Em muitas partes do mundo o aumento na demanda de água tem estimulado pesquisas relacionadas às práticas de reuso sustentáveis. Dentre as atividades humanas, a irrigação agrícola se revela como uma das práticas de maior consumo de recursos hídricos naturais. Uma alternativa para minimizar este problema é o reuso de efluentes gerados por sistemas biológicos de tratamento de esgotos. O objetivo desta pesquisa foi avaliar os efeitos da irrigação com esgoto tratado na dinâmica do carbono (C) e nitrogênio (N) e na atividade microbiana de um solo sob pastagem. O estudo foi conduzido em uma pastagem de capim-Bermuda Tifton 85 (Lins-SP), onde o delineamento experimental foi o de blocos completos com seis tratamentos: SI (sem irrigação e sem fertilização), A100 (água potável + 520 kg de N ha-1 ano-1); E0, E33, E66 e E100 (irrigação com esgoto tratado + 0, 33, 66 e 100% de 520 kg de N ha-1 ano-1). Os tratamentos receberam entre 420 a 1500 mm de esgoto tratado e água por ano, correspondendo a uma entrada pelo esgoto tratado de 640 a 2300 kg ha-1 ano-1 de C e de 135 a 480 kg ha-1 ano-1 de N. Utilizando como referência os estoques de C e N de SI, o menor decréscimo de C ocorreu em E33 (1,2 Mg ha-1) e o maior em A100 (7,9 Mg ha-1). Alterações no estoque de N do solo ocorreram após quatro anos de irrigação, onde A100 apresentou decréscimo de cerca de 450 kg de N ha-1. Os estoques de N dos tratamentos irrigados com esgoto tratado não foram afetados. A entrada de C e N orgânicos pelo esgoto tratado não afetaram a composição isotópica do C (\'delta\' 13C) e do N (\'delta\' 15N) da fração estável da matéria orgânica do solo (MOS) do solo. A alteração de \'delta\' 13C nos solos dos tratamentos irrigados (-0,7 a -1,2%o ), em relação a SI, foi resultante da mineralização do carbono orgânico remanescente do solo (plantas C3). Os valores de \'delta\' 15N do N da MOS (0 a 5 cm) foram significativamente maiores (+2,2%o) nos tratamentos irrigados com esgoto tratado do que em SI e A100, refletindo diferenciadas taxas e processos de ciclagem de N. A abundância natural de 15N nas folhas do capim-Bermuda refletiu a composição isotópica do N do solo, com enriquecimento de +2,5%o e +4,9%o em relação a A100 e SI, respectivamente. As taxas líquidas de mineralização e nitrificação negativas ou nulas nas épocas Seca-04, Chuvas-05 e Seca-05 indicaram predominância de processos de imobilização do N pela microbiota em virtude uma alta relação C:N da MOS. Nas épocas de Chuvas-06 e Seca-06 as taxas tornaramse positivas indicando a diminuição da relação C:N da MOS, término do efeito priming e, portanto, ciclagem interna de N. Os solos dos tratamentos apresentaram baixo consumo (-0,1kg de C ha-1 sem-1) ou pequena emissão média de CH4 (+0,8 kg de C ha-1 sem-1). A disponibilidade de N e a umidade do solo não representaram fatores limitantes nos tratamentos, assim as emissões de CO2 não diferiram entre si na maior parte das datas de coleta (médias de 14,7 e 12,2 Mg de C ha-1 para épocas de chuvas e seca, respectivamente). Os maiores fluxos de CO2 relacionaram-se com os períodos de maior precipitação e/ou irrigação do que com os tratamentos. Os maiores fluxos de N2O foram observados após a aplicação de N mineral nos tratamentos irrigados com esgoto tratado, sendo proporcionais as maiores quantidades de N adicionado. As relações médias entre o C da biomassa microbiana e o C orgânico total (Cmic:COT) dos tratamentos variaram de 2,3 a 3,8% ao longo das épocas, indicando boa resiliência do agroecossistema, onde os microrganismos apresentaram variações temporárias de biomassa. Interferências positivas do manejo (corte do capim e fertilização com N mineral) resultando em aumento de Cmic foram observadas no 1º ano hidrológico e Seca-06, como resultado da maior umidade do solo e com isso condições mais favoráveis para a disponibilização de C. Na Seca-04, com o aumento da atividade metabólica, e Chuvas-05, sem alteração deste parâmetro, ao longo do manejo, o quociente metabólico (qCO2) apresentou um cenário de eficiente conversão de C-CO2 em biomassa microbiana. No 2º ano hidrológico, com a diminuição das lâminas de irrigação os tratamentos irrigados e fertilizados apresentaram decréscimo de Cmic e respiração mantida (Seca-05) ou aumentada (Chuvas-06) após o manejo, os valores de qCO2 indicaram condições desfavoráveis a microbiota. Com a pouca interferência dos tratamentos, os indicadores eco-fisiológicos não foram suficientemente sensíveis para mostrar o manejo com menor impacto na qualidade do solo, revelando apenas cenários do metabolismo microbiano ao longo das práticas