Abstract (Introduction): In the removal of chromium (VI) from tannery wastewater, physicochemical methods are the most used. However, these require high operating costs, and worse still, generate secondary pollutants that again require complementary treatments for their elimination. Given this, the applicability of vegetable organic biomass (VOB) emerges as an environmental alternative based on: the simplicity of its obtaining, the reduction as waste, it does not generate secondary pollutants and, above all, it removes chromium (VI). (Objective): Use VOB waste in an aerobic sequential biological reactor (SBR) for the removal of chromium (VI) in the treatment of tannery wastewater. (Methodology): 3 aerobic SBR systems were implemented; 2 controls (SBR1 and SBR2) and 1 study subject (SBR+VOB). Each system was fed with tannery wastewater (18 L) and connected to an aeration mechanism (12.7 L/min). The bacterial inoculum, a fundamental part of an SBR system, was gained from the selective culture of chromium (VI) reducing bacteria (RBCrVI) taken from the wastewater under study, and integrated into SBR2 and SBR+VOB at 0.6 g/L. The VOB was obtained from Stenotaphrum secundatum residues, fragmented, sieved, sterilized and integrated into the SBR+VOB at 1.5 g/L. (Results): The SBR+VOB system achieved the highest percentage of chromium (VI) removal (93 %), followed by SBR2 (80.1 %), and finally SBR1 (2.8 %). With respect to COD and TSS, the statistical test (Tukey) showed that there was no significant difference between the system under study and the controls, recording COD removal percentages ranging from 87.8 % to 88.4 %, and TSS ranging from 63.8 % to 69.2 %. (Conclusions): The viability of using VOB waste to remove chromium (VI) in the treatment of tannery wastewater has been evidenced. The results of this research create a promising panorama to mitigate the effects derived from inadequate management of tannery wastewater and organic solid waste.

Resumen (Introducción): En la remoción de cromo (VI) de aguas residuales de curtiembre, los métodos fisicoquímicos son los más empleados. Sin embargo, estos demandan altos costos operativos y, peor aún, generan contaminantes secundarios que nuevamente requieren tratamientos complementarios para su eliminación. Ante ello, la aplicabilidad de la biomasa orgánica vegetal (BOV) emerge como una alternativa ambiental sobre la base de: la simplicidad de su obtención, la disminución como residuo, no genera contaminantes secundarios y, sobre todo, de remover cromo (VI). (Objetivo): Usar residuos de BOV en un reactor biológico secuencial (RBS) aerobio, para la remoción de cromo (VI) en el tratamiento de agua residual de curtiembre. (Metodología): Se implementaron 3 sistemas RBS aerobios; 2 controles (RBS1 y RBS2) y 1 materia de estudio (RBS+BOV). Cada sistema fue alimentado con agua residual de curtiembre (18 L) y conectado a un mecanismo de aireación (12.7 L/ min). El inóculo bacteriano, parte fundamental de un sistema RBS, se obtuvo a partir del cultivo selectivo de bacterias reductoras de cromo (VI) (BRCrVI), tomadas del agua residual en estudio e integradas al RBS2 y RBS+BOV a 0.6 g/L. La BOV se obtuvo de residuos de Stenotaphrum secundatum, fragmentado, tamizado, esterilizado e integrado al RBS+BOV a 1.5 g/L. (Resultados): El sistema SRB+BOV alcanzó el mayor porcentaje de remoción de cromo (VI) (93 %), seguido por SBR2 (80.1 %) y, por último, de RBS1 (2.8 %). Con respecto a la DQO y SST, la prueba estadística (Tukey) arrojó que no había diferencia significativa entre el sistema en estudio y los controles, por lo que registró porcentajes de remoción de DQO que van de 87.8 % a 88.4 % y SST que van de 63.8 % a 69.2 %. (Conclusiones): Se ha evidenciado la viabilidad del aprovechamiento de residuos de BOV para remover cromo (VI) en el tratamiento de agua residual de curtiembre. Los resultados de la presente investigación crean un panorama prometedor para mitigar los efectos derivados de la inadecuada gestión de las aguas residuales de curtiembre y de los residuos sólidos orgánicos.

Bisphenol A (BPA), an endocrine disruptor used in different commercial polymers, is a persistent pollutant commonly found in effluents. Conventional wastewater treatment processes have low chemical removal efficiency and are expensive. This work evaluated BPA removal using laccase enzyme produced from white rot fungus Pleurotus ostreatus. For the enzymatic production, residues of acai berry and pineapple were used as laccase inducers. The use of natural inducers led to a high enzyme production (1139 and 1031 U mL−1 to acai and pineapple, respectively). Bisphenol A was removed to a concentration lower than LOD (limit of detection) after 4 h. The degradation mechanism of BPA occurred by oxidation of methyl to hydroxymethyl group in a propane portion, with breakdown of the aromatic ring. The developed technology brought to the scene a new green, viable methodology, using vegetable waste, adding value to these residues and bringing an alternative to the BPA treatment.

