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Four experiments were conducted with crab processing waste. Addition of 1.5% propionic/formic acid prevented degradation up to 14 d. Desirable fermentation was achieved when 32% of the treated crab waste was ensiled with 32% straw, 16% molasses, and 20% water with or without .1% microbial inoculant. The pH of the silage was lowered and high concentration of lactic acid was observed. Use of .2% NaOCl or .4% H₂O₂ retarded spoilage of crab processing waste up to 7 d. Ensiling of the treated waste (32%), straw (32%), molasses (16%), and H₂0 (20%) indicated that the chemical used in preservation enhanced fermentation. Addition of .4% NaOCl and 1.5% acetic acid to the crab processing waste retarded degradation up to d 4. The trimethylamine (TMA) concentration and NH₃ evolution were highest for the untreated waste while the lowest concentration for TMA and NH₃ evolution were observed for the NaOH-treated waste. Addition of 1% NaNO₂ or combination of .4% NaOCl/CaOCl (1:1, w/w) preserved the waste for up to 10 d. The evolution of NH₃ and H2₂S, and TMA concentration were lowest for the waste treated with 1% NaNO₂. Apparent digestibility of DM, organic matter, CP, energy, NDF, ADF, cellulose and hemicellulose decreased linearly (P<.01) with level of crab waste-straw silage in diets containing 0, 50, and 100% crab waste-straw silage. Nitrogen retention increased linearly (P<.05) with level of crab waste-straw silage. The apparent absorption was higher (P<.01) and retention was positive (P<.05) for Ca, Mg, Na, K, Cu and Fe with sheep fed the highest level of crab waste-straw silage. Daily gain, feed efficiency and carcass characteristics tended to be higher for steers fed 30% crab waste-straw silage, dry basis. The flavor and overall desirability of cooked meat were not adversely affected by feeding up to 30% crab waste-straw silage, dry basis. Modifying the existing methods of quantifying chitin showed that initial decalcification or deprotinization of the samples with chemicals are not necessary. Similar values were obtained for chitin when ADF/ashing method was compared to the ADF/deacetylation method. These methods prevented loss of chitin during preparation. Digestibility of chitin was higher (58%) for sheep fed 100% crab waste-straw silage compared to the value of 37% in sheep fed 50% crab waste-straw silage. When ADF/ashing method was used in quantifying chitin, higher disappearances were obtained for samples containing 100% crab meal kept in the rumen or incubated in vitro for 72 h. / Ph. D.

