van klei-minerale deur verbreding van die XRD pieke. Fourier transform infrarooi (FTIR) spektra is op kleimonsters van die verweerde grond gegenereer. Amorfe fases is bevestig deur gestruktureerde waterbindings met frekwensies tussen 3700 en 3300 cm−1 vir suurbehandelde grond. Metaal-vasleggings eksperimente is uitgevoer deur herhaaldelik die onversteurde grond aan die suurmynwater bloot te stel. Yster is die metaal wat hoofsaaklik in die grond vasgehou is. Metale soos Al, Mn, Na, K, Ca en Co was vrygestel in oplossing deur die grond. Die vrylating van Si deur die grond word geassosiëer met die oplossing van kleiminerale. Die onversteurde grond toon beperkte vermoë om suur te neutraliseer en metale te bind in die grond wanneer dit met suurmynwater geloog word. Metale was hoofsaaklik ge-ekstraëer in die wateroplosbare fase vir die langtermyn verweringsbehandelings. Aluminium was die mees mobiele fraksie wat ontrek is van die water oplosbare fraksie (2035 mg/kg). Uituilbare en suuroplosbare fraksies het nie ‘n groot hoeveelheid metale vasgehou nie. Gronde wat versamel is naby die prosesseringsdam het die hoë konsentrasies vanFe (21175 mg/kg) en Si (3070 mg/kg) in die gereduseerde fraksie gehad. Die reduserende fraksie het ook die hoogste konsentrasie van Cr (15.85 mg/kg), Cu (41.53 mg/kg), Pb (8.0 mg/kg) en Zn (10.65 mg/kg) gehad in vergelyking met ander fraksies in die grond. Vir die beheer eksperiment was die konsentrasie van Cu (77.3 mg/kg), Pb (10.8 mg/kg) en Zn (24.1 mg/kg) hoër as in die besoedelde grond en laer vir Cr (6.05 mg/kg). Dus kan daar van hierdie eksperimente afgelei word dat die onversteurde grond beperkte kapasiteit het om swaar metale in grond vas te hou in die nie-biobeskikbare fraksie. As gevolg van die aard van die suurmynwater, is die grond nie voldoende om die metale effektief in grond te behou nie. Die bevindinge van hierdie studie dui daarop dat die kapasiteit van die ongerepte grond om pH te buffer en metale in grond te behou baie beperk is. Dit kan toegeskryf word aan die lae kleiinhoud, lae konsentrasie van sekondêre karbonate en die lae pH van die grond. Die loging van suurmynwater van die logingsdam is dus nie gereguleer deur die gronde nie en stel die naasliggende waterbronne in gevaar.

Thesis (PhD)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: In recent years acid mine drainage (AMD) has become the focus on many mine sites throughout the world. The Witwatersrand gold mines have been the main focus of AMD in South Africa due to their extensive impact on especially groundwater resources. The Witwatersrand Basin is a regional geological feature containing the world-famous auriferous conglomerate horizons. It is divided into sub-basins and the East Rand Basin is one of them. Due to the regional scale of the East Rand Basin AMD issues, a systems approach is required to provide a useful tool to understand the pollution source term and fate and transport dynamics and to aid in environmental decision making and to evaluate the geochemical impact of mitigation measures and evaluate future scenarios. The numeric geochemical models, using a systems perspective, show that the mine waste facilities, specifically the tailings dams are significant contamination point sources in the East Rand Basin, specifically for acidity (low pH), SO4, Fe, Mn, U, Ni, Co, Al and Zn. When the AMD solution enters the soil beneath the tailings, ferrous and SO4 concentrations remain elevated, while Mn, U, Ni and Co and perhaps other metals are adsorbed. After ~50 years the pollution plume starts to break through the base of the soil profile and the concentration of the adsorbed metals increase in the discharging solution as the adsorption capacity of the soil becomes saturated. The pollution pulse then starts to migrate to the shallow groundwater where contamination of this resource occurs. Toe seepage from the tailings either first reacts with carbonate, where acidity is neutralised to a degree and some metals precipitated from solution, where after it reaches the surface water drainage, such as the Blesbokspruit, where it is diluted. Some evaporation can occur, but evaporation only leads to concentration of acidity and dissolved constituents, thereby effectively worsening the AMD solution quality. The mixing models have shown that the dilution factor is sufficient to mitigate much of the AMD, although seasonal variability in precipitation and evapotranspiration is expected to have some influence on the mixing ratio and some variability in the initial solution will also be reflected in variation in surface water quality. From a sustainability perspective, a basic cost benefit analysis shows that the costs for the operating mine and society in general is lower when mitigation measures are employed during operation. For a theoretical mine in the ERB with an operating life of 100 years, the cost of operational mitigation measures is ~R 31 billion. This value is 4% of turnover and 19% of profits over the time period. Post closure remediation costs are ~R 67 billion. This value is 8% of turnover and 41% of profit over the time period. Although the initial capital investment in mitigation measures is substantial, although some measures will