ABSTRACT Ginger (Zingiber officinale Roscoe) waste is a residue from industrial factories that has potential for utilization in the production of bio-extract for pest control. Therefore, this study aimed to investigate the toxicity of fermented ginger waste extract through contact toxicity and oral toxicity methods in controlling the common cutworm (Spodoptera litura Fabricius) and the beet armyworm (Spodoptera exigua Hübner). The experiment was a completely randomized design (CRD) with 10 replicates. Mortality rates were recorded at 48, 72, and 96 h after treatment under laboratory conditions. Fermented ginger waste extract at concentrations of 0%, 5%, 25%, 50%, and 100% (w/v) was used. The results showed that for the contact toxicity method at 100% concentration after 96 h, the common cutworm had the highest mortality rate of 76.00 ± 1.29% (LC50 = 14.450 μg larva-1), while the beet armyworm had the highest mortality rate of 66.00 ± 0.95% (LC50 = 68.426 μg larva-1). For the oral toxicity method, the common cutworm had the highest mortality rate of 52.00 ± 1.70% at 100% concentration after 96 h (LC50 = 91.275 μg larva-1), and the beet armyworm had the highest mortality rate of 58.00 ± 1.02% at 100% concentration after 96 h (LC50 = 88.400 μg larva-1). Therefore, the results of this study demonstrate the efficacy of fermented ginger waste extract in controlling common cutworm and beet armyworm under laboratory conditions, and it has the potential for further application in field conditions.

Resumen:La demanda creciente del sector vivienda en la ciudad de Machala-Ecuador convirtió a las invasiones en el modelo común de crecimiento desorganizado de esta ciudad, donde utilizan el estero “El Macho” para la eliminación de desechos y aguas negras. Estudios preliminares respecto al contenido de metales pesados en este estero concluyen que las concentraciones de metales como el cadmio son superiores a los límites establecidos en la normativa del Texto Unificado de Legislación Secundaria del Ministerio del Ambiente. En la presente investigación se evaluó la remoción de cadmio de muestras de aguas del estero “El Macho” utilizando espuma de poliuretano activada con nanopartículas de plata como adsorbente. Para la recolección de los datos de adsorción se diseñó de un reactor tubular vertical, utilizando 1,560 g de adsorbente de poliuretano modificado con nanopartículas de plata, pH 8 y tamaño de la espuma de poliuretano de forma cubica de 0,5 cm de lado. Se cuantificó las concentraciones de cadmio mediante espectroscopia de absorción atómica, en muestras de aguas del Estero antes y después de su paso por el reactor. Se concluye que la espuma de poliuretano activada con nanopartículas de plata, como adsorbente, alcanzó un porcentaje de remoción de 48,75% y, por lo tanto, es efectivo para el tratamiento de aguas contaminadas con cadmio.

Abstract:The growing demand of the housing sector in the city of Machala-Ecuador turned invasions into the common model of disorganized growth of this city, where they use the “El Macho” estuary for the disposal of waste and sewage. Preliminary studies regarding the content of heavy metals in this estuary conclude that the concentrations of metals such as cadmium are higher than the limits established in the regulations of the Unified Text of Secondary Legislation of the Ministry of the Environment. In the present investigation, the removal of cadmium from water samples of the “El Macho” estuary was evaluated using polyurethane foam activated with silver nanoparticles as an adsorbent. To collect adsorption data, a vertical tubular reactor was designed, using 1,560 g of polyurethane adsorbent modified with silver nanoparticles, pH 8 and cubic-shaped polyurethane foam size of 0.5 cm of side. Cadmium concentrations were quantified by atomic absorption spectroscopy in samples of Estero water before and after passing through the reactor. It is concluded that the polyurethane foam activated with silver nanoparticles, as an adsorbent, reached a removal percentage of 48.75% and therefore, it is effective for the treatment of water contaminated with cadmium.

