Among the different available remediation technologies, it is well-known that bioremediation methods which mainly depend on microorganisms to degrade, transform, detoxify or break down the contaminants, they are recognized as cost-effective and environmental-friendly methods. In fact, microorganisms “engine of bioremediation process” carry out their normal duty under aerobic or anaerobic conditions, which without doubt extends and motivates the desires to make use of such abilities to reduce environmental threats caused by various contaminants. However, to achieve satisfactory results during any bioremediation process, providing optimal conditions for microorganisms is considered as an essential/crucial task. Composting as one of the applied bioremediation technologies used to remediate soils contaminated with organic contaminants like PAHs still needs more investigation although a valuable effort has been devoted to elucidate the behaviour of this process in the remediation of PAHs-contaminated soils. However, till recently, anaerobically treatment of PAHs-contaminated soil received less attention as it was believed that PAHs are poorly or even impossible to be degraded under such conditions. Therefore, the present study tried to touch both aerobically bioremediation of PAH-contaminated soil through composting and anaerobically treatment of the same soil under strict methanogenic conditions. For both remediation approaches, the effect of some controlling factors had been also evaluated through experiment design methodology employing central design (CCD) technique. Regarding the composting process, the obtained results demonstrated that this technology is an advantageous and indisputable method to decontaminate PAHs-contaminated soils within short period. Additionally, compost derived from the organic fraction of municipal solid wastes (OFMSW) was found to enhance the contaminants (PAHs) removal rate to high extent. Moreover, a lucid correlation between the contaminants removal rate and the compost stability degree was observed, such that more stable composts better enhanced the remediation process as these composts are believed to have a considerable fraction of humic matter which facilitates the desorption of the contaminants, and get more available as a consequence. At the same time, treatments with stable composts do not produce high temperature during the composting process, and normally they are in the mesophilic ranges which are more favourable for such bioremediation process. Bioaugmentation of the process through introducing white-rot fungi with desired catalytic capacity (Trametes Versicolor) in attempt to accelerate the degradation process demonstrated that no effect or enhancement was achieved through such approach. In the second part of the research, anaerobically treatment of PAHs-contaminated soil has been investigated under strict methanogenic conditions employing two types of inocula; thermophilic and mesophilic. The obtained results demonstrated the effectiveness of such biological treatments in this field. Nevertheless, the process was relatively less effective compared with composting. Furthermore, under these conditions and due to unclear reasons, reversible results were obtained as PAHs concentrations were increased with prolonged incubation, indicating the reversed bioformation of PAHs under such oxygen-deficient conditions. Therefore, future work should be devoted to clarify the reasons behind this behaviour.

No description available.

The study objectives were to identify the best practice components of a biosolids composting utilization program; to determine current and emerging provincial and federal regulatory frameworks applicable to biosolids composting facilities in Manitoba; and to produce an annotated process map for planning, initiating and operating a biosolids composting facility. Recommendations from this study are to develop a stand-alone regulation that addresses composting requirements for probable feedstocks in provincial legislation, to clearly set out the requirements for such facilities; to update the Environmental Regulation for Treatment and Disposal of Biosolids in Manitoba policy document to acknowledge and provide guidance for biosolids composting as a potential management method; and to update and finalize the Manitoba Draft Compost Facility Guidelines to reflect current requirements for compost facilities and to include biosolids as a potential feedstock. The adoption of a categorization scheme for biosolids is also recommended to support determining appropriate management options based on biosolids quality.