agrícolas. A quantidade de C exportada por E33, como biomassa (15,2 Mg de C ha-1 ano-1) não diferiu das maiores produções, a alteração em seu estoque de C foi inferior aos demais tratamentos irrigados, sugerindo ser o manejo mais sustentável, em termos de C, utilizando esgoto tratado como irrigação. Os tratamentos E100 (Seca-04) e E66 (Chuvas-05) representaram os manejos com as maiores exportações de N, respondendo linearmente até 940 ha-1 de N ano-1. De acordo com as variáveis avaliadas, o manejo com maior sustentabilidade produtiva e ambiental foi o tratamento E100, situação onde as saídas de N não superaram as entradas / In many parts of the world, the increasing demand and, especially in arid regions the natural scarcity of water has stimulated researches in terms of sustainable water reuse practices. Within human activities, common agricultural irrigation reveals one of the most consumptive practices of natural water resources. One alternative to minimize this problem represents the reuse of effluent generated by biological sewage treatment systems. The objective of this study was to investigate the impact of treated wastewater application in the dynamic of carbon (C) and nitrogen (N), and microbial metabolism of a soil under pasture. The study was carried out at Lins, São Paulo State, Brazil on a Tifton 85 bermudagrass pasture irrigated with secondary treated sewage effluent using a randomized complete block design with six treatments: SI (control, without irrigation and fertilization), W100 (potable water irrigation + 520 kg of N ha-1 year-1); E0, E33, E66 and E100 (treated wastewater irrigation + 0, 33, 66 and 100% of 520 kg of N ha-1 year-1). Samples of treated effluent/water, soil, plant (litter fall), and gases were taken from January 2004 through October 2007 and the treatments were kept under irrigation management receiving between 420 and 1,500 mm of water and treated sewage corresponding to an input of 640 to 2,300 kg ha-1 yr-1 of C and 135 to 480 kg ha-1 year-1 of N . Soil C stocks decreased slightly in the E33 treatment (-1.3 Mg ha-1) and a larger decrease was observed in W100 (-7.9 Mg ha-1). The inputs of organic C by the treated sewage did not affect the soil carbon isotopic composition (\'delta\' 13C), and in the irrigated treatments measured shifts in the isotopic signature (-0,7 a -1,2%o ) were caused by the mineralization of the remaining soil organic matter (SOC) (C3 plants). After 4 years of irrigation the only significant changes in soil N stocks were found in the W100 treatment (-450 kg de N ha-1). The \'deta\' 15N signature of the soil organic matter (0-5 cm depth) in the treatments irrigated with treated sewage was significantly higher (+2,2%o) than WI and W100, this suggests higher nitrogen cycling. The \'delta\' 15N signature of grass was enriched relative to the soil of W100 and WI +2,5%o and +4,9%o respectively). Negative or null rates of mineralization and nitrification occurred in the dry season of 2004, rainy and dry season of 2005 indicated an immobilization by the microorganisms, as a result of a high C:N ratio in the SOC. In the dry and wet seasons of 2006, mineralization and nitrification rates became positive suggesting a decrease of the C:N ratio, and the end of both priming effect and, thus the beginning of N cycling in the soil organic matter. Soils in the treatments showed low CH4 consumption rates (-0.1 kg de C ha-1 semester-1) and in some cases low emissions (+0.8 kg de C ha-1 emester-1). Nitrogen availability and soil moisture did not appear to be limiting factors for the treatments, thus CO2 emissions did not differ from each other over the collections (averages of 14.7 e 12.2 Mg of C ha-1 for wet and dry season, respectively). The highest CO2 fluxes were more related to periods of high precipitation and/or irrigation than to the applied treatments. The highest emissions of nitrous oxide were observed after the application of mineral N to the treatments irrigated with treated sewage, and the emissions were straightly related to the N addition. Values of Cmic:TOC (microbial C : Total Organic C) in the treatments averaged between 2.3 and 3.8 % through the seasons which means a significant resilience of the ecosystem, indicating that soil microbial community varied seasonally in their Cmic. Addition of mineral nitrogen and grass cutting practices influenced positively resulting in increase of Cmic in the first hydrological year and in the dry season in 2006, as well as an increase of soil moisture resulting in good conditions for C availability. With the increase metabolic activity