Resumo Olodo têxtil é um resíduo do tratamento do efluente das lavanderias têxteis e sua incorporação em materiais alternativos tem sido proposta como possibilidade para sua destinação. Foi realizada uma busca sistemática na literatura nesta perspectiva, visando observar as concentrações de material residual e seu preparo, as matrizes utilizadas, o desempenho tecnológico e imobilização do resíduo têxtil. As matrizes empregadas foram argamassas, concretos e tijolos cerâmicos, sendo observados, de maneira geral, efeitos deletérios nas características mecânicas dos materiais produzidos. Em concretos e argamassas, a finura impactou no aumento da demanda de água, o que elevou a porosidade das misturas; e a matéria orgânica e metais pesados, na hidratação do cimento. Estudos recentes propuseram, então, o pré-tratamento do material residual como uma alternativa favorável. Incrementos na porosidade também ocorreram nos tijolos cerâmicos, porém, devido ao elevado teor de matéria orgânica. Quanto a imobilização do resíduo, os materiais cimentícios apresentaram desempenho satisfatório; já os tijolos cerâmicos, obtiveram alguns resultados fora dos limites normativos. Portanto, é necessário ampliar as discussões quanto ao pré-tratamento realizado no lodo têxtil, bem como seus impactos no desempenho mecânico e ambiental.

Abstract Textile sludge is a waste from the effluent treatment of textile laundries and its incorporation into alternative materials has been proposed as a possibility for its disposal. A systematic search was carried out in literature from this perspective, aiming to observe concentrations of waste material and its preparation, matrices used, technological performance and immobilization of textile waste. The matrices used were mortars, concretes and ceramic bricks, in general, deleterious effects were observed on mechanical characteristics of the materials produced. In concrete and mortars, the fineness had an impact on increase in water demand, which increased mixtures porosity; and organic matter and heavy metals, in cement hydration. Recent studies therefore proposed waste material pre-treatment as a favorable alternative. Increases in porosity also occurred in ceramic bricks, however, due to high organic matter content. Regarding waste immobilization, cementitious materials showed satisfactory performance; ceramic bricks, on the other hand, obtained some results outside the normative limits. Therefore, it is necessary to expand discussions regarding the pre-treatment carried out on textile sludge, as well as its impacts on mechanical and environmental performance.

Resumo O objetivo deste estudo é explorar abordagens mais sustentáveis, substituindo o cimento Portland (OPC) por pó reciclado misto (RMP) derivado de resíduos de construção e demolição (RCD), focado na redução das emissões de carbono. O RCD foi submetido à moagem e peneiramento até a obtenção de uma fração < 0,15 mm. Em seguida, as partículas foram termicamente ativadas a 800°C em mufla por 0,5, 1, 2 e 3 horas. Os níveis de substituição de OPC por RMP foram definidos a partir do método de empacotamento de partículas, variando entre 0 e 65%. O estudo foi realizado em pastas com relação água/finos entre 0,07 e 0,14 e aditivo superplastificante (SP), com avaliação da resistência à compressão aos 28, 63 e 91 dias. Quanto ao desempenho mecânico e ambiental das pastas de cimento Portland compostas com RMP a resistência à compressão foi superior à referência, chegando a 37 MPa para um teor de substituição de 45% aos 28 dias, promovendo uma redução de 53% na emissão de CO 2 por m³ de pasta. O estudo indicou que tratar e empacotar as partículas de RMP aumenta o desempenho mecânico e ambiental, tornando-se alternativa para promover a economia circular e reduzir as emissões do cimento.

Abstract The aim of this study is to explore more sustainable approaches by replacing Portland cement (OPC) with recycled mixed powder (RMP) derived from construction and demolition waste (CDW), with a focus on reducing carbon emissions. The CDW was subjected to grinding and sieving until a fraction <0.15 mm was obtained. The particles were then thermally activated at 800°C in a muffle for 0.5, 1, 2, and 3 hours. The OPC replacement levels by RMP were defined based on the particle packing method, ranging from 0 to 65%. The study was carried out on pastes with a water/fines ratio ranging from 0.07 to 0.14 and superplasticizer admixture (SP), evaluating the compressive strength at 28, 63, and 91 days. The mechanical and environmental performance of Portland cement pastes composed with RMP showed compressive strength higher than the reference, reaching 37 MPa for a 45% replacement content at 28 days, reducing the CO2 emissions per m³ of paste by up to 53%. This study suggested that the treatment and packaging RMP particles may potentially increase the mechanical and environmental performance, making it an alternative to promote the circular economy and low-carbon cement.

