Thesis (M.S.)--University of Wisconsin--Madison, 1981. / Typescript. eContent provider-neutral record in process. Description based on print version record. Includes bibliographical references (leaves 76-82).

Thesis (M.S.)--Bowling Green State University, 2006. / Document formatted into pages; contains xiii, 108 p. : ill., maps. Includes bibliographical references.

Thesis (M.Phil.)--Hong Kong University of Science and Technology, 2005. / Includes bibliographical references (leaves 80-82). Also available in electronic version.

The increasing cost of fossil fuels, combined with concerns about their impact on our environment has led to a renewed interest in hydrogen as a clean, sustainable, alternative energy vector. Using sewage biosolids as the substrate for fermentative hydrogen production offers several advantages over the use of other biomass sources. It is available at little or no cost and is abundant, being produced wherever there are human settlements, with 1.3 million tonnes (dry solids) per year currently being produced in the U.K alone. This research demonstrated the feasibility of hydrogen production from sewage biosolids via anaerobic fermentation. To do this a number of issues specifically relating to the nature of sewage biosolids had to be addressed. Firstly, the solids content and rheology made automatic feeding difficult. The feedstock also contained high levels of indigenous microorganisms and a high ratio of insoluble to soluble carbohydrate. To address these challenges, a novel reactor design using wide bore tubing and computer controlled pumping equipment was successfully used to construct a working continuously fed bio-reactor. A combination of heat treatment at 70°C for one hour and pre-treatment with a commercially available food processing enzyme mixture was found to be the most efficient method of inactivating competing microorganisms and improving substrate quality. Hydrogen was successfully produced via batch fermentation of primary sewage biosolids which had undergone heat treatment and enzymatic digestion. When fermentation took place at pH 5.5 a peak hydrogen production rate of 3.75 cm3 min"1 was observed. At this pH the hydrogen yield was 0.37 mol H2 mol~ : carbohydrate, equivalent to 18.14 L H2 kg"1 dry solids. Fermentative hydrogen production from sewage biosolids was also demonstrated in a five litre, continuously fed bio-reactor for the first time. A comparison of different hydraulic retention times showed that hydrogen production was most stable at a HRT of 24 hours. A hydrogen producing fermenter was successfully linked to a methanogenic bio-reactor in a two stage digestion process.