in the dry season of 2004 and a continuous metabolic activity in the rainy season in 2005, the metabolic quotient (qCO2) resulted in an efficient scenario of conversion of C-CO2 into microbial biomass. In the second year, with a decrease of the irrigation depths and an increase in salts concentration after fertilization, the treatments irrigated with treated sewage and fertilizers presented decrease of Cmic with stable respiration (dry season 2005) or increase respiration (wet season 2006) after the management, and as a result qCO2 indicated inappropriate conditions for the microorganisms. In the dry season (2006) the physiological profile of the soil remained instable with no stress and Cmic increased and soil respiration remained inaltered. According to these results, the microbial indicators were not efficiently sensitive for revealing the more impacting management to the soil. The co-physiological indicators showed only the regular microbial metabolism along the agricultural practices. Carbon biomass exported by the grass in the E33 (15.2 Mg C ha-1 yr-1) did not differ from the biomass produced in the other treatments and the alterations in its C stocks were low compared to the other treatments. As a result, E33 seems to be the more sustainable and efficient practice for treated sewage use. Both the E66 and E100 treatments had high measured rates of N export, responding linearly up to 940 kg of N ha-1 yr-1. Thus, according to the variables studied, the management with highest sustainability was E100 where N outputs did not surpass the inputs

O objetivo deste trabalho foi o de avaliar o efeito de tratamentos por calor nas propriedades mecânicas de resistência flexional e microdureza Knoop de três marcas comerciais de resinas compostas para uso direto (FillMagic, P60 e TPH), na condição de incluída ou não em revestimento durante um tratamento térmico (calor seco/170°C), por três períodos (5, 10 e 15 min). A temperatura adotada para os tratamentos foi baseada em análises prévias (termogravimetria e calorimetria exploratória diferencial) com a finalidade de se determinar a temperatura de início de perda de massa e de transição vítrea das resinas. Os corpos-de-prova (n=7) foram confeccionados com o auxílio de uma matriz metálica (10 mm x 2 mm x 2 mm), sendo o compósito inserido em bloco único e irradiado numa única superfície (600mW/cm 2 por 40s). Foram obtidos, no total, sete grupos experimentais por resina, sendo o controle a condição de apenas fotoativada. Os espécimes foram submetidos ao ensaio de resistência à flexão, com distância entre apoios de 8 mm, em uma velocidade constante de 0,5 mm/min e célula de carga de 1000N. A dureza Knoop foi obtida com carga de 100 g e tempo de penetração de 15 s. As médias de resistência flexional, em MPa, foram de 174,80 para a resina FillMagic, 182,64 para a P60 e 172,22 para a TPH. Na mesma ordem, as médias de microdureza Knoop foram de 73,1; 102,0 e 74,0.A análise de variância dos resultados obtidos permitiram concluir que os tratamentos experimentais aumentaram a resistência flexional das resinas indistintamente. Os valores de microdureza também aumentaram, mas houveram diferenças de suscetibilidade ao tratamento térmico entre as resinas / The aim of this study was to assess the effect of heat treatment on mechanical properties of flexure strength and Knoop micro hardness of three commercially available brands of resin composites for direct use (FillMagic, P60 and TPH) included or not in investments during heat treatment (dry heat/170ºC) by three periods (5, 10 and 15 min.) The temperature adopted for the treatments was based on previous analysis (thermo gravimetric and differential exploratory heating) in order to determine the initial temperature of mass loss and glass transition of resin composites. The samples (n=7) were prepared with a metallic matrix (10 mm x 2mm x 2mm) in which the resin composite was inserted in a single block and only one surface was irradiated (600mW/cm 2 40s). Seven experimental groups were obtained for each resin composite in which the control group was solely light-cured. The flexure strength test was performed with a support distance of 8 mm, cross-head speed of 0.5 mm/min. and 1000 N load. Knoop micro hardness was obtained with a load of 100 g and penetration time of 15 s. The flexure strength averages in MPa were 174.80 for FillMagic, 182. 64 for P60 and 172. 22 for TPH. Thus, Knoop micro hardness means were 73.1; 102.0 and 74.0. The analysis of variance indicated that the experimental treatments increased flexure strength of resin composites. Micro hardness values also increased, but there were differences in the resin composites susceptibility to the heat treatment

