A study was undertaken to evaluate the effectiveness of alum coagulation, permanganate and chlorine dioxide preoxidation, and powdered activated carbon pretreatment for the removal of trihalomethane (THM) precursors from the Po River, the Ni River and the Ni River Reservoir waters in eastern Virginia. The effects of temperature and storage were also studied. Samples were collected on two occasions and were analyzed for total organic carbon (TOC), THM-formation potential (THMFP), color, UV-absorbance and pH. Samples were then treated in a manner similar to that ina typical water treatment plant by bench-scale jar tests and reanalyzed for TOC, THMFP, color and UV-absorbance. The results indicate that the THMFPs of both Po and Ni River waters were high. Alum coagulation at pH 6.0 reduced TOC by as much as 48 percent while THMFP reductions averaged 63 percent. Permanganate preoxidation at dosages as high as 2.0 mg/L reduced THM precursors by less than 14 percent. Powdered activated carbon at 10 to 20 mg/L reduced THM precursors by less than four percent. Application of 2 mg/L chlorine dioxide reduced THM<-precursors by eight percent over what could be achieved by alum coagulation alone. A major conclusion was that treatment of the Po River by conventional measures to meet existing and future drinking water standards for THMs would be difficult, if not impossible. / Master of Science

Municipal treated wastewater entering rivers contain biologically active pharmaceuticals capable of inducing effects in aquatic life. Phytoremediation of three of these pharmaceuticals and an herbicide was investigated using Sandbar willow (Salix exigua) and Arabidopsis thaliana. Both plants were effective at removing compounds from solution, with removal of 86% of the synthetic estrogen, 17α-ethynylestradiol, 65% of the anti-hypertensive, diltiazem, 60% of the anti-convulsant, diazepam (Valium®), and 51% of the herbicide atrazine, in 24 hours. Distribution of compounds within roots and shoots, in soluble and bound forms, differed among compounds. Uptake and distribution of pharmaceuticals within the study plants confirmed pharmaceutical behaviour can be predicted based on a physiochemical property, their octanol-water partitioning coefficients. An effective method for detection of 17α-ethynylestradiol within surface water using solid phase extraction and gas chromatography-mass spectrometry was developed. Previously unreported breakdown of 17α-ethynylestradiol into another common estrogen, estrone, during preparative steps and gas chromatography was resolved. / xv, 216 leaves ; 29 cm.

