Dissertations / Theses on the topic 'Organic wastes'

Composting is a sustainable method to deal with huge amount of daily organic waste due to its robustness and easy operation. However, food waste (FW) as the main material in composting has disadvantages such as the heterogenous properties, high foreign matters contamination, high moisture content, low C/N ratio, poor structure, low porosity and high acidity during the initial phase of composting. These shortcomings not only influence degradation efficiency but also cease the composting process. Therefore, a bulking agent is required to increase the porosity and adjust the moisture content as well as C/N ratio of the composting mixture (Wong et al., 2010). For previous research, sawdust (SD) and tree barks were commonly used as the bulking agent in composting system but the demand for sawdust and tree barks significantly increased the cost of the composting process, and this has stimulated the demand of alternative substitutes. Therefore, the ideal situation is to find the bulking agent which is not only suitable for composting but is also a waste. Traditional Chinese medicine is widely used nowadays and huge amount of residues are accumulated and treated in landfilling (Wang and Li, 2013). According to previous research, only 5% of the active ingredients can be extracted from the medicinal plants which means there are still a large fraction of active ingredients remain in the herbal residues (Wu et al., 2013). In addition to the bulking property of Chinese medicinal herbal residues (CMHRs), it is assumed mature CMHRs compost have the ability to hinder regular metabolic pathway of phytopathogens after land application (Bernal-Vicente et al., 2008). The first experiment of this study investigated the formula between food waste, sawdust and CMHRs in order to achieve efficient composting. The experimental results demonstrated positively the use of CHMRs is a suitable candidate to co-compost with food waste. In terms of biodegradation decomposition efficiency and compost maturity, the treatment 1:1:1 (FW: SD: CHMRs, dry wt. basis) showed the best performance among all treatments with 67% organic matter degradation and 157% seed germination index. Only well-matured composting product can suppress plant diseases in soil since it has some microorganisms which can inhibit phytopathogens. The treatment 5:5:1 (FW: SD: CHMRs, dry wt. basis) also reached maturity but with a longer composting period; however, it was the treatment which could accommodate the highest quantity of food waste. The log copy number of the bacterial population was 7-8 initially, which decreased and stabilized along the composting. Results revealed that the CHMRs can be used as a bulking agent with food waste, and a dry weight ratio of 1:1:1 (FW: SD: CHMRs) would be optimum to achieve higher organic decomposition and faster maturity. However, the initial lower microbial population in the treatment, though without any adverse effect on the overall microbial decomposition, will warrant further work to indicate the total population is not a practical means to illuminate the effective microbial decomposition. Besides, the advantage in using CHMRs will need further experiment to indicate its potential pathogen suppression capability. Humification during co-composting of food waste, sawdust and CMHRs was investigated to reveal its correlation with compost maturity. The huge decrease in the treatment 1:1:1 (FW: SD: CHMRs, dry wt. basis) of aliphatic organics in humic acids (HA) demonstrated the degradation of the readily available organics, while an increase in aromatic functional groups indicated the maturity of compost. Disappearance of hemicellulose and weak intensity of lignin in the CMHRs treatments indicated that the lignin provided the nucleus for HA formation; and the CMHRs accelerated the compost maturity. Humic acid to fulvic acid (HA/FA) ratio of 1:1:1 treatment was the highest at the end of composting and showed a clear correlation with compost maturity as also evidenced through the presence of higher aromatic functional groups in the HA fraction. Pyr-TMAH-GC-MS results indicated that dominant groups were aliphatic and alicyclic esters and ethers at the early composting stages in all treatments. Long chain fatty acids were broken down into smaller molecular compounds earlier in treatment 1:1:1 (FW: SD: CHMRs, dry wt. basis), resulting from the faster decomposition rate. The complicated ring-structure components appeared dominantly at the later phase of composting. The peak intensities in treatment 1:1:1 (FW: SD: CHMRs, dry wt. basis) indicated that the composts became mature earlier than the other two treatments. In brief, the treatment with dry weight ratio 1:1:1 had greatest humification degree with more cyclic structures and stable final products at the end of composting. Water and acetone extract of composts with food waste and CMHRs were tested with their antipathogenic effect on two kinds of commonly found phytopathogens, Alternaria solani (A. solani) and Fusarium oxysporum (F. oxysporum). Seventeen bacterial species and 22 fungal species were isolated and identified as prevalently existed microbes during composting process. The results of MIC50 indicated that the treatment with dry weight ratio 1:1:1 (FW: SD: CHMRs, dry wt. basis) required least concentration of composts extraction to kill half quantity of the phytopathogens, 16% for A. solani and 22% for F. oxysporum extracted by acetone. The phytopathogen suppression capacity of composts was partially due to antagonistic abilities from some of the isolated microorganisms as well as the inhibition of active compounds. As shown in the comparison, the interfere/compete between antagonistic microorganisms and target pathogens were more powerful than individually influenced by chemical compounds. However, the influencing factors should not be considered independently since antagonistic interactions between microbes in composts and phytopathogens are highly dependent on the abiotic properties of the composts and the alternative environment. In a word, the antipathogenic effects from composts were synergism of both antagonism and chemical factors. Suppressive capacity on phytopathogens is one of the major function of mature composts and the antipathogenic effect was stimulated when CMHRs was used as the bulking agent in composting process. The abiotic inhibitory rates of treatment 1:1:1 (FW: SD: CHMRs, dry wt. basis) indicated that more powerful bioactive components were remained at the end of composting than in the treatment 5:5:1 and control which had no CMHRs but plastic beads as the bulking agent. Hence sensitive and comprehensive analytical technique of ultra-performance liquid chromatography coupled with time-of-flight mass spectrometry (UPLC-QTOF-MS) was utilized to acquire a better understanding of the complicated structures of final composting products. Seven dominant among 22 active compounds with antibacterial/antifungal properties were obtained in the treatments with CMHRs while 17 kinds of compounds with higher contents were shared in all treatments, which should be derived from food waste. The bioactive components from CMHRs composting were mainly from the groups of alkaloids, flavonoids and coumarins. Mature composts were used as biofertilizer to protect plants (Brassica chinensis and Lycopersicon esculentum) from phytopathogenic infection. This study showed the crop yields were increased with the addition of mature CMHRs composts to acid soil, and 5% CMHRs compost was the optimum application rate, while at the higher application rate of 10% (dry weight basis, w/w) plant growth was inhibited which might be due to the higher salt contents and the phytotoxicity of alkaloids, flavonoids and coumarins in the CMHRs. According to the biomass results, Brassica chinensis was more sensitive to the inhibitory effect of phytopathogen inoculation, while nutrient supply was to a less extent due to the short growth period as compared to Lycopersicon esculentum. The present study showed clearly that mature compost provided Lycopersicon esculentum and Brassica chinensis sufficient nutrients such as nitrogen and phosphorus. Additionally, the advantage of using mature CMHRs compost as a soil conditioner was also observed for blocking phytopathogenic infection from plant roots. The mechanism was mainly derived from the bioactive components in mature CMHRs compost which inhibited phytopathogenic activities in soil. Many identified compounds were alkaloids, flavonoids and coumarins which have powerful antifungal and antibacterial abilities and most of them maintained during growth period though their amounts reduced greatly due to their photolytic and pyrolytic properties. Therefore, mature CMHRs compost can be the substitute to reduce the usage of fungicides and its associated environmental hazards. The present study demonstrates clearly the beneficial effects of using CMHRs as a bulking agent to co-compost with food waste with the additional phytopathogens suppression property. Therefore, it is concluded that Chinese medicinal herbal residues can be a good choice of bulking agent in food waste composting system. Organic matter degradation and humification process were accelerated by CMHRs addition and mature CMHRs compost had antipathogenic effect and protect plants from infection

