Dissertations / Theses on the topic 'Solid waste biodegradation'

Waste management in the leather industry worldwide is an issue of major importance for both solid and liquid wastes. It has been recognised that there are major environmental impacts from the poorly managed disposal of such wastes and these have a clear health impact upon human society. Within Europe, under EU driven legislation, the costs of wastes management are increasing rapidly and there is a clear need to research improved methods to cost effectively deal with leather industry wastes. Biodegradation (anaerobic), as a management option, of solid wastes from the leather industry is an area that is attracting increased interest in recent years as being a technique that has wide public acceptability as well as process efficiency. However, tanning agents that prolong the lifetime of leather goods have a negative impact on biodegradation and this needs to be addressed before efficient treatment can occur. To drive the agenda this research has the aims of • Highlighting the effects of tanning agent on anaerobic digestion. • Understanding the mechanism(s) by which different leather tannages can biodegraded. • Developing a process to reverse the action of tannage. Leather solid wastes were anaerobically digested using Serum Bottle Assays (SBA). The effect of a range of vegetable, mineral and aldehyde tanning agents of leather on the rate of anaerobic digestion was assessed. Common tanning agents used included; myrica, valonea, glutaraldehyde and chrome. To further identify key factors for cost effective anaerobic digestion, tanned hide powders and tanned leathers were also pre-treated using autoclaving, liming, enzymes etc, in an attempt to determine whether tannage may be reversed. Major techniques used in the research include: anaerobic digestion, Biochemical Methane Potential (BMP), Total Solids contents (TS), Gas Chromatography (GC) and Gas Chromatography Mass Spectrometry (GC-MS). Hydrolysable tannins are less resistant to anaerobic digestion than condensed tannins. However, enzymatic pre-treatment reduces the resistance and this offers a new effective pre-treatment route. Thermal pre-treatment also decreased resistance to anaerobic digression especially for chrome, glutaraldehyde, myrica and tannic acid tanned leathers. Chemical pre-treatment also generally lowered the resistance to anaerobic digestion. Selective pre-treatment offers a means of improving the cost effectiveness of anaerobic digestion of leather and therefore enabling a new waste management method to be adopted by the industry. A relationship emerges, in some cases, between chemical structure of tanning agent and inhibition of anaerobic digestion. This offers the possibility of producing new, designed organic tanning agents with, suitable properties, to be adopted by the industiy, The research agenda within the leather industry is still ongoing and recommendations for future research are addressed

Conventional landfills are built to dispose of the increasing amount of municipal solid waste (MSW) generated each year. A relatively new type of landfill, called a bioreactor landfill, is designed to optimize the biodegradation of the contained waste to stabilized products. Landfills with stabilized waste pose little threat to the environment from ozone depleting gases and groundwater contamination. Limited research has been done to determine the importance of biodegradation enhancement techniques and the analytical methods that are used to characterize waste stability. The purpose of this research was to determine the effectiveness of several biodegradation enhancements and to evaluate the analytical methods which predict landfill stability. In the first part of this study leachate recirculation, and moisture and temperature management were found to significantly affect the biodegradation of MSW. Leachate recirculation, increased moisture, and higher temperatures increased the first order degradation rates of cellulose and volatile solids. Of the three enhancements, temperature was shown to have the biggest impact on the biodegradation of waste, but sufficient moisture is critical for degradation. Plastic material was also shown to significantly impact the measurements for volatile solids and lignin, which is important if these measurements are used to establish waste stability. In the second part of the study the analytical methods used to characterize waste were evaluated to determine if relationships existed between the methods and which methods were the best predictors of waste stability. Volatile solids and cellulose were found to be the best parameters to monitor waste in landfills. These parameters correlate well with each other, age of the waste, and other parameters. Volatile solids and cellulose are also relatively easy to determine, quick, and show little variation.
Master of Science

Cellulose to lignin ratio is one of the widely used indicators of degree of landfill stabilization. This ratio shows the amount of carbohydrate or cellulose consumed by anaerobes compared to relatively inert lignin. However, the method of lignin measurement contains an intrinsic error. Plastics are contained in the landfill samples and these are characterized as lignaceous materials due to their acid-insolubility. Lignin is typically measured as the organic residue that is acid insoluble but is combustible upon ignition. Additionally lignin may degrade under anaerobic, high temperature conditions associated with wet conditions in sediments and bioreactor landfills.

In this study, it has been found that the typical measure of lignin, a gravimetric measure, also includes plastics, leading to erroneous measures of both lignin and the cellulose/lignin (C/L) ratio. Typically, 100% of the plastic will be measured as lignin. Since plastic amounts to approximately 10% of landfill contents, lignin measurements will be 10% greater than actual amounts. Laboratory reactors were set up with known amounts of paper and plastic. The degradation of the cellulose and lignin in paper was measured and compared to plastics, which was collected by hand and weighed. Ratios of cellulose to plastics and lignin to plastics were obtained. It was found, based on the cellulose to plastic ratio and lignin to plastic ration that lignin degrades under anaerobic conditions although at a much slower rate than cellulose. These findings indicate that the cellulose to lignin ratio cannot be used as the sole indicator of stabilization in the landfills. The inclusion of the biochemical methane potential test data along with C/L is thought to provide a better indication of landfill stabilization.

Master of Science

This was a study undertaken to investigate municipal solid waste (MSW) landfill stability parameters and landfill leachate properties to determine how solid waste and leachate characteristics can be used to describe stability. The primary objective was to determine if leachate properties could be used to determine stability of the overlying refuse. All landfills studied were engineered landfill bioreactors giving insight to how leachate recirculation affects stability. This study investigated the correlation between cellulose, lignin, volatile solids, and biochemical methane production (BMP). These parameters can been used to characterize landfill stability. The BMP tests indicate that a saturated waste can produce methane. Cellulose is an indicator of landfill stability. Wastes high in cellulose content were found to have high BMP. Paper samples studied indicated gas production from high-cellulose paper was higher compared to low-cellulose samples. Lignin has been found to correlate fairly well with BMP. Increasing cellulose to lignin ratios correlate well with increasing BMP levels, further supporting the use of the BMP test to indicate solid waste stability. In the BMP test for leachate, a mixture of the standard growth medium (less 80% distilled water) and 80% v/v leachate incubated for 15 days produced the most consistent BMP results. Leachate cellulose and BMP correlated well. The chemical oxygen demand (COD) and biochemical oxygen demand (BOD) also had some correlation to BMP tests. Leachate COD was found to decrease over time in landfill bioreactors. The use of leachate rather than MSW to determine stability would be more efficient.
Master of Science

The numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components--a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic biodegradation, nitrogen and sulfate cycling, precipitation and dissolution of metals, and adsorption and gasification of various anthropogenic organic compounds, occur simultaneously. These processes may involve reactions of several species and the available biochemical models for solid waste biodegradation do not provide users with the flexibility to selectively simulate these processes. This research work includes the development of a generalized biochemical process model, BIOKEMOD-3P, which can accommodate a large number of species and process reactions. This model is able to simulate bioreactor landfill processes in a completely mixed condition; when coupled with a multi-phase model it will be able to simulate a full-scale bioreactor landfill. This generalized biochemical model can simulate laboratory and pilot-scale operations which are important to determine biochemical parameters important for simulation of full-scale operations. To illustrate application of BIOKEMOD-3P, two sets of laboratory MSW bioreactors were simulated in this research work. The first demonstrated simulation of data from anaerobic biodegradation of MSW in experimental bioreactors. In another application, simultaneous nitrification and denitrification processes in MSW bioreactors were simulated. The results from these simulations generated information about various modeling parameters that would help implement these processes in a full-scale bioreactor landfill operation.
Ph.D.
Department of Civil and Environmental Engineering
Engineering and Computer Science
Environmental Engineering PhD

There are more than three thousand landfills in the United States, in which approximately 55% (1998, U. S. EPA 1999) of the MSW generated in the US is buried. The majority of the landfills are conventional, but in the last two decades new types of landfills, called leachate recycle and bioreactor landfills, have been designed and tested as an enhanced environment for biochemical degradation of municipal solid waste. All the landfills are regulated under Subtitle D of the Resource Conservation and Recovery Act (RCRA). The shortage of time and money has limited the amount of research done on waste stability analysis. The purpose of this study was to evaluate the importance of lignocelluloses in biodegradation and the secondary settlement based on dry density and typical landfill evaluating parameters. Both parts of the study samples were collected and analyzed from eleven landfills. In the first part of the study, bioreactor landfills were found more effective, faster in the degradation of VS and cellulose as compared to conventional landfills. The time required for stabilization is reduced to about 1/3 that of conventional landfills. The lignocelluloses degradation that occurs in these landfills is happening in two phases. In the initial, rapid degradation phase, the primary degradation substrate is cellulose. In the second phase, after cellulose degraded to 15-20% of the waste, degradation of the remaining cellulose along with lignin and the hemicelluloses takes place. The start of lignin and hemicellulose degradation results in an increase in the biochemical methane potential (BMP). In the second part of the study, the addition of moisture to the landfills presented a contentious issue. Moisture is encouraged for MSW refuse degradation, but for settlement it reduces compressibility. In leachate recycle landfills, the dry density is higher than in conventional landfills; therefore there is more available room for further MSW load. The increase can reach up to 40 percent in total volume.
Master of Science