M.Sc. / Pollution of the earth is presently one of the most important environmental issues of the world and various attempts, including creation of public awareness have been initiated over the past few years to address this situation. There is especially a global concern about the progressive pollution of valuable freshwater systems which most organisms, including humans, are reliant upon. This includes South Africa's aquatic ecosystems, many of which have been degraded over the past few decades. The Olifants River in Mpumalanga is one of the most threatened river systems in South Africa. It is impacted by various anthropogenic activities, particularly mining in the upper catchment, and urbanisation, industrial and agricultural activities in the upper and lower catchments. Previous investigations have shown that these activities are responsible for the degradation of this river system. The broad objective of this study was to obtain data on water and sediment quality, as well as bioaccumulation of metals in fish via monitoring of the Olifants River. It formed part of a major study concerned with the experimental investigation of lethal and sub-lethal effects of metals on fish physiology, supported by a field investigation into the water quality and metal contamination of the biotic and abiotic components of the Olifants River system. Physico-chemical properties of the water as well as the concentrations of some metals (Al, Fe, Cu, Zn, Ni, Mn, Pb & Cr) in the water and sediment were seasonally investigated. The extent of bioaccumulation of these metals in selected organs/tissues (muscle, gills, liver & skin) of Oreochromis mossambicus and Clarias gariepinus from Loskop Dam (upper catchment) and Mamba Weir, Kruger National Park (lower catchment) was also investigated. High levels of various macro-constituents and metals were detected at many sites in the study area and in many cases they exceeded the guideline limits set for aquatic ecosystems. Localities 2, 3, 6, 8, 10, 12 and 17 were observed to be severely impacted (see Chapter 9- Table 9.1) by elevated concentrations of pollutants influencing variables such as TDS and sulphates. This confirms that these sites are being impacted by mining. This was further confirmed by low pH-values at localities 3, 5, 8, 9, 10 and 12 which indicate on acid mine drainage originating from the many coal mines in the upper catchment of the Olifants River. Nutrient enrichment (elevated levels of phosphates, nitrates and nitrites) occurred at many sites in the catchment but in particular at localities 3, 4, 6, 10, 11, 14, 15 and 17. Point source pollution from sewage treatment works and non-point sources from agricultural runoff and informal settlements are the main contributors to these elevated levels of nutrients. The Selati River, impacted in particular by elevated phosphate levels, is the main contributor to the high nutrient levels detected at locality 17. It is evident from the evaluation of the metal concentrations in the water and sediment (Table 9.2) that most of the sites in the Olifants River catchment are being impacted by metal pollution. Oreochromis mossamhicus and C gariepinus sampled at selected sites in the Olifants River accumulated selected metals in the following order; Fe>Zn>Al>Cr>Ni>Pb>Mn>Cu. Levels were generally high in the liver and gills, while much lower levels were detected in the skin and muscle tissues. Gill tissue is in direct contact with the aqueous environment and therefore gives a good indication of the extent of exposure. Skin tissues usually contained relatively low levels of metals (except for Zn). Although muscle tissues usually accumulated low metal concentrations it is an important tissue to monitor in bioaccumulation studies as it can lead to metal poisoning if contaminated muscle tissues are consumed by humans. Adult specimens were mostly sampled and within this range there was a slight decrease in Cu, Al, Fe, Ni, Mn and Cr concentrations with increasing age. Temporal variation in metal accumulation by fish possibly occurred due to variations in metal concentrations in the water and sediment at a locality. These differences were caused by seasonal variation in climatical conditions (eg. rainfall, temperature), as well as temporal fluctuations of pollutant inputs into the river system. Aquatic organisms at both localities 15 (Loskop Dam) in the upper catchment and 17 (Mamba weir, Kruger National Park) in the lower catchment are at present being chronically exposed to elevated levels of the investigated metals, compared to both the control site and results in literature. The impact of the highly polluted Selati River in the lower catchment was evident in the difference between metal concentrations detected in fish at locality 17, and at locality 19 (Phalaborwa Barrage) upstream of the Olifants-Selati confluence. The present study clearly indicates that the Olifants River is subjected to various sources of pollution which could be detrimental to the health of this aquatic ecosystem. It is recommended (see Chapter 9) that a multi-disciplinary approach including a biomonitoring programme, should be followed to ensure a sustainable freshwater ecosystem.

No description available.

Transition state theory was applied to the nitrification process in soil-water systems, and a computerized, theoretical rate model was developed to include NH₄⁺ and 0₂ concentrations, pH, temperature, moisture content, and local differences in nitrifying capacities of Nitrosomonas bacteria. The model was restricted to enriched calcareous soils thus simplifying the application of basic physicochemical principles. Experimental rate data from an agricultural and a native desert soil provided verification of a zero order reaction for nitrification with respect to NH₄⁺ concentrations above a certain saturation level, as previously reported. The saturation concentration in soils was found to be about 1.0 to 5.0 ppm. A theoretical linear relationship between activation energy and ionic strength was confirmed by application of the above data. However, each local population of nitrifiers tended to display different values for the slope and intercept of the linear relationship. The structure of the activated complex for NH₄⁺ oxidation to NO₂⁻ was determined to be more like NH2OH or NH₄⁺ than NO₂⁻. As a first approximation, the NH₂OH activated complex was included in the rate model. The equation form for the equilibrium between the reactants and the activated complex was found to differ from the stoichiometric reaction between NH₄⁺ and O₂ to form NH₂OH. The equilibrium expression was found to be more closely approximated by the relationship, 2 NH₄⁺ + O₂ ≶ (ACTIVATED COMPLEX) + + H⁺. A method was developed to compute soil pH values as a function of moisture content. Verification was obtained by using data obtained from the agricultural and native desert soils, including cases where samples were acidified. The calculated pH values were used in the nitrification rate model. Further verification of the model was obtained using data from the literature for two soils from the Northern Great Plains. Data pairing of observed and predicted rates for these soils yielded R values of 0.944 and 0.940. The rate model was programmed in FORTRAN IV computer language and designed to operate in conjunction with existing computer models. Thus, this relatively sophisticated model may be applied to field simulation studies with a minimum of adaptive procedures. The model should aid in obtaining reliable predictions of NO₃⁻ formation and movement under a wide range of field conditions.