Composting is considered as an effective and sustainable food waste treatment technology from the perspectives of volume reduction, stabilization and releasing the pressure on landfills. Community composter is a decentralized composting facility in fed-batch operational mode which is usually being installed in the backyard of institutes, hospitals, housing estate etc. to handle the food wastes generated daily. Albeit numerous operational issues including high initial acidity and oil content, poor decomposition and odor generation are commonly encountered in these facilities, which make it difficult to be accepted by the public. Therefore, the aim of the present study is to develop a composting mix formulation that can provide a solution to all these issues in a fed-batch food waste composting process. The first phase of this study aims at finding out an optimized formulation in a batch-scale food waste composting process through the use of alkaline amendments and microbial inoculum. For the first two experiments, artificial food wastes were prepared by mixing 1.3kg bread, 1kg boiled rice, 1kg cabbage, 0.5kg fully boiled pork and mixed with sawdust to obtain a C/N of 30 and adjusted moisture of the mixtures to 55%. The effect of different concentrations of zeolite compared to lime was studied in the first experiment. Zeolite was amended with food wastes and sawdust mixtures at 2% (ZI-2), 5% (ZI-5), 10% (ZI-10) to compare with lime in 2.25% (L-2.25) w/w (dry weight basis) and composted for 56 days. Results demonstrated that 10% of zeolite was optimal amendment rate compared to lower dosage of zeolite (2% & 5%) with stronger pH buffering capacity and greater decomposition efficiency. Addition of 2.25% of lime buffered the pH efficiently but increased the ammonia loss significantly which eventually reduced total nitrogen (TN) content of final product and posed odor emission problem. Amendment of 10% zeolite provided a higher adsorption affinity on ammonia resulting in 2.05% of TN value of final product which was higher than 1.72% of lime treatment. Furthermore, significantly higher seed germination 150% was achieved of ZI-10 compost compared to 135% of L-2.25 due to low ammonium content of product. The first experiment showed that application of less than 10% zeolite was not sufficient to buffer the acidity; as a result, organic matter decomposition was inhibited. However, the cost and reduction in treatment percentage of food waste in 10% application rate of zeolite is an issue of concern. To tackle this dilemma, food waste was amended with struvite salts at 1:2 molar ratio of MgO and K2HPO4 (Mg:P) with or without zeolite amended at either 5% or 10% amendment (Mg:P, Z5 + Mg:P & Z10 + Mg:P) and a control treatment with food waste only was also included. Results showed that treatment of Z10 + Mg:P was synergistically achieved of pH and EC buffering, and N conservation but not for the case of 5 % zeolite. Treatment of Z10 + Mg:P further reduced the N loss to 18% compared to 25% and 27% of Mg:P and Z5 + Mg:P respectively. However, there was insignificant difference in the final nitrogen content and decomposition rate among all treatments with struvite salts amendment. Comparing to the treatment of Z-10 of the first experiment to Z10 + Mg:P of the second experiment, Z-10 showed superior performance since better decomposition efficiency, shorter time to require to pass the GI (28 Days) and lower cost because of salts exclusion. To develop a multipurpose formulation for the fed-batch operational food waste composter, high lipids problem in food waste cannot be neglected because it is a critical factor to hinder the decomposition efficiency. Inoculation of oil degradative microorganisms was reported as an effective approach to facilitate the lipids. Therefore, the third experiment was to investigate the overall composting performance supplemented with 10% zeolite and microbial consortium. 10% zeolite with bacterial consortium significantly reduced the lipid contents from 7% to 1% compared to control treatments. Furthermore, treatments amended with 10% zeolite was proved to reduce ammonia emission and total volatile fatty acids level in the composting mass, therefore the total odor emission level can be reduced. Zeolite at 10% was found to be a suitable optimum additive for both synthetic and real-food wastes. Therefore, treatment of 10% zeolite with bacterial consortium is selected as an optimized formulation for further study of its application in a fed-batch composter. Following the food waste zeolite composting formulation obtained in Phase I, the aim of Phase II was to develop an ideal composting mix formulation for on-site commercial composters. Although the results have been demonstrated 10% zeolite with bacterial consortium facilitated the composting efficiency in batch composter, those amendments may be over-estimated if applied in a fed batch composter by using real food wastes. With this constraint, the applicability of these additives in commercial fed-batch composter needs to be assessed using locally generated food wastes. Treatments included food waste and sawdust mixtures at 4:1 mixing ratio (wet weight basis) were mixed with 2.25% of lime (L2.25), 10% of zeolite (Z10) and 10% zeolite with bacterial inoculum (Z10+O) and a control of food waste with sawdust mixture only was also included. 35 kg compost mixture was fed into each composter respectively daily for a period of 42 days. Only Z10+O was the most suitable composting mix for fed-batch food waste composting process with continuous sustained high temperature (55-60oC), optimal moisture (55%-60%), alkaline pH and low EC during the experimental period. Bacterial inoculum significantly improved the lipids decomposition from 22.16% (C) to 3.10% (Z10+O) after the composting period. In contrast, lime and zeolite alone treatments could not maintain the optimal pH that led to reduce degradation and longer stabilization period. Only compost taken from Z10+O treatment could be classified as mature compost. The aim of the third study phase was to examine an optimal application rate of food waste compost produced from decentralized food waste composter for plant. A plant growth experiment was conducted in this phase to evaluate the change in soil properties and plant growth of Brassica chinensis and Lycopersicon esculentum. The experiment was conducted in a loamy soil amended with 0%, 2.5%, 5% and 10% food waste compost amendment rate compared to the control soil with chemical fertilizer amendment only. Results indicated that 5% was the optimal application rate of food waste compost for both crops among all treatments which can be evidenced by the highest biomass production and nutrients value of the plant tissues. Plant available nutrients such as NH4+, NO3-, PO43- were proportionally increased with increase in compost application rate. However, 2.5% of the food waste compost did not provide sufficient nutrients for plant growth and 10% showed negative effects due to increased salts content. Plants amended with chemical fertilizer had relatively low biomass production compared to compost amended treatments due to soil compaction and fast leaching of nutrients. It can be concluded that application of 10% zeolite with microbial consortium is an ideal composting mix formulation for on-site commercial composters and 5% is an optimal application rate of food waste compost of Brassica chinensis and Lycopersicon esculentum

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Dissertação (Mestrado)
IPEN/D
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

The objective of this study is to illustrate that phase separation improves the efficiency of an anaerobic system which digests semi-solid organic wastes. Organic fraction of municipal solid waste (OFMSW) was the semi-solid organic waste investigated. In the first part of the study, the optimum operational conditions for acidified reactor were determined by considering the volatile solid (VS) reductions and average acidification percentages at the end of two experimental sets conducted. Organic loading rate (OLR) of 15 g VS/L.day, pH value of 5.5 and hydraulic retention time (HRT) of 2 days were determined to be the optimum operational conditions for the acidification step. Maximum total volatile fatty acid and average acidification percentage were determined as 12405 mg as HAc/L and 28%, respectively in the reactor operated at optimum conditions. In the second part, an acidification reactor was operated at the optimum conditions determined in the first part. The effluents taken from this reactor as well as the waste stock used to feed this reactor were used as substrate in the biochemical methane potential (BMP) test. The results of BMP test revealed that the reactors fed by acidified samples indicated higher total chemical oxygen demand (tCOD) removals (39%), VS reductions (67%) and cumulative gas productions (265 mL). The result of this study indicated that the separation of the reactors could lead efficiency enhancement in the systems providing that effective control was achieved on acidified reactors.