Thesis (MEng)--Stellenbosch University, 2014. / ENGLISH ABSTRACT: Concerns surrounding the world’s current dependence on quickly depleting fossil fuels and their negative environmental impacts have brought about much research into renewable and sustainable energy sources. With population and economic growth not only is this dependence increasing but there is an increasing production of waste by society in general. With space becoming a premium commodity and environmental protection a necessity, landfilling of the majority of the world’s waste is no longer feasible. Thus, research is being carried out into waste-to-energy (WTE) processes and refuse derived fuels (RDF). This study focuses on thermochemical conversion, specifically pyrolysis of solid wastes as a means of energy product recovery. Before a specific waste stream can be used in WTE or RDF contexts its composition and degradation behaviour needs to be investigated. For this reason, a full physical characterisation of the municipal solid waste (MSW) from the Stellenbosch municipality was carried out. It was found that the composition of waste differs between areas within the municipality but the composition of the waste in general compares well with international data. It was found that six main components present in the recyclables stream; namely high and low density polyethylene (HD/LDPE), poly(ethylene terephthalate) (PET), glossy paper, office paper and newspaper would be suitable for thermochemical conversion. The thermal properties and pyrolytic degradation of these six components were investigated by multi heating rate thermogravimetric analysis (TGA) from which kinetic parameters (activation energy, pre-exponential factor and kinetic rate constants) were calculated by a differential isoconversional method. The volatiles released during degradation were identified by way of online mass spectrometry (TGA-MS) yielding six individual kinetic schemes. In order to gauge to what extent milligram pyrolytic experimentation (TGA-MS) can be used to predict larger scale pyrolytic behaviour, runs were performed on one plastic (HDPE) and one paper (glossy paper) sample on a gram scale pyrolytic plant under both slow and vacuum conditions. It was found that, especially for high thermal conductivity samples, yields on gram scale experimentation can be accurately predicted on a milligram scale. Further, the compositions of slow pyrolysis oils from glossy paper, obtained by gas chromatography–mass spectrometry (GC-MS), were compared to TGA-MS results as well as off gases captured from TGA runs by thermal desorption (TGA/TD-GC-MS). It was found that TGA-MS and TGA/TD-GC-MS can be used to predict the main functional groups in pyrolysis oil produced on a gram scale. Thus small scale experimentation can be used to determine the suitability of different waste components for pyrolytic conversion. / AFRIKAANSE OPSOMMING: Kommer oor die wêreld se huidige afhanklikheid van fossielbrandstowwe en die negatiewe uitwerking op die omgewing het baie navorsing oor hernubare en volhoubare energie bronne meegebring. Bevolking en ekonomiese groei veroorsaak 'n toename in hierdie afhanklikheid en in die produksie van afval deur die samelewing. Daar is baie min onbenutte grond oop en die beskerming van die omgewing het noodsaaklik geword. Dus is storting van die meeste van die wêreld se afval nie meer ‘n aanvaarbare opsie nie. As gevolg daarvan word daar tans navorsing in afval-tot-energie (ATE) prosesse en afval afgeleide brandstowwe (AAB) gedoen. Hierdie studie fokus op die termochemiese omskakeling van afval, spesifiek pirolise, as 'n methode vir energie-produk hernuwing. Voordat 'n spesifieke afvalstroom gebruik kan word as 'n AAB moet die samestelling en afbrekings gedrag eers ondersoek word. Daarom is 'n volledige fisiese karakterisering van die munisipale afval (MA) van Stellenbosch munisipaliteit uitgevoer. Resultate het getoon dat daar ‘n verskil in die samestelling van afval tussen die gebiede binne die munisipaliteit is. Afgesien daarvan vergelyk die samestelling van die afval in die algemeen goed met internasionale data. Daar is gevind dat daar ses belangrike komponente teenwoordig is in die herwinbare stroom wat geskik sou wees vir termochemiese omskakeling, naamlik; hoë en lae digtheid poliëtileen (HD/LDPE), poli(etileen tereftelaat) (PET), glans, kantoor en koerant papier. Die termiese eienskappe en termiese afbreking van hierdie ses komponente is ondersoek deur middel van multi-verhittimgs tempo termogravimetriese analise (TGA) waaruit kinetiese parameters (aktiveringsenergie, pre-eksponensiële faktor en kinetiese snelheidskonstantes) deur 'n differensiële omskakelings metode bereken is. Die vlugtige komponente wat tydens die afbreking vrygestel is, is geïdentifiseer deur aanlyn-massaspektrometrie (TGA-MS) wat ses individuele kinetiese skemas verskaf. Om vas te stel tot watter mate milligram pirolitiese eksperimente (TGA-MS) gebruik kan word om op ‘n groter skaal die pirolitiese gedrag te kan voorspel, is eksperimentele lopies op een plastiek- (HDPE) en een papier (glans papier) monster op 'n laboratorium skaal pirolise opstelling onder stadige- en vakuum omstandighede uitgevoer. Daar is gevind dat, veral met hoë hitte geleiding komponente, die opbrengs op gram skaal eksperimente akkuraat voorspel kan word op ‘n milligram skaal. Verder was die samestelling van die stadige pirolise olies uit glans papier, wat verkry word deur gaschromatografie-massaspektrometrie (GC-MS), vergelyk met TGA-MS resultate sowel as af-gasse gevang van TGA lopies deur termiese desorpsie (TGA/TD-GC –MS). Daar is gevind dat TGA-MS en TGA/TD-GC-MS gebruik kan word om die belangrikste funksionele groepe in pirolise olie, wat op 'n gram skaal geproduseer word, te voorspel. Dus kan milligram eksperimente gebruik word om die geskiktheid van afval komponente vir pirolitiese omskakeling te bepaal.

M.Tech. (Civil Engineering) / This study presents work on the design and construction of three dual-chamber microbial fuel cells (MFCs) using a sandwich separator electrode assembly (SSEA) and membrane cathode assembly (MCA) for the dual purposes of energy generation from domestic wastewater and wastewater treatment. MFC1 was designed using an improvised SSEA technique (i.e. a separator electrode membrane electrode configuration, SEMEC) by gluing a sandwich of anode, membrane and a mesh current collector cathode to an anode chamber made from a polyethylene wide-mouth bottle. The reactor was filled with 1500 mL of domestic wastewater and operated on a long fed-batch mode with a residence time of 3 weeks. The reactor was inoculated with a mixed culture of bacteria present in the wastewater stream. The aim was to study the impact of wastewater COD concentration on power generation and wastewater treatment efficiency. For MFC2 and MFC 3, cathodes were constructed using the MCA technique consisting of a membrane and a mesh current collector cathode, with the anode electrode at the opposite side of stacked Perspex sections used for the anode chamber. The impact of electrode material on current production was examined in this study. For MFC2 a mesh current collector treated with polytetrafluoroethylene (PTFE) and activated carbon (AC) functioned as the cathode, while the MFC3 cathode was an uncatalyzed mesh current collector. The two reactors were both filled with 350 mL of domestic wastewater...