Anaerobic digestion of the Organic Fraction of Municipal Solid Waste (OFMSW) generates a mixture of methane (CH4), carbon dioxide (CO2) and water (H2O). Beyond the field capacity the water generated is collected and recirculated as leachate in Bioreactor Landfills (BLs.) Leachate recirculation has a profound advantage on biodegradation of the Organic Fraction of Municipal Solid Waste (OFMSW) in the landfills. Mature leachate from older sections of landfills (>20 years) and young leachate were blended prior to recirculation in the ratios 3/3 mature, 3/3 young, 1/3 mature-2/3 young and 2/3 old-1/3 young and their effect on biodegradation and biogas production monitored. In addition to analysis of the effect of blending old and new leachates, the study also analyses the effect of an open vs. a closed recirculation loop and the effect of organic loading rates of OFMSW in landfills. Data collected from initial batch tests supplement column bioreactors simulating bioreactor landfills with real world OFMSW from operational landfill facilities in Ontario, Canada. The results are conclusive that the biogas generation can be improved by up to 92% by blending the leachate in an open loop recirculation system as compared to a conventional closed loop system employed in landfills today.

Orientador: Sueli Yoshinaga Pereira
Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Geociências
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Resumo: Dois permeâmetros de carga constante e grandes dimensões, com 0,057 e 0,042 metros cúbicos, respectivamente, foram utilizados em laboratório, sob condições controladas, para as determinações das condutividades hidráulicas saturadas de Resíduos Sólidos Urbanos (RSU) coletados no Aterro Sanitário Delta A, localizado na cidade de Campinas-SP. Duas fases experimentais foram delineadas envolvendo diferentes parâmetros como composição gravimétrica e grau de compactação. Para cada fase experimental foram realizados vários ensaios para as determinações das condutividades hidráulicas saturadas em função dos tempos de operação dos permeâmetros e levantamento das principais variáveis físicas envolvidas neste processo, como teor de umidade, capacidade de campo, carga hidráulica e vazão. Simultaneamente, os lixiviados oriundos de cada ensaio realizado foram coletados e monitorados pelas análises dos principais parâmetros e espécies químicas para avaliação das etapas envolvidas no processo de biodegradação dos RSU. As condutividades hidráulicas saturadas, determinadas nos ensaios realizados, variaram de 1,6E-02 a 5,7E-05 m/s em função dos diferentes graus de compactação. Algumas variáveis químicas se mostraram eficientes na identificação das etapas de biodegradação, como potencial redox, ácidos orgânicos voláteis, nitrogênio amoniacal, acetato e carbono total dissolvido. O comportamento dessas variáveis em função dos tempos de operação permitiu a identificação das etapas acidogênica/acetogênica na biodegradação dos RSU
Abstract: Two constant load and large dimensions permeameters, with 0.057 and 0.042 cubic meters, respectively, were used in laboratory, under controlled conditions, for the determination of saturated hydraulic conductivity of Municipal Solid Waste (MSW) collected in the Delta A Sanitary Landfill, located at city of Campinas-SP. Two experimental phases were outlined involving different parameters such as gravimetric composition and degree of compression. For each experimental phase were carried out various tests for the determination of satured hydraulic conductivity as a function of the operation times of the permeameters and physical survey of the main variables involved in this process, such as, moisture content, field capacity, hydraulic head and volumetric flow rate. Simultaneously, the leachates coming of each test performed were collected and monitored by the analysis of the main parameters and chemical species for evaluation of the steps involved in the biodegradation of MSW. The saturated hydraulic conductivities, determined in tests, ranged from 1.6E-02 to 5.7E-05 m/s for different degrees of compression. Some chemical variables such as redox potential, volatile fatty acids, ammoniac nitrogen, acetate and dissolved total carbon, were effective in identifying the stages of biodegradation. The behavior of these variables as a function of time of operation allowed the identification of the acidogenic/acetogenic steps in the biodegradation of the MSW
Mestrado
Geologia e Recursos Naturais
Mestre em Geociências

Os resíduos do processo de curtumes e a crescente importância da geração de energia a partir de fontes renováveis fazem com que seja necessário estudar formas de biodegradação dos resíduos produzidos pela indústria coureira e gerar energia a partir disso. Os resíduos sólidos produzidos pelos curtumes contêm cromo e costumam ser dispostos em aterros industriais perigosos. O biogás com alto teor de metano é o produto dessa decomposição, através de digestão anaeróbia. A partir desses conceitos, esse trabalho propõe realizar ensaios de biodegradação com lodo, proveniente de uma estação de tratamento de efluentes de curtumes, e com farelo de couro wet-blue (couro curtido ao cromo) em biorreatores de bancada. O objetivo principal foi isolar, quantificar e identificar os microrganismos que apresentam potencial de produzir biogás com alto teor de metano. Ainda, a forma de armazenamento prévio do lodo adicionado também foi analisada. Primeiramente, incubou-se o lodo com farelo de couro wet-blue em biorreatores de bancada (dez ensaios de biodegradação divididos em duas montagens) e análises de quantificação e de qualificação do biogás gerado foram feitas. Depois, realizou-se a coleta de alíquotas da biomassa gerada nos biorreatores em diferentes fases do crescimento. O isolamento da biomassa coletada foi conduzido em frascos tipo penicilina com meio de cultura propício para o crescimento de arqueas metanogênicas, onde era possível a incubação em atmosfera anaeróbia. A partir dos crescimentos dos microrganismos, realizaram-se testes de contagem, isolamento, coloração de Gram, além de novos testes de coleta de biomassa dos próprios frascos. Como resultado, a influência do armazenamento prévio do lodo na biodegradação deste com farelo de couro wet-blue ainda não foi totalmente elucidada. Os microrganismos isolados não eram arqueas metanogênicas. Realizou-se a contagem de microrganismos, em dois ensaios de biodegradação que tiveram sua biomassa coletada. O primeiro biorreator analisado (biorreator 4) apresentou 1,90 x 109 e 4,45 x 106 UFC/mL para o sólido precipitado e para o líquido sobrenadante, respectivamente. O segundo biorreator analisado (biorreator 7) apresentou 1,35 x 109 e 1,09 x 109 UFC/mL para o sólido precipitado sem e com adição de lodo ao meio de cultivo antes da autoclavagem, respectivamente, e 9,10 x 106 e 8,30 x 106 UFC/mL para o líquido sobrenadante sem e com adição de lodo ao meio de cultivo antes da autoclavagem, respectivamente. Foi detectado metano apenas nos frascos que continham alíquotas de biomassa provenientes dos biorreatores que estavam pouco diluídos, provenientes da coleta em fase final de produção de biogás, com quantidades elevadas de microrganismos. O percentual de metano encontrado nesses frascos variou entre 25,75 e 53,66% e foi detectado após a terceira semana de incubação. A homogeneização do lodo se mostrou um fator de grande influência na biodegradação. A técnica de isolamento com a utilização de frascos de penicilina mostrou-se adequada para a quantificação de microrganismos metanogênicos presentes nos ensaios de biodegradação, mas ainda não adequada para o isolamento das arqueas metanogênicas.
The tanning process waste and the increasing importance of energy generation from renewable sources make the study of alternative biodegradation ways of the waste produced by leather industry and the generation of power from it a necessity. The solid residues produced by tanneries contain chromium and are usually disposed in hazardous industrial landfills. Biogas with high methane content is the product of this decomposition by anaerobic digestion. Based on these concepts, this study proposes to perform biodegradation tests with sludge, from a tannery effluent treatment plant, and with wet-blue (leather tanned with chromium) shavings in bench bioreactors. The main objective was to isolate, quantify and identify microorganisms with potential to produce biogas with high methane content. Further, the prior storage form of the added sludge was also analyzed. First, the sludge and the wet-blue shavings were incubated in bench bioreactors (ten biodegradation tests divided into two assemblies) and quantification and qualification analysis of the generated biogas were made. Later, biomass aliquots generated in the bioreactors were collected at different growth stages. The collected biomass isolation was conducted in penicillin type injectable vial filled with culture medium propitious for methanogenic archaea growth, where it was possible to incubate in anaerobic atmosphere. From microorganisms’ growth, test of counting, depletion, Gram stain and other biomass collection of the vials themselves were carried out. As a result, the prior sludge storage influence on biodegradation tests of sludge with wet-blue shavings was not yet fully elucidated. Isolated microorganisms were not methanogenic archaea. The microorganism counting was held in two biodegradation tests with collected biomass. The first bioreactor analyzed (bioreactor 4) showed 1,90 x 109 and 4,45 x 106 CFU/mL for the precipitated solid and the supernatant liquid, respectively. The second bioreactor analyzed (bioreactor 7) showed 1,35 x 109 and 1,09 x 109 for the precipitated solid without and with added sludge in the culture medium before autoclaving, respectively, and 9,10 x 106 and 8,30 x 106 CFU/mL for the supernatant liquid without and with added sludge in the culture medium before autoclaving, respectively. Methane was only detected in vials containing collected biomass aliquots from final stages of biogas production bioreactors that were bit diluted and had high amounts of microorganisms. The percentage of methane found in these vials ranged between 25,75 and 53,66% and was detected after three weeks of incubation. The sludge homogenization proved to be a great influence factor on biodegradation. The isolation technique with penicillin type injectable vial proved to be appropriate for methanogenic microorganisms’ quantification in biodegradation tests, although it is not fully understood for the methanogenic archaea isolation.