Orientador: Egle Novaes Teixeira
Dissertação (mestrado) - Universidade Estadual de Campinas. Faculdade de Engenharia Civil, Arquitetura e Urbanismo
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Resumo: Com o crescimento urbano e a mudança dos padrões de consumo, houve o aumento da quantidade e qualidade do material descartado. Desta forma, com a produção de material cada vez mais complexo e a composição do resíduo sendo freqüentemente alterada, a estratégia de gestão e gerenciamento para solucionar o problema, fica mais difícil. A tendência mundial, em relação aos problemas provenientes do resíduo sólido, é a busca contínua de formas adequadas para dispô-lo e, com a consciência ambiental sendo fortemente incentivada, deve-se buscar minimizá-lo, como princípio. A realidade do futuro sustentável do ambiente traz como premissas, a redução, reutilização e reciclagem, ou seja, a Minimização de Resíduo. O objetivo deste trabalho foi avaliar o potencial de Minimização do Material Biodegradável de Alimentação contido no Resíduo Sólido Domiciliar de Municípios da Região Metropolitana de Campinas. Identificou-se o que estava presente no resíduo sólido domiciliar, através de caracterização (determinação da composição gravimétrica), adaptada para a minimização, que foi realizada durante o período de um ano, nos domicílios dos municípios de Valinhos, Vinhedo e na macrozona três do município de Campinas. Escolheu-se os bairros e trinta domicílios por município, considerando-se a classe social. Em cada dia pré estabelecido, coletou-se o resíduo diretamente nas casas, perfazendo um total de 480 amostras no período analisado. Após o tratamento dos dados, foi calculado o potencial de minimização do material biodegradável de alimentação, que apresentou valores acima de 50%, indicando que muito tem para ser feito. As possibilidades de minimização do resíduo foram avaliadas e para cada tipo de desperdício são apresentadas maneiras para viabilizá-lo. No âmbito de gerenciamento integrado de resíduo dos municípios, esta pesquisa fornece parâmetros científicos para embasar ações e mecanismos de planejamento que incentivem e conduzam a população ao desenvolvimento consciente, à melhor utilização dos produtos/ material, sem desperdício e levando em consideração a esgotabilidade do ambiente
Abstract: An increase of the amount and quality of the discarded material has arisen as a result of the urban growth and the change of consumption standards. With the production of material each day more complex and the composition of the waste being frequent1y modified, the treatment to this problem becomes more difficult. The worldwide trend, in relation to the problems associated with solid waste, is the continuous search for adequate forms for its disposal, and with the environment conscience being strongly stimulated; one must pursue means to minimize it, as a principle. The reality of the sustainable future of the environment brings as premises, the reduction, reutilization and recycling, or either, the Waste Minimization. The objective of this work was to evaluate the potential of Minimization of the Food Biodegradable Material contained in the Domiciliary Solid Waste in Cities of the Metropolitan Region of Campinas. It was identified what was present in the domiciliary solid waste, through the characterization, determination of the gravimetrical composition, that was carried through during the period of one year, in Valinhos, Vinhedo and in the macro zone three of Campinas, choosing the regions and the thirty domiciles, collecting the residue direct1y in these and considering its social standards. After the treatment of the data, the potential of the minimization of the biodegradable food material, which was found to be above 50%, was calculated and the possibilities of minimization were evaluated taking into account viable mechanisms to make it. Within the scope of the integrated municipal solid-waste management plan, the current research provides scientific parameters to support actions and mechanisms that stimulate and lead the population to the conscientious development, better use of the materials, without wastefulness and taking in consideration the environment exhaustion
Mestrado
Saneamento e Ambiente
Mestre em Engenharia Civil

The wine industry produces large amounts of liquid and solid organic wastes in the form of lees and pomace. The high concentration of organics, measured as chemical oxygen demand (COD) contained in these wastes complicates disposal or reuse, however, this same characteristic makes them ideal for anaerobic conversion to methane gas, a cleaner energy source than fossil fuels. The main objective of this research was to determine whether these wastes could be treated anaerobically to produce methane, and to isolate ideal conditions for conversion. Research activities included 1) a waste audit of a medium-sized winery to determine the type and quantities of organic waste produced, 2) characterization of the waste, 3) enrichment of anaerobic cultures, 4) a set of biochemical methane potential (BMP) tests to assess the impact of different waste combinations on methane yields, and 5) a second set of BMP tests to assess the impact on methane yields by different waste types at different food to microorganism ratios (F/M) and at different waste combinations. The research yielded the following general results. 1) Two anaerobic cultures were successfully enriched to degrade lees and tartaric acid. 2) BMP testing showed the enriched cultures could be overwhelmed by an excess of lees, and pomace could be degraded to some extent (~ 30% COD) but over long periods of time (> 100 days). Both wastes were successfully converted to methane but at different rates. Post-experiment analysis showed an F/M ratio of 5 might be ideal for methane conversion. 3) Another set of BMP tests revealed lees was converted to methane more efficiently at an F/M ratio of 4, yielding 0.25 ± 0.01 L CH4/g COD consumed. An ideal F/M ratio was not identified for pomace. Co-treatment of lees and pomace at different combinations did not reveal an ideal mix as all three combinations tested were statistically similar in yields, an average of 0.13 ± 0.02 L CH4/g COD consumed. It was found that pomace had inhibited methanogenesis in the co-treatment tests; however, further research is needed to determine the cause and extent of this inhibition.

De-inking sludge and its contaminants were studied in supercritical water (SCW), where temperature and pressure are above water's critical point of 374ºC & 22.1 MPa. Phase behavior of pure organics in the sludge were studied with a diamond anvil cell (DAC) technique, and optical & FT-IR microscopes. Oxidation experiments in SCW were performed in batch and flow reactors for the complex sludge and pure decachlorobiphenyl (10-CB).
From the visual observations in the DAC, homogeneous phases with water were found for cellulose at 329ºC; for naphthalene (NT) at 383ºC; for benzo(a)pyrene (BaP) at 508ºC and for polystyrene (PS) at 570ºC. Adding O2 shifted the formation of the single phase to lower temperature. Complete dissolution of 10-CB occurred only when excess O2 was present (at 548ºC with 225% excess O2 or at 450ºC for 596 s with 93% excess O2). Adding Na2CO3 significantly enhanced dissolution rate of 10-CB, for example, using 2.5-mol% Na2CO 3, complete dissolution was achieved at 434ºC even with low O 2 concentration (69.5% theoretical O2).
The homogeneous conditions are important for the oxidation study of the sludge in batch reactors. Oxidation experiments of heavy metal (Pb, Cr, Cd)-, NT and BaP-contaminated sludge in SCW were conducted. It was found that all organics in the sludge, including stable polycyclic aromatic hydrocarbons could be almost completely oxidized to CO2 and H2O. The water-soluble heavy metal salts were effectively removed by precipitation to insoluble oxides and salts with little leachability. During the oxidation of 10-CB at 225% excess O2, only 99.2% destruction rate was obtained accompanied by severe corrosion of the reactor. However, using 100% theoretical Na2CO3, all 10-CB was destroyed at 159.5% excess O 2 with little corrosion. 10-CB was also successfully destroyed in a flow reactor.
Oxidation pathways of the major components of the sludge and a sequence of corrosion reactions were proposed.
It can be concluded that the SCW oxidation process is an effective technique for the destruction of organic wastes including very stable hazardous compounds (e.g., BaP & 10-CB) due to the homogeneous conditions of chemical reactions and removal of heavy metals.