RESUMO Este estudo tem como objetivo desenvolver um material compósito ecológico, reciclável e de baixo custo para uso em galpões de armazenamento e oficinas de máquinas. O novo compósito consiste em um bloco de pó de pedra e cascalho unidos por polipropileno reciclado através de tratamento térmico. O foco principal deste estudo é determinar os efeitos de variações nas proporções de polímeros nas propriedades de resistência e permeabilidade do compósito estudado, visando alcançar propriedades ótimas, ou seja, alta resistência e baixa permeabilidade. Para isso, utilizou-se o arranjo fatorial 2², composto por quatro tratamentos e três pontos centrais, cada um replicado três vezes. Os dados foram analisados estatisticamente com nível de confiança de 95% a partir de metodologia adaptada. Isso envolveu testes de resistência à compressão, resistência à flexão em 3 pontos, abrasão Los Angeles e absorção de água por imersão, nos quais três porcentagens de teor de polímero (PC) - 15, 25 e 35% - e agregados (areia fina, areia média, e areia grossa - FS, MS e CS) foram usadas para preparar o compósito. O compósito desenvolvido foi considerado adequado para utilização em armazéns e oficinas de máquinas, pois apresentou características físicas e mecânicas adequadas, ou seja, baixa taxa de absorção de água e alta resistência à compressão e abrasão, além de ser um compósito ecologicamente correto.

ABSTRACT This study aims to develop an eco-friendly, recyclable, and cost-effective composite material for use in storage sheds and machine workshops. The new composite consists of stone dust and gravel bricks bonded by recycled polypropylene through heat treatment. The main focus of this study is to determine the effects of varying polymer proportions on the resistance and permeability properties of the studied composite, intending to achieve optimal properties, i.e., high resistance and low permeability. To do this, the 2² factorial arrangement was employed, comprising four treatments along with three central points, each replicated three times. The data was statistically analyzed at a 95% confidence level from an adapted methodology. This involved tests of compression strength, 3-point bending strength, Los Angeles abrasion, and water absorption by immersion, in which three percentages of polymer content (PC) - 15, 25, and 35% - and aggregates (fine sand, medium sand, and coarse sand - FS, MS, and CS) were used to prepare the composite. The developed composite was deemed suitable for use in storage warehouses and machine workshops, as it presented physical and mechanical appropriate characteristics, i.e., a low water absorption rate and high resistance to compression and abrasion, in addition to being an environmentally friendly composite.

ABSTRACT Objective: Design a procedure for the management of livestock waste under the principles of the circular economy based on the sustainability of production. Materials and methods: The bibliographic review was used to analyze the literature published on the topic of study. Using the induction-deduction and analysis-synthesis methods, the information collected was interpreted and the proposed procedure was developed with its stages and steps. The Iadov method was used for the methodological validation of the procedure. To process the responses, the Statistical Package for Social Sciences, in Spanish, the Statistical Package for Social Sciences, version 23, was used and descriptive statistical analysis was carried out. Results: Through the stages and steps, the essential aspects were incorporated to achieve sustainable management of livestock waste. With the Iadov method, the satisfaction index was calculated, which resulted in 0.77, which indicated that the procedure proposal was approved and its usefulness was recognized. The procedure is intended to serve as a premise for the prevention, minimization of waste and for the sustainability of livestock production. Conclusions: The circular economy offers potential for improving waste management by considering them as secondary raw materials. The procedure is proposed as an instrument that facilitates and guides the transition towards the circular economy; furthermore, it allows the best use of the economic potential of waste, job creation, reduction of the negative impact on the environment and adaptation of existing treatment technologies to the conditions of the company.

RESUMEN Objetivo: Diseñar un procedimiento para la gestión de residuos ganaderos bajo los principios de la economía circular en función de la sostenibilidad de la producción. Materiales y métodos: Se utilizó la revisión bibliográfica para analizar la literatura publicada sobre el tema de estudio. Con los métodos de inducción-deducción y análisis-síntesis se interpretó la información recogida y se elaboró el procedimiento propuesto con sus etapas y pasos. Se recurrió al método Iadov para la validación metodológica del procedimiento. Para el procesamiento de las respuestas se empleó el Statistical Package for Social Sciences, en español Paquete Estadístico para las Ciencias Sociales, versión 23, y se realizó el análisis estadístico descriptivo. Resultados: A través de las etapas y pasos se incorporaron los aspectos esenciales para el logro de la gestión sostenible de residuos ganaderos. Con el método de Iadov se calculó el índice de satisfacción que dio como resultado 0.77, lo que indicó que se aprobó la propuesta del procedimiento y se reconoció la utilidad del mismo. Se pretende que el procedimiento sirva como premisa para la prevención, minimización de los residuos y para la sostenibilidad de la producción ganadera. Conclusiones: La economía circular ofrece potencialidades para el perfeccionamiento de la gestión de residuos al considerarlos como materias primas secundarias. El procedimiento se propone como un instrumento que facilite y oriente el tránsito hacia la economía circular; además, permite el mejor aprovechamiento de las potencialidades económicas de los residuos, creación de empleo, disminución del impacto negativo al medio ambiente y adecuación de las tecnologías de tratamiento existentes a las condiciones de la empresa.