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CNPq
O acentuado crescimento do agronegócio implicou no aumento do consumo de insumos e na geração de resíduos nas atividades agropecuária e agroindustrial. Nos grandes centros urbanos do litoral brasileiro, por exemplo, 70% de lixo verde são constituídos por poda de árvores e resíduos de coco verde, criando um sério problema para os aterros sanitários. Os primeiros resultam da poda das árvores da cidade pelas companhias de energia elétrica e os últimos resultam do consumo da água de coco verde. O mercado de coco verde tem crescido mundialmente nos últimos anos principalmente nos países de clima tropical, devido à valorização de alimentos saudáveis e naturais. Os resíduos do coco verde levam de 8 a 10 anos para se decompor e a sua incorreta destinação leva a que se constituam em focos de insetos, geração de gases mal cheirosos e de efeito estufa. Desta forma, o presente trabalho destinou-se a compostagem de resíduos sólidos vegetais tendo como matéria prima poda de árvores e coco, ambos verdes, provenientes da zona urbana de Salvador para produção de adubo e/ou ração para ruminantes. Os resíduos foram selecionados baseando-se na sua viabilidade, levando em consideração a origem, tamanho e estado de maturidade. Foi feito balanço de massas mediante a adição de minerais de baixos teores e ajuste da relação C/N pela adição de uréia em proporções diversificadas. Também se adicionou micro-organismos provenientes de compostagem anterior de poda de árvore e proveniente da biomassa em compostagem. Foram isolados e inoculados micro-organismos celulolíticos e nitrificantes presentes no bioprocesso. Efetuou-se monitoramento e controle dos teores de umidade, temperatura, emissão de amônia e pH. O resultado revelou que a inoculação com micro-organismos celulolíticos e nitrificantes e o enriquecimento com compostos de fósforo e cálcio acelerou a compostagem do resíduo de coco verde e poda de árvore, no entanto, a compostagem ocorreu de forma parcial, em particular sobre o pó, dado que parte da fibra de coco não está sendo degradada. Os tratamentos cuja relação C/N foi reduzida para 30/1 e enriquecidos com minerais de baixos teores na concentração de 1,16%, 0,98% e 0,32% para KH2PO4, Na2HPO4 e CaCO3, respectivamente, compostaram em menor tempo, sendo que o processo decorreu de forma mais satisfatória quando o volume do resíduo era maior. Contudo, apesar da elevada qualidade nutricional que o composto apresenta ainda não pode ser usado como ração devido à elevada concentração de fibras que pode trazer conseqüências para a saúde dos animais. Contudo, poderá ser utilizado como adubo, pois atende às exigências oficiais para essa finalidade.
The sharp growth of agribusiness resulted in increased consumption of inputs and the generation of wastes in the agricultural and agro-industrial activities. In large urban centers of the Brazilian coast, for example, 70% of green wastes consists of trimming of trees and green coconut wastes, creating a serious problem for landfills. The first result of pruning of trees in the city by electric power companies and the last result from the green coconut water consumption. The market for green coconut has grown worldwide in recent years mainly in tropical countries due to the appreciation of healthy and natural foods. The residue of green coconut leads of 8 to 10 years to decompose, and constitute in focus of insects, smelly gas generation and greenhouse effect. Thus, the present work aimed composting of vegetables solid waste, using as raw material, green coconut and green pruning trees in diversified levels of species, from urban zone of Salvador to produce fertilizer and/or animal feed for ruminants. The residues were selected based on their feasibility, taking into consideration the origin, size and state of maturity. Mass balance was done by adding low levels minerals and C/N ratio adjustment was done by adding urea in diverse proportions. Also it was added microorganisms from previous composting of trimming trees and from biomass in composting. Futhermore to short the bioprocess time specific microorganisms such as cellulolytic and nitrifying bacteria where isolated and added I the process. Levels of moisture, temperature, pH and ammonia emission were monitored and controlled. The results revealed that the inoculation with nitrifying and cellulolytic micro-organisms and enrichment of phosphorus and calcium compounds accelerated waste composting, nevertheless, composting occurred partially, in particular under powder because part of coconut fiber was not being degraded. The treatments whose C/N ratio was reduced to 30/1 and enriched with minerals of low levels in the concentration of 1.16 %, 0.98 % and 0.32 % of KH2PO4, NaHPO4 and CaCO3, respectively, composted quickly, but the process held more satisfactory way when the residue volume was greater. However, despite the high nutritional quality of the compound, it can not yet be used as feed due to incomplete degradation of the fiber, but can be used as a fertilizer.

O objetivo deste trabalho foi reaproveitar poda de árvores urbanas e lodo de esgoto para compostagem. Foi investigada a adição de cal hidratada e de inóculos em compostagem em laboratório e em campo (esterco bovino). O conteúdo microbiológico, atividades enzimáticas, temperatura, pH e concentrações de carbono e nitrogênio foram determinados. A contagem padrão de bactérias e os fungos (leveduras e fungos filamentosos) atingiram valores máximos na faixa de 1012 e de 108 UFC/mL, respectivamente. A calagem inibiu os coliformes totais e termotolerantes, além das Salmonellas e das quatro enzimas investigadas quando foram utilizados cal e lodo de esgoto na proporção 1:1. Na compostagem em campo, a massa não foi sanitizada, tendo sido utilizado 25 % p/p de cal em relação ao lodo de esgoto; a fase termófila ocorreu durante um pequeno período. As atividades das celulases, proteases, fenoloxidases e tanases atingiram os maiores percentuais na fase ativa de degradação dos resíduos. A umidade da compostagem em campo variou entre 55 a 65 %. Durante as compostagens submetidas à calagem, o pH atingiu valores alcalinos enquanto nos demais tratamentos, esse parâmetro foi em torno da neutralidade. O húmus obtido apresentou a relação carbono:nitrogênio entre 9:1 e 16:1 com 60 dias de compostagem. A granulometria da poda urbana, o volume dos resíduos em tratamentos de laboratório e a presença da cal influenciaram a compostagem. Poda de árvores e lodo de esgoto podem ser reaproveitados por tratamento de compostagem para produção de húmus cujo produto final pode ser utilizado na recomposição de solo
The objective of this work was to reuse the urban tree pruning and sewage sludge for composting. The addition of slaked lime and inocula to compost, both in laboratory and in the field, was investigated. The microbiological content, enzyme activities, temperature, pH and concentrations of carbon and nitrogen were determined. The standard counting of bacteria and fungi (yeasts and filamentous fungi) reached maximum values in the range of 1012 and 108 CFU/mL, respectively. Liming inhibited the total coliforms and fecal coliforms. In addition, Salmonellas and the four enzymes investigated were also inhibited when a 1:1 slaked lime to sewage sludge ratio was used. In the experiments in the field, the mass was not sanitized and was used slaked lime at 25 % w/w in relation to sewage sludge; the thermophilic phase occurred in a short period. The activities of cellulases, proteases, phenoloxidases and tannases reached the highest percentage in the active phase of waste degradation. The moisture in the composting field ranged from 55 to 65%. During the composting in the presence of slaked lime, pH reached alkaline values while in other treatments, pH was around neutrality. The final product showed a carbon: nitrogen ratio between 9 and 16 after 60 days of composting. The particle size of the urban pruning, the volume of waste in laboratory treatments and the presence of slaked lime influenced composting. The urban tree pruning and sewage sludge can be reused after the composting treatment for humus production, whose final product can be used in the recovery of soil