Els residus biodegradables reben una atenció especial en el marc legislatiu europeu actual (Revised Framework Directive 2008/98/CE) i en la seva transposició a Espanya a traves del Plan Nacional Integrado de Residuos 20082015 (PNIR), degut al significatiu impacte ambiental derivat quan aquestos residus no són tractats correctament i al seu potencial ús com recursos renovables mitjançant l’obtenció de compost i biogàs. Pel correcte tractament d’aquestos residus és imprescindible el desenvolupament d’instal·lacions i plantes de tractament eficaces i eficients. La correcta avaluació de l’efectivitat i eficiència d’aquestes instal·lacions requereix una mesura fidedigna del contingut de matèria orgànica biodegradable dels residus i per tant de la seva estabilitat. Aquesta mesura permetria: i) establir una classificació dels residus i productes en base a la seva biodegradabilitat i estabilitat; ii) la correcta avaluació de les plantes de tractament en funcionament; iii)el disseny de noves i optimitzades instal·lacions, i iv) la determinació del potencial impacte ambiental dels productes finals. La informació obtinguda mitjançant l’anàlisi de paràmetres purament físics o químics dels residus no es capaç de reflectir la naturalesa biològica dels residus. És molt extensa la bibliografia que descriu, proposa i avalua l’ús d’índexs biològics, aerobis i anaerobis, per caracteritzar els residus orgànics. De la mateixa manera, aquestos índexs, han estat proposats en diferents normatives de paises europeus com paràmetres d’estabilitat. En aquesta Tesis s’han desenvolupat noves metodologies per a la determinació d’índexs biològics aerobis i anaerobis, optimitzant les metodologies ja referenciades, eliminant les seves limitacions i ampliant la seva utilitat: índexs respiromètrics aerobis, expressats com velocitat de consum d’oxigen i consum acumulat durant un temps determinat i índexs anaerobis, expressats com producció acumulada de biogàs i metà durant un temps determinat o total. Aquestes metodologies s’han avaluat i verificat mitjançant les següents aplicacions: 1) Optimització del procés de compostatge de fangs procedents d’EDARs urbanes, determinant la relació d’estructurant‐fang mínima necessària per obtenir un producte final higienitzat i estabilitzat a escala industrial. 2) Completa avaluació d’una planta de tractament mecànic‐biològic (MBT) amb capacitat per tractar 240.000 tones/any de residus municipals, monitoratge del procés i determinació de les eficàcies d’eliminació de matèria orgànica en cada etapa. 3) Estudi específic del pretractament mecànic d’una MBT i la seva influencia en l’eliminació de matèria orgànica biodegradable. 4) Determinació de potencials totals de producció de biogàs mitjançant l’anàlisi d’índexs biològics anaerobis de curta durada. 5) Determinació de les correlacions entre indexs aerobis i anaerobis. Determinació de les correlacions entre els diferents indexs aerobis i discusió sobre la diferent informació que poden proporcionar. 6) Caracterització completa de residus basant‐se en la diferent informació proporcionada pels indexs respiromètrics aerobis. 7) Redacció d’un protocol estandarditzat per a la determinació de la biodegradabilitat de residus orgànics de diferent origen i tipologia per l’Agencia de Residus de Catalunya, basant‐se en la determinació d’índexs biològics aerobis. Els resultats obtinguts en tots aquestos treballs i estudis confirmen la idoneïtat de l’ús dels índexs biològics com mesura real del contingut de matèria orgànica biodegradable dels residus i per tant de la seva estabilitat. A més es poden considerar com un paràmetre clau pel disseny i control de plantes de tractament de residus.
Los residuos biodegradables reciben una atención especial en el marco legislativo europeo actual (Revised Framework Directive 2008/98/CE) y en su transposición en España a través del Plan Nacional Integrado de Residuos 20082015 (PNIR), debido al significativo impacto ambiental derivado cuando no son tratados correctamente y a su potencial uso como recursos renovables mediante la obtención de compost y biogás. Para ello, es imprescindible el desarrollo de instalaciones y plantas de tratamiento eficaces y eficientes. La correcta evaluación de la efectividad y eficiencia de estas instalaciones requiere una medida fidedigna del contenido de materia orgánica biodegradable de los residuos y por consiguiente de su estabilidad. Esta medida permitiría: i) establecer una clasificación de residuos y productos en base a su biodegradabilidad y a su estabilidad; ii) la correcta evaluación de las plantas en funcionamiento; iii) el diseño de nuevas y optimizadas instalaciones; y iv) la determinación del potencial de impacto ambiental de los productos finales. La información obtenida mediante el análisis de parámetros puramente físicos o químicos de los residuos no es capaz de reflejar la naturaleza biológica de los residuos. Es muy amplia la bibliografía que describe, propone y evalúa el uso de índices biológicos, aerobios y anaerobios, para caracterizar los residuos orgánicos. Asimismo, éstos índices han sido propuestos en diferentes normativas de países europeos. En esta Tesis se han desarrollado nuevas metodologías para la determinación de índices biológicos aerobios y anaerobios, optimizando las metodologías ya referenciadas, eliminando sus limitaciones y ampliando su utilidad: índices respirómetricos aerobios, expresados como velocidad de consumo de oxígeno y su consumo acumulado durante un tiempo determinado e índices anaerobios expresados como producción acumulada de biogás y metano durante un tiempo determinado o total. Estas metodologías se han evaluado y verificado mediante las siguientes aplicaciones: 1) Optimización del proceso de compostaje de lodos procedentes de EDARs urbanas, determinando la relación de estructurante‐lodo mínima necesaria para obtener un producto final higienizado y estabilizado a escala industrial. 2) Completa evaluación de una planta de tratamiento mecánico‐biológico (MBT) con capacidad para tratar 240.000 toneladas/año de residuos municipales, monitorización del proceso y determinación de las eficacias de eliminación de materia orgánica en cada etapa. 3) Estudio específico del pretratamiento mecánico de una MBT y su influencia en la eliminación de materia orgánica biodegradable. 4) Determinación de potenciales totales de producción de biogás mediante el análisis de índices biológicos anaerobios de corta duración. 5) Determinación de correlaciones entre índices aerobios y anaerobios. Determinación de correlaciones entre diferentes índices aerobios y discusión sobre la diferente información que proporcionan. 6) Caracterización completa de residuos basándose en la diferente información proporcionada por los índices respirométricos aerobios. 7) Redacción de un protocolo estandarizado para la determinación de la biodegradabilidad de residuos orgánicos de diferente origen y tipología para la Agència de Residus de Catalunya basándose en la determinación de índices biológicos aerobios. Los resultados obtenidos en todos estos trabajos confirman la idoneidad del uso de índices biológicos como medida real del contenido de materia orgánica biodegradable de los residuos y por lo tanto de su estabilidad. Además pueden considerarse como un parámetro clave para el diseño y control en plantas de tratamiento de residuos.
Biodegradable waste receives especial attention in the European Legislation (Revised Framework Directive 2008/98/CE) and this has been also reflected in Spanish Legislation in the Plan Nacional Integrado de Residuos 20082015 (PNIR), due to the high importance that this municipal solid waste fraction has on the waste treatment environmental impact when it is not treated correctly and the possibility of recycling the biodegradable waste, to finally obtain compost or/and biogas that means green energy. For this purpose is necessary to develop suitable facilities for all waste treatments and assure the correct and efficient operation of such treatment and management facilities or plants. The correct determination of process efficiency in these facilities requires a reliable measure of the biodegradable organic matter content of the wastes and their stability. This measure would allow: i) to establish a waste classification based on the biodegradability and stability; ii) the correct evaluation of plant and facilities performance; iii) the design of new and optimum facilities and waste treatments; and iv) to determinate the environmental impact of the final products of these facilities. The information given by the analysis carried out just considering physical and chemical parameters is not able to reflect the correct biological nature of the wastes. It is really considerable the bibliographic references regarding the description, use and evaluation of biological indices, both aerobic and anaerobic, to characterize organic wastes. Additionally, these indices have already been proposed in some European countries’ Legislations. In this Thesis, new methodologies have been developed to determine aerobic and anaerobic biological indices, trying to optimize the already published methodologies by detecting their weaknesses, proposing improvements and increasing their utility. The indices obtained using these methodologies are: aerobic respirometric indices, expressed as the oxygen consumption rate and cumulative oxygen consumption during a given time and anaerobic indices, expressed as cumulative biogas and methane production during a given time or total biogas or methane production. These methodologies have been assessed, evaluated and verified in different facilities, different treatments and in several works with different aims: 1) Optimization of the composting process of dewatered wastewater sludge, determining the minimum ratio of pruning waste used as bulking agent to obtain a hygienized and stabilized product in full scale facilities. 2) Complete assessment of a mechanical‐biological treatment (MBT) plant treating 240.000 tones each year of municipal solid wastes. Process monitoring an determination of process efficiency regarding organic matter biodegradation. 3) Specific study of the mechanical pretreatment in a MBT plant and how it affects to the biodegradable organic matter removal. 4) Determination of the biogas production potential using anaerobic biological indices, measured in a short experimental time. 5) To obtain correlations between aerobic and anaerobic indices. Additionally, to correlate aerobic indices among them and analyzing the different information that they provide. 6) Using the information provided by aerobic respiration indices to completely characterized organic wastes. 7) Establishment of a standardized protocol to determine the biodegradability of organic wastes, from different origin and nature using aerobic biological indices to Agència de Residus de Catalunya. The results obtained in all works and studies confirm the suitability of biological indices to be measure the biodegradable organic matter content and stability of solid wastes. Additionally, these indices can be considered as key parameters to design and control waste treatment facilities and processes.