Orientador: Durval Rodrigues de Paula Junior / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Agrícola / Made available in DSpace on 2018-08-23T09:19:32Z (GMT). No. of bitstreams: 1 Padovani_VeraCristinaRamalho_D.pdf: 3929608 bytes, checksum: 7486cc17cc63c5040d3493cce947d41d (MD5) Previous issue date: 2013 / Resumo: O objetivo deste trabalho foi avaliar em condições de campo o comportamento de três espécies florestais produzidas em dois tipos substratos, submetidas a diferentes dosagens de adubação de cova (2,0; 4,0 e 8,0 kg), utilizando o composto orgânico de lodo de esgoto (COLE) em comparação com a testemunha (0,0 kg), e testar a viabilidade de uso do lodo de esgoto como adubo orgânico na adubação pós - plantio de mudas de árvores. O lodo de esgoto foi submetido à análise química de macro e micronturientes, pH, sólidos voláteis, umidade, relação C/N e metais pesados, antes de ser higienizado e estabilizado através da compostagem, com restos de capim roçados das áreas verdes e recebeu a denominação de COLE. Após o término do processo de compostagem, o composto foi submetido a análises químicas, microbiológicas e parasitológicas, além da condutividade elétrica. As mudas de árvores nativas utilizadas no experimento foram às espécies Platypodium elegans (Amendoim bravo), Pterocarpus violaceus (Aldrago) e Poecilanthe parviflora (Coração de negro), que representam respectivamente os grupos ecológicos das pioneiras, secundárias e clímax, e foram produzidas no viveiro municipal da Faculdade Municipal Professor Franco Montoro /Mogi Guaçu, em dois substratos diferentes, sendo um à base de COLE e outro de esterco de curral curtido (tradicional). O delineamento experimental foi o de parcelas subdivididas no tempo com blocos casualizados, com cinco repetições por parcelas, utilizando três espécies diferentes produzidas em dois substratos diferentes (à base de COLE e esterco de curral curtido) e quatro tratamentos diferentes que correspondem a dosagens de COLE que variaram de 0,0 Kg, 2,0 Kg, 4,0 Kg e 8,0 Kg/ cova. Foram avaliadas as características químicas e físicas do solo e as medidas de crescimento das mudas como altura, diâmetro das plantas aos 24 meses após o plantio e análise química do tecido vegetal para determinação da concentração de macro e micronutrientes, aos 36 meses após o plantio. Os resultados das análises microbiológica, parasitológica e química indicaram que o composto de lodo de esgoto é adequado para ser utilizado como composto orgânico em adubação de cova para essências florestais. As plantas da espécie Poecilanthe parviflora produzidas à base de substrato COLE, apresentaram redução na altura, nos teores de Ca e Mg com adição do COLE, além do desequilíbrio nutricional. A adição do COLE na cova de plantio das espécies Platypodium elegans e Pterocarpus violaceus não promoveu aumento significativo da altura e diâmetro em comparação com a testemunha. O uso do COLE como adubo orgânico para fertilização de espécies nativas e exóticas plantadas em áreas verdes apresenta-se como uma alternativa para destinação e disposição dos resíduos gerados no município / Abstract: The purpose of this research was to evaluate under field conditions the behavior of three forest species produced in two types substratum exposed to different dosages of fertilizer pits (2.0, 4.0 and 8.0 kg) using the organic compost sewage sludge (COLE) compared to control (0.0 kg) and test the feasibility of using sewage sludge as a fertilizer in organic fertilization post plantation of tree seedlings. The sewage sludge was subjected to chemical analysis for micronutrients, pH, volatile solids, humidity, the C / N relation and heavy metals before being sanitized and stabilized through composting, with the remains of green areas scuffed grass and received the denomination COLE (sewage sludge organic compound). After completion of the composting process, the compound was subjected to microbiological, parasitological and chemical analyzes additionally to electrical conductivity. The seedlings used in the experiment are native trees species Platypodium Elegans, Pterocarpus violaceus Poecilanthe parviflora, which respectively represents the pioneer, secondary and climax ecological groups. They were produced at the municipal nursery of the Municipal University "Professor Franco Montoro" in Mogi Guaçu using two different substratum: one based in COLE and the other cattle manure (traditional). The experimental outline used was plots subdivided in time into random blocks of five repetitions per plot using three different species produced in two different substratum (based COLE and cattle manure) and four different treatments that correspond to doses of COLE ranging from 0.0, 2.0, 4.0 and 8.0 kg / pit. We evaluated the chemical and physical characteristics of the soil and seedling growth measurements such as height, diameter of plant at 24 months after planting and chemical analysis of plant tissue to determine the concentration of macro and micronutrients at 36 months after planting. The results of the microbiological, parasitological and chemical analyses indicate that the compost of sewage sludge is suitable for use as a fertilizer in the organic compound pit for forest species. The plants of the species Poecilanthe parviflora produced based on substratum COLE, besides nutritional imbalance, presented reduction in height based on levels of Ca and Mg adding COLE. The addition of the organic compound sewage sludge (COLE) in the planting pit of the remaining species did not cause a significant increase in height and diameter when compared with the dosage control, but increasing doses of COLE promoted increase in height and diameter of plants compared to the dosage control. The use of sewage sludge compound (COLE) an organic fertilizer canbecame reduces costs with the fertilization of native. Exotic species planted in green areas becoming a viable alternative for the destination and disposal of waste generated in the municipality / Doutorado / Agua e Solo / Doutora em Engenharia Agrícola