Le stockage est la méthode de traitement des déchets non dangereux la plus communément utilisée dans le monde entier car elle est un moyen simple et économique pour leur élimination. Malgré une volonté nationale et européenne pour réduire le stockage de déchets biodégradables, une quantité non négligeable est encore enfouie entrainant la mise en place de modes de gestion spécifique. Autrefois exploitées comme de simples fosses de remplissage, les installations de stockage de déchets non dangereux (ISDND) sont aujourd’hui des ouvrages complexes dont l’objectif est de réduire l’impact environnemental et de valoriser énergétiquement le biogaz produit par la biodégradation de la matière organique. Afin d’accélérer les processus de biodégradation un casier de déchets peut être exploité en mode bioréacteur en réinjectant des lixiviats pour augmenter la teneur en eau des déchets. Le défi des années 2000 était de dimensionner et valider les systèmes de réinjection de lixiviat pour garantir une distribution optimale de la teneur en eau dans les massifs de déchets. Aujourd’hui, la question est de de suivre l’évolution de la biodégradation en tous points d’un massif pour notamment comprendre l’effet de ce mode de gestion. Les méthodes géophysiques en plus d’être non-destructives et spatialisantes sont utilisées depuis des années sur les ISDND et pourraient être sensibles à l’évolution de la biodégradation d’un massif de déchets, comme cela a été démontré pour la biodégradation d’autres milieux. Ainsi la problématique de cette thèse est d’évaluer la capacité de certaines méthodes géophysiques pour suivre l’évolution des paramètres bio-physico-chimiques d’un massif de déchets au cours de sa biodégradation. Un premier travail bibliographique a permis d’identifier quatre méthodes électriques parmi les méthodes géophysiques disponibles pour répondre à cette question :• La résistivité électrique• Le potentiel spontané• La polarisation provoquée• La polarisation provoquée spectraleAprès cet état de l’art, le travail de thèse a été séparé en trois parties. La première a été consacrée à la mise en place du suivi de ces quatre méthodes à l’échelle du laboratoire dans des conditions contrôlées, la seconde à analyser le suivi géophysique long terme sur le site industriel de la SAS Les Champs Jouault et la dernière a évaluée les observations à ces deux échelles. Enfin, la conclusion présente le potentiel de la méthode de mesure du potentiel provoquée comme la plus pertinente pour suivre l’évolution de la biodégradation d’un déchet non dangereux au cours du temps et aborde son utilisation dans un cadre industriel
Storage is the most commonly used waste treatment method in the world because it is a simple and economical way to dispose of solid waste. Despite a national and European desire to reduce the storage of biodegradable waste, a significant amount is still buried, leading to the implementation of specific management methods. Formerly exploited as mere filling pits, MSWL are today complex structures whose objective is to reduce the environmental impact and energetically valorize the biogas produced by the biodegradation of organic matter. In order to accelerate biodegradation processes, a waste cell can be operated in bioreactor mode by reinjecting leachates to increase the water content of the waste. The challenge of the 2000s was to size and validate leachate re-injection systems to ensure optimal distribution of water content in the waste mass. Today, the question is to monitor evolution of the biodegradation in all points of a waste mass in particular to understand the effect of this management mode. Geophysical methods in addition to being non-destructive and spatializing have been used for years on MSWLs and could be sensitive to the evolution of a waste mass biodegradation, as has been demonstrated for the biodegradation of others environments. Thus the problematic of this thesis is to evaluate the capacity of certain geophysical methods to monitor the evolution of the bio-physicochemical parameters of a waste mass during its biodegradation. A first bibliographic work identified four electrical methods among the geophysical methods available to answer this question:• Electrical resistivity• Self potential• Time domain induced polarization• Spectral induced polarizationAfter this state of the art, the thesis work was separated into three parts. The first one was devoted to the implementation of the monitoring of these four methods at the laboratory scale under controlled conditions, the second to analyze the long-term geophysical monitoring at the industrial site of SAS Les Champs Jouault and the last one to evaluate the observations at these two scales. Finally, the conclusion presents the potential of time domain induced polarization method as the most relevant to monitor the evolution of a waste mass biodegradation over time and discusses its use in an industrial setting

Les procédés anaérobies de traitement de déchets apparaissent clairement pouvoir répondre à l'enjeu socio-économique actuel que représente la valorisation énergétique de la fraction organique contenue dans les déchets ménagers. En effet, les processus de dégradation anaérobies font intervenir en cascade, différentes réactions et populations de micro-organismes permettant de transformer la matière organique en biogaz riche en méthane. Une bonne connaissance des effets des paramètres opérationnels sur l'orientation des métabolismes s'avère ainsi nécessaire à l'émergence de solutions permettant d'optimiser ces procédés. Ceci est notamment le cas pour la dernière étape, appelée méthanogenèse. Dans ce contexte, l'approche isotopique reposant sur la mesure de la composition isotopique (13C/12C) du méthane et du dioxyde de carbone, devrait pouvoir répondre à cet objectif en permettant l'identification des métabolismes à l'origine de la production du méthane. La transposabilité à l'étude de la digestion anaérobie des déchets de cette approche isotopique déjà utilisée dans les écosystèmes naturels, a tout d'abord été vérifiée expérimentalement. Les effets de certains paramètres opérationnels connus pour avoir un impact fort sur le processus de digestion anaérobie, tels que la température et la concentration en azote ammoniacal, ont ensuite été étudiés. Il a été mis en évidence qu'en condition thermophile, la méthanogenèse acétoclaste observée en condition mésophile, était remplacée par une oxydation syntrophique de l'acétate lors de la digestion anaérobie des déchets ménagers. Des expériences sur acétate ont montré que cet effet sur les voies métaboliques n'était toutefois pas systématique et pourrait ne pas être dû à un effet direct d'une augmentation de la température, mais plutôt à l'accroissement de la concentration en ammoniaque qui en résulte. D'autres expériences ont clairement établi qu'une augmentation de la concentration en azote ammoniacal conduisait également à la mise en place de l'oxydation syntrophique de l'acétate. Le couplage de l'approche isotopique avec des analyses microbiologiques a révélé que cette réaction d'oxydation syntrophique de l'acétate, à haute concentration en azote ammoniacal, pouvait s'établir telle que déjà décrite, par la mise en place d'une relation symbiotique bactéries/archées hydrogénotrophes strictes, mais également de manière différente en impliquant des membres de la famille Methanosarcinaceae qui pourraient réaliser seuls les deux étapes de la réaction (oxydation et méthanogenèse hydrogénotrophe). L'application de l'approche isotopique a également permis de mettre en évidence, lors d'une expérience visant à simuler la recirculation de différents effluents au sein d'une installation de stockage de déchets bioactive, l'influence de la nature de l'effluent sur l'orientation des métabolismes méthanogènes. Enfin, l'influence de la proportion de déchets verts, lors de la co-digestion biodéchets / déchets verts, sur la concentration en ions ammonium libérés ainsi que sur l'orientation du métabolisme en résultant, a été étudiée. Les potentialités d'une utilisation de l'approche isotopique sur site ont également été investiguées au travers d'une campagne de mesures sur une installation de stockage de déchets non dangereux
Anaerobic waste treatment processes are clearly part of the answer to a current important socio-economic issue in waste management: energy production from the organic fraction of municipal solid waste. The anaerobic digestion of municipal solid waste is a complex process involving numerous reactions and microorganism communities. At the end of the degradation process, some biogas with a particularly high methane content is produced. A detailed knowledge on how operational parameters affect metabolism orientations is required to optimize these treatment processes. This is in particular the case for the last degradation reaction called methanogenesis. In this context, an isotopic approach based on isotopic composition measurements (13C/12C) for methane and carbon dioxide can provide some clues with regard to this objective. Indeed, this methodology enables the determination of the methanogenic pathways by which methane is produced.Transferability of the isotopic approach used for natural ecosystems to the field of anaerobic digestion of municipal solid waste was first experimentally verified. In a second time, the effects of some operational parameters known to strongly impact the anaerobic digestion process, such as temperature and ammonia concentration, were studied. During anaerobic digestion of reconstituted municipal solid waste in thermophilic conditions, it was shown that aceticlastic methanogenesis (occurring in mesophilic conditions) was replaced by a syntrophic acetate oxidation reaction. Additional experiments using acetate as sole substrate were performed and showed that this effect on the metabolic pathways was not systematic. Consequently, it cannot be due to a direct effect of the temperature increase. It could rather be explained by the induced and indirect increase in ammonia concentration. Additional experiments clearly demonstrated that an increase in ammonia concentration led to the establishment of a syntrophic acetate oxidation reaction. The isotopic approach was combined with microbiological analyses and showed that the syntrophic acetate oxidation reaction occurring at high ammonia concentration during acetate incubations could have been performed through a syntrophic relationship between bacteria and strict hydrogenotrophic archaea, as previously described in the literature. Interestingly, the syntrophic acetate oxidation could also have occurred using a different pathway relying on members of the Methanosarcinaceae family putatively able to perform the two steps of the reaction (oxidation and hydrogenotrophic methanogenesis). In addition, the implementation of the isotopic approach during an experiment designed to simulate a landfill bioreactor evidenced the influence of the effluent's nature on the methanogenesis metabolism orientation. The influence of green waste proportion during the co-digestion of biowaste / green waste mixtures on resulting ammonia concentrations and methanogenesis pathways was also studied through dedicated experiments. Finally, the potential of the isotopic approach for landfill-scale application was investigated through a measurement campaign on a landfill site