A seven-step sequential extraction scheme was used to track changes in operationally defined copper speciation during the composting of a mixture of grass clippings and sawdust originating from tanalised timber. Starting materials were either unamended or treated with differing amounts of soluble copper, using a copper acetate solution, and then composted in the laboratory. Results showed that at the start of the experiment over 80% of the copper present in the unamended materials occurred in forms not immediately available for plant uptake. However, composting processes enabled the release of this copper which then, over time, became more bioavailable. Large amounts of copper in the copper amended materials were initially detectable in all fractions except the residual one, but over time it was seen to move from all fractions to the EDTA extractable fraction, thought to determine organically complexed / chelatable metals (Amir, 2005). This continued until an equilibrium was reached and then the water and calcium nitrate extractable forms appeared to hold the excess. Copper as determined by these extracts would be available for plant uptake. In the second experiment, three different organic wastes (grass/sawdust, pig slurry/sawdust and sewage sludge cake/sawdust) to which copper had been added as copper acetate, sulphate or EDTA, were composted in the laboratory. Samples were taken at 0, 105 and 318 days and subjected to a range of analyses: copper by sequential extraction using two different extraction schemes, a chelating resin membrane (CRM) procedure and by XRF spectrometry; FTIR analysis for functional groups; total carbon, nitrogen and sulphur; pH, EC, NH4+ and NO3- nitrogen, COD, germination indices and optical properties of water extracts. Sequential extractions demonstrated clear changes in copper distribution amongst various fractions within the materials, with copper originally present in the materials being transferred from the oxidisable fractions to easily extractable (and hence potentially phytoavailable) fractions. Transfer of copper from available to less available fractions in copper amended materials was also seen with movement of copper within copper EDTA treated materials being the slowest of all. Initial amounts of copper in fraction 1 extracted from all samples determined the rate at which copper was transformed. CRM determined copper correlated strongly with copper from fraction 1 of the Tessier scheme, although changes over time did not correspond well. Other parameters measured indicated that that the material was maturing (decreases in C/N and polysaccharide functional groups). However, other results demonstrated that the composts were still immature and unstable. Such slow decomposition was attributed to the high lignin content of the materials. Nevertheless, immobilisation of potentially phytotoxic level of copper was still demonstrated. The usefulness of chelating resin membrane as a predictor of phytoavailable copper is also discussed.

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Tese (Doutorado em Tecnologia Nuclear)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN-CNEN/SP

This thesis aimed at investigating a process based on anaerobic mixed culture fermentation (AMCF) of organic waste to produce carboxylates, molecular hydrogen and ethanol. The novelty of this study was to estimate the potential production of these bulk chemicals from selected renewable feedstocks and to experimentally investigate their production from the AMCF of three distinct types of feedstock without physicochemical pre-treatment: grass, a lignocellulosic substrate; cheese whey, a lactose-rich residue; and fish processing wastewater, a complex effluent containing proteins and fats. The estimation showed that AMCF of a small fraction (less than 1.6%) of the selected feedstock would be required to suffice the current production of carboxylates from oil-based feedstock, whilst up to 51% of the feedstock would be needed to satisfy the current production of ethanol and molecular hydrogen. In the experiments with AMCF of grass, low organic loading rates and long solids retention times were required to increase the substrate conversion because of the hard-biodegradability found in the substrate without any physicochemical pre-treatment. For the AMCF of cheese whey, the production of carboxylates decreased the pH to low levels and consequently inhibited the fermentation. For the AMCF of fish processing wastewater, the feedstock showed high biodegradability with production of biogas under batch condition and stable production of carboxylates under semi-continuous condition. The release of ammonium during the degradation of proteins was considered one of the main factors to avoid the pH drop when carboxylates were produced throughout the fermentation. In conclusion, the study showed that the feedstock nature and the operating condition play a key role in how to drive the AMCF to the production of these chemicals and avoid methanogenesis. Whilst hydrolysis limits the fermentation for hardly biodegradable feedstock, volatile fatty acids formation and pH inhibit the AMCF of more easily biodegradable feedstock.

Environmental pollution by polychlorinated chlorinated organic wastes is of great concern. Catalytic hydrodechlorination is considered clean and efficient methodology for safe disposal of chlorinated organic wastes. This work aims at studying the catalytic hydrodechlorination reaction for the removal of environmentally polluting chlorinated organic wastes: 1,2,4-trichlorobenzene (1,2,4-TCB) and Trichloroethylene (TCE). The research has focused on evaluation of the activity, selectivity and stability of newly synthesized Pd based catalysts for hydrodechlorination of 1,2,4-trichlorobenzene and trichloroethylene. The first part, related to the HDC of 1,2,4-TCB, is to obtain active and stable catalyst for the hydrodechlorination of C-Cl bond of aromatic compounds to non chlorinated organic aromatic compound (benzene). While the second part aims at obtaining catalysts that allow high selectivity to ethylene formation during the HDC Trichloroethylene. Pd based hydrotalcite derived mixed oxides with different surface property were explored as catalysts for hydrodechlorination reaction. In addition, bimetallic and monometallic heterogeneous catalytic systems were investigated for selective hydrodechlorination reaction. Detailed characterization of the active centers of the newly synthesized catalysts by different techniques was achieved. This work presents original ideas, which could find a practical application, for the treatment of organo-halogenated pollutants.
La contaminación ambiental mediante compuestos policlorados aromáticos y alifáticos es de gran preocupación. La reacción de hidrodecloración catalítica selectiva (HDC) se presenta como una nueva tecnología eficaz para una eliminación segura de estos tipos de compuestos orgánicos clorados. Es por ello, que este trabajo de investigación se ha enfocado en el estudio de nuevos catalizadores activos, selectivos y estables en diferentes reacciones de hidrodecloración de dos familias de compuestos orgánicos clorados: 1,2,4-triclorobenceno (1,2,4-TCB-compuestos aromáticos clorados) y el tricloroetileno (representativo de un compuesto clorado alifático). La primera parte de la tesis relacionadas con el HDC de 1,2,4-TCB, tiene como objetivo la obtención de catalizadores activos y estables para la hidrogenación del enlace C-Cl en compuestos aromáticos y la obtención final del compuesto aromático orgánico declorado. Mientras que la segunda parte tiene por objeto la obtención de catalizadores que permitan una gran selectividad a etileno y no hacia etano (hidrogenación profunda del tricloroetileno) durante la HDC de tricloroetileno. Por otra parte se ha realizado un estudio profundo en la síntesis de estos nuevos catalizadores, así como en la caracterización de los centros activos de dichos catalizadores, para su correlación con la actividad, selectividad y estabilidad de dichos catalizadores. Presenta ideas originales, lo que podría encontrar una aplicación práctica, para el tratamiento de compuestos órgano-halogenados contaminantes.