be implemented during operation, it is a smaller percentage of profits than eventual post-closure mitigation. / AFRIKAANSE OPSOMMING: In die laaste paar jaar het suur mynwater loging (SML) die fokus geword by baie myn areas regoor die wêreld. Die Witwatersrand goud myne het die hoof fokus van SML in Suid Afrika geword as gevolg van die groot impak wat Witwatersrand SML op veral grondwater bronne het. Die Witwatersrand Kom is ‘n regionale geologiese struktuur wat die wêreld beroemde goud-draende konglomeraat horisonne bevat. Die Witwatersrand Kom word onderverdeel in sub-komme, waarvan die Oos- Rand Kom een is. As gevolg van die regionale skaal van die Oos-Rand Kom SML probleem sal ‘n sistemiese benadering ‘n bruikbare middel wees om besoedelingsbron migrasie en eindpunt dinamika te verstaan asook om omgewingsbesluitneming en die geochemiese impakte en mitigerings metodieke asook toekoms senarios te evalueer. Die numeriese geochemiese modelle, wat vanuit ‘n sitemiese oogpunt beskou is, wys dat die myn afval fasiliteite, veral die slikdamme in die Oos-Rand Kom, beduidende kontaminasie puntbronne is van veral suur inhoud, SO4, Fe, Mn, U, Ni, Co, Al and Zn. Wanneer die SML oplossing die grond onder die slikdamme binnedring, bly Fe2+ en SO4 konsentrasies hoog, terwyl Mn, U, Ni en Co asook ander metale geadsorbeer word. Na ~50 jaar begin die besoedelingsoplossingspluim deur die basis van die grond profile breek. Die konsentrasie van die geadsorbeerde metale neem dan toe in die oplossing wat deur die grondprofiel beweeg het soos wat die adsorpsie kapasiteit van die grond versadig word. Die besoedelingspuls begin dan stadig na die vlak grondwater akwifeer migreer waar dit dan besoedeling van die grondwater versoorsaak. Water wat van die slikdam basis sypel reageer eers met karbonaat, waar suur tot so ‘n mate geneutraliseer word, dat sommige metale uit die oplossing neerslaan, waarna dit die oppervlak water lope, soos die Blesbokspruit, beryk en verdun word. Verdamping van die SML oplossing kan plaasvind, maar verdamping veroorsaak die konsentrasie van suur en opgeloste stowwe, wat die SML probleem dus kan vererger. Meng modelle het gewys dat die verdunning faktor genoegsaam is om baie van die SML te mitigeer, alhoewel seisoenale fluktuasies in reënval en verdampings syfers kan verwag word om ‘n mate van invoed op die meng verhouding tussen die SML oplossing en oppervlak water te hê wat dan in die oppervlak water kwaliteit gereflekteer sal word. Vanuit ‘n volhoubaarheidsperspektief is ‘n basiese koste voordeels analise gedoen. Hierdie analise het gewys dat die koste van ‘n operasionele myn en die samelewening as geheel laer is wanneer mitigasie metodieke tydens operasie toegepas word. Vir ‘n teoretiese myn in die Oos-Rand Kom met ‘n operasionele lewe van 100 jaar, is die operasionele mitigeringsmetodieke koste ~R31 miljard. Hierdie waarde is 4% van die myn omset en 19% van winste oor die tyds periode. Na operasionele remdiasie kostes is ~R67 miljard. Hierdie syfer is 8% van omset en 41% van winste oor die tydperk. Alhoewel die inisiële kapitaal uitleg van mitigasie metodes groot is, alhoewel sekere metodes eers tydens operasie implimenteer sal word, is die uitleg ‘n kleiner persentasie van winste as wanneer remediasie na operasie implimenteer word.

Lignite (brown coal) mine-mouth power plants supply a significance portion of electricity generated annually in Texas. Most lignite is produced from the Wilcox Group at surface mines located near a power plant. At the Oak Hill Mine, a lignite mine in the Sabine Uplift area of northeast Texas, the presence of low pH seeps has delayed the release of some portions of the reclaimed land from bond of some until all surface water bodies achieves a stable pH between 6 and 9. But this federal requirement may require an artificial elevation of surface water pH above the natural range for low volume, groundwater-fed surface water bodies in that region. The primary objective of this thesis is to determine whether the distribution of groundwater pH at Oak Hill Mine has become more acidic as a result of mining activity. This study shows that low pH (<6.0) groundwater was common within the mine permit area prior to mining activities; the 95% confidence interval for the median pH of overburden pre-disturbance (OP) wells is 4.7 to 4.8. This naturally occurring, low pH groundwater is produced by the weathering (oxidative dissolution) of pyrite in the Carrizo Sand and overburden Wilcox Group. Although low pH groundwater occurs naturally within the Oak Hill Mine permit area, groundwater pH has also decreased (groundwater has become more acidic) as a result of mining activities. The 95% confidence interval for the median pH of overburden reclamation (OR) wells is 4.1 to 4.2, indicating that mining activities has changed the median groundwater pH by approximately -0.5 standard units. Underburden groundwater is less acidic than overburden groundwater, but also becomes more acidic after mining activities. Underburden pre-disturbance (UP) groundwater has a median pH of 6.2 to 6.3 at the 95% confidence interval, whereas underburden reclamation (UR) groundwater has a median pH of 5.6 to 5.8 at the 95% confidence interval. / text