Thesis submitted in fulfilment of Master's Degree in Technology: Biotechnology, Durban Institute of Technology, 2004. / M

Thesis (M. Sc. (Soil Science)) -- University of Limpopo, 2019 / Water scarcity poses significant risks to global food security. The use of treated wastewater for irrigation could be a sustainable remedy for water scarcity in arid to semi-arid regions. Furthermore, it has been the most readily available source of water which can serve as an adaptation strategy to shortage of irrigation water. The objectives of the study were to determine (1) whether different disposal points following wastewater treatment could have effects on the quality of treated wastewater used for irrigation at the University of Limpopo (UL) experimental farm and (2) the response of selected critical nutrients, microbial and enzyme activities on soils irrigated with treated wastewater at the UL Experimental Farm. Water samples were collected monthly at three disposal points, namely, the exit point of treated wastewater from the treatment plant (Pond 16), the entry point into the night-dam and the exit point from the night-dam at the UL Experimental Farm. The water samples were analysed for pH, electrical conductivity (EC), sodium (Na), nitrate (NO3-), phosphate (PO42-), sulphate (SO42-), salinity, magnesium (Mg), calcium (Ca), potassium (K), chlorine (Cl), total dissolved solids (TDS), total soluble salts (TSS), lead (Pb), copper (Cu), cadmium (Cd), zinc (Zn), Ascaris lumbricoides, Escherichia coli, Shigella spp., Salmonella spp. and Vibrio cholera. A field experiment was conducted on a separate 4-ha virgin field (VF), cultivated field (CF) and fallowed field (FF), with soil samples collected from 0- 5, 5-15 and 15-30 cm soil depth in each field and analysed for pH, EC, mineralisable P, NH4+, NO3-, organic carbon (OC), active carbon (AC), potential mineralized nitrogen (PMN), fluorescein diacetate (FDA) and phosphatase (PTS) enzyme activity. All data were subjected to ANOVA using Statistix 10.1. The treated wastewater had, at the three sampling points, significantly different EC, Na, NO3-, PO42-, SO42-, Cu, Zn, Shigella spp., V. cholerae, A. lumbricoides and E. coli, whereas salinity, pH, Mg, Ca, K, Cl and Cd were not affected by the sampling point. Generally, the night-dam entry and exit points had significant increases in PO42-, K and Ca when compared to Pond 16 exit. In contrast, the flow of wastewater from Pond 16 through the furrow to the entry and exit of the night-dam resulted in decreases of Na, NO3- and Cl. The exit point of water from the night-dam at UL Experimental Farm had the least harmful materials, rendering it the safest point with the best water quality for irrigation. In the field study, NH4+, NO3- and PMN were significantly different in soil depth. However, NO3- field × depth interaction effects were not significantly different. In contrast to all soil parameters, FDA and PTS activity for both soil depth and field × depth interaction effects were highly significantly different. The EC and pH were not affected by soil depth or field type. The negative effects of treated wastewater were mainly observed in the cultivated field. In conclusion, treated wastewater with fallowing could be used as the best approach to overcome water shortages, with the uses having the potential to reduce the need to apply high synthetic chemical fertilisers. Keywords: water reuse, disposal points, essential nutrients, microbial activities

This master´s thesis studies qualities of aerated concretes, is monitoring influenece concrete composition, quantity of aerating admixture and plasticized admixture on the durability of concrete. It is monitored especially air flow and his influence on durability on concrete. In theoretical part are explained mechanisms of damage concrete, phenomena, which influence compressive strength of concrete and then there are the results of resistance against the influence of chemical defrosting substances. In experimental work were designed, mixed and tested recipe of concerete. We investigated different atribute, especially resistance of the chemical defrosting and air flow in hardened concrete. The result of master´s thesis is effect of flow air in concrete on the durability.