One of the strategic aspects of the development of large urban agglomerations is undoubtedly the management of solid wastes. To cope with the need for waste disposal, two strategies can be followed: the incineration and the storage in landfill, with or without pre-treatment. The latter solution, widely practiced in Italy, requires many careful considerations about the environmental, sanitary and geotechnical aspects, in order to ensure the usability of this service in safety conditions during the time of landfill management, which ordinarily exceeds decades. The topic of the research is the theoretical modeling of the secondary bio-mechanical compressibility of Municipal Solid Wastes (MSW), through laboratory tests and verifications with large-scale facilities. The research, developed during the period 2010-2012, has a practical interest because the incorrect assessment of the waste settlements may lead to imprecise evaluations of the storage capacity of the plant, as well as difficulties in the operation of the accessory works, due to both the total and differential settlements. These settlements are a consequential overlapping of the immediate, primary and secondary components, which differ among their for intensity and evolution. The immediate settlement occurs whenever a load is applied over a waste layer, during the storage phase; the primary settlement is related to the compressibility, delayed in time, of the solid skeleton, due to the start of fluid motions, either liquid or gaseous, within the voids of the porous medium. The secondary settlement, or long-term settlement, is produced by compression of the solid skeleton under effective constant stress. The well-known creep phenomenon is coupled, in the MSW, with phenomena of biological degradation resulting from the transformation of organic matter in leachate and biogas. The aim of the research was to calibrate a one-dimensional bio-mechanical decoupled model for the evaluation of settlement strains and their evolution over time, starting from the biological and mechanical parameters of the municipal solid waste. The analysis of the bio-mechanical waste parameters, which represents the preliminary phase of the research, is based on data coming from the literature, as well as on the results of some experiments carried out by means of biological reactors, at the laboratories of the University of Padua and Grenoble, using an original waste (in Padua) or a pretreated waste (in Grenoble). Once the bio-mechanical parameters of the model were calibrated, it was possible to quantify the changes in volume due to both the creep and biological components, that are simultaneously present but activated at different times, because of the effects of the organic component and the conditions of biological degradation (anaerobic and/or aerobic). Therefore, the study of the model was completed by verifications from monitoring data of large-scale landfills, coming from both the literature and in situ investigations of existing plants. Survey methods 1. Introductive activities In the initial phase of this research, a review of the municipal solid waste (MSW) management is presented at the global, European and national level. These strategies concern: incineration, selection and recycling of the waste, reduction of organic material by aerobic and/or anaerobic degradation and storage in landfills. A particular emphasis is given to the methods of mechanical and biological pretreatment, which are able to limit the emissions of pollutants and reduce the incoming volumes, through the preventive stabilization of the organic matter (bioreactor landfill, landfill mining, in situ aeration). 2. State of the knowledge on the mechanics of MSW In the second part of this research, the framework of knowledge about the chemical, physical, hydraulic and mechanical properties of this heterogeneous porous medium, which is the municipal solid waste, was defined. 3. Development of a bio-mechanical model for the secondary compressibility of MSW In the third phase of this study, an assessment about the main characteristics of the MSW and the possible transformations that it can experience over time, was made. In particular, the following aspects were examined: composition, particle size, density, water content, degree of compaction and statistical representativeness. Referring to the chemical parameters, the characteristics of biodegradation were analyzed, in relation to the incidence of the organic matter and the type of process (aerobic and anaerobic). In this context, the biogas and leachate production, the temperature, the gravimetric water content and the involved stress level, were examined. Therefore, the characterization of the mechanical parameters affecting the development of the secondary settlements, was made. Settlement prediction models, currently present in the literature, can be classified according to different criteria, depending on the assumptions on which they are based: there are models derived from the soil mechanics laws (Sowers, 1973; Bjarngard and Edgers, 1990), rheological models (Gibson and Lo, 1961), experimental models (Yen and Scanlon, 1975; Edil et al., 1990, Ling et al., 1998), models incorporating the biodegradation (Marques et al., 2003; Hettiarachchi et al ., 2009) and constitutive models (Machado et al., 2008; Sivakumar Babu et al., 2010). The model, developed in this research work, considers two distinct (creep and biological) components, present simultaneously but activated at different times, because of the effects of the organic component and the conditions of biological degradation (anaerobic and/or aerobic). The model parameters were calibrated from the results of an experimental investigation, carried out in laboratory medium scale reactors, and from in situ observations, related to large scale facilities. 4. Laboratory analysis and experimental research In order to obtain a complete range of representative data, experimental investigations on the behaviour of two types of waste, subjected to compression, were carried out, using in parallel two laboratory reactors. These experiments, which represent the fourth phase of the research work, were implemented at the laboratory of Environmental Engineering of the University of Padua (ICEA Department) and at the LTHE laboratory (Laboratoire d'étude des Transferts en Hydrologie et Environnement) of the University of Grenoble (France). Tests at the University of Grenoble were carried out under the supervision of the Professor Jean-Pierre Gourc, during a stage lasted five months (May-October 2012). The employed material is a municipal solid waste (MSW) coming from the Legnago landfill (VR, Italy), obtained from both an original unaltered waste and a bio-mechanical pretreated waste. The original MSW was subjected to compression tests on a reactor present at the University of Padua, for a period of 180 days, receiving weekly a predetermined amount of incoming leachate, in order to improve the degradability conditions. In parallel, the bio-mechanically pretreated MSW was subjected to compression tests on a reactor present at the University of Grenoble, for a period of 77 days, without any liquid injection. Thus, these tests have allowed to highlight the dependence of bio-mechanical parameters with the initial state of the waste. 5. Extension of the model to the large scale landfills In the last phase of the research, starting from the experimental data obtained from small and medium scale laboratory reactors, a prediction of the secondary settlements for large scale landfills was made. The behaviour of the single elementary cell was integrated to a series of vertical cells, in order to simulate the behaviour of a waste column in landfill. For this purpose, the prediction of the proposed bio-mechanical model was compared with monitoring data coming from the Chatuzange landfill (France), the Yolo County landfill (USA) and the S-landfill (USA), obtaining very encouraging results. The main results of the research can be summarized in the following aspects: * The need of calibration of this bio-mechanical proposed model for the evaluation of the secondary settlement strains, considering the two distinct (creep and biological) components, is highlighted. The model was calibrated considering data from the literature, as well as laboratory tests carried out at the University of Padua and Grenoble. Further validations were given by the study of the settlements of three landfill. The advantage of a correct calibration is observed over very wide time periods, as shown by comparisons with large scale landfills. * The models that include the component of biological degradation are efficient, only if they are able to consider and quantify the settlement component due to the biogas production in anaerobic processes. This circumstance is crucial in large scale MSW landfills. * A modest aerobic pretreatment, bringing forward the times of biodegradation of the organic matter, can limit the settlements and reduce the periods of storage in landfills
Uno degli aspetti strategici dello sviluppo dei grandi agglomerati urbani è senza dubbio la gestione dei rifiuti solidi. Per far fronte alle necessità di smaltimento si possono seguire due strategie: quella dell’incenerimento e quella dello stoccaggio in discarica, con o senza pre-trattamento. Quest’ultima soluzione, molto praticata in Italia, richiede delle attente valutazioni di carattere ambientale, sanitario e geotecnico, al fine di garantire la fruibilità del servizio in sicurezza, durante il tempo di gestione che ordinariamente supera i decenni. L’attività di ricerca s’inserisce nell’ambito della modellazione teorica della compressibilità secondaria bio-meccanica dei Rifiuti Solidi Urbani (RSU), attraverso test di laboratorio e riscontri con opere in vera grandezza. La ricerca, sviluppata nel corso del triennio 2010-2012, riveste un certo interesse pratico ove si consideri che l’inesatta valutazione dei cedimenti dei rifiuti possa comportare un’imprecisa stima della capacità di accumulo dell’impianto, nonché difficoltà di funzionamento delle opere accessorie a causa dei cedimenti totali e differenziali. Quest’ultimi derivano dalla sovrapposizione delle componenti: immediata, primaria e secondaria, differenti per intensità e decorso. Il cedimento immediato si produce ogni qualvolta si applichi un carico al di sopra di uno strato di rifiuto, durante lo stoccaggio; il cedimento primario è legato alla compressibilità differita nel tempo dello scheletro solido, a causa dell’instaurarsi di moti di fluido, sia liquido che gassoso, all’interno dei vuoti. Il cedimento secondario, o di lungo termine, oggetto della presente Tesi di Dottorato, è prodotto dalla compressione dello scheletro solido sotto tensioni effettive costanti. Il ben noto fenomeno di creep si accoppia, negli RSU, a fenomeni di degradazione biologica, derivanti dalla trasformazione della sostanza organica in percolato e biogas. Scopo della ricerca è stato quello di calibrare un modello bio-meccanico disaccoppiato di tipo monodimensionale per la valutazione delle deformazioni da cedimento e del loro decorso nel tempo, partendo dai parametri biologici e meccanici del rifiuto urbano. L’analisi dei parametri bio-meccanici del rifiuto, costituente la parte preliminare della ricerca, si fonda, oltre che su dati provenienti dalla letteratura specialistica, sui risultati di esperienze con reattori biologici presso i laboratori delle Università di Padova e di Grenoble, utilizzando materiale tal quale (a Padova) o pretrattato (a Grenoble). Una volta calibrati i parametri del modello bio-meccanico è stato possibile quantificare le variazioni di volume riconducibili alle due distinte componenti, di creep e biologica, presenti simultaneamente ma attivatesi con tempi diversi, in ragione dell’incidenza della componente organica e delle condizioni di degradazione biologica (anaerobica e/o aerobica). Completa lo studio il riscontro con i dati provenienti da opere in vera grandezza, ricavati sia dalla letteratura specialistica che da indagini in situ su discariche esistenti. Modalità di indagine 1. Attività introduttive Nella fase iniziale del lavoro viene presentata una rassegna sulla gestione dei rifiuti solidi urbani (RSU) a livello mondiale, europeo e nazionale. Queste strategie riguardano l’incenerimento, l’attività di selezione(raccolta differenziata) e riciclo del materiale, la riduzione dell’attività biologica del materiale tramite degradazione aerobica e/o anaerobica, e lo stoccaggio in discarica. Particolare evidenza è data ai metodi di pretrattamento meccanico e biologico, in grado di limitarne le emissioni inquinanti e di ridurre i volumi conferiti attraverso la preventiva stabilizzazione della sostanza organica (discarica bioreattore, landfill mining, aerazione in situ). 2. Stato delle conoscenze sulla meccanica degli RSU Nella seconda parte della ricerca si è tracciato il quadro delle conoscenze riguardo alle proprietà chimiche, fisiche, idrauliche e meccaniche del mezzo poroso eterogeneo, qual è il rifiuto solido urbano. 3. Elaborazione di un modello bio-meccanico per la compressibilità secondaria degli RSU Nella terza fase dello studio si è resa necessaria una valutazione delle principali caratteristiche del rifiuto e delle possibili trasformazioni che esso può sperimentare nel tempo. In particolare, sono stati esaminati i seguenti aspetti: composizione merceologica, granulometria, densità, contenuto d’acqua, grado di compattazione e rappresentatività statistica. Con riferimento ai parametri chimici, sono state prese in esame le caratteristiche di biodegradazione in relazione all’incidenza della sostanza organica ed al tipo di processo, aerobico e anaerobico. In tale ambito sono state esaminate le produzioni di percolato e di biogas, la temperatura, il contenuto d’acqua gravimetrico ed il livello di tensione coinvolto. Si è proceduto, quindi, alla caratterizzazione dei parametri meccanici che incidono sullo sviluppo dei cedimenti secondari. I modelli di previsione dei cedimenti, attualmente presenti nella letteratura tecnica, possono essere classificati secondo differenti criteri, in relazione alle ipotesi su cui si fondano: modelli derivanti dalle leggi della meccanica delle terre (Sowers, 1973; Bjarngard ed Edgers, 1990), modelli di tipo reologico (Gibson e Lo, 1961), modelli empirici (Yen e Scanlon, 1975; Edil et al., 1990; Ling et al., 1998), modelli incorporanti la biodegradazione (Marques et al., 2003; Hettiarachchi et al., 2009) e modelli di tipo costitutivo (Machado et al., 2008; Sivakumar Babu et al., 2010). Il modello sviluppato nella ricerca considera le due distinte componenti, di creep e biologica, presenti simultaneamente ma attivatesi con tempi diversi, in ragione dell’incidenza della componente organica e delle condizioni di degradazione biologica (anaerobica e/o aerobica). I parametri del modello sono stati calibrati sulla base dei risultati di un’indagine sperimentale condotta in laboratorio con reattori di medie dimensioni ed osservazioni in sito relative ad opere in vera grandezza. 4. Analisi di laboratorio e ricerca sperimentale Per ottenere una gamma completa di dati rappresentativi, sono state condotte delle ricerche sperimentali sul comportamento di due tipi di rifiuto soggetti a compressione, utilizzando, in parallelo, due serie di indagini di laboratorio. La sperimentazione, che costituisce la quarta fase della ricerca, è stata condotta presso il laboratorio di Ingegneria Sanitaria Ambientale dell’Università di Padova (Dipartimento ICEA) e presso il laboratorio LTHE (Laboratoire d’étude des Transferts en Hydrologie et Environnement) dell’Università di Grenoble (Francia). Le prove all’Università francese sono state condotte sotto la guida del Professor Jean-Pierre Gourc, durante un periodo di stage di cinque mesi (maggio–ottobre 2012). Il materiale utilizzato è un rifiuto solido urbano proveniente dall’impianto di Legnago (VR), ottenuto sia da rifiuti tal quali, sia da un pretrattamento bio-meccanico. L’RSU originario (tal quale), è stato sottoposto a prove di compressione su un reattore presente all’Università di Padova, per un periodo di 180 giorni, ricevendo, settimanalmente, una determinata quantità entrante di percolato, al fine di migliorarne le condizioni di degradabilità. Parallelamente, l’RSU pretrattato bio-meccanicamente è stato sottoposto a prove di compressione su un reattore presente all’Università di Grenoble, per un periodo di 77 giorni, senza alcuna iniezione di liquido. Tale sperimentazione ha consentito di mettere in luce la dipendenza dei parametri bio-meccanici in funzione dello stato iniziale del rifiuto. 5. Estensione del modello alle opere in vera grandezza Nell’ultima fase della ricerca, sono stati esaminati i riscontri provenienti dal monitoraggio di opere in vera grandezza. Partendo dai dati sperimentali, su piccola e media scala, ottenuti dai reattori di laboratorio, si è proceduto al calcolo delle deformazioni da cedimento di opere in vera grandezza. Il comportamento della singola cella elementare è stato generalizzato ad una serie di celle verticali, in grado di simulare il comportamento di una colonna di rifiuti all’interno della discarica. A tal fine si sono confrontati i risultati con i dati di monitoraggio provenienti dalle discariche di Chatuzange in Francia e di Yolo County e S-Landfill negli USA, ottenendo risultati molto incoraggianti. Il principale prodotto della ricerca si può sintetizzare nei seguenti aspetti: * Si evidenzia la necessità della taratura del modello bio-meccanico proposto per la valutazione delle deformazioni secondarie da cedimento, considerando le due distinte componenti, di creep e biologica. Il modello è stato tarato sulla base dei dati provenienti dalla letteratura specialistica, nonché attraverso prove di laboratorio presso le Università di Padova e Grenoble. Ulteriori conferme sono state desunte dallo studio dei cedimenti di tre impianti di stoccaggio degli RSU. Il beneficio di una corretta taratura si osserva su intervalli di tempo molto ampi, come dimostrato dai riscontri con opere in vera grandezza. * I modelli che includono la componente di degradazione biologica si rivelano efficienti solo se in grado di considerare e di quantificare la componente di cedimento dovuta alla produzione di biogas nei processi anaerobici, circostanza questa molto influente nei grandi cumuli urbani di RSU. * Un modesto pretrattamento aerobico, anticipando i tempi di biodegradazione della sostanza organica, consente di limitare i cedimenti e di abbreviare i tempi di stoccaggio in discarica