Abstract Introduction. The amount of usable water is currently limited due to the deterioration of its sources and indiscriminate use. An alternative to this problem is producing under green houses, where it is possible to obtain better water use efficiency (WUE) by reducing crop evapotranspiration (ETc) without compromising its productive potential. Objective. To evaluate the effect of 3 levels of volumetric moisture content depletion in coir on the vegetative-generative behavior of hydroponic tomato and sweet pepper produced under greenhouse cultivation. Materials and methods. The study was conducted during August to December 2020 and January 2021, at Estación Experimental Agrícola Fabio Baudrit Moreno, Alajuela, Costa Rica. Three treatments were applied: 11, 22 and 32% of water depletion in the substrate. Morphophysiological and reproductive parameters such as: the leaf area (AF), the number of leaves (NH), width (AH) and length of the leaf (LH), the length (LT) and the diameter of the stem (DT), the number of nodes (NN), dry matter (DM), stomatal conductance (gs), crop evapotranspiration (ETc), water use efficiency (WUE), the total yield (Rt), the commercial (Rc) of first (F1), second (F2) and third (F3) and waste fruits (Fd) were evaluated. Results. In the tomato treatments (TT) there was no effect on NH, LT, LH and NN; on the other hand, differences were reported in AH, DT and in MS, with treatment TT11 obtaining the higher values. The sweet pepper (TC), the treatment TC11 was statistically superior to the other treatments in number (NH), width (AH) and length (LH) of the leaf, in number of nodes (NN), production of fresh (MF) and dry matter (MS) and in diameter of the stem (DT), while there were no differences between treatments in stem length (LT). There were no differences in ETc and Rt, for both crops, but there was a difference in the commercial yield once it was divided by quality of fruit, TT11 presented the highest production of first and second fruit quality, while treatment TC11 presented the highest production of first, second and third fruit quality. For both crops, there were significant differences between treatments in terms of stomatal conductance. TT11 and TC11 treatments obtained the highest value of EUA with 37.32 kg.m-3 and 21.46 kg.m-3, respectively. Conclusion. In both crops, treatments with 11 and 22% water depletion showed an adequate balance between vegetative and productive growth, which was reflected in greater production of better quality commercial fruits, less waste and greater WUE.

Resumen Introducción. El uso de agua dulce en agricultura se encuentra limitado debido al deterioro de sus fuentes y su uso indiscriminado. El riego deficitario en agricultura protegida es una alternativa para mejorar la eficiencia en el uso del agua, a través de la reducción de la evapotranspiración del cultivo, sin comprometer su potencial productivo. Objetivo. Evaluar el efecto de 3 niveles de agotamiento del contenido de humedad volumétrica en un sustrato de fibra de coco, sobre el comportamiento vegetativo-generativo de los cultivos de tomate y chile dulce hidropónicos en invernadero. Materiales y métodos. El estudio se realizó en la Estación Experimental Agrícola Fabio Baudrit Moreno, Alajuela, Costa Rica. En ambos cultivos se aplicaron 3 tratamientos con 11, 22 y 32% de agotamiento hídrico en el sustrato, en un diseño experimental en bloques completos al azar. Se evaluaron parámetros morfofisiológicos y productivos tales como área foliar (AF), número de hojas (NH), ancho (AH) y longitud de hoja (LH), longitud (LT) y diámetro del tallo (DT), número de nudos (NN), materia seca (MS), conductancia estomática (gs), evapotranspiración del cultivo (ETc), eficiencia de uso de agua (EUA), rendimiento de fruto comercial (Rc) de primera (F1), segunda (F2) y tercera (F3), fruto de desecho (Fd) y rendimiento total (Rt). Resultados. En los tratamientos en tomate (TT) no hubo efecto sobre el NH, LH, LT y NN; mientras que con TT11 se obtuvieron valores superiores en AH, DT y MS. En chile dulce (TC), el TC11 obtuvo mayor NH, AH, LH, NN, DT y MS que los demás tratamientos; mientras que no hubo diferencias entre tratamientos en LT. En ambos cultivos, no hubo efecto sobre la ETc y el Rt, sin embargo, con 11% de agotamiento se obtuvo mayor producción comercial de F1 y F2 por lo que consecuentemente hubo mayor EUA con 37,32 kg.m-3 y 21,46 kg.m-3, respectivamente. Para ambos cultivos, la gs fue diferente entre tratamientos. Conclusión. En ambos cultivos, los tratamientos con 11 y 22% de agotamiento hídrico evidenciaron un adecuado balance entre crecimiento vegetativo y productivo, que se reflejó en mayor producción de frutos comerciales de mejor calidad, menos desecho y mayor EUA.