La correcta gestió dels residus orgànics és un dels principals reptes actuals a la Unió Europea, en resposta al fort increment en la seva producció en les darreres dècades. Les creixents limitacions en la incineració i el dipòsit en abocador de residus orgànics ha conduit cap a un increment en el reciclatge en el sòl d'aquests residus en forma d'esmena orgànica, perfilant-se aquesta com la principal via de gestió actual i futura. Malgrat tot, els residus orgànics són també el destí final de contaminants originats amb les activitats humanes. Per tant, el reciclatge de residus orgànics en sòls pot també representar un risc, ja que podria malmetre de manera irreparable els organismes edàfics i les funcions que duen a terme, bàsiques per al funcionament dels ecosistemes terrestres i les societats humanes.
Actualment, a la Unió Europea no existeixen requeriments de qualitat mínima per a permetre el reciclatge de residus en el sòl, amb l'excepció dels fangs de depuradora, pels quals existeix una legislació específica. A més, en els escassos casos en què existeix aquesta avaluació de qualitat, el criteri utilitzat és exclusivament basat en anàlisis químiques, i fins ara, els bioassaigs no han estat incorporats en la legislació malgrat els seus avantatges en termes de rellevància per a situacions reals. Malgrat tot, un pas necessari per a aquesta incorporació és la definició de quins bioassaigs són adients per a aquesta finalitat.
En aquesta tesi, diversos bioassaigs amb organismes terrestres i aquàtics (Microtox, cladòcers, microorganismes del sòl, plantes, lumbrícids, enquitreids i col·lèmbols), paràmetres biològics (letals i subletals), i procediments (fase sòlida o extractes dels residus) són comparats per al seu ús el l'avaluació de risc ecotoxicològic de diversos residus orgànics per tal de seleccionar-ne els més adients. Posteriorment, per cada residu, i a partir d'un conjunt de dades de toxicitat per a diversos organismes habitants del sòl, s'estimen dosis segures d'esmena, les quals es comparen amb les dosis habituals i amb treballs de camp sobre els efectes d'esmenes orgàniques en la biota del sòl. Finalment, s'estudia la validesa dels resultats de toxicitat d'un residu orgànic obtingut en el sòl artificial OECD per a fer extrapolacions de resultats en sòls naturals. A més, s'avalua la influència de les propietats tant en els organismes test com en la pròpia toxicitat d'un mateix residu.
Correct organic wastes management is one of the main challenges in the European Union given its production increase in the last decades. Increasing limitations to organic waste incineration and landfilling, together with its fertilizing potential, has lead to their recycling as soil amendment. In fact, waste use in soil is currently the main waste management option, and it is predicted to increase in the next years. However, organic wastes also are the final sink of pollutants released by human activities. Disposal in soil might lead to irreparable damage for soil organisms and their functions, which play a central role in terrestrial ecosystems and human societies.
No requirements of a minimum organic wastes quality exist in the European Union for their recycling in soils, with the exception of sewage sludge, for which specific legislation exist. In this particular case, only chemical assays are taken into account and, to date, bioassays are not considered for this purpose, despite their advantages in terms of relevance for real situations. However, a first step for the inclusion of bioassays into legislation for the quality assessment of wastes is to define suitable methods for this purpose.
In this thesis, a wide range of bioassays (Microtox, daphnids, soil microorganisms, plants, earthworms, enchytraeids, and collembolans), endpoints (lethal and sublethal), and procedures (waste's solid-phase and eluates), are evaluated to be used for the ecotoxicological risk assessment of different organic wastes (dewatered, composted and thermally-dried sewage sludges, and thermally-dried pig slurry) in order to select the most suitable methods for this purpose. Furthermore, safe amendment rates for each waste are derived from laboratory data and compared with usual amendment rates and with published field works on waste effects on soil-dwelling organisms. Finally, the validity of OECD artificial soil for waste testing is also assessed by comparison of toxicity results in different natural soils using the same waste. In addition, the biasing influence of soil properties on waste toxicity results is also evaluated, through their effects on the test organisms as well as through their influence on the toxicity of wastes.

Anaerobic digesters decompose organic matter biologically in the absence of oxygen. In some cases, in addition to waste management, the purpose of anaerobic digestion (AD) is to produce methane, which can be used for energy. In the Fraser Valley region, potentially 30 MW of energy can be generated through AD with the additional benefits of reduced odour, green house gas (GHG) emissions and soil and water contamination, which is produced currently from artificial fertilizers. The main goal of this research project is to develop an anaerobic digestion calculator that would assist farm and herd owners in the Lower Fraser Valley in making decisions on choosing suitable anaerobic digestion technologies for their own farms. The calculator is developed from Excel spreadsheets and graphical user interfaces (GUIs). These user interfaces take inputs, send the inputs to the corresponding spreadsheet cells, and block invalid inputs from causing calculation error. The new calculator uses the Lawrence and McCarty kinetic model to calculate substrate consumed during AD. This calculator takes hydraulic retention time (HRT) and feed, via animal counts, single-defined flow or mixing several waste sources, as inputs. From these inputs and default kinetic parameters, which can be modified, reactor size, biogas production rate, effluent characteristics, capital cost and revenue of the AD plant are calculated and summarized for users. Users can select one of the three possible digester configurations: completely-mixed, plug-flow and mixed plug-flow and heat and electricity co-generation or biogas upgrading. Currently the calculator is valid for simulating AD in the mesophilic temperature range only. Further modifications are needed to include other kinetic models, input more feed types and simulate thermophilic AD.

The luxCDABE genes (i.e. full cassette) were inserted into the bacterial strain used in this study, E. coli HB101, using a multi copy plasmid, (pUCD607). A number of experiments were carried out in this thesis to study the potential of using the biosensor, E. coli HB101 (pUCD607), for ecotoxicity testing. Growth and bioluminescence of E. coli HB101 (pUCD607) were characterised and optimised, as well as the stability of this biosensor to a range of environmental parameters. The biosensors were found to be sensitive to a range of pollutants and provided a highly consistent bioluminescence response under conditions likely to be encountered in environmental toxicity testing. Assessment of the potential of the lux-based bioassay for revealing the combination of toxicities of metals was carried out. This is necessary because samples in ecotoxicity testing may contain a number of types of pollutants. The biosensors showed high sensitivity of response to mixed metals and identified the combined toxicity of the mixture. Biosensor bioluminescence could also be used to diagnose the distinction between toxicity after 15 and 30 minutes exposure. Results suggested that exposure time is an important factor affecting on the toxicity of metals in mixtures. The results from challenging lux-based biosensors with heavy metals with various concentration of Cl- demonstrated the effect of Cl- ion complex formation for metals on the bioluminescence of E. coli HB101 (pUCD607). The bioluminescence response of the biosensor also related to the results from computer modelling (GEOCHEM) and was used to diagnose the effect of Cl- on metal toxicity. The results showed that E. coli HB101 (pUCD607) is sensitive to complexes of metals such as are formed by Cl- ion. Immobilised cells of E. coli HB101 (pUCD607) were used to investigate the toxicity of metals, both singly and in mixture. This work aimed to assess the potential of immobilised cells, as an alternative form of biosensor, for use in ecotoxicity testing. Bioluminescence response of immobilised cells varied with the test solution pH and showed that it has great potential for use in low pH environments. Immobilised cell biosensors demonstrated sufficient sensitivity to identify the toxicity of individual and mixed metals. High levels of bioluminescence of immobilised cells lasted up to 5 hours after bead production, suggesting that biosensor immobilisation increases the flexibility of the toxicity assay.

Food and drink processing industries are extremely large consumers of thermal energy as well as bio waste producer. There are huge opportunities to utilise the bio wastes for energy generation. In this project two cases were studied. Fermented grains and hops are used for the beer production and at the end the used materials are disposed with the yeast as organic wastes, in a similar way rice spirit is produced from a mixture of grains which are discarded at the end as spent grains. The feasibility of using the waste individually or in a mixture as feed for Anaerobic Digestion (AD) was evaluated. This project has considered the concepts of generating a more environmentally friendly thermal energy using solely the bio wastes from the industry and if applicable the low grade waste heat available to integrate a waste to energy system. In order to assess the viability of the use of the bio wastes, experimental work in the laboratory for the characterisation of the waste streams as well as an energy audit was performed. Continuous Stirred Tank Reactors (CSTR) were run for a period of time at mesophilic and thermophilic conditions, using the waste grains individually and in a mix. Once the bio methane potential was determined, simulations of the process were executed using engineering software and compared with the data gathered from the site visit. It is found that the figures of final composition of the product as well as the mass and energy balance were similar to the data obtained. The results showed the potential to use the spent grains as feed for the AD plant to produce biogas is positive, covering up to 70% of the total fuel required for production in the case of the brewery and 100 % in a spirit plant. It was also noticed that running the system at thermophilic temperature had a better performance in terms of methane content. The biogas could be used instead of the fossil fuel being used at the moment. Replacing the current use of fossil fuel will be a positive impact in CO2 emissions reduction as well as economic performance for the brewery, since these bio wastes are often given away to farmers free of charge or more expenses would be incurred in discarding them from the site. This will lead to self-sustained production process and improve the waste management.