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O estudo com células experimentais de Resíduos Sólidos Urbanos (RSU) permite avaliar a degradação dos diferentes tipos de resíduos sólidos por meio da ação dos microrganismos bactérias e fungos totais em um curto período de tempo, ao contrário do que ocorre em aterros sanitários tradicionais. Assim, o objetivo dessa pesquisa foi realizar o monitoramento de células experimentais de RSU quanto a aspectos físico-químicos e microbiológicos, preenchidas com resíduos da cidade de Campina Grande-PB, com o intuito de avaliar a eficiência dos processos degradativos. Para isso, realizou-se a construção, preenchimento e monitoramento de 2 (duas) células experimentais localizadas na Universidade Federal de Campina Grande (UFCG). Essas células foram preenchidas com RSU da Cidade de Campina Grande, coletados em locais e quantidades previamente selecionadas. As células foram instrumentadas com medidores de temperatura e recalque ao longo da profundidade, piezômetro e dreno de gás, além de 12 pontos de coleta de resíduos. Os períodos de monitoramento foram de: outubro de 2009 a outubro de 2011 na célula experimental I e de setembro de 2011 a setembro de 2013 na célula experimental II, onde amostras de resíduos sólidos foram retiradas de cada camada (superior, intermediária e inferior) para realização das análises físicoquímicas e microbiológicas. Foram realizadas análises de granulometria do solo para compor as camadas de base e cobertura, composição gravimétrica, volumétrica, pH, sólidos voláteis, teor de umidade, cloretos, alcalinidade, ácidos voláteis, precipitação e evaporação, contagem de bactérias aeróbias e fungos totais de acordo com normas e metodologias adaptadas com o propósito de observar o processo de degradação nas diferentes células experimentais. De acordo com os resultados obtidos verificou-se que as composições gravimétricas e volumétricas realizadas, nos diferentes períodos de tempo, foram típicas de cidades em desenvolvimento, com elevados teores de matéria orgânica e que o desenvolvimento dos parâmetros pH, alcalinidade, teor de umidade, concentrações de ácidos voláteis, sólidos voláteis e cloretos favoreceu o crescimento dos microrganismos bactérias aeróbias e fungos totais, em ambas as células estudas propiciando comportamento semelhante dos microrganismos, ao longo do tempo de monitoramento. Observou-se que os teores de pH nas duas células experimentais monitoradas foram favoráveis no crescimento desse grupo de bactérias e que os resíduos sólidos urbanos encontram-se em estágio avançado de degradação. A redução dos sólidos voláteis em todos os níveis de profundidade das células experimentais indicou a degradação da matéria orgânica. Pode-se concluir que as fases de degradação nas células experimentais I e II ocorreram de maneira mais rápida quando comparadas a aterros sanitários em decorrência da área/superfície ser maior que o volume dos resíduos, o que facilitou a interação do meio ambiente com atividade enzimática dos diferentes grupos de bactérias e fungos totais presentes nas diferentes camadas das células experimentais.
The study with experimental cells of Municipal Solid Waste (MSW) allows evaluating the degradation of the different types of solid waste through the action of the microorganisms bacteria and total fungi in a short period of time, unlike what occurs in traditional landfills. Thus the objective of this research was to carry out the monitoring of experimental cells of MSW as the physical chemical and microbiological aspects, filled with waste from the city of Campina Grande-PB, in order to evaluate the efficiency of degradative processes. For this, realized the construction, the fill and monitoring of two (2) experimental cells located at the Federal University of Campina Grande. These cells were filled with RSU of the City of Campina Grande, collected in places and amo unts previously selected. Cells were instrumented with temperature gauges and repression along the deep, piezometer and gas drain, beyond 12 points of waste collection. The monitoring periods were: October 2009 to October 2011 in the experimental cell I and from September 2011 to September 2013 in the experimental cell II, where solid waste samples were taken from each layer (upper, middle and lower) for realization of the physicochemical analysis and microbiological. Were realized soil granulometry analyzes to compose the layers of the base and cover, gravimetric composition, volumetric, pH, volatile solids, moisture content, chlorides, alkalinity, volatile acids, precipitation and evaporation, the count of aerobic bacteria and total fungi of agreement with standards and adapted methodologies in order to observe the degradation process in the different experimental cells. According to the results obtained it was found that the gravimetric and volumetric compositions realized, in the differents time periods, were typical of cities in developing, with high contents of organic matter and that the development of the parameters pH, alkalinity, moisture content, concentrations of volatile acids, volatile solids and chlorides favored the growth of the microorganisms aerobic bacteria and total fungi, in both studied cells providing similar behavior of microorganisms, during the monitoring time. It was observed that the pH levels in the two experimental cells monitored were favorable in the growth of this group of bacteria and that municipal solid waste are at an advanced stage of degradation. The reduction of volatile solids in all depth levels of the experimental cells indicated the degradation of organic matter. It can be concluded that the degradation stages in the experimental cells I and II occurred more rapidly when compared to landfills due to the area/surface be greater than the volume of waste, facilitating the interaction of the environment with enzymatic activity of different groups of bacteria and total fungi present in the different layers of the experimental cells.

