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Polycyclic aromatic hydrocarbons (PAHs) are environmentally significant because of their ubiquity and the toxicity of some. Their recalcitrance and persistence makes them problematic environmental contaminants. Microbial degradation is considered to be the primary mechanism of PAH removal from the environment. Biodegradation kinetics of individual PAHs by pure and mixed cultures have been reported by several researchers. However, contaminated sites commonly have complex mixtures of PAHs whose individual biodegradability may be altered in mixtures. Biodegradation kinetics for fluorene, naphthalene, 1,5-dimethylnaphthalene and 1- methylfluorene were evaluated in sole substrate systems, binary and ternary systems using Sphingomonas paucimobilis EPA505. The Monod model was fitted to the data from the sole substrate experiments to yield biokinetic parameters, (qmax and Ks). The first order rate constants (qmax/Ks) for fluorene, naphthalene and 1,5- dimethylnaphthalene were comparable, although statistically different. However, affinity constants for the three compounds were not comparable. Binary and ternary experiments indicated that the presence of another PAH retards the biodegradation of the co-occurring PAH. Antagonistic interactions between substrates were evident in the form of competitive inhibition, demonstrated mathematically by the Monod multisubstrate model. This model appropriately predicted the biodegradation kinetics in mixtures using the sole substrate parameters, validating the hypothesis of common enzyme systems. Competitive inhibition became pronounced under conditions of: Ks1 << Ks, S1 >> Ks1 and S1 >> S. Experiments with equitable concentrations of substrates demonstrated the effect of concentration on competitive inhibition. Ternary experiments with naphthalene, 1,5-dimethylnapthalene and 1-methylfluorene revealed preferential degradation, where depletion of naphthalene and 1,5-dimethylnapthalene proceeded only after the complete removal of 1-methylfluorene. The substrate interactions observed in binary and ternary mixtures require a multisubstrate model to account for simultaneous degradation of substrates. However, developing models that account for sequential degradation may be useful in scenarios where PAHs may not be competitive substrates. These mixture results prove that substrate interactions must be considered in designing effective bioremediation strategies and that sole substrate performance is limited in predicting biodegradation kinetics of complex mixtures.

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Fluorinated fire fighting foams provide superior performance for extinguishing Class B flammable liquid fires when compared to other types of fire fighting foams. Perfluorocarboxylates and perfluorosulfonates have historically been surfactants used in these foams with a recent shift to fluorotelomer-based foams due to environmental and health concerns surrounding perfluorinated compounds such as PFOA and PFOS. Releases of aqueous film forming foams from training, accidental spills, or fire events where wastewater is not captured have, among other sources, led to detectable concentrations of fluorinated compounds in groundwater, surface water, and drinking water supplies globally. Persistence, toxicity, and bioaccumulation potential of these substances are areas of ongoing research. Biodegradability data for these AFFFs in published studies and manufacturers’ material safety data sheets may be based on a comparison of BOD and COD measures. The present study concludes that COD is an inappropriate measure of organic content for fluorinated compounds due to the carbon-fluorine bond strength, and thus published biodegradability data must be critically evaluated for validity. TOC measured an average of 91% of carbon content for four fluorinated test substances, recommending it for use as an analytical parameter in biodegradability tests when specific compounds’ identities are not required, e.g. in the absence of an LC/MS. Biodegradability of three fluorinated foams (AFFF, AR-AFFF, and FP) purchased from a major U.S. manufacturer measured in the range of 77-96% based on DOC die-away during a 28-day test using activated sludge inoculum. This meets OECD criteria for “ready biodegradability� and NFPA biodegradability recommendations in Standards 18, 18A, and 1150. Defluorination of two foams was measured using ion chromatography and, based on an estimate for total fluorine content developed in part from manufacturer MSDSs, was found to liberate a detectable level of fluorine that was 1 to 2 orders of magnitude less than the estimated value. In this 28-day test, foams underwent significant biodegradation but fluorinated compounds’ biodegradation was likely incomplete.

10 ABSTRACT Charles University in Prague, Faculty of Pharmacy in Hradec Králové Department of Pharmaceutical Technology Consultant: PharmDr. Ondřej Holas, PhD. Student: Jiřina Blažková Title of thesis: A study of biodegradable polyesters based nanoparticles properties Nanoparticles (NPs) are particles with a diameter size ranging between 1 - 500 nm. They are preferably used as drug delivery systems or imaging systems. NPs are able to encapsulate both hydrophilic and hydrophobic drugs and also macromolecules such as peptides or mRNAs. The aim of this study was to specify selected properties of NPs prepared from poly (lactide-co-glycolide) polymer (PLGA) using polyvinyl alcohol as a surfactant. Nanoprecipitation was chosen as a preparation method. NPs were prepared from a branched PLGA copolymer and from a conventional linear PLGA polymer/oligomer. The main task was a stability study. The effect of the pH and the type of the used polymer of the nanoparticle suspension on the morphology of the nanoparticles was evaluated over one month period. The following parameters of nanoparticles with two model drugs (curcumin and procaine) were also monitored: encapsulation efficiency, drug loading and recovery yield. Dissolution tests were performer and the suitability of individual polymers for different types of drugs...