If not purified leachate from landfills would cause damages on the environment. At most landfills in Sweden local treatment of leachate is achieved, at the rest the leachate is transported to sewertreatment. While no comprehensive legal provisions for discharge exist in Sweden there is a difference in discharges between the installations for landfill. If no comprehensive legal provisions is produced guidance must improve. Treatment of leachate and self monitoring system at fifteen installations in Sweden has been studied and compared. A study of literature about different treatment solutions has also been performed. Practical information about the landfills has been gathered through visits. Processes of treatment described in literature correspond to measures. Variations exists between the self monitoring systems at the installations both between parameters for analyses, how often controls take place and were testpoints are situated. Knowledge of reactions and techniques for treatment of compounds common in leachate exist. Further research about compounds whose effect we do not know for certain must be achieved. / Lakvattenrening och egenkontrollprogram vid femton deponier i Sverige har studerats och jämförts. En litteraturstudie angående olika reningstekniker har även utförts. Information om deponierna och reningsprocesserna har inhämtats via studiebesök och miljörapporter. Vid jämförelse av rening har olika processer studerats separat. Den beskrivning av processerna som finns i litteraturen stämmer väl med uppmätta resultat. Exempel på detta är ammoniumhalter som reduceras i luftad damm, halter totalkväve som minskar genom rening i Satsvis Biologisk Reaktorteknik och reducerad halt suspenderat material som inträffar vid rening genom markfilter. Egenkontrollprogrammen vid de olika deponierna varierar dels i avseende på vilka parametrar som kontrolleras och dels hur ofta kontroller utförs och var provpunkter är belägna. För de vanligast förekommande ämnen som existerar i lakvatten finns kunskap om reaktioner och fungerande tekniker för rening. Problem uppstår för de ämnen vilkas reaktioner och förändringar man ej känner till. Farhågor finns dessutom att det i lakvatten finns föreningar vars existens och verkan vi ej känner till. På grund av detta krävs ytterligare forskning på lakvatten.

The thesis deals with the development of new type of lightweight floors based on secondary raw materials. In the introduction, the current knowledge in the field of lightweight building materials, especially screeds and lightweight porous concrete, is presented. The thesis describes brief history of production of aerated concrete and its development up to the present. Further, the thesis describes the procedure of design and testing of new lightweight materials for use in floors. The proposed recipe has been thoroughly tested and the best combination of components for use in lightweight porous concrete floor screed has been selected. The thesis also examines the microstructure of the material being developed. The main result of the dissertation is the developed product, which is already used in practice and is produced and sold on the market as part of the system of lightweight building materials.

No description available.

This research entails the investigation of the effects of a bioaugmentation product from BiOWiSH® called Aqua, referred to as “Aqua” for the remainder of this paper, on the nitrogen removal rate in a membrane aerated bioreactor (MABR). This research was conducted using a MABR design that consisted of a silicone membrane and continuous flow airline with compressed air. The membrane system was designed to supply oxygen, creating an aerated layer at the membrane-biofilm interface and an anoxic layer at the biofilm-water interface. Laboratory experiments were conducted to compare the nitrogen removal rates of natural bacteria alone to natural bacteria paired with Aqua. However, it was not possible to determine if a difference existed between the nitrogen removal rates of the MABR systems with only natural bacteria versus those with natural bacteria augmented with Aqua. The mean nitrogen removal rate observed when the media in the system reached steady state was 0.39 mg-N/L-hr. with a carbon to nitrogen (C: N) ratio of 12:1. The only increase in the nitrogen removal rate observed was when the C: N ratio was doubled to 24:1 and the nitrogen removal rate increased to 0.56 mg-N/L-hr. Although it appeared that the Aqua did not have an influence on the nitrogen removal rate in the MABR systems, many other variables still need to be assessed to reach a conclusion. To improve the efficiency of the system more tubing should be added, or the glucose should be removed from the growth media because the maximum O2 mass transfer rate is only enough O2 for nitrification. The addition of glucose at 12:1 ratio increased the O2 demand in the system to be five times greater than the O2 supplied from the silicone tubing. This research determined that use of trace minerals, Aqua dosing method, and Aqua dosing concentration were not contributing factors in nitrogen removal from growth media under the conditions of this experiment.

High concentrations of heavy metals in the soils have potential long-term environmental and health concerns because of their persistence and accumulation tendency in the environment and along the food chain. This study was aimed at studying the feasibility of heavy metals removal from the soil using plants naturally growing in the surroundings of selected polluted sites in Tanzania and soil application of the sorbent materials zeolite and autoclaved aerated concrete (AAC). The results showed that Sporobolus sp. is a hyperaccumulator of Cu. Four other species, Launea cornuta (Oliv &amp; Hiern) O. Jeffrey, Tagetes minuta (L.), Sporobolus sp. and Blotiella glabra (Bory) Tryon showed high potential for phytoextraction of Cu. No hyperaccumulators of Pb and Zn were identified in the area, but Tephrosia candida and Tagetes minuta (L.) were identified as potential plants for phytoextraction of Pb, while Conyza bonariensis (L.) Cronquist, Launea cornuta (Oliv &amp; Hiern) O. Jeffrey, Tagetes minuta (L.), Blotiella glabra (Bory) Tryon, Pteridium aquilinum (L.) Kulm and Polygonum setogulum A. Rich were identified as potential plants for phytoextraction of Zn. The result from sorbent experiments showed that both materials had a potential for remediating metal polluted soils. The AAC had a higher removal capacity for both Zn and Pb than zeolite. The removal capacity of zeolite and AAC in a mixed metal experiment (Pb and Zn) showed a little difference in the sorption capacity of AAC and Zeolite for Pb and Zn respectively. Speciation of the metal in soil shows that the major part of the metal was associated with firmly attached component of the metal in the soil. Compared with the total metal concentration analysed, the available component accounted for 13-39% for Zn and 31-39% for Pb. It can be suggested to co-remediate polluted soils using reactive sorbent nodules and hyper-accumulating plant species. Identification of the best combinations and designs remains the subject of future research. / <p>QC 20121130</p>