The potential application of sulphate reducing bacteria for the bioremediation of acid mine drainage has already been recognised, and offers significant financial advantages over conventional chemical treatment approaches. Although the technology has been demonstrated successfully on both small- and large-scale, it’s extensive implementation has been constrained by the provision of suitable and cost effective electron donor and carbon sources. Primary sewage sludge is readily available in large quantities, but the slow rate of solubilization and low yield of soluble products do not apparently favour its use for this application. A number of pre-treatment steps have been introduced in an attempt to improve the yield and rates under methanogenic conditions. However, although early work suggested that degradation of lignocellulose and proteins may be more rapid under sulphate reducing conditions, the fate of primary sewage sludge under these conditions has been ignored. It was proposed that by combining the hydrolysis of primary sewage sludge and biological sulphate reduction, in a settling sludge bed, both processes would be enhanced. The aim of this study was to test this hypothesis on laboratory- and pilot-scale, and attempt to elucidate the underlying mechanism involved. The solubilization of primary sewage sludge was enhanced in the presence of sulphate reduction in continuous laboratory-scale reactors. Particulate matter accumulated in the bed of non-sulphidogenic systems, but not in sulphidogenic ones. This was attributed to increased solubilization and the smaller average floc size in the latter. Solubilization occurred within the settling sludge bed of the reactors, and offered a possible explanation for the better performance of the multiple- over single-stage reactor. A pilot-scale Falling Sludge Bed Reactor was constructed at Grootvlei Gold Mine, Springs, South Africa, and resulted in the solubilization of more than 70% of the influent primary sewage sludge. The system was also found to be highly resilient to severe perturbations, and returned rapidly to steady-state. Flask studies revealed that the hydrolysis of both proteins and complex carbohydrates was accelerated in the presence of biological sulphate reduction or sulphide. A study of the enzymology of sludge digestion revealed that sulphate reduction had little direct effect on the activity of the hydrolytic enzymes, but that reactor design was critical in the prevention of washout of these enzymes. Finally, a descriptive model was developed to explain the enhanced hydrolysis of primary sewage sludge. The model incorporated the effect of sulphidogenesis on floc fracture and reflocculation, and likely implications for mass transfer limitations.

Five different combinations of Hydraulic Retention Times (HRT) and temperatures were used in a two stage (feed and test reactor) Autothermal Thermophilic Aerobic Digestion System to assess the impact of these parameters on the production of odorous gases. The gases monitored were hydrogen sulphide, dimethyl sulphide, methyl mercaptan, ammonia, and amines. Other liquid parameters were also monitored in order to better understand the impacts of temperature and HRT. These parameters are total solids content, volatile solids content, volatile solids destruction, specific oxygen uptake rate, alkalinity, ammonia concentration, and pH. In order to assess the character of the sludge and understand the digestion process the carbohydrate, fat, and protein content were also measured in the inputs and in the test reactor. It was found that all of the odorous compounds measured were affected by stage of digestion and temperature more than by HRT. Of the five compounds monitored, none were affected by changes in the HRT of the test reactor. However, the concentrations measured in the feed and test reactors were often a degree of magnitude apart. The reduced sulphur compounds (hydrogen sulphide, methyl mercaptan, and dimethyl sulphide) were found in higher concentrations in the feed reactor than in the test reactor; whereas ammonia and amines were found in much higher concentrations in the test reactor than in the feed reactor. Also, ammonia concentrations were significantly higher in both reactors when the temperature was higher; and amine concentration was higher in the test reactor when the temperature was higher. One set of tests for volatile fatty acid concentration was also undertaken. While breakdown of the carbohydrates and fats occurred throughout the process, proteins were broken down into their amino acids, releasing reduced sulphur compounds in the feed reactor and then deaminated, releasing ammonia and amines in the test reactor. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