A pesquisa avalia comparativamente algumas propriedades físicas e químicas da poliamida 6.6 convencional e biodegradável. Avalia também o tempo de biodegradabilidade da amostra de fio biodegradável e convencional. As propriedades físicas analisadas foram de resistência, alongamento e tenacidade. Já as propriedades químicas foram relativas ao comportamento das amostras quanto ao tingimento e avaliações de solidez posteriores ao tingimento. As amostras avaliadas foram retiradas de malhas produzidas com fio de poliamida 80 dtex f68 x 2, normal e biodegradável, sendo purgadas, alvejadas e tintas. Os resultados das análises físicas, apesar de estatisticamente diferente, possuem os valores das médias muito próximos, o que na prática representam valores aceitáveis dentro do controle estatístico de processo. Ambas as amostras normal e biodegradável apresentaram mesmo comportamento químico, não havendo nenhuma diferença. Com relação ao tempo de biodegradabilidade, sob condições laboratoriais, o dióxido de carbono produzido pelas amostras foi monitorado e medido para determinar a porcentagem de biodegradação de acordo com a norma ASTM D 5511. O fio biodegradável apresenta um tempo de biodegradação 16 vezes mais rápido do que o fio de poliamida normal, tendo 81,7% de biodegradação após 735 dias de teste. Isto representa um ganho muito grande em termos ecológicos, tratando-se de uma fibra sintética / The study evaluates comparatively some physical and chemical properties of conventional and biodegradable polyamide 6.6. It also evaluates the period of biodegradation of the biodegradable and conventional yarn. The physical properties analyzed were strength, elongation and toughness. The chemical properties were related on the behavior of the samples in dyeing and evaluation of subsequent strength dyeing. The evaluated samples were taken from knitwear produced with polyamide yarn 80 dtex f68 x 2, normal and biodegradable, being purged, bleached and dyed. The results of the physical tests, although statistically different, have values very near the average, which in practice represent acceptable values within the statistical control process. Both normal and biodegradable samples had the same chemical behavior, and there is no difference. With respect to biodegradation time under laboratory conditions, the carbon dioxide produced by the samples was monitored and measured to determine the percentage of biodegradation according to ASTM D 5511. The biodegradable yarn has a biodegradation time 16 times faster the yarn normal polyamide, having 81.7% biodegradation after 735 days of testing. This is an expressive gain in ecological terms for a synthetic fiber

Os polietilenoglicóis (PEGs) são polímeros sintéticos não iônicos, solúveis em água, que possuem diferentes propriedades físico-químicas devido ao efeito de sua cadeia longa, conferindo assim uma vasta disposição na aplicação industrial do PEG. Como exemplos de aplicação destacam-se o uso como lubrificante solúvel em água para moldes de borracha, fibras têxteis e operações de formação de metais, sendo também usado em tintas à base de água, revestimento de papéis, polimento, na indústria cerâmica, na confecção de fases estacionárias para cromatografia, entre inúmeras outras. O PEG também pode ser adicionado às dietas de ruminantes baseadas em foragem com alto teor de taninos, onde ele se insere como um agente complexante do tanino. Contudo, devido à ampla aplicação do PEG, mostra-se uma maior preocupação com seu uso e disposição no meio ambiente, uma vez que sua concentração, seja no solo ou água, possa ser grande. No entanto, pouco se sabe acerca do seu destino no ambiente, principalmente em condições tropicais, sendo que não foram encontrados na literatura estudos de monitoramento de águas subterrâneas e superficiais, e nem mesmo estudos de impacto ambiental. Neste contexto, este projeto se insere na busca sobre o destino do PEG-4000 no ambiente, buscando informações sobre sua mobilidade, degradação e sorção em solos, utilizando técnicas radiométricas (14C-PEG). Complementando o estudo do PEG, foi avaliado o transporte de pesticidas na presença do PEG, uma vez que ele possui uma alta solubilidade, podendo atuar como co-solvente, avaliando assim o papel do PEG na presença de contaminantes / Polyethylene glycols (PEGs) are non-ionic synthetic polymer, soluble in water, which have different physical and chemical properties because of its long chain, thereby providing a broad industrial application of PEG. Examples of application are the use as water-soluble lubricant for rubber molds, textile fibers and metallurgy, also used in water-based paints, paper coating, polishing, ceramic industry, in construction of stationary phases for chromatography, and numerous others. PEG can also be added to the diets of ruminants based on forage with a high content of tannins, where it comes as a complexing agent of tannin. However, due to the wide application of PEG, it is a greater concern about its use and disposal in the environment, since their concentration, either in soil or water, can be large. However, little is known about their fate in the environment, especially in tropical conditions, which were not found in the literature studies for monitoring underground and surface water, and even environmental impact studies. In this context, this project falls in the search on the fate of PEG-4000 in the environment, seeking information on their mobility, degradation and sorption in soils, using radiometric techniques (14C-PEG). Complementing the study of PEG, was evaluated the pesticides transport in the presence of PEG, since it has a high solubility and can act as co-solvent, thereby assessing the role of PEG in the presence of contaminants