Este trabalho tem como objetivo estudar as mudanças das propriedades de superfícies e estruturais ocorridas em amostras de madeira termorretificadas. Duas espécies foram escolhidas para representar cada um dos grupos das madeiras: folhosas e coníferas. As amostras foram tratadas termicamente no intervalo de temperaturas entre 100 e 200 C, em atmosfera com ar. A variação da molhabilidade das espécies foi estudada a partir do ângulo de contato medido pelo método da gota séssil e monitorado no tempo ao longo de um ano. As amostras tratadas termicamente apresentaram ângulos de contato maiores, devido ao aumento nas suas características de hidrofobicidade. As técnicas de espectroscopia de infravermelho por refletância total atenuada e de espalhamento de raios-X foram utilizadas sendo possível detectar um aumento na cristalinidade da superfície das amostras, então responsável por esse aumento na hidrofobicidade. A técnica de FTIR permitiu distinguir os grupos funcionais das amostras de madeira (folhosas e coníferas), mesmo sendo obtidos espectros com baixa intensidade de sinal. Medidas de retratibilidade foram feitas nas amostras e as folhosas foram as que apresentaram maiores valores de retratibilidade volumétrica. Para tratamentos térmicos em mais altas temperaturas, foi observada uma redução considerável na retratibilidade volumétrica das amostras. Durante a secagem da madeira, o Eucalyptus grandis (cerne) foi o que apresentou uma maior contração volumétrica e a Araucaria angustifolia (cerne), a menor. Quando tratada em altas temperaturas, o Eucalyptus grandis (cerne) apresentou uma maior contração volumétrica e o Pinus elliotti, uma pequena expansão. A perda de massa também foi monitorada durante o tratamento térmico para todas as espécies. As folhosas apresentaram uma maior redução dos valores de massa em função do tratamento térmico, comparativamente às coníferas. O sistema CIE Lab de cor foi utilizado para se classificar as amostras termorretificadas. Uma análise multivariada de dados foi feita para acompanhar como cada parâmetro determinante da cor variava com a espécie e com o tratamento. Um dendrograma foi gerado, unindo espécies e tratamentos que apresentavam aproximadamente uma mesma cor final das amostras de madeira, contribuindo para as etapas de caracterização. / The main aim of this work was the characterization of changes of properties occurred on the surface and structure of heat-treated wood in response to thermal treatments. In order to cover different types of heat-treated wood, two species were elected as models for two great groups of woods, the so-called hard and soft woods. The samples were thermally treated in temperature range from 100 to 200 C under air atmosphere, and the water contact angle was periodically measured with the sessile drop method during one year. High values of contact angle were observed for the samples after the thermal treatment, reflecting their increased hydrophobicity. Probably, the reason for such increased hydrophobicity is the increase in the crystallinity of the samples, probed by ATR-infrared spectroscopy and X-ray scattering analyses. Even with FTIR analysis showing low-intensity bands, it was possible to distinguish between woods from the two groups, hard and soft woods by using this technique. Measurements of wood shrinkage were also carried out for the samples, with hard wood showing higher values of volumetric shrinkage. Moreover, for thermal treatments at higher temperatures, the volumetric shrinkage of the wood sampes was markedly reduced. During the drying process, the highest and lowest values of volumetric contraction were obtained for Eucalyptus grandis (heartwood) and Araucaria angustifólia (heartwood), respectively. Surprisingly, when treated at higher temperatures the samples from Pinus elliotti showed a small expansion, but Eucalyptus grandis (heartwood) was still the more contractile wood. Also, during the thermal treatment, the loss of mass was evaluated for all the samples. Hard woods exhibited a large reduction of mass in response to the heating in comparison with soft woods, with no exceptions. The CIE Lab system was used to categorize the heat-treated woods. A multivariate data analysis was used to monitor each color parameter, and its dependence on the type of heat treatment. From these analyses, a dendogram was generated, and the samples with almost the same final color were grouped regarding the species and type of treatment.