Two different types of sludges from two popular sewage treatment systems were used in this study; namely, anaerobic pond sludge from a wastewater stabilisation pond system and filter pressed primary sludge from a primary sewage treatment plant. Under Egyptian conditions, Ascaris eggs represent the main health concern for sludge application on land and, accordingly, the effect of sand drying beds and a passive composting system (using agricultural wastes as bulking agents and cement dust as an additive to the sludge) were studied in terms of the inactivation of Ascaris eggs. From the characterisation and assessment of the anaerobic pond sludge from the Mit Mazah wastewater stabilisation pond system, it has been concluded that the sludge was well digested and free of viable Ascaris eggs. Consequently, this sludge is considered to be safe for land application, after appropriate dewatering. For the purposes of the study, anaerobic pond sludge was seeded with Ascaris vitilorum eggs (cattle ascarid). Within 30 days of dewatering on sand drying beds during the winter season (October and November), the Ascaris eggs were found to be inactivated only in the top layers, where the average solids content was approximately 85%. By the end of the two month drying period, the middle and bottom layers of sludge on the drying beds contained an average solids content of 74% to 77% and 72 to 73%, respectively, yet viable Ascaris eggs were still detected. During a second sludge application during the winter season (December and January), unfavourable weather conditions prevailed and, by the end of the 60 days drying period, total solids content averaged 54% in the top layer of sludge. The middle and bottom layers had an average total solids content of 49% and 44%, respectively. Throughout the winter drying period, all samples collected were positive for viable Ascaris eggs throughout the full depth of sludge. However, during the summer season, samples collected from the drying beds after 17 days of drying did not contain viable Ascaris eggs in the top sludge layers, where the solids content ranged from 74% to 63%. After one month of summer drying, no viable Ascaris eggs were detected throughout the entire depth of sludge on the drying beds and the lowest solids content recorded was 80% for the bottom layers. From this study, it can be concluded that, during the wet season in Egypt, drying beds were not efficient in destroying Ascaris eggs throughout the entire sludge depth. During the summer season, Ascaris eggs can be inactivated much more rapidly, compared to the winter season. Desiccation does not seem to be the only factor influencing the destruction of Ascaris eggs, with sludge temperature, solar radiation intensity and exposure time being possible major factors. By comparing the composting of filter pressed primary sludge in passive and windrow piles (used as control piles), it has been proved that the passive composting system is much more efficient in maintaining regular high temperatures in the composting mixture for a much longer duration (additional 10 days), due to the favourable aerobic conditions. Moreover, passive composting preserves the nitrogen content through the naturally controlled internal temperature, less need for turning and lower loss of moisture. By the end of the composting process, the total nitrogen content for the passive and windrow piles was a gain of 17.5% and a loss of 0.7%, respectively, while the ammoniacal nitrogen content in the product was 1109 mg/l and 837 m/l, respectively. From the hygienic point of view, passive composting technology proved to be much more effective in inactivating Ascaris eggs present in the primary sludge, compared to the windrow pile system. Viable Ascaris eggs were not detected after 30 days of composting using the passive system, compared with 60 days of composting for the windrow pile. Industrial cement dust as an additive and agricultural wastes (from fennel and basil production) were incorporated with sludge to form a range of composing mixtures. From the sludge/cement dust composting piles with agricultural wastes as bulking agent, it can be concluded that more than 35% concentration of cement dust was unfavourable for the decomposition process, due to the high pH and high temperature levels attained as a result of the effect of cement dust and dehydration of the organic matter. Moreover, loss of nitrogen was very high, due to the release of ammonia, encouraged by the high pH and high temperature in the composting mixture. The passive composting system was very efficient in naturally controlling the internal temperature in all the sludge/cement dust piles with bulking agent. Excessive heat was released to the atmosphere through the chimney effect created by the circulation of air through the perforated pipes and upwards into the pile. Internal temperatures for even the piles with the highest proportion of cement dust did not exceed 73°C. Inactivation of Ascaris eggs was achieved after only 15 days of composting for all the different cement dust concentrations, mainly due to the influence of high pH and high temperature levels for long periods but