Thesis (Ph. D.)--Utrecht University, 2007. / "This publication has been submitted as a Ph. D. thesis for the award of the degree of Doctor at Utrecht University, the Netherlands, 16 February 2007"--T.p. verso. Vita. Includes bibliographical references (p. 131-141).

The focus of this thesis was to analyze the least cost of producing rations for ducks in three age categories from a mixture of conventional feed ingredients and three different processed food waste products and to examine the financial and economic feasibility of establishing an industrial plant to produce these food waste products in the Montreal region. The first part of the thesis was investigated through the use of a linear programming model. The effect of recognizing the variability of protein levels in the various feed ingredients was examined through the use of chance-constrained programming. / The second part of the thesis was examined using economic and financial analyses for the investment. The basic plant requirements to produce the three processed food waste products were the same, however energy costs were different for the three products. Revenue was generated from tipping fees and the sale of the three processed food waste products. (Abstract shortened by UMI.)

Biogas has the potential to provide energy to communities, especially those where grid electrification will not be installed for a long time and who experience problems in accessing energy resources. The purpose of this study was to investigate whether biogas technology could provide households and a school with an acceptable, affordable, efficient, and sustainable alternative energy resource, thereby providing opportunities for cost savings, reduction of the labour burden and income generation. Three case studies were selected, two households and Myeka High School in rural Maphephetheni. Maphephetheni is situated approximately 80 km west of Durban and is characterised by the lack of grid electrification. The two households selected as case studies were both using firewood and paraffin for thermal energy. Collection of firewood was a tiresome burden to women and paraffin was expensive to purchase. The third case study, Myeka High School was using solar energy and LP gas to support its energy needs. Biogas digesters were donated to the two households and the school. Data before and after installation of biogas was collected through questionnaires, informal interviews and observations. Monitoring and evaluation of the case studies was carried out. Results collected revealed that biogas was an acceptable source of energy because the household and school equipped with the floating dome biogas digesters accepted cooking on biogas while the household used the fertiliser from biogas on their crops. However it was not affordable both to the household and the school because in the household income did not allow for its purchase while savings on energy expenditure from both the school and household could not offset the cost in the six years estimated by the engineer but it would take 11 years. Biogas was found to be efficient and sustainable provided proper management was available. Although income generation opportunities were not fully utilised, there was an opportunity for income generation through the biogas provided there was encouragement, support and markets available. Recommendations are that government policy should provide for training of stakeholders on proper management techniques. Government or organisations involved with biogas energy could do this, as well as provide an extension service for the dissemination of biogas and other renewable energy information. However, government policy should as in other countries provide for subsidies, risk underwritten bank loans or tax incentives to manufacturers. / Thesis (M.Soc.Sc.)-University of Natal, Pietermaritzburg, 2003.

Die folgende Arbeit beschreibt Potentiale und Risiken der Nutzung industrieller Abprodukte am Beispiel des Apfeltrester – einem Pressrückstand der Apfelsaftgewinnung. Dieser spielt aus finanzieller und ökologischer Sicht als Abprodukt eine steigende Rolle bei der Biogassynthese. Dabei werden die Ergebnisse des vorangegangenen Fachpraktikums vorgestellt und diskutiert. Darauf aufbauend wurden Thesen erstellt und anhand ermittelter Messwerte sowie der Literatur verifiziert. Schlussendlich werden in einer Wirtschaftlichkeitsrechnung Kosten von Bezug, Lagerung und Beschickung den Gewinnen aus der Einspeisevergütung gegenüber gestellt. Es konnte gezeigt werden, dass Apfeltrester unter Laborbedingungen nicht die befürchtete Übersäuerung des anaeroben Abbauprozesses zur Folge hatte, sondern unter vergleichbaren Erträgen mit leicht höherer Sicherheit zur Maissilage bis zu einem gewissen Anteil zu Maissilage und Stallgülle zugesetzt werden kann. / Due to the increasing ecological and financial importance of industrial waste products in the recovery of biogas the following thesis describes potentials and risks of the usage of one of these products using apple pomace – the filter cake of the apple juice production. Thereby the issues of the three-month practical course in the LHL Eichhof, a laboratory in middle Germany, are shown and discussed. As conclusion several theses are given and verified with help of the taken measurements and scientific literature. At the end an economical calculation compares the present costs of purchase, storage and processing with the proceeds of the reimbursement by the german renewable energy sources act (EEG). Against the misgiving that apple pomace could decrease the pH-value to an unacceptable level for the anaerobic decomposition process the fermentation of this product gets a comparable output even with a little more reliability compared to corn silage when added up to a defined level to corn silage and slurry.