Le traitement des sols à la chaux est une méthode couramment utilisée pour améliorer les propriétés mécaniques de sols aux performances insuffisantes. Cependant, ces améliorations mécaniques ne sont pas prises en compte dans les calculs de dimensionnement. Cette thèse propose une méthodologie pour pallier à ce problème. Un programme expérimental approfondi est réalisé afin de décrire avec précision le comportement mécanique d’un sol traité et les processus associés à la structuration introduite par le traitement. La composition chimique, et notamment la quantité de composés cimentaires hydratés, est déterminée par analyses thermogravimétriques et thermodifférentielles. Un couplage non-linéaire entre la quantité d’hydrates et la limite élastique se basant sur ces résultats expérimentaux est proposé. À partir de ces résultats, une nouvelle formulation a été développée afin de modéliser la dégradation de la structure en plasticité, et a servi au développement d’une nouvelle loi de comportement élasto-plastique basée sur le modèle de Cam Clay Modifié. Cette dernière a montré reproduire correctement les principaux traits de comportement spécifiques aux sols traités. Il est démontré que ce modèle est également adapté aux sols naturellement structurés. Afin de prendre en compte les effets du traitement et la présence de structure dans le dimensionnement, un programme basé sur la méthode des éléments finis, comprenant le pré- et le post-processing de la géométrie et des résultats du problème, a été développé. Une validation rigoureuse a confirmé l'implémentation correcte de la méthode et son potentiel pour l’optimisation du dimensionnement des ouvrages / The effects of lime treatment on the mechanical properties of soils are usually not accounted for in the design of geotechnical structures. As a result the potential of lime treatment has not been fully exploited. In this thesis, a comprehensive experimental program has been carried out to identity the key features of the mechanical behaviour of structured materials. The chemical modifications arising from lime treatment were quantified using thermal analysis methods. From these results a non-linear chemo-mechanical coupling was established between the concentration of cementitious compounds and the yield stress. Using these results, a new formulation to model the degradation of the structure at yield has been developed and implemented in a constitutive model for structured materials. This new model, developed in the framework of the Modified Cam Clay model, requires a limited number of additional parameters that all have a physical meaning and can all be determined from a single isotropic compression test. The model has proven to be successful in reproducing the key features of structured materials and for the modelling of the mechanical behaviour of lime treated specimens under various stress paths. Due to similarities in behaviour, it is shown that the formulation is also suitable for naturally structured soils. To account for a structured material in the design of geotechnical structures, a fully functional finite element program for elasto-plastic problems was developed including the pre- and post-processing of the results. A thorough validation has confirmed the good implementation of the finite element method and its suitability for the modelling of complex geometries involving structured materials

Philosophy of Doctor - PHD / The aim of this study was to compare the water quality of raw wastewater and treated sewage effluents from three different sewage treatment plants in the Western Cape, South Africa. The treatment plants investigated are on the same river system. Sewage treatment plant 1 and 2 use older technologies, while sewage treatment plant 3 has been upgraded and new technologies (membrane bioreactor) were incorporated in the treatment processes. The first objective was to determine the occurrence of total coliforms, Escherichia coli (E. coli) and fluoroquinolone and sulfamethoxazole antibiotic residues in raw wastewater and treated sewage effluents. Bacteria in treated sewage effluents can result in diseases such as dysentery, gastroenteritis, and typhoid upon exposure. A chromogenic test was used to screen for coliforms and E. coli. Enzyme linked Immunosorbent Assays (ELISA) were used to quantitate antibiotic residues (fluoroquinolones and sulfamethoxazole) in raw wastewater and treated sewage effluents. This study showed that bacteria are present in raw wastewater and residual bacteria are released with treated sewage effluents from sewage treatment plants. / South Africa