may also be due to the high release of ammonia gas. The passive composting of sludge amended with 30% cement dust without bulking agent was inefficient for both the decomposition process and inactivation of Ascaris eggs. No biological activity was taking place during the two months fermentation stage, due to the prevailing anaerobic conditions (lack of air voids and high moisture content) By considering all the different parameters for evaluating a treated compost, including the stability, maturity, nutrient content, heavy metals content and viable Ascaris eggs content for the sludge/cement dust piles with bulking agent, it can be concluded that more than 30% cement dust concentration would be unfavourable, according to the relatively high loss of nitrogen. More than 35% cement dust concentration is certainly unfavourable, mainly as a result of the delay of the decomposition process, the elongation of the composting period and the high loss of nitrogen content. There is no need to separate out the agricultural waste bulking materials after composting because they are organic in nature. Likewise, there is no need to consider separating out the cement dust, as the physicochemical analysis of the final sludge/cement compost with bulking materials showed its suitability for adding to agricultural land as an amendment. In conclusion, sand bed drying is considered to be a suitable process for dewatering of anaerobic stabilisation pond sludge in Egypt and, for extended periods between pond desludging of the order of 6 years, the dewatered sludge will be suitable for direct application to agricultural land. Passive composting is an appropriate technique for preparation of Egyptian filter pressed primary sludge for safe application to agricultural land. Cement dust additions of less than 30% concentration, to the composting mixture in a passive composting system produces sanitised and mature compost. The potential for co-disposal of agricultural wastes and cement kiln dust as bulking agents and additive, respectively, with sewage sludge in the production of compost, is very promising to produce a safe and beneficial outcome to the community.

The study objectives were to identify the best practice components of a biosolids composting utilization program; to determine current and emerging provincial and federal regulatory frameworks applicable to biosolids composting facilities in Manitoba; and to produce an annotated process map for planning, initiating and operating a biosolids composting facility. Recommendations from this study are to develop a stand-alone regulation that addresses composting requirements for probable feedstocks in provincial legislation, to clearly set out the requirements for such facilities; to update the Environmental Regulation for Treatment and Disposal of Biosolids in Manitoba policy document to acknowledge and provide guidance for biosolids composting as a potential management method; and to update and finalize the Manitoba Draft Compost Facility Guidelines to reflect current requirements for compost facilities and to include biosolids as a potential feedstock. The adoption of a categorization scheme for biosolids is also recommended to support determining appropriate management options based on biosolids quality.

This thesis investigated the final products from the current effluent treatment system for woolscouring (wool washing) plants, namely, (i) sludge produced from the chemical flocculation of solids in the wastewater from the wash bowls, and (ii) concentrated suint (sheep sweat) produced from evaporation of the liquid phase separated from the sludge. In addition, fibrous wastes from the woolscouring process were studied. The aims of the study were to (i) investigate whether suint could be applied in a sustainable way to arable land as a potassium fertiliser, and (ii) assess the conditions under which the sludge could be composted for use as a soil conditioner to return organic matter to soil. Experiments involving suint were performed at both laboratory and glasshouse scales, while experiments involving the solid woolscour wastes were based both in the laboratory and using a small-scale (4.5 m3 total capacity) in-vessel composting unit established at a New Zealand woolscour. Decomposition was measured using net-nitrogen mineralisation and weight loss methods. Suint, the water-soluble contaminants on the fleece, contained high levels of potassium (20% on a dry weight basis) and also appreciable quantities of sulphur, sodium, and chlorine. Biological treatment before evaporation stabilised the resulting suint and improved the consistency of its composition. Suint did not affect the soil processes examined, in that it partly decomposed in soil, did not inhibit the turnover of model organic compounds, did not affect soil properties such as pH and electrical conductivity, and did not lead to increased leaching of mineral nitrogen. Suint was either neutral or positive towards plant performance when applied to soil at a rate of 100 kg potassium per hectare. Suint was therefore judged to be suitable for application to land and could be targeted to soils known to be deficient in