La anodización es un proceso electrolítico que convierte la superficie metálica en un recubrimiento de óxido insoluble. El aluminio es el material anodizado con más frecuencia. El llamado “abrillantado” del aluminio se realiza comúnmente con baños de ácido fosfórico concentrado. Después de la anodización, las piezas deben enjuagarse cuidadosamente, y es en ésta operación en la que se produce una dilución de la solución del baño arrastrada en la capa de óxido formada. Es en este aspecto donde se plantea la mejora de la calidad medioambiental del sector mediante un plan de recuperación y reutilización de los ácidos diluidos en las aguas de lavado, especialmente del ácido fosfórico. Las membranas son una herramienta atractiva que ofrece un amplio rango de aplicaciones, especialmente en el campo de la alimentación, bebidas, bioquímica, etc. Hay muchos ejemplos que pueden encontrarse en el tratamiento de efluentes, la desalinización de aguas o la concentración de soluciones. La separación de diferentes componentes se consigue por la acción de una membrana separadora y por la influencia de una fuerza impulsora a ambos lados de la membrana (presión, concentración, campo eléctrico). Son objetivos de este trabajo: Realizar un aporte a la investigación sobre la recuperación de materia prima en efluentes industriales mediante técnicas de membrana El eficaz aprovechamiento de la materia prima mediante el reciclado de los ácidos a los baños de anodizado La reducción del volumen de aguas residuales finales, con la correspondiente reducción en la contaminación ambiental del medio receptor La elaboración de una propuesta técnico-económica innovadora en el sector del recubrimiento metálico Los principales resultados obtenidos son: Se ha encontrado que las membranas de nanofiltración DK de Osmonics y la MPF-34 de Koch permiten una adecuada separación entre el Al3+ y los ácidos fosfórico y sulfúrico de las aguas de lavado. Los rechazos promedio (del ensayo de concentración) de Al3+ y H3PO4 para la membrana MPF-34 son de 99,7% y de 66,9% respectivamente y para la membrana DK de 99,5% y de 32,3% respectivamente. - Se han desarrollado expresiones para poder estimar adecuadamente los rechazos de Al3+, H3PO4 y H2PO4- en función de la composición del alimento con la membrana MPF-34. Se ha visto que estos valores son los intrínsecos de la membrana. Estas expresiones se obtuvieron mediante un estudio fenomenológico debido a que la complejidad del problema no permite hacerlo desde el punto de vista mecanístico. Se ha encontrado que la estabilidad de la membrana DK en el medio ácido del alimento es suficiente para asegurar un funcionamiento adecuado a nivel industrial. Un tratamiento utilizando la membrana DK permite una recuperación del 73% del ácido fosfórico. En el ácido fosfórico recuperado la relación Al/H3PO4 es de 0,11% en peso mientras que en la disolución alimento inicial era de 6%. Se ha visto que las membranas tanto poliméricas como cerámicas con un PMC de 1000 Da o más no permiten una recuperación adecuada del ácido fosfórico, debido a que el máximo rechazo de Al alcanzado ha sido del 58%. Para las condiciones estudiadas y debido a la naturaleza del las disoluciones tratadas la electrodiálisis no permite una recuperación adecuada del ácido fosfórico Se ha visto que la UFAP no permite separar el Al debido a que no es posible formar complejos Al-Polímero en medios ácidos como el del alimento. La adición de especies que permitan variar el pH de las disoluciones complicaría la recuperación del ácido debido a la presencia de impurezas adicionales. / Most of the hazardous waste in a metal finishing operation comes from the wastewater generated by rinsing operations. The acidic solution that is dragged out from the bath into the following rinsing tanks is the primary source of contamination of rinse water. The use of acidic solutions is very common in metal processing. Sulphuric acid, hydrochloric acid, phosphoric acid, chromic acid and nitric acid are used in chemical bath for anodising, galvanising, brightening, plating and pickling process. The known strategies to reduce the pollution in the wastewater effluent are based on the recovery of contaminant compounds to be recycled to the process reducing the expense in fresh compounds. By definition, recycling includes all measures in order to reduce volume of effluent by recovery raw materials from wastewaters. Membrane separation has become a competitive technology to traditional water treatment processes because of highly effective in removing most inorganic and organic contents to produce a very pure effluent.