Techn. Universiẗat, Diss., 2005--München.

Thesis--University of Lund. / Extra t.p. with thesis statement inserted. Includes reprints of author's articles. Includes bibliographical references.

Thesis--University of Lund. / Extra t.p. with thesis statement inserted. Includes reprints of author's articles. Includes bibliographical references.

University, Diss., 2002--Mainz.

University, Diss., 2004--Karlsruhe.

Syftet med projektet är att behandla flygaskan med hjälp av surt processvatten för att utvinna olika metaller, som zink, så att det sedan kan deponeras på ett enklare och billigare sätt, samt även at utveckla en metod för att utvinna mer zink med minsta möjliga andel surt processvatten (5 % HCl). Olika metaller med fokus på zink studerades i labbskala på Högskolan i Borås. Flygaskan och det sura processvattnet som har använts i denna studie är från Renova ABs anläggning. Resultatet visar att vid behandling av flygaskan med surt processvatten var den maximala mängden zink som utvanns 88% under de olika försöken som gjordes i labbet. Det finns olika faktorer bakom resultatet, såsom halten av surt processvatten, pH, blandningstiden och askans elementsammansättning, vilka kan påverka halten utvunnen zink. / Sweden produces large amount of fly ash from waste combustion annually. Combustion the waste generates two types of ashes, bottom ash/slag, and fly ash. Bottom ash is considered to be more environmentally friendly and has a wide area of application such as road constructions on landfills. While the fly ash has high level of heavy metals and for instance dioxines which are harmful for the environment. This type of ash are deposited in a landfill and gets classified as a hazardous waste which is expensive given that the deposit fee is high. The fact that fly ash contains valuable metals as zinc, methods of recovering it are being developed such as acid leaching. This is a promising method as the leachate used are acid process water making the usage of the chemicals substantially lower which makes it financially viable. Waste incinerators in Sweden produce approximately 200 000 tons of fly ash annually and the majority of it is transfered to Norway to get treated and put on a landfill. Some waste management companies, e.g. Renova, are using another method called “the Bamberg method” where fly ash is mixed with sludge to form a cake and put in the company’s own landfill. The projects goal is to leach the fly ash by using acidic process water to obtain the metallic substance particularly zinc making it easier and cheaper to landfill the ash and also to optimize this method to get the most zinc out of the ash using minimum amount of the acidic process water (5% HCI). The laboratory work took place in the University of Borås. Fly ash and the acid process water which were used under the laboratory work was obtained from RenovaAB. The results shows that leaching the fly ash with acidic process water gave different release of zinc but was 88% at most. The variation in the results depends on a few factors such as amount of acidic process water, pH, time, blending time and the ashes content. This project took environment and access to acidic water in consideration, which optimized the method of using less amount of acid process water to get the most zinc as possible. The results shows that leaching fly ash with acid process water is cost efficient and easy way to recover zinc, which satisfy the goals of the project.

Thesis (MSc. Agriculture (Agronomy)) --University of Limpopo, 2015 / Agronomic field trial was planted at two sites, Ukulima and Syferkuil, in Limpopo Province, to determine the response of cowpea to variable rates and methods of zinc application under supplementary irrigation and rainfed conditions, respectively. The experiment was laid out in a split plot arrangement and fitted into a randomized complete block design (RCBD). Treatments consisted of two factors namely zinc rates (0, 5, 10, 15, 20 and 25 kg ha-1) and methods of application (soil and foliar) with white cowpea variety (IT00K-1217) seeds sown. The zinc fertilizer was applied as ZnSO4 (38.5% Zn) while basal phosphorus (30 kg P ha-1) was applied in the form of single super phosphate (10.5% P) so as to eliminate P constraints. Soil application of the zinc fertilizer was band placed near the row of cowpea plant while foliar application was done 3-5 weeks after plant emergence. Growth parameters measured included plant height, number of primary branches, canopy cover, number of trifoliate leaves, days to 50% flowering and pod formation, and fresh biomass as well as yield component attributes. Twenty young cowpea leaves and immature green pods were each harvested at approximately 75% physiological maturity. Crude protein, total nitrogen, potassium, phosphorus, zinc, and iron content and uptake were assessed in the different plant parts. Growth, yield and nutrients data collected were subjected to analysis of variance. Treatments means were separated using Tukey’s test at probability level of 5%, while the response variables were modelled using quadratic polynomial equation. Results obtained revealed that total above ground biomass yield of 6219 kg ha-1 and fresh pod weight of 142.3 g were obtained when zinc was soil applied under rainfed condition compared to 6019 kg ha-1 and 138.0 g for total above ground biomass yield and fresh pod weight, respectively when foliar applied. Soil application gave a total above ground biomass yield of 6298 kg ha-1 and pod fresh weight of 150.9 g while foliar application gave total above ground biomass yield and pod fresh weight of 4791 kg ha-1 and 124.0 g, respectively at Ukulima. Soil application also gave a significantly higher grain yield (2251 kg ha-1) than the foliar application (1503 kg ha-1) at Ukulima. A higher but inconsequential effect on grain yield was obtained with soil over foliar application at Syferkuil. Application of zinc fertilizer at a rate beyond 5 kg ha-1 resulted in a grain yield reduction of up to 22.2% and 6.6% respectively at vi Ukulima and Syferkuil. Thus, this rate appeared optimum for both grain and fodder production when soil applied at both sites. Based on the quadratic model, total biomass (4897 kg ha-1) and grain (1602 kg ha-1) yields were optimized at an estimated zinc rate of 54.7 and 33.4 kg ha-1, respectively under supplementary irrigation, while total biomass (5913 kg ha-1) and grain (2696 kg ha-1) yields were obtained at an estimated optimum zinc rate of 20.1 and 26.8 kg ha-1, respectively under rainfed condition. A scorching effect of cowpea leaves was observed following foliar application of zinc fertiliser at 25 kg ha-1 that resulted in a decreased growth and yield at Ukulima. Foliar application resulted in improve cowpea leaf zinc concentration (43.9 mg kg-1) compared to soil application (23.2 mg kg-1) at Syferkuil. It also resulted in increased crude protein, total N, P, Fe and Zn uptake compared to soil application at Ukulima. Both soil and foliar zinc application gave 28.5% zinc concentration in the fresh immature pods samples collected. Findings from this study reveal that foliar zinc sulphate application resulted in higher grain and biomass yields as well as zinc concentration in the various cowpea plant parts. Based on the quadratic model used in this study, the optimum zinc rate required to guarantee high cowpea yield and zinc-rich grain and leaf content at both trial sites is highly variable; and thus requires further study for validation. Keywords: Cowpea production, grain yield, dryland farming, leafy vegetables, foliar fertilizer, improved nutrition, zinc deficiency.

Zugl.: Berlin, Techn. Univ., Diss., 2007

Zugl.: Aachen, Techn. Hochsch., Diss., 2008.

Zugl.: Aachen, Techn. Hochsch., Diss., 2008