The presence of nutrients, such as nitrogenous compounds, in wastewater can pose serious environmental concerns to water systems leading to reduced water quality and potential risks to the public health. Nutrient removal in conventional wastewater treatment systems is becoming increasingly more costly due to the extensive energy requirements and high aeration costs. Anaerobic ammonium oxidation (Anammox) is an alternative method for nutrient removal which can reduce overall treatment costs due to less aeration requirements and less sludge production. Anammox process can be implemented with other innovative technologies, such as membrane aerated biofilm reactors (MABR) to achieve effective and sustainable nutrient removal. A major challenge associated with Anammox process is effective control of nitrite oxidizing bacteria (NOB). High temperature in wastewater treatment systems can promote Anammox bacterial growth and inhibit NOB activity. This research aims to investigate the feasibility of integrating Anammox processes with MABR technologies and to examine the effects of high temperature aeration supplied to MABR systems on Anammox bacterial growth and NOB suppression. The nitrogen removal by Anammox bacteria in a lab-scaled MABR is examined to determine the impact of aeration temperature on inhibition of NOB. / Thesis / Master of Applied Science (MASc)

This work aims to study the niobium influence in the crystallographic texture and the corrosion resistance of ferritic stainless steels on aerated and de-aerated environments. For this objective the ferritic stainless steels P409, P410, P430A, P430E (Nb stabilized) were used; and austenitic stainless steel, P304, and carbon steel, A36, were used as comparative materials. These materials had a mechanical characterization (hardness and tension test), and the steels P430A and P430E had a crystallographic characterization too. That crystallographic characterization (by EBSD) was analyzed through to inverse pole figure (IPF) and crystal orientation distribution function (CODF). The samples were submitted to anodic potentiodynamic polarization test in solutions: 3.56% NaCl, and 1N H2SO4 on aerated environment, and 3.56% NaCl at de-aerated environment. The samples were examined by SEM after the polarization tests. The analysis of the results clearly showed that the crystallographic texture influence the corrosion resistance. The niobium in the stainless steel reduces the presence of preferential orientation, therefore, the influence of the texture in the corrosion resistance, but helps to increase the corrosion resistance by the formation of niobium carbbonites. Finally it was observed that for polarization tests in aerated environments and de-aerated have a very small variation in behavior that depends on the steel, but this variation is not statistically significant. / O objetivo deste trabalho é estudar a influência do nióbio na textura cristalográfica e resistência à corrosão de aços inoxidáveis ferríticos em ambientes aerados e desaerados. Usou-se para o estudo os aços inoxidáveis ferríticos P409, P410, P430A, P430E (estabilizado ao Nb) e como objetos de comparação usaram-se os aços inoxidáveis austenítico P304 e o aço ao carbono A36. Neles realizou-se uma caracterização mecânica (dureza, ensaio de tração), e para os aços P430A e P430E foi feita uma caracterização cristalográfica (via EBSD) por meio de figura de polos inversa (IPF) e da função de distribuição de orientação cristalina (FDOC). As amostras foram submetidas a ensaios de polarização potenciodinâmica anódica para soluções de 3,56% NaCl e 1N de H2SO4 em ambiente aerado e solução de 3,56% NaCl em ambiente desaerado. As amostras foram examinadas por microscopia MEV após os ensaios de polarização. A análise dos resultados mostrou claramente que a textura cristalográfica influência a resistência à corrosão. O nióbio diminui a presença de orientações preferenciais, e, por consequência, a influência da textura na resistência à corrosão, no entanto aumenta a resistência à corrosão nos aços inoxidáveis pela formação de carbonetos de nióbio. Por último observou-se que para ensaios de polarização em ambientes aerados e desaerados existe uma ligeira variação no comportamento que depende de cada aço, mas que não é estatisticamente significativa. / Mestre em Engenharia Mecânica