The technical and economic feasibility of an inverted pavement has been proven abroad and in Brazil, but there are still doubts relating to the parameters that may affect the performance of this type of pavement, particularly in Brazil. There is a lack of studies that identify and characterize the variables that are directly related to the structural behaviour of the cement-treated layer and the contribution of each layer (thickness and elastic modulus) to inverted pavement performance as a whole. Furthermore, the main Brazilian specifications allow designers to make most decisions based on their experience, often generating doubts and uncertainties ranging from the design of the structure to the execution of quality control, directly reflecting on the pavement’s service life. Two test sections designed as inverted pavements, which were evaluated in Brazil, are assessed to identify and characterize the variables directly related to the structural behaviour of inverted pavements. In addition, a comparative analysis of the design, materials, construction, and quality control methods for Brazilian and South African inverted pavements is assessed. Both test sections were built based on the same design principles, but have been presented through different structural performances since their implementation in 2001. Each test section was monitored with deflection measurements between 2003 and 2016. In 2017, two inspection pits were opened in each test section. Samples were collected from all layers, and sent to the laboratory. Additionally, the tests carried out in the laboratory and in-situ in both sections during their construction in 2001, requested in the quality control, were also analysed in this study. The test results from the quality control and the test results obtained exclusively for this study (alongside the available literature) were compared and analysed against each other. Based on the analyses and discussions carried out throughout this research, it is possible to conclude that both the thickness and elastic modulus variables of the unbound base and the cement-treated layer played the most important roles in the behaviour of the inverted pavement, besides the support provided to the cement-treated layer by the underlying layer. Furthermore, the difference in the behaviour of both test sections can be linked to these three variables in addition to the constructive techniques adopted. No direct correlations were found for obtaining resilient modulus through CBR, and obtaining CBR values through DCP tests may vary according to the type of soil. The back-calculated modulus are good and reliable indicators of resistance, however, it is essential to apply adjustment factors. Furthermore, it was possible to identify a linear function with R² = 0.845, where ITS varies as a function of USC, according to the tests result carried out in 2001. However, unfortunately, no satisfactory correlations were found between UCS and ITS, UCS and ft, and ITS and ft from the results obtained in 2017. It is possible that these results are due to the specimens being damaged. / Dissertation (MSc (Transportation Engineering))--University of Pretoria, 2021. / Civil Engineering / MSc (Transportation Engineering) / Unrestricted

Drought has an increasing importance in the Czech republic. It is necessary to look for potential irrigation water sources, which are important for agriculture. Treated wastewater can be one of them. It has potentially negative impact on soil physico-chemical properties, which is well-known from many researches in arid regions. The aim of this diploma thesis was to investigate, if the drip irrigation with treated wastewater (from constructed wetland) also has a potentially negative impact on two soils in the Czech republic. In one year experiment drip irrigation with treated wastewater was carried out in the greenhouse. Four treatments of irrigation was used for both soils - irrigation with treated wastewater, irrigation with groundwater, irrigation with treated wastewater + rainwater, irrigation with groundwater + rainwater. An amount of rainwater correspond with total precipitation of two locations, where the soils were brought from (Kostelec nad Ohří - Ústí nad Labem region and Hostětín - Zlín region). pH and electrical conductivity of soil leachate, total concentration of Na, K, Ca, Mg a P, bulk density, particle density and porosity was measured in both soils in 5 and 10 centimeters from source of irrigation. Values of pH of soil leachate fluctuated in every treatment in both soils during the...