potassium or to areas where crops with a high potassium demand are grown. Sludge, composed of dirt (soil particles, faecal matter, and skin and fibre debris) and wool grease, was highly variable in terms of its rate of decomposition, ranging from 0.8 to 27.8% of the initial total nitrogen mineralised over 30 days at 37℃. Fibrous wastes, such as opener (fibre and contaminants removed from the wool by agitation prior to scouring) and scoured wool cleaner (wool fibre and dust removed from scoured and dried wool) wastes, also showed variability in decomposition rates. Sludge decomposition was improved by as much as threefold when co-incubated with fibrous wastes. Although it was shown that the polyacrylamide and pesticide content of sludge did not inhibit its decomposition, the effect of the grease content was not fully understood. Chemical properties of woolscour sludge, such as the carbon to nitrogen ratio, suggested that sludge was a substrate of good resource quality. From a biological perspective, however, the data suggested that woolscour sludge was limited in available nutrients; sludge nitrogen was derived principally from keratin, which decomposed at a low rate resulting in the slow release of mineral nitrogen and low levels of microbial activity. Thus, sludge appeared a poor substrate for composting. However, the results from composting trials indicated that the sludge could be successfully processed after blending with a bulking agent such as sawdust. The blended material showed a 90% reduction in wool grease over 21 days of composting when the moisture content of the composting mass was kept optimal. Compost temperature exceeded 55℃ when wool fibre was added to the blend. Initial results from a case study involving the commercial composting of the entire sludge production (16 tonnes per day) from a New Zealand woolscour indicated that a saleable compost could be produced from a material that would otherwise go to landfill, and served to illustrate the commercial significance of these research results.

Made available in DSpace on 2014-06-11T19:32:53Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-08-31Bitstream added on 2014-06-13T19:03:36Z : No. of bitstreams: 1 goncalves_vp_dr_jabo.pdf: 2137160 bytes, checksum: e87c3ecace3827353ad491c1f873e090 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Escherichia coli é a bactéria mais comum entre os patógenos entéricos causadores de doenças intestinais. As diferentes classes de E. coli causadoras de diarréia são reconhecidas através dos fatores de virulência que elas apresentam. As E. coli produtoras de Shiga toxina (STEC), especialmente o sorotipo O157:H7 tem sido associado a diversas doenças no ser humano. Além do sorotipo O157:H7, vários outros sorogrupos não-O157 também estão associados a infecções em humanos. Estas bactérias podem ser recuperadas de muitos animais, mas o gado bovino é reconhecido como o seu mais importante reservatório natural. Para análise da sobrevivência de cepas STEC não-O157 em sistemas de compostagem, inicialmente foram coletadas fezes de três vacas saudáveis que apresentaram E. coli portando o gene stx2, característico de cepas STEC. Foram montados dois sistemas de compostagem: o primeiro foi realizado em vala de 60cmd, no qual E. coli apresentando o gene stx2 foi eliminada após 8, 25 e 30 dias nas temperaturas de 40, 42 e 38°C, respectivamente; o segundo sistema foi realizado sobre o solo em um monte em forma de pirâmide com 1md, no qual as bactérias foram eliminadas após 4, 4 e 7 dias nas temperaturas de 65, 56 e 52°C, respectivamente. A temperatura alcançada durante a compostagem e os microrganismos presentes no esterco parecem ser os responsáveis pela eliminação do patógeno nos sistemas de compostagem, o qual pode ser útil para a redução da carga patogênica presente no esterco destinado para aplicações no solo. / Escherichia coli is the most common bacteria among the enteric pathogens able to cause intestinal disease. Several classes of diarrhea-causing E. coli are recognized on the basis of their virulence factors production. Shiga-like toxigenic E. coli (STEC), especially serotype O157:H7, have been associated with many diseases in human beings. Besides sorotype O157:H7, many others non-O157 sorogroups have also been associated with human infections. These bacterias can be isolated from a range of animals, but cattle is generally recognized as the major natural source. To analyze the survival of non-O157 STEC strains in composting system, first was collected faeces from three healthy cows that contain E. coli STEC cells carrying the stx2 gene. Two composting systems were used: the first one was a cave with 60cmd were the E. coli STEC cells with stx2 gene were eliminated after 8, 25 and 30 days at 40, 42 and 38°C, respectively; the second one was a heap pyramid system with 1md, where the cells were eliminated after 4, 4, 7 days at 65, 56 and 52°C, respectively. The reached temperature in the composting systems and the indigenous microorganisms present in the manure seems to contribute to pathogen elimination, what may be a useful means of reducing the pathogen load of manure destined for soil application.