ABSTRACT Finding sustainable methods for utilizing biosolids, also known as municipal sewage sludge (SS), presents a pressing challenge in modern waste management practices. Therefore, this study aimed to evaluate the impact of SS amendment on growth, biochemical, proximate, and heavy metal bioaccumulation parameters of berseem clover (Trifolium alexandrinum L.) fodder crop under field conditions. Trifolium alexandrinum was cultivated using different rates of SS mixing (i.e., T0: 0% as control with no SS application, T1: 5%, and T2: 10%). The results obtained showed a significant (p < 0.05) increment in growth, biochemical, and proximate parameters of T. alexandrinum with an increasing SS mixing rate. The highest productivity of T. alexandrinum fodder (1.92 kg m-2 fw) was observed in the T2 treatment as compared to the control treatment. The heavy metal analysis of shoot and root parts of T. alexandrinum showed that the contents (mg kg-1) of eight elements (Cd 0.02-0.13, Co 0.04-0.08, Cu 5.94-0.05, Cr 0.43-1.68, Fe 7.08-15.93, Ni 0.89-2.90, Mn 1.62-5.38, and Zn 3.30-7.04) increased significantly (p < 0.05) with SS mixing rate. The bioaccumulation factor (BAF) was below 1 except for Cu and Zn exhibiting their rapid uptake by plants from SS-treated soils. However, dietary intake modeling (DIM < 1) and health risk index (HRI < 1) studies showed that the levels of heavy metals did not exceed the permissible limits in any SS treatment. Overall, SS amendment has a positive impact on the growth, biochemical, proximate, and heavy metal characteristics of T. alexandrinum. Therefore, this study suggested a strategy for low-cost soil fertilization and fodder crop production which could sustainably benefit waste recycling.

Abstract Polyhydroxyalkanoates (PHA) are biodegradable plastics synthesized by a wide variety of microorganisms and are identified by sharing very similar characteristics with petrochemical plastics. These biopolymers can be used to replace plastic materials, the same ones that currently represent a major environmental pollution problem as they are poorly degradable. The most recent studies focus on the search for PHA extraction strategies, using bioremediation in petrochemical plastics, fuels, and in water treatment that seek to reduce the impact of environmental pollution. All this is carried out through chemical reactions that bacteria carry out with carbon sources, generating PHA while contaminating waste is eliminated. The main advantage of these compared to petroleum-derived plastics is that being produced by microorganisms. The objective of this review is to show the production of polyhydroxyalkanoates in bacteria as an alternative to the increase in environmental pollution.

Resumen Los polihidroxialcanoatos (PHA), son plásticos biodegradables sintetizados por una gran variedad de microorganismos y se identifican por compartir características muy similares con los plásticos de origen petroquímico. Estos biopolímeros pueden ser aprovechados para reemplazar materiales de plástico, los mismos que actualmente representan un gran problema de contaminación ambiental al ser poco degradables. Los estudios más recientes, se enfocan en la búsqueda de estrategias de extracción de PHA, empleando la biorremediación en plásticos petroquímicos, combustibles, y en tratamiento de aguas que buscan reducir el impacto de la contaminación ambiental. Todo esto se lleva a cabo mediante reacciones químicas, que las bacterias realizan con las fuentes de carbono, generando PHA mientras se eliminan los desechos contaminantes. La biodegradabilidad es la principal ventaja de estos materiales sintetizados por medio de microrganismos, en comparación con los plásticos convencionales que no poseen esta propiedad. El objetivo de esta revisión es evidenciar la producción de polihidroxialcanoatos (PHA), en bacterias como alternativa ante el aumento de la contaminación ambiental.

ABSTRACT Introduction: In the treatment of waste water at the “Desembarco del Granma” textile factory there is a neutralization tank, which resembles a continuous reactor with agitation. This equipment uses H2SO4, which must be replaced by a chemical agent with a lower impact on the environment. Objective: To determine the viability of using the existing reactor at the “Desembarco del Granma” textile factory for the neutralization of residual water when using CO2. Materials and Methods: Continuous stirred reactors were compared at laboratory and industrial levels, where the criterion of geometric similarity was considered. The Aspen Plus program was used to simulate the industrial reactor, considering the kinetics obtained at the laboratory level. The fluid package selected was the UNIQUAC. Results and Discussion: The speed at the tip of the impeller is the same for both reactors and the relationship between the diameter of the impeller and that of the tank remains practically constant, so there is geometric similarity between the reactors. The pH of the residual water neutralized with CO2 was 7.2, showing adequate neutralization. Conclusions: Geometric similarity was evidenced between continuous stirred reactors at laboratory and industrial levels. The pH of the neutralized wastewater in the industrial reactor, determined by simulation, was 7.2. It was proven, with the use of Aspen Plus, that the textile company's industrial reactor can be used for the wastewater neutralization process when CO2 is used instead of H2SO4.