Дисертація на здобуття наукового ступеня доктора технічних наук за спеціальністю 03.00.20 – біотехнологія. – Національний технічний університет України «Київський політехнічний інститут імені Ігоря Сікорського» Міністерства освіти і науки України, Київ, 2019. Представлені науково обґрунтовані рішення з біотехнологічної інтенсифікації процесів, що використовуються у комунальній інфраструктурі населених пунктів. Розроблено біотехнологію видалення сполук заліза та мангану з підземних вод на швидких фільтрах з цеолітовим завантаженням при внесенні культур мікроорганізмів родів Leptothrix і Sphaerotillus. Реалізація біотехнології дозволяє досягти ефективності очищення води за залізом та манганом: з природними культурами - 94-99 % та 71-87 %; з селектованими - 98-99 % та 94-97 % відповідно. Розроблено технологію інтенсифікації процесу деамонізації у біофільтрах шляхом внесення у фільтруюче завантаження попередньо розрахованої кількості культур нітри- та денітрифікаторів, що дозволяє скоротити підготовчий режим роботи фільтра з 18 до 2 діб. Розроблено технологію одержання близьких за своїм складом до природних мікроценозів препаратів, використання яких збільшує ефективність біодеструкції на 26,4±0,2 у порівнянні з традиційними.
Dissertation for obtaining the scientific degree of the doctor of technical sciences in the specialty 03.00.20 - biotechnology. - National Technical University of Ukraine "Igor Sikorsky Kyiv Polytechnic Institute", Ministry of Education and Science of Ukraine, Kyiv, 2019. The dissertation is devoted to scientific substantiation of new energy and resource efficient and ecological biotechnologies for intensification of processes of preparation of drinking water and utilization of solid household waste in municipal infrastructure objects, containing removing iron, manganese and nitrogen compounds from water as well as intensification for biodestruction of organic compounds in solid wastes. In the study of the work of rapid filters on the water intake of the village of Khoroshiv, results were obtained that showed the iron / oxygen ratio to be at level of 0.12 - 0.25, which is according to existing ideas not enough to provide deep treatment, that was obtained practically. This lead us to idea of biotechnological process to take place. To confirm the above assumption, experiments were carried out on filtration of water with an iron concentration of 13,3 ± 0,8 mg / dm3 at a different filtration rate and in the presence of bacteria in the filter material. The results of additional experiments showed that usage of oxygen (which allowed biological growth) lead to deeper treatment than in case of hypochlorite usage. That is, the results obtained not only confirmed the role of microorganisms in the process of non-irritation / demaganization, but also showed the possibility of practical application of biotechnology methods to improve the efficiency of water purification from iron and manganese. For the thorough examination of the biological agent from the filtering material of the various filters, 10 cultures of iron and manganese oxidizing microorganisms were isolated. The evaluation of the morphology of the cultures obtained, according to the scheme, allowed them to be classified as Siderocapsa, Leptothrix, Sphaerotillus, Galionella, Metallogenium, Hyphomicrobium. The data of following experiments showed a predominant role in the processes of water disinfection of microorganisms of Leptothrix, Sphaerotillus, Metallogenium and Siderocapsa. Increasing the activity of a biological agent can be achieved by creating selective cultures of Leptotrix and Sphaerotilus, that can contribute to a deeper removal of manganese from water (up to 98% for Mn). To implement the proposed schemes a number of technological tasks were solved, including: to develop effective methods of transfer of inoculum to the loading of filters, to select the most suitable filtering loading for the specified purposes, to determine the optimum parameters and regimes of filtering and washing of the filtering layer. Based on the results of the research carried out for the implementation of biotechnology for disinfection and demagnetization on rapid filters, two technological schemes were developed using natural or selected microorganisms cultures. The study of the possibility of intensifying the deamonization of underground water technology was carried out by conducting a complex of pilot studies on the water of the artesian well in the city of Khmelnytsky. The experimental plant included filter with an aerator, loaded with a special filter material, on which the microorganisms are effectively fixed and retained. The results of the experiments allowed to reveal important dependencies. Since the concentration of dissolved oxygen at the filter inlet has an opposite effect on the flow of processes, it was appropriate to investigate their regularities at different values of this indicator. The results of experiments showed that when the oxygen supply was reduced from 8 to 5.5 mg / dm3, the concentration of ammonium in the filtered water was in the range of 0.11-0.12 mg / dm3, nitrites - 0.27-0.28 mg / dm3, and nitrates gradually decreased from 11.0 to 2.4 mg / dm3, that is, at high concentrations of oxygen due to nitrification, a significant amount of nitrates was produced, and as the oxygen content decreased due to denitrification, the decomposition of nitrates and their concentration declined. The mathematical model was prepared to describe this process and the resulting program was realized in Swift 4.0. The results of the comparison of the experimental data obtained with the forecast by model showed that the prediction error of the model does not exceed 6.0%, that is, it is much smaller than the allowable value for engineering calculations. Based on the results of the research and the developed model, a technology for intensifying the biofiltration process for ammonia removal was developed to decrease time of filters preparation. The use of technology has allowed to shorten the start time of the filter for use from 18 to 2 days. The interconnection between the morphological composition of the solid waste and the biocenoses formed therein was investigated by sorting several samples that arrive at the polygons mm. Kiev and Khmelnitsky. The correlation with coefficient R=0,65-0,68 was stablished and mathematical model to describe the process was obtained. An assessment of the adequacy of the developed model was carried out by comparing the predicted data obtained from the model with the experimental data for the map of the polygon in Chernivtsi with an approximate time of stay of the SHW for 5 years. Comparison of the predicted composition of the biocenosis with the actual allocated showed that the difference between the predicted and actual data on the number of bacteria in the biocenose was 12.5%, and according to the morphological composition - did not exceed 15%, which confirmed the adequacy of the developed model. An assessment of the effectiveness of the proposed technology was carried out by laboratory on samples of MSW in Kyiv using a traditional Bacillus-based preparate and mixed one, the composition of which was determined by simulation. According to the data obtained, the use of a mixture accelerated the biodestruction and rate of subsidence of the sample (by 26,4 ± 0,2%).
Диссертация на соискание ученой степени доктора технических наук по специальности 03.00.20 - биотехнология. - Национальный технический университет Украины «Киевский политехнический институт имени Игоря Сикорского» Министерства образования и науки Украины, Киев, 2019. В диссертации представлены результаты научно обоснованных технологических решений биотехнологической интенсификации процессов, которые широко используются в коммунальной инфраструктуре населенных пунктов. Разработана биотехнология удаления соединений железа и марганца путем внесения микроорганизмов родов Leptothrix и Sphaerotillus. Реализация биотехнологии позволяет достичь эффективности очистки воды от желез и марганца: с природными культурами - 94-99% и 71-87%; с селектированными - 98-99% и 94-97% соответственно. Разработана технология интенсификации деамонизации в биофильтрах путем внесения в фильтрующую загрузку предварительно рассчитанного количества культур нитри- и денитрификатор, что позволяет сократить время пуска фильтра с 18 до 2 суток. Предложена технология получения близких по составу к естественным микроценозам препаратов, повышающих эффективность биодеструкции ТБО на 26,4 ± 0,2 по сравнению с традиционными.