Submitted by SARA FERNANDES MARTINS null (sfmartins@sabesp.com.br) on 2016-10-27T17:52:47Z No. of bitstreams: 1 MARTINS, S. F. Análise econômica da produção de lodo de esgoto compostado para uso na agricultura..pdf: 5468270 bytes, checksum: 1f4788221e67f542e606190b230822f2 (MD5) / Rejected by Felipe Augusto Arakaki (arakaki@reitoria.unesp.br), reason: Solicitamos que realize uma nova submissão seguindo as orientações abaixo: O título presente na capa, folha de rosto e ficha catalográfica "ANÁLISE ECONÔMICA DA PRODUÇÃO DE LODO DE ESGOTO COMPOSTADO PARA USO NA AGRIGULTURA" esta diferente do título que consta na folha de aprovação "ANÁLISE ECONÔMICA DA PRODUÇÃO DE LODO DE ESGOTO COMPOSTADO PARA USO NA AGRICULTURA". Por favor, corrija as informações e realize uma nova submissão Agradecemos a compreensão. on 2016-11-03T17:33:47Z (GMT) / Submitted by SARA FERNANDES MARTINS (mesolta@hotmail.com) on 2016-11-09T16:52:02Z No. of bitstreams: 1 MARTINS, S. F. Análise econômica da produção de lodo de esgoto compostado para uso na agricultura.pdf: 5452439 bytes, checksum: 88989d1552469e2e5b19992cc577b3eb (MD5) / Approved for entry into archive by Juliano Benedito Ferreira (julianoferreira@reitoria.unesp.br) on 2016-11-10T15:30:10Z (GMT) No. of bitstreams: 1 martins_sf_me_jabo.pdf: 5452439 bytes, checksum: 88989d1552469e2e5b19992cc577b3eb (MD5) / Made available in DSpace on 2016-11-10T15:30:10Z (GMT). No. of bitstreams: 1 martins_sf_me_jabo.pdf: 5452439 bytes, checksum: 88989d1552469e2e5b19992cc577b3eb (MD5) Previous issue date: 2016-08-30 / O objetivo geral deste estudo é avaliar economicamente a produção do lodo de esgoto compostado com e sem material estruturante (ME), na Estação de Tratamento de Esgotos (ETE) “Lageado”, da Sabesp de Botucatu, para fins de uso agrícola. Resultante do processo de tratamento primário e secundário de esgotos, o lodo de esgoto é um resíduo de difícil destinação por diversas razões, como por exemplo, o alto custo de transporte e disposição em aterro sanitário. Esta ETE produz 16 toneladas de lodo por dia, o que gera um custo anual aproximado de R$ 1.466.438,40 em transporte e disposição. Foi estimado o custo anual de produção do lodo de esgoto compostado com ME, com base no processo de produção de um lote de caráter experimental. Para o produto final que não utilizou ME, a estimativa foi elaborada com base no processo atual de secagem e revolvimento de lodo fresco. A análise mostrou que independente do uso do ME, o custo para processamento do lodo é inferior ao custo atual de disposição em aterro, sendo de R$ 96,88 t-1 para o composto com ME e de R$ 63,41 t-1 para o sem ME, frente aos R$ 254,59 t-1 de disposição final. Foram realizadas análises de amostras dos produtos finais para estimar o valor econômico contido através nos nutrientes presentes e ambos apresentaram quantidade satisfatória de nutrientes, além de atender os parâmetros da Resolução CONAMA 375/06 e exigências do Ministério da Agricultura (MAPA). Considerando hipoteticamente que a Companhia pudesse comercializar estes produtos como fertilizantes, com base nos valores médios pagos pela agricultura, o composto com ME geraria uma receita de R$ 270.467,12 e o produto sem ME de R$ 39.653,28. Os processos de compostagem e de revolvimento do lodo seco representam 38% e 27% do custo para disposição em aterro, respectivamente. Esta análise mostrou que qualquer um dos processos adotados será economicamente mais viável do que o custo de disposição em aterro. Os resultados fornecem uma direção para tomadas de decisões quanto a parcerias para fornecimento de ME, adequações para redução do custo de movimentação interna do lodo, possibilidade de registro e distribuição do composto final e determinação da distância ótima para distribuição do lodo seco ou composto. / The aim of this study is to economically evaluate the production of composted sewage sludge with and without structural materials (SM), at the SABESP´s (Basic Sanitation Company of the State of Sao Paulo) Sewage Treatment Plant (STP) "Lageado" in Botucatu, for agricultural use purpose. As a result of the process of primary and secondary treatment of sewage, the sewage sludge has