The anaerobic digestion of cheese whey was studied in an upfiow anaerobic sludge blanket reactor for its start-up characteristics, the effects of various process parameters, the effect of sulfate addition and the determination of optimal operating conditions. Start-up of an UASB reactor treating cheese whey was extremely difficult due to its tendency to acidify. Various start-up strategies were tested to facilitate start-up and to ensure stable operation. Among the operating parameters, sludge loading rate was the most critical for proper start-up of the UASB reactor. The initial sludge loading rate during start-up period should not exceed 0.25 g COD/g VSS. The response of whey digestion to several process parameters was investigated. Without pH-control, over 97% COD removal was obtained for influent concentrations from 5 to 28.8 g COD/1 and HRT of 5 days. However, instability was observed when the influent concentration was increased to 38.1 g COD/1. Gas production from whey is affected by organic loading rate (OLR). At an OLR less than 4 g COD/l-d, higher influent strength resulted in a higher methane production rate. When the OLR was greater than 6, higher strength feed or shorter hydraulic retention time (HRT) produced less methane. From the profiles of substrate concentration measured at various levels above the bottom of the reactor, two reaction stages, acidogenesis and methanogenesis were distinguished. It was experimentally illustrated that the rate of acidogenesis is much faster than the rate of methanogenesis in a whey anaerobic digestion system. The accumulation of VFAs in the first stage being faster than its assimilation in the second stage creates a distinct acidogenic phase in the bottom of the reactor. The instability caused by high influent concentration could be attributed to the accumulation of VFAs beyond the assimilative capacity of the methanogenic stage. A set of empirical models for accumulation and degradation of VFAs was developed using linear regression analysis. The requirement for maintaining this system in a dynamic balance was that the degradation capacity for VFA in the second stage be greater than the accumulation of VFA in the first stage. Based on this idea, the optimal influent concentration was given as between 25 to 30 g COD/1 for system stability. A hypothesis was proposed in this study that a proper amount of sulfate may be applied to moderate the detrimental influence of excess hydrogen on a stressed anaerobic reactor. The effect of sulfate was tested to study the biochemical mechanism. The permissible influent COD concentration was increased from 30 g COD/1 to 50 g COD/1 by using sulfate addition. The pH in the reactor was on the average 0.8 units higher and the concentration of butyric acid in the acidogenic phase much lower with added sulfate than without sulfate addition. The significant improvement of process stability and treatment efficiency made by the addition of sulfate clearly illustrated that sulfate acted like a stimulator which helped to maintain conditions favorable to methanogenesis. The mechanism of this stimulation is explained according to thermodynamics and hydrogen regulation which suggested that sulfate is able to promote the β-oxidation of VFAs by consuming hydrogen. A two-stage inhibition mechanism was proposed to explain the inhibition of high VFA concentrations and the stimulation of sulfate. Higher hydrogen pressure is the cause of preliminary inhibition, resulting in the accumulation of VFAs, which subsequently inhibit the activity and growth of methanogens in the second inhibition stage. The mechanism of inhibition of methanogens from VFAs was interpreted as being caused by the acidification of the internal cytoplasm and destruction of the pH gradient by non-ionized acids based on the theory of bacterial membrane transport. A new control strategy for stabilization of an anaerobic system is recommended. Under the optimal operating conditions based on the results in the first three steps, over 97% reduction of COD was achieved when the influent COD was 30 g /l using an HRT of 2 days, an OLR of 16.61 g COD/l-d and sulfate concentration of 0.2 g/1. / Applied Science, Faculty of / Chemical and Biological Engineering, Department of / Graduate

Continuous flow, daily fill and draw, and batch aeration digesters were studied on a laboratory scale, to develop low temperature characteristics and design criteria for aerobic digestion of waste activated sludge. These results were compared against full-scale data from three independent sources. Raw sludge used in these studies was obtained from a municipal high rate activated sludge plant. The digestion systems were operated at liquid temperatures of 20, 10, and 5°C, and at six different sludge ages. Measurement of all parameters studied for the continuous feed systems were made under steady-state conditions. Parameters studied were divided into three main groups, namely: (1) Parameters related to aerobic digestion kinetics, such as solids destruction and oxygen uptake rate; (2) Parameters related to aerobic digestion sludge characteristics, such as biochemical oxygen demand, viable bacteria, organic carbon, nitrogen forms, and odour values; (3) Parameters relating to supernatant quality, such as dissolved solids, organic carbon, biochemical oxygen demand, chemical oxygen demand, nitrogen forms, and pH. The results show that the effect of low temperature on aerobic digestion performance was pronounced. The combined effect of sludge age and temperature was shown to be an important design parameter. Kinetic reaction rates and temperature sensitivity coefficients were calculated for the various conditions studied on the basis of volatile suspended solids. It was shown that reaction rates for batch digestion and continuous feed digestion systems were not interchangeable. This is significant, as most pilot plant and bench-scale studies on aerobic digestion are being conducted using batch digestion, the results of which are then being used for design of continuous feed digesters. It appears that, as temperature decreases, the daily fill and draw method of digester operation resulted in significantly higher reaction rates than the continuous feed method of digester operation. At higher temperatures, the two were about equal. Oxygen uptake rate was not considered a reliable indicator of digested sludge stability; instead, mixed liquor BOD₅, was introduced as a possible means of determining such stability. Nitrification and denitrification is shown to be appreciable during aerobic digestion in all systems and at all temperatures studied. Although somewhat tentative, the results show important nitrification and denitrification trends at temperature and pH levels well below optimum values for these processes. The difference between batch and continuous feed digestion is shown in various ways, but probably most clearly through monitoring supernatant characteristics. The continuous feed systems show increased solubilization of organics with increased sludge age, whereas the batch systems do not show any solubilization of organics. Reasonable correlation is demonstrated between the laboratory and full-scale aerobic digestion data. / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

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