Dissolved organic matter (DOM) plays a vital role in biogeochemical processes and can flux CO2 to the atmosphere when labile fractions are degraded, hence DOM degradation is increasingly studied. Some studies have suggested that fluorescence-derived substrate characteristics are useful metrics for estimating bioavailability (as prerequisite condition for biodegradability), however, recent findings on soil organic matter emphasize the importance of ecosystem scale factors such as physical separation of substrate from soil microbial communities and soil physiochemical cycles driving organic matter stability. I extend this principle to soil derived DOM and hypothesize that such environmental conditions, covariant with season, land use and landscape position, impact the composition of soil DOM and activity and abundance of the microbial community, which together govern DOM biodegradability. As a result, DOM bioavailability may not reliably be predicted using substrate characteristics alone. To test these hypotheses, I assessed aqueous soil extracts for water extractable organic carbon (WEOC) content, biodegradability, microbial biomass and fluorescence spectroscopy on water extractable organic matter (WEOM) across a range of environmental conditions in northern Vermont, USA. My results indicate that changes in environmental conditions affect composition, quantity, and biodegradability of DOM. WEOC concentrations were highest in the fall and lowest in the summer, while no significant differences were found between land covers or landscape position, however, DOM biodegradability was significantly higher in the agricultural (AG) site across seasons. Despite a shift in utilized substrate from less aromatic DOM in summer to more aromatic DOM in winter, biodegradability was similar for all seasons. The only exception were cold temperature incubations where microbial activity was depressed, and processing was halted. These results indicate that bioavailability cannot be reliably predicted based on fluorescence-based metric alone, rather, my core findings illustrate a complex picture of how environmental conditions, landscape characteristics, and substrate composition interact to drive the biodegradability of labile carbon pools in the soil environment. This thesis includes i) a background and comprehensive review of literature to inform the reader of any relevant topics, ii) a paper submitted for publication to Biogeochemistry (Chapter 2), and iii) supplemental information containing figures and tables pertinent to the paper.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.

The rapid accumulation of municipal solid waste is a significant environmental concern in our rapidly growing world. Due to its low cost, high energy recovery and limited environmental impact anaerobic digestion (AD) is a promising solution for stabilizing the organic fraction of municipal solid waste (OFMSW). Hydrolysis is often the rate-limiting step during AD of wastes with high solid content; this step can be accelerated by pretreatment of waste prior to AD. This thesis presents the results of alkaline pretreatment of OFMSW using NaOH and KOH. Four different pH levels 10, 11, 12 and 13 at two temperatures 23±1°C and 80±1°C were examined to study the effects of the pretreatment on (i) enhancing the solubility of the organic fraction of the waste, and (ii) enhancing the AD process and the biogas production. The effects on solubility were investigated by measuring changes in the soluble COD (SCOD) concentrations of pretreated wastes and the enhanced AD was investigated by measuring volatile solids (VS) destruction, total COD (TCOD) and SCOD removal in addition to biogas and methane production using biochemical methane potential (BMP) assay and semi-continuous laboratory reactor experiments. Pretreatment at pH 13 at 80±1°C demonstrated the maximum solubility for both NaOH and KOH pretreated samples; however the BMP analysis demonstrated that pretreatment at pH 12 at 23±1°C showed the greatest biogas yield relative to the removed VS for both chemicals. Thus pretreatment at pH 12 at 23±1°C using NaOH and KOH were examined using semi-continuous reactors at three different HRTs: 10, 15 and 20 days. Pretreatment demonstrated a significant improvement in the AD performance at SRTs of 10 and 15 days.