No description available.

Eight natural waters from throughout the United States were subjected to different degrees of alum coagulation and activated carbon adsorption treatment (not in series). The concentration of trihalomethanes (THMs) formed by the reaction between the natural aquatic organics and doses of free chlorine were determined by gas chromatography at ten discrete time intervals over a total of 168 hours of reaction time. Since bromide ion concentration and temperature were held constant, and the chlorine dose was based on the final nonvolatile total organic carbon (NVTOC) concentration, THM formation was modeled with the independent variables: reaction time, pH, and a surrogate parameter for organic precursor. Several surrogate parameters were investigated to quantify the THM formation potential. A multiplicative surrogate (UV*TOC) representing the product of the NVTOC concentration and the UV adsorbance at 254 nm was found to be the best surrogate for activated carbon treated waters and was found to be approximately equivalent to NVTOC for alum treated waters. The THM formation was found to fit a two stage reaction with respect to reaction time; relatively rapid formation in the first eight hours followed by a slower formation from 24 to 168 hours. The data base was analyzed with a statistical software package that performs multiple linear regression analysis. Three types of models were developed: a linear model, a nonlinear model and a logarithm transform model. The models were checked for predictive accuracy by a number of methods including the examination of statistics from the regression analyses, scatterplots of predicted versus observed THM values, and the number of predicted values within 20% of the observed value. The logarithm transform model was found to be the best overall model, although other models were more accurate for specific applications as to reaction time or water type. Gel permeation chromatography (GPC) was employed to examine the molecular weight distribution of the aquatic organics in three of the eight waters and to determine the effects of alum coagulation and activated carbon adsorption on these distributions. In general, alum coagulation preferentially removed high molecular weight organics while activated carbon removed a broad spectrum of molecular weight organics.