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Tese (Doutoramento)
IPEN/T
Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP

The most cost effective treatment scheme for effluent from Midfield Meats, an abattoir in Warrnambool, Australia, was evaluated via a series of laboratory and commercial scale experiments. Effectiveness was measured in terms of suspended solids (SS) and biological oxygen demand (BOD) reduction. Economic assessment was based on predicted reduction in trade waste charges versus infrastructure and running costs. From the range of potential treatment technologies, those deemed most appropriate for trialling included pre-screening, sedimentation, coagulation and flocculation treatment and dissolved air floatation (DAF). Prior to evaluation of treatment types, flow, loads and contaminant characterisation of the waste streams was conducted to aid in selection of treatment type and capacity. Prescreening was found to be the most cost effective, followed by sedimentation, coagulation and flocculation treatment and finally DAF. The most economical treatment scheme that satisfied the requirements of Midfield Meats included a combination of prescreening and sedimentation. DAF and coagulation and flocculation treatment satisfactorily treated the wastewater, however were not cost effective under the current trade waste agreement.

Several operational and environmental conditions can result in poor biogas yield during the operation of anaerobic digesters and anaerobic bioreactor landfills. Over time, anaerobic co-digestion and leachate blending have been identified as strategies that can help address some of these challenges to improve biogas production. While co-digestion entails the co-treatment of multiple substrates, leachate blending involves combination of mature and young landfill leachate. Despite the benefits attributed to these strategies, their impact on recirculating bioreactor landfill scenarios and anaerobic digesters requires further investigation. In the first phase of this thesis, an attempt to assess biogas production improvement from organic fraction of municipal solid waste in simulated bioreactor landfills through recirculation of blended landfill leachate was conducted. Real old and new leachate blends (67%New leachate:33%Old leachate, 33%New leachate:67%Old leachate) as well as 100%New and 100%Old leachate were recirculated through six laboratory-scale bioreactors using open-loop and closed-loops modes. Compared with the control bioreactor where 100% new leachate was recirculated and operated as a closed-loop, cumulative biogas production was improved by as much as 77 to 193% when a leachate blend of 33%New:67%Old was recirculated. Furthermore, comparison of the results from open-loop and closed-loop operated bioreactors indicated that there was approximately 28 to 65% more biogas in open-loop bioreactors. The Gompertz model applied to the methane data produced a better fit (R2 > 0.99) than first order and logistic function models. Leachate blending reduced the lag phase by almost half and thus helps in alleviating the ensiling during the start-up phase. In the second phase, a biochemical methane potential (BMP) assay was conducted to investigate the synergistic effect of percentage sewage scum addition; 10%, 20% and 40% (volatile solids basis) on biogas production during mesophilic co-digestion with various organic substrates viz; organic fraction of municipal solid waste, old leachate, new leachate and a leachate blend prepared from 67%old leachate and 33%new leachate under sub-optimal condition. Results show that the net cumulative bio-methane yield was improved with increased sewage scum percentage during co-digestion because of positive synergism. Meanwhile, the addition of 40% sewage scum to the individual co-substrates improved net cumulative bio-methane yield by 28% - 67% when compared to their respective mono-substrate digestion bio-methane yield. Furthermore, reactors containing leachate blends consistently produced more biogas over other sets because of blending. Kinetic modelling applied to the bio-methane production data shows modified Gompertz equation achieved a better fit with up to an R2 value of 0.999. Finally, co-digestion substantially reduced the lag time encountered during mono-digestion. In the last phase, the biomethane potential involved in the ACo-D of sewage scum, organic fraction of municipal solid waste was investigated in this phase using either thickened waste activated sludge or leachate blend (67%old leachate and 33%new leachate) as a tertiary component. Compared to the mono-digestion of TWAS, results shows that biomethane yield was enhanced in by as much as 32 - 127% in trinary mixtures with SS and OFMSW mainly due to the effect of positive synergism. Furthermore, LB addition improved biomethane production in trinary mixtures of SS:LB: OFMSW by 38% than in corresponding trinary mixtures of TWAS. Whereas an optimal combination of 40%SS:10%TWAS:50%OFMSW and 20%SS:70%LB:10%OFMSW produced the highest biogas yield of 407mL.gVS-1 and 487mL.gVS-1 respectively. The application of the first order model showed that lower hydrolysis rates promoted methanogenesis with k = 0.04day-1 in both 20%SS:70%LB:10%OFMSW and 20%SS:50%LB:30%OFMSW. Estimations by the modified Gompertz and logistic function were conclusive methane production rate improved by as much a 60% in a trinary mixture over the production rate during mono-digestion of TWAS alone. The results of the various experiments of this thesis therefore suggest that leachate blending can be used as a strategy to improve biogas production in both bioreactor landfills and anaerobic digesters. Also, sewage scum as an energy-rich substrate can be better utilized during co-digestion with other low-energy substrates.

Thesis (M.S.)--Cleveland State University, 2009.
Abstract. Title from PDF t.p. (viewed on Feb. 16, 2010). Includes bibliographical references (p. 82-89). Available online via the OhioLINK ETD Center and also available in print.

The study presented in this thesis is part of a research effort that is focused on recovery and recycling of energy and material resources from organic waste products. The major objective of this study was to investigate the use of hydrothermal treatment at moderate temperatures (100-250°C) to disintegrate and oxidise the organic component of three waste streams: wastewater treatment sludge; wood waste; and simulated dairy waste. The purpose of disintegrating the organic matter was to achieve two objectives: (1) production of thermal decomposition organic by-products that could be used to enhance the production of anaerobic gas from the treated wastes; and (2) reduction of the quantity of the waste. The three wastes material selected in this research are generated in large quantities. The organic component of wood mostly consists of cellulose fibres. The dairy waste contains fat, proteins and hydrocarbons and the sludge contains fat, proteins, hydrocarbons, and fibres. The effect of adding the oxidant, H202, to reduce the organic content and enhance the thermal decomposition process was also investigated. The disintegration of organic particles was evaluated by assessing the conversion of the particulate chemical oxygen demand (PCOD) and the production of dissolved COD (SCOD). The reduction of the organic content was evaluated using the removal of the volatile solids (VS) and the total COD (TCOD) of the particulate and dissolved organic matter. The three waste types were subjected to hydrothennal treatment using various combinations of temperatures (100-250°C with increments of 50°C), reaction times (20, 40 and 60 minutes) and oxidant (H20 2) dosages (0, 50, 100 and 150% of the initial TCOD). The treated samples were mixed with seed microorganisms and incubated at 35°C in airtight serum bottles to achieve anaerobic gas production. The study confamed that hydrothermal treatment was capable of reducing the organic content of the three waste types effectively. The COD removals achieved were in the range of 1-85% for the sludge, 2-86% for the dairy waste, and 8-86% for the wood waste. The treatment efficiency was dependent on the reaction time, reaction temperature and amount of oxidant supplied. The decomposition of the organic paiiiculate matter was accompanied by the production of dissolved organic matter. The maximum accumulation of soluble organic matter (as measured by SCOD) was achieved when the majority of the particulate organic matter was decomposed. The maximum SCOD concentrations and the majority of the particulate organic matter removals were achieved as the TCOD removal reached 20% for the dairy waste, 40% for the sludge and 60% for the wood waste. The maximum SCOD concentrations were approximately 11,000 mg/L for the sludge (52% of the initial TCOD), 8,500 mg/L for the wood (32% of the TCOD), and 16,000 mg/L for the dairy waste (78% of the TCOD). The treatment by-products responded to anaerobic treatment and produced significant quantities of anaerobic gas. Even with the reductions in the organic content, hydrothermal treatment resulted in improved total gas production for all three waste sources. The total gas production from the wood waste was the most significant. The specific gas production for the untreated wastes was in the following order: dairy waste (0.44-0.55 mL/mg TCOD) >sludge (0.26-0.34 mL/mg TCOD) > wood (0.07-0.11 mL/mg TCOD). Following treatment, the specific gas production was in the following order: sludge (0.13-0.69 mL/mg TCOD) >dairy waste (0.11- 0.58 mL/mg TCOD) >wood (0.02-0.42 mL/mg TCOD). The improvement in gas production from the wood waste suggested that the organic by-products generated from the wood using hydrothermal treatment were more readily available for anaerobic gas production than the original organic component of the wood.