RESUMEN Introducción: En el tratamiento del agua residual en la textilera “Desembarco del Granma” existe una cisterna de neutralización, que se asemeja a un reactor continuo con agitación. En dicho equipo se emplea H2SO4, el cual debe ser sustituido por un agente químico con un impacto menor sobre el medio ambiente. Objetivo: Determinar la viabilidad de la utilización de reactor existente en la textilera “Desembarco del Granma” para la neutralización del agua residual al emplear CO2. Materiales y Métodos: Se compararon los reactores continuos con agitación a nivel de laboratorio e industrial, donde se consideró el criterio de similitud geométrica. Se utilizó el programa Aspen Plus para simular el reactor industrial, considerando la cinética obtenida a nivel de laboratorio. El paquete de fluidos seleccionado fue el UNIQUAC. Resultados y Discusión: La velocidad en la punta del impulsor es igual para ambos reactores y la relación entre el diámetro del impelente y el del tanque se mantiene prácticamente constante, hay similitud geométrica entre los reactores. El pH del agua residual neutralizada con CO2 fue 7,2, manifestando una adecuada neutralización. Conclusiones: Se evidenció similitud geométrica entre los reactores continuos con agitación a nivel de laboratorio e industrial. El pH del agua residual neutralizada en el reactor industrial, determinado por simulación fue de 7,2. Se comprobó, con el empleo del Aspen Plus, que el reactor industrial de la textilera se puede usar para el proceso de neutralización del agua residual cuando se emplee CO2 en lugar de H2SO4.

Abstract One of the problems of human activity is the continuous accumulation of garbage, both inorganic and organic, its management, treatment and final disposal. Currently is possible to implement techniques to reduce them and promote the environment improvement. One of these processes is the treatment of organic waste through the composting process, which is a method that transforms organic matter via aerobic decomposition, to gives a stable product, which adds nutrients to the soil, improving its physical and chemical properties that have been attenuated by agricultural activities. The present work evaluates the quality of the final composting products (compost and leachates) generated within a prototype composter from organic kitchen waste and organically light components that, supported by a microbial accelerator and mechanical processes, reduce the process time by 600% compared to conventional processes with a similar product quality according to existing quality parameters. The results show that the organic fertilizer has a humidity of 73% slightly higher than established, does not present a high concentration of toxic heavy metals that are below the permissible limit and a C/N ratio of 6.5 that is adequate to be used as an additive. organic soil improver.

Resumen Uno de los desafíos que debe enfrentar la sociedad actual tiene que ver con la acumulación, gestión, tratamiento y disposición final de desechos orgánicos e inorgánicos. Por eso, en el panorama contemporáneo se requiere de la implementación de técnicas destinadas a mitigar esta problemática con el fin de promover la mejora del entorno ambiental. En cuanto al tratamiento de residuos de origen orgánico, se pueden mencionar estrategias como el proceso de compostaje, un método que propicia la transformación de la materia orgánica mediante la descomposición aeróbica, lo cual genera un producto final estabilizado. Este producto, al ser integrado al suelo, enriquece sus propiedades físicas y químicas, las cuales pueden haberse visto mermadas debido a actividades agrícolas. Explicado lo anterior, el objetivo del presente estudio fue evaluar la calidad de los productos resultantes del compostaje (composta y lixiviados) obtenidos en el seno de un prototipo de compostero, el cual se nutre de desechos orgánicos provenientes de la cocina, así como de componentes orgánicos ligeros. Además, se vale de un coadyuvante microbiano y procesos mecánicos para reducir el tiempo de compostaje hasta en 600 % en comparación con los métodos convencionales, sin menoscabo de la calidad del producto final, según los parámetros de calidad vigentes. En conclusión, los resultados evidencian que el abono orgánico obtenido mediante este procedimiento presenta una humedad del 73 %, ligeramente superior a la estipulada, y carece de una concentración elevada de metales pesados que supere los límites permitidos. Además, se confirma que la relación C/N alcanza un valor de 6.5, lo cual lo convierte en un aditivo orgánico idóneo para mejorar las condiciones de los suelos agrícolas.