Thesis (MSc)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: Biofouling of water systems is a problem extensively experienced in industry. Although this subject is the focus of many studies, the ability of microorganisms to survive exposure to biocides is still poorly understood. This study aimed to assess the biocidal effect of ozone on planktonic cells and biofilm communities, to evaluate different ozone generation techniques, and to follow population shifts within the biofilm community. Specific objectives included determining the effect of different ozone concentrations, the effect of different exposure times, and an assessment of microbial responses after exposure to sub-lethal ozone concentrations. Typically, 300 ml of an ovemight bacterial culture was exposed to ozone that was generated by anodic oxidation (0.3% wt or 18- 20% wt, respectively) or silent electric discharge (3.5% wt 03). The ozone was purged into the culture for 5-, 7-, 10- and 15 min., respectively. Enumeration of cells following ~10 min. exposure to 18-20% wt ozone showed a significant reduction in viable cell numbers. In contrast, when exposed to the two lower 03 concentrations, there was little change in the viable cell numbers even after prolonged exposure (30- and 60 min.). To evaluate biofilms, ozone was bubbled into the irrigation that was pumped through replicate flow cell channels. Response to ozone exposure was evaluated after staining the biofilms with the Baclight Viability probe, observation with fluorescence microscopy, and image analysis. The higher ozone concentration (18-20% wt 03) more effectively disrupted the biofilm structure of denser biofilms than the lower concentration, especially after 90 min. exposure. When compared to the controls, the 90 min. exposure resulted in a notable reduction in viable cells from 69% to 38% and a corresponding increase in nonviable cells from 29% to 62%. The lower concentration ozone (3.5% wt 03) was effective against the less dense, thinner biofilms evaluated, but not effective against the thicker biofilm. An analysis of the differences between continuous culture biofilms and batch culture biofilms showed that the biofilms in the batch system were less rigid. To evaluate microbial response to biocides, techniques such as Biolog whole-community metabolic profiles and terminal restriction fragment length polymorphisms (T-RFLP) were used. Biolog analysis of planktonic cells revealed changes following exposure to sub-lethal biocide concentrations, however carbon utilisation profiles resembled that of the controls after 24-48 hours. For biofilm communities, no carbon utilization differences could be detected under these conditions. There was, however differences in T-RFLP patterns between treated and untreated biofilm communities. / AFRIKAANSE OPSOMMING: Biobevuiling van watersisteme is 'n probleem wat algemeen in industriëe ervaar word. Alhoewel hierdie onderwerp die fokus van vele studies is, word die vermoëns van mikroorganismes om blootstelling aan biosiede te weerstaan steeds swak verstaan. Die doel van hierdie studie was om die biosidiese effek van osoon op planktoniese selle en biofilm gemeenskappe waar te neem, om die verskillende osoon generasie tegnieke te evalueer, asook om verskuiwings in die samestelling van die biofilm gemeenskap waar te neem. Spesifieke doelwitte sluit in die bepaling van die effek van verskillende osoon konsentrasies, die blootstellingtye, en 'n waarneming van mikrobiese reaksies na blootstelling aan sub-dodings osoon konsentrasies. Drie honderd ml van 'n oornag bakteriese kultuur was aan osoon, wat deur anodiese oksidasie (0.3% wt of 18% - 20% wt) of geluidlose elektriese ontlading (3.5% wt), gegenereer is, blootgestel. Tye van blootstelling was 5-, 7-, 10-, of 15 min., onderskeidelik. Bepaling van selgetalle na :2:10 min. blootstelling aan 18 - 20% wt osoon, het 'n betekenisvolle verlaging in die getal lewensvatbare mikrobeselle getoon. In teenstelling hiermee, het blootstelling aan twee laer osoon konsentrasies min verskil in die lewensvatbare selgetalle, selfs na verlengde blootstellingstye (30- en 60 min.), getoon. Om biofilms te evalueer is osoon in die medium geborrel wat deur replikaat vloeisel kanale gepomp is. Na osoon blootstelling, was die vloeisel onderwerp aan beeld analise deur gebruik te maak van die Baclight lewensvatbare peiler en fluoressensie mikroskopie. Die hoër osoon konsentrasie (18 - 20% wt 03) het die struktuur van dikker biofilms meer effektiefuiteengeskeur as die laer konsentrasie, veral na 90 min. blootstelling. In vergelyking met die onderskeie kontroles, het die getalle van lewensvatbare selle na 90 min. blootstelling drasties verlaag vanaf 69% tot 38% en 'n ooreenstemmende toename in die nie-lewensvatbare selgetalle vanaf 29% tot 62%. Die laer osoon konsentrasie (3.5% wt 03) was meer effektief teenoor die minder digte en dunner biofilms wat ge-evalueer was, maar nie so effektief teenoor die dikker biofilms nie. 'n Analise van die verskille tussen kontinue-kultuur biofilms en lotkultuur biofilms het getoon dat die lot-kultuur biofilms minder rigied is. Vir die evaluering van mikrobiese reaksies na biosied blootstelling, is tegnieke soos Biolog gemeenskap metaboliese profiele en eind-restriksie-fragment-lengte polimorfisme (TRFLP) gebruik. Biolog analise van planktoniese selle het verskille getoon na blootstelling aan sub-dodelike biosied konsentrasies. Koolstof benutting het wel na 24 - 48 ure met dit van die kontrole ooreengestem. Vir biofilm gemeenskappe was daar geen noemenswaardige verskille in koolstof benutting nie. Daar was wel verskille in T-RFLP patrone tussen die onbehandelde en biosied-behandelde biofilm gemeenskappe.

published_or_final_version / Botany / Master / Master of Philosophy

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