<p> The central theme of the study is to identify strength-stiffness correlations for chemically treated subgrade soils in Indiana. This was done by conducting Unconfined Compression (UC) tests and resilient modulus tests for soils collected at three different sites, namely : US 31, SR 37 and I-65. At each site, soil samples were obtained from 11 locations at 30 ft spacing. The soils were treated in the laboratory with cement, using the same proportions used for construction, and cured for 7 and 28 days before testing. Results from the UC tests were compared with the resilient modulus results that were available. No direct correlation was found between resilient modulus and UCS parameters for the soils investigated in this study. A brief statistical analysis of the results was conducted, and a simple linear regression model involving the soil characteristics (plasticity index, optimum moisture content and maximum dry density) along with UCS and resilient modulus parameters was proposed.  </p>

El presente trabajo de investigación ha sido desarrollado como ayuda para la ejecución de proyectos bajo la modalidad de Obras por Impuestos, toda vez que esta modalidad, es mejor que otras alternativas de financiamiento en nuestro país, como las Asociaciones Público Privadas (APP’s), en cuanto a costos, recorte de plazos y eficiencia en los procesos. Esto permitirá usar los resultados obtenidos como herramienta de consulta para dar inicio a proyectos de Plantas de Tratamiento de Agua Residual – PTAR en el ámbito local y nacional, bajo esta modalidad, cabe indicar que este tipo de obras han sido declaradas de interés nacional por el Estado bajo el Decreto Supremo que aprueba el Plan de Saneamiento 2017 – 2021 (D.S. N° 018 - 2017 – Vivienda). Los estudios realizados han sido hechos para la ciudad de Cajamarca, ciudad que a la fecha no cuenta con una PTAR, por el colapso de su actual infraestructura en el año 2005, generando malestar a la población y faltando al derecho fundamental de la población de vivir en un ambiente sano y saludable. El proyecto consiste en la construcción de una PTAR, con una tecnología de Bioreactores de Membranas (MBR), el monto estimado para la construcción asciende a los S/. 86, 634,096.49 y el plazo de ejecución son de 20 meses. Cabe señalar que esta alternativa tecnológica ha sido seleccionada tras un análisis comparativo de ingeniería económica, con la alternativa tecnológica de Filtros Percoladores. La tecnología elegida nos mostró resultados favorables por su impacto económico para el erario nacional, además de un impacto costo-eficiente menor, tomando en cuenta la población beneficiaria de la ciudad de Cajamarca. Por otro lado, cabe recalcar que todos los permisos deberán estar aprobados y saneados por las entidades públicas. / This research work has been developed as an aid for the execution of projects under the Works for Taxes modality, since this modality is better than other financing alternatives in our country, such as Public Private Partnerships (PPPs), in in terms of costs, shortening deadlines and efficiency in the processes. This will allow the use of the results obtained as a consultation tool to initiate projects of Waste Water Treatment Plants - PTAR at the local and national level, under this modality, it should be noted that these types of works have been declared of national interest by the State under the Supreme Decree that approves the 2017-2021 Sanitation Plan (DS N ° 018 - 2017 - Housing). The studies carried out have been made for the city of Cajamarca, a city that to date does not have a WWTP, due to the collapse of its current infrastructure in 2005, generating discomfort for the population and lacking the fundamental right of the population to live In a healthy and healthy environment. The project consists of the construction of a WWTP, with a technology of Membrane Bioreactors (MBR), the estimated amount for construction amounts to S /. 86, 634,096.49 and the execution period is 20 months. It should be noted that this technological alternative has been selected after a comparative analysis of economic engineering, with the technological alternative of Percolator Filters. The chosen technology showed favorable results due to its economic impact on the national treasury, as well as a lower cost-efficient impact, taking into account the beneficiary population of the city of Cajamarca. On the other hand, it should be emphasized that all permits must be approved and sanitized by public entities. / Trabajo de investigación

Malaria is a vector-borne disease that presents the most persistent and serious public health burden in Liberia. Numerous studies have examined the relationship between ITN use and malaria prevalence. However, little research has explored the effectiveness of ITNs in controlling malaria among children in postwar Liberia. The aim of this study was to examine the association between ITN ownership, parental economic status, ITN installation support, and malaria prevalence among children. This was a quantitative cross-sectional study guided by the health belief model. The study used secondary data from the 2011 Liberia Malaria Indicator Survey. Chi-square for association and Logistic regression were used to analyze the data. The results revealed a significant association between parental education and malaria prevalence. There was also a significant association between parental economic status and malaria prevalence. However, there was no significant association between ITN ownership and malaria prevalence after controlling for parental education and ownership of structure. These findings may foster social change by helping public health authorities in Liberia integrate ITN use with other strategies like mosquito larvae elimination and indoor/outdoor insecticide spraying as part of a comprehensive approach to malaria control. Additionally, massive awareness and economic capacity building should be undertaken to empower malaria endemic communities with the understanding that malaria can be rapidly reduced with other robust strategies in combination with ITN use. These strategies, if implemented, may effectively control malaria prevalence among children and the emotional and financial burdens endure by their families.