AD is regarded as a sustainable technology that could assist the UK Government meet internationally agreed GHG emission targets by 2050. However, the mature status of the technology is based on expensive systems that rely on high energy feedstock to be profitable. Meanwhile, the natural biodegradation of cow slurry is a recognised contributor to climate change despite having a relatively low CH4 potential because of the large volumes produced. Economic mixing is essential to the cost-effectiveness of farm AD but techniques applied are not always appropriate as slurry is a shear thinning thixotropic Herschel-Bulkley fluid and therefore challenging to mix. The apparent viscosity of slurry and the shear stress induced was most influenced by solids content (exponential change) followed by temperature (linear). Most shear thinning occurred before a rising shear rate of 20s-1 was achieved with the fluid acting near-Newtonian above. Thixotropic recovery occurred within 1 hour of resting. Rheological values were also much higher than previously reported. Highest CH4 production occurred in the first 10 days of the batch process using a range of mixing regimes with different shear rates and rest periods. During fed-batch operations, changing shear rate had a minimal effect on CH4 production using a 30-day HRT whereas shorter rest periods increased production. Specific CH4 production rate was highest when feeding and mixing coincided. However, when HRT was reduced (OLR increased) the CH4 produced by all mixed regimes significantly increased with highest values being achieved using high intensity mixing rested for short periods. Lower HRTs also requires smaller digesters. Parasitic mixing energy invariably had the most influence on net energy production. Signs of instability were evident after 20 days using the low HRT. Significant microbial adaptation was also observed as the experiments progressed. The research outcomes demonstrate that mixing regime and HRT can be managed to maximise net energy production whilst reducing capital expenditure.

Municipal solid waste (MSW) production has significantly increased in the rapidly urbanizing developing world and also changed composition with increased decomposable organic fraction in MSW (OFMSW) and plastics content. This has stressed the environment in many ways while city managers and citizens have responded with various technological and management solutions leading to a need for scientific, environmental, technological and sustainability assessments of the emerging problems. This sets the research agenda and framework for this study wherein the MSW generation, composition, processing and treatment methods, open dumping practices, environmental liability, natural degradation, sustainability issues etc. have been studied for the city of Bangalore as a model for such an emerging problem. Results show that MSW generation ranged from 0.1-0.4 kg/person/day and the OFMSW content was >80% emerging predominantly from fruit, vegetable and food wastes. About 10-15% of daily MSW generated appeared to be haphazardly dumped around the city in ~700 small to large dumps ranging from 10-6,500 m2 with potential for large GHG emissions. Their spread and characteristics were assessed for 3 consecutive years using a novel rapid survey method developed at IISc involving motorcycle borne student volunteer teams, GPS enabled locating, physical measurements and satellite image interpretations. Results indicated that dump sites were of three types, ephemeral small sized in the core area (303) functioning as transfer stations, medium sized ones in outer areas that were closed rapidly with construction debris and very soon inhabited with dwellings and the larger and longer duration dumps (2-3 years, 393) in the peripheral regions within 10 km from the city administrative boundary. This method was compared with physical measurement and satellite imaging and gave very high level of accuracy and is hence suggested for other cities as well. A smaller fraction of MSW is also dumped in open drains that lead to choking and flooding of 3 locations and this was studied with some detail. The environmental footprint of such dumps were assessed by theoretical and experimental on-site and off-site approaches and experimental results show low GHG (CH4) emissions and emission factors that was largely attributable to the shallow depth of dumps (~0.7 m) and its low pH. The decomposition rates were experimentally determined for open dump sites and drivers for decomposition monitored. By providing differential access to macro-fauna, meso-micro organisms and only soil contact in field scale experiments it was determined that the greatest loss in weight occurred primarily due to the rapid drying process that brings down decomposition within 6 days. During the early stages of decomposition, mostly micro with meso organisms are responsible and after 6 days, the moisture content falls below 60% making microbiological decomposition difficult and enabling other foraging organisms to take over. The weight loss (decay) could be patterned both on exponential decay or a two component fit representing a rapid initial decay followed by a slower long term decay process similar to soil application of organic matter. Monitoring the decentralized MSWM practices in the city suggests that small scale composting and biomethanation is gaining acceptance and is the possible direction for OFMSW in growing cities.

Municipal solid waste (MSW) production has significantly increased in the rapidly urbanizing developing world and also changed composition with increased decomposable organic fraction in MSW (OFMSW) and plastics content. This has stressed the environment in many ways while city managers and citizens have responded with various technological and management solutions leading to a need for scientific, environmental, technological and sustainability assessments of the emerging problems. This sets the research agenda and framework for this study wherein the MSW generation, composition, processing and treatment methods, open dumping practices, environmental liability, natural degradation, sustainability issues etc. have been studied for the city of Bangalore as a model for such an emerging problem. Results show that MSW generation ranged from 0.1-0.4 kg/person/day and the OFMSW content was >80% emerging predominantly from fruit, vegetable and food wastes. About 10-15% of daily MSW generated appeared to be haphazardly dumped around the city in ~700 small to large dumps ranging from 10-6,500 m2 with potential for large GHG emissions. Their spread and characteristics were assessed for 3 consecutive years using a novel rapid survey method developed at IISc involving motorcycle borne student volunteer teams, GPS enabled locating, physical measurements and satellite image interpretations. Results indicated that dump sites were of three types, ephemeral small sized in the core area (303) functioning as transfer stations, medium sized ones in outer areas that were closed rapidly with construction debris and very soon inhabited with dwellings and the larger and longer duration dumps (2-3 years, 393) in the peripheral regions within 10 km from the city administrative boundary. This method was compared with physical measurement and satellite imaging and gave very high level of accuracy and is hence suggested for other cities as well. A smaller fraction of MSW is also dumped in open drains that lead to choking and flooding of 3 locations and this was studied with some detail. The environmental footprint of such dumps were assessed by theoretical and experimental on-site and off-site approaches and experimental results show low GHG (CH4) emissions and emission factors that was largely attributable to the shallow depth of dumps (~0.7 m) and its low pH. The decomposition rates were experimentally determined for open dump sites and drivers for decomposition monitored. By providing differential access to macro-fauna, meso-micro organisms and only soil contact in field scale experiments it was determined that the greatest loss in weight occurred primarily due to the rapid drying process that brings down decomposition within 6 days. During the early stages of decomposition, mostly micro with meso organisms are responsible and after 6 days, the moisture content falls below 60% making microbiological decomposition difficult and enabling other foraging organisms to take over. The weight loss (decay) could be patterned both on exponential decay or a two component fit representing a rapid initial decay followed by a slower long term decay process similar to soil application of organic matter. Monitoring the decentralized MSWM practices in the city suggests that small scale composting and biomethanation is gaining acceptance and is the possible direction for OFMSW in growing cities.

M.Tech. (Chemical Engineering)
The design process was carried out in two stages: feedstock analysis and system design. Under feedstock analysis, the study investigated the amount of the organic fraction of municipal solid waste (OFMSW) generated at the study area which was situated at the University of Johannesburg’s Doornfontein Campus (UJ DFC) in downtown Johannesburg South Africa. Furthermore, the feedstock analyses involved characterisation studies on the target waste under which several laboratory tests were undertaken. The system design involved sizing of the suitable biogas digester to be used in the system applying mathematical models and feedstock parameters obtained from the feedstock analyses. Via the application of the Simple Multi-Attribute Rating (SMART) technique of multiple-criteria decision analysis (MCDA) as a decision support tool, the most preferred option of biogas plant model was selected from a list of potential alternatives available on the market. And, in addition, a suitable site around the study area was selected by applying the analytical hierarchy process (AHP) technique of MCDA. Other system components and accessories such as the piping, scrubbers and valves were sized, selected, integrated into the system and finally layout drawings were produced using Inventor computer aided drafting (CAD) Software. Furthermore, feasibility assessments were conducted on the proposed system such as energy usage assessments and economic analyses using the net present value (NPV), internal rate of return (IRR) and benefit-cost ratio (BCR) techniques...