Resumo Um dos desafios que a sociedade atual deve enfrentar tem a ver com a acumulação, gestão, tratamento e eliminação final de resíduos orgânicos e inorgânicos. Portanto, no panorama contemporâneo, é necessária a implementação de técnicas que visem a mitigação deste problema, a fim de promover a melhoria do ambiente ambiental. Em relação ao tratamento de resíduos de origem orgânica, podem ser citadas estratégias como o processo de compostagem, método que promove a transformação da matéria orgânica por meio da decomposição aeróbica, que gera um produto final estabilizado. Este produto, quando integrado ao solo, enriquece suas propriedades físicas e químicas, que podem ter sido diminuídas devido às atividades agrícolas. Posto o exposto, o objetivo deste estudo foi avaliar a qualidade dos produtos resultantes da compostagem (composto e chorume) obtidos dentro de um protótipo de compostor, que é nutrido por resíduos orgânicos provenientes da cozinha, bem como componentes orgânicos leves. Além disso, utiliza adjuvante microbiano e processos mecânicos para reduzir o tempo de compostagem em até 600% em relação aos métodos convencionais, sem comprometer a qualidade do produto final, de acordo com os parâmetros de qualidade vigentes. Concluindo, os resultados mostram que o fertilizante orgânico obtido através deste procedimento apresenta umidade de 73%, um pouco superior ao estipulado, e carece de alta concentração de metais pesados que ultrapasse os limites permitidos. Além disso, confirma-se que a relação C/N atinge um valor de 6,5, o que o torna um aditivo orgânico ideal para melhorar as condições dos solos agrícolas.

Abstract: The study investigated the effects of construction waste powders exposed to elevated temperatures on the properties of cement mortar. The waste powders were obtained from demolished granite and clay blocks after more than 15 years of their service life. The exposure temperatures were 200 °C, 400 °C, 600 °C, and 800 °C. The heat-treated and untreated waste powders replaced cement in mortars at 10% and 20% by weight. The use of untreated recycled granite and clay powders adversely affected the mechanical strength and transport properties of the cementitious mixtures. On the other hand, the effects of thermal exposure varied for the two powder materials. As the exposure temperature increased, the performance of mixtures containing granite powder gradually deteriorated, while mixtures containing clay powder improved. The efficiency was both worst and best at 800 °C. For instance, a mixture containing 10% clay powder treated at 800 °C exhibited compressive strength equivalent to the reference mortar with no waste material. In contrast, under the same conditions, the compressive strength of the mixture containing granite powder was 33% lower. These results indicate that identifying the type and characteristics of recycled materials is essential for their utilization and application of enhancement methods

Resumen El compostaje es una de las alternativas biotecnológicas más aplicadas para el tratamiento y valorización de los residuos verdes (RV). Sin embargo, su transformación es un reto, debido a las características fisicoquímicas de los RV que afectan los tiempos del proceso y la calidad del producto. Esto limita la aplicación de esta tecnología en países en desarrollo como Colombia. Este artículo presenta aportes alrededor de los avances en la investigación del compostaje de RV, con base en resultados de seis años de estudios realizados por los autores. Se aborda una reflexión sobre: i) el análisis de la calidad fisicoquímica de los sustratos, ii) la evaluación de estrategias para mejorar el proceso y la calidad del producto, y iii) las perspectivas sobre las alternativas implementadas hasta el momento. Los resultados de las investigaciones muestran que las estrategias a diferentes escalas han sido efectiva para reducir los tiempos de proceso (entre 43 y 67 días), mejorar las condiciones para la higienización del material (temperatura en rangos termofílico por mayor tiempo (6 días adicionales) comparado con tratamientos sin estrategias) y un cumplimiento de los estándares de calidad del producto. La reflexión propone nuevas perspectivas para continuar con los estudios de mejoramiento del compostaje de RV, entre los que se abordan temas asociados a uso de co-sustratos, de aditivos, de inóculos bacterianos, así como la evaluación de la calidad del producto y el empleo de herramientas de optimización en el compostaje de RV. Estos estudios ayudan a posicionar el compostaje de RV como una opción adecuada para el manejo de la fracción lignocelulósica presente en los residuos sólidos municipales (RSM).

Abstract Composting is one of the most applied biotechnological alternatives for the treatment and recovery of green waste (GW). However, its transformation is a challenge, due to the physicochemical characteristics of GWs that affect the process time and product quality. This limits the application of this technology in developing countries such as Colombia. This article presents contributions on the advances in GW composting research, based on results of six years of studies carried out by the authors of this paper. Reflections are addressed on: i) the analysis of the physicochemical quality of the substrates, ii) the evaluation of strategies to improve the process and the quality of the product, and iii) the perspectives on the alternatives implemented so far. The results of the investigations show that the strategies at different scales have been effective in reducing process times (between 43 and 67 days), improving the conditions for sanitizing the material (temperature in thermophilic ranges for a longer time -6 additional days- compared to treatments without strategies) and compliance with product quality standards. The reflection proposes new perspectives to continue with the studies of improvement of GW composting, among which issues associated with the use of co-substrates, additives, and bacterial inoculum are addressed