This study was carried out to evaluate the potential of high-rate anaerobic digestion of high-solids organic fraction of municipal solid waste (OFMSW) for the production of organic acids and alcohols in leaching bed reactors (LBRs). For this purpose, two different experimental set-ups, namely Set-1 and Set-2, were operated. In the Set-1, only OFMSW without paper was studied in two identical LBRs, whereas, four identical LBRs, fed with OFMSW with paper and cow manure in different proportions, were operated in the Set-2. In this study, 50-60% of hydrolysis efficiency was achieved in the LBRs of Set-1, whereas this value was decreased to 20-25% in the LBRs of Set-2
which was resulted from OFMSW containing cellulose and less volume of water addition in the Set-2. The mass of total volatile fatty acids (tVFA) production was found as 7000-9000 mg at the end of 80 days in the LBRs of Set-1, fed with OFMSW without paper, whereas it was 3000 mg at the end of 40 days in the LBR of Set-2, containing only OFMSW with paper. It was also observed that cow manure addition increased the amount of tVFA production in the LBR of Set-2. In conclusion, LBRs were found as alternative reactors for the degradation of OFMSW compared to completely stirred tank reactors (CSTRs) in terms of rapid hydrolysis and acidification, which can result in high hydrolysis yield and tVFA production.

Natural organic matter (NOM), a complex mixture of organic compounds, influences drinking water quality and water treatment processes. The presence of NOM is unaesthetic in terms of colour, taste and odour, and may lead to the production of potentially carcinogenic disinfection by-products (DBPs), as well as biofilm formation in drinking water distribution systems. Some NOM removal processes such as coagulation, magnetic ion exchange resin (MIEXTM) and membrane filtration produce sludge and residuals. These concentrated NOM-containing sludges from alum precipitation, membrane treatment plants and MIEX regeneration must therefore be treated prior to disposal. The white-rot fungi possess a non-specific extracellular oxidative enzyme system composed of lignin peroxidase (LiP), manganese-dependent peroxidase (MnP) and laccase (Lac) that allows these organisms to mineralise lignin and a broad range of intractable aromatic xenobiotics. Rojek (2003) has shown the capabi lity of Phanerochaete chrysosporium ATCC 34541 to remove 40-50% NOM from solution, however, this was found to be mainly due to adsorption and to be a partially metabolically linked activity. Consequently, the bioremediation of NOM wastes by selected white-rot fungi was further investigated in the present study. The P. chrysosporium seemed to preferentially remove the very hydrophobic acid (VHA) fraction, and so was most effective for a NOM preparation with a high proportion of hydrophobic content (and so high in colour and specific UV absorbance (SUVA)). The extent of NOM decolourisation by P. chrysosporium in three growth media with different C:N ratios followed the trends: Waksman (C:N = 6) > Fahy (C:N = 76) > Fujita medium (C:N = 114), such that the lower the C:N ratio, the greater NOM removal. This was consistent with the findings of Rojek (2003), who used a different NOM preparation and demonstrated that the removal of NOM increased with decreased C:N ratio (1.58-15.81). As removals of NOM with P. c hrysosporium ATCC 34541 were low, and little biodegradation occurred, this organism was compared with P. chrysosporium strain ATCC 24725, Trametes versicolor ATCC 7731, and three strains of yeast (Saccharomyces species arbitrarily denoted 1, 2 and 3). T. versicolor gave the greatest removal (59%) which was attributed largely to degradation, whereas the NOM removal by the two strains of P. chrysosporium (37%) and the yeast was predominantly due to adsorption as indicated by the deep brown colouration of the biomass. Saccharomyces sp. 1, 2 and 3 removed 12%, 61% and 23% of the colour, respectively. Although Saccharomyces sp. 2 had similar high colour reduction to T. versicolor, the specific removal values differed markedly: 0.055 compared to 0.089 mg NOM/mg biomass, respectively. The low level of the ligninolytic enzymes secreted by both strains of P. chrysosporium corresponded with the low degree of NOM removal by biodegradation as shown by high performance size exclusion chromatography (HPSEC). The high NOM removal attained by T. versicolor was attributed to the activities of the ligninolytic enzymes, especially laccase. The NOM removal was attributed to the breakdown of the high molecular weight compounds to form a pool of low molecular weight materials, which were then most likely utilised by the T. versicolor. Growth of T. versicolor cultures at 36oC caused inhibition or denaturation of the activity of the phenoloxidase enzymes compared to those grown at 30oC. The low activity of LiP in both cultures suggested that this enzyme may not play much of a role in NOM removal. The higher levels of MnP and Lac activities at 30oC were responsible for the greater NOM removal (73% vs. 59%) and thus the cleavage of aromatic rings, conjugated and C-Cβ αbonds in phenolic moieties, as well as catalysing alkyl-aryl cleavage in the NOM structures. T. versicolor cultured in Waksman medium with higher initial glucose (5 g/L cf. 2 g/L) led to lower ligninolytic enzyme activities and a lower degree of NOM removal (25% less colour reduction), probably due to preferential use of glucose over NOM as carbon source. NOM removal (mg removed) increased linearly with NOM concentration up to 600 mg C/L (62 mg (A446); 31 mg (A254)), above which removal decreased markedly. This trend coincided with increasing total ligninolytic enzyme activity, where the level of Lac increased up to 600 mg C/L NOM although MnP decreased gradually across the range while LiP was only detected for 100 and 300 mg C/L NOM. Hence, the removal of NOM from solution by T. versicolor was associated with high oxidative enzyme activity, particularly of laccase. Laccase was the major extracellular enzyme secreted by T. versicolor and by deduction, played a major role in NOM removal. The optimum temperature for Lac activity secreted by T. versicolor cultured in Waksman medium supplemented with 4.5 g/L wheat bran plus 0.5% Tween 80 was determined to be 50oC. The optimum pH for the Lac activity for guaiacol and NOM was identified as pH 4.0-4.5. Although the optimum enzyme activity occurred at 50oC, 30oC was recommended for enzymatic removal of NOM as the phenoloxidase enzyme activity may be denatured if the NOM removal process were considered to run for long period at high temperature. Although agitation led to apparent enzyme denaturation, fermentations with continuous agitation promoted enzyme activity faster than those with occasional agitation (agitated every 6 hours for 30 minutes at 130 rpm and 30oC) as it provides better mass transfer. However, it seemed that continuous agitation had an adverse effect on the fungal growth and enzyme production over extended fermentation periods. Addition of 4.5 g/L wheat bran to modified Waksman medium in the absence of NOM led to high production of Lac activity compared with LiP and MnP activities, showing its great potential as a laccase inducer. Addition of Tween 80 alone to the cultures led to a small improvement in Lac activity; however, with the presence of wheat bran it caused marked increases in LiP, MnP and Lac activit ies. When NOM was added to cultures of T. versicolor with the two supplements, it led to markedly reduced Lac activity, but increased LiP and MnP activities, and no improvement in NOM removal compared with the cultures in the absence of supplements (12 mg (or 61%) cf. 15 mg (or 73%) for 100 mg C/L after corrected for colour from and adsorption by wheat bran).