a difficult end disposal for several reasons, such as the high cost of transportation and disposal in landfill. This STP produces 16 tons of sludge per day, which generates an approximate annual cost of R$ 1,466,438.40 in transportation and disposal. This study estimated the annual cost to produce the composted sewage sludge with SM, based on the production process of a experimental lot. For the final product that was not added the SM, the estimated cost was developed based on the current process of drying and revolving fresh sewage sludge. The analysis showed that regardless using SM or not, the cost per ton for processing the sewage sludge is lower than the current cost of disposal in landfills, representing R$ 96,88 t-1 for the compound with SM and R$ 63,41 t-1 without SM, compared to the R$ 254,59 t-1 cost for final disposal. Analyzes of the final products samples were performed to estimate the economic value of the present nutrients and both were satisfactory due to the amount of nutrients, in addition to comply with the parameters from the CONAMA Resolution nº375/06 and requirements of the Ministry of Agriculture (MA). Considering the hypothesis that the company could market these products as fertilizers, and based on the price paid by agriculture, the compound with SM would generate an income of R$ 270.467,12 and the one without SM R$ 39.653,28. The composting process and the drying and revolving sewage sludge process represent, respectively, 38% and 27% of the cost for disposal in landfill. This analysis shows that any of the processes taken will be more viable economically, than the cost of disposal in landfill. The results allow a link to decision-making about finding partnerships to supply the SM, adjustments to reduce the internal cost of sewage sludge transfer, the possibility of registering and distribution of the final compound and determining the optimum distance to distribut the dry or composted sewage sludge.

As compostagens abrigam uma grande riqueza microbiológica, englobando populações com distintos requerimentos e tolerâncias fisiológicas que se sucedem ao longo do processo de biodegradação aeróbica da matéria orgânica e que resultam na elevação espontânea de temperatura até 80° C. Com a utilização de abordagens de metagenômica e metatranscritômica, investigamos a composição e a diversidade taxonômica, bem como as funções metabólicas de comunidades microbianas da compostagem termofílica do Parque Zoológico de São Paulo. Foram analisadas amostras em série temporal de duas composteiras (ZC3 e ZC4), as quais exibiram temperaturas entre 50ºC-75ºC ao longo de 99 dias do processo. Verificamos que a degradação de toda a biomassa foi realizada essencialmente por bactérias, e que a estrutura e composição das comunidades microbianas variam ao longo do processo, com elevada abundância relativa das Ordens Clostridiales, Bacillales e Actinomycetales, assim como observado em outros sistemas de compostagem. Entre os organismos abundantes no processo, identificamos unidades taxonômicas operacionais (OTUs) referentes a organismos não-cultiváveis e/ou com genoma ainda desconhecido. O genoma parcial de uma destas OTUs foi reconstruído, a qual provavelmente pertence a um novo gênero da ordem Bacillales. A dinâmica do processo de compostagem foi evidenciada pela variação do número de OTUs e do índice de diversidade filogenética ao longo do tempo, sendo que o início do processo e a fase após a revira apresentaram a maior diversidade. Os resultados indicam que o processo de revira (aeração da massa de composto) impacta fortemente a estrutura e a composição da microbiota e que a desconstrução da biomassa vegetal ocorre de forma sinérgica e sequencial. A variedade de microrganismos e de funções metabólicas ativas na compostagem termofílica reforça o seu potencial de ser uma promissora fonte de bactérias e enzimas termorresistentes úteis em processos industriais. / Composting harbors considerable microbial richness, comprising populations with distinct physiological requirements and tolerances that succeed one another throughout the aerobic biodegradation of the organic matter, resulting in spontaneous temperature rise up to 80° C. Using metagenomic- and metatranscritomic-based approaches, we investigated the composition and taxonomic diversity as well as metabolic functions of microbial communities of a thermophilic composting operation in the São Paulo Zoo Park. We have analyzed time-series samples from two composting cells (ZC3 and ZC4) which exhibited sustained thermophilic profile (50°C-75°C) over 99 days of the process. We found that all biomass degradation was essentially performed by bacteria. The structure and composition of microbial communities vary throughout the process with a high relative abundance of Clostridiales, Bacillales and Actinomycetales, as observed in other composting systems. Among the organisms abundant in the process, we identify Operational Taxonomic Units (OTUs) of uncultivated organisms or with unknown genomes. The partial genome of one of these OTUs was obtained and shown to belong probably to a new genus of Bacillales. Our time-series data showed that the number of OTUs and phylogenetic diversity index changed during composting revealing the dynamics of the process, with the beginning and the stage after turning procedure presenting the highest diverse microbiota. These results indicate that the turning procedure (compost aeration) strongly impacts the microbiota structure and composition and that the deconstruction of the biomass occurs synergistically and sequentially. The huge diversity of microorganisms and metabolic functions active in thermophilic composting strengthen its potential as a promising source of new bacteria and thermostable enzymes that may be helpful in industrial processes.

Plastic are a highly durable, lightweight and low cost family of polymeric materials that form an essential and integral component of today’s world. Their continued world-wide large scale manufacture has led them to be a major component of man-made waste. A large proportion of plastic waste is directed to the landfill sites, however their low degradation rates, scarcity of landfill sites and growing water and land pollution problems require alternatives to be developed. Composting is a natural process involving aerobic decomposition of organic wastes by a mixed microbial consortium that involves thermophilic microbes during the process due to the heat generated during decomposition. In this study we investigated the biodegradation of polyurethane under composting conditions. Polyurethanes are heteropolymers with a wide range of applications in the medical, automotive, construction and domestic field and in Europe account for 7% of all plastic manufacture and have been shown to be susceptible to biodegradation, particularly by fungi. In this thesis, it was found that loss in tensile strength of >70% occurs at both mesophilic (25°C) and thermophilic (45° and 50°C) temperatures under laboratory conditions and so is susceptible to degradation at all stages of the composting process. Moreover, polyester PU buried in compost piles at a commercial composting site during the maturation phase of an in silo composting process also underwent substantial degradation. Non-culture based analysis by TRFLP, DGGE and 454 pyrosequencing revealed that the fungal communities colonising the surface of PU was substantially different from the surrounding compost indicating selection of fungi on the PU surface. Pyrosequencing revealed that under laboratory conditions, at 25°C Fusarium solani, and 45°C and 50°C, Candida ethanolica was the dominant organism recovered from the PU surface, whereas at the commercial composting site an unidentified fungal clone and Arthrographis kalrae were the dominant organisms recovered. When the microparticulate polyester PU dispersion impranil was added to compost, a substantial shift in the indigenous fungal population was observed along with an increase in fungal viable numbers, however, addition of larger solid PU had no lasting effect on the surrounding compost community. This study demonstrates that polyester PU is highly susceptible to degradation in during composting and indicates a future potential for directing PU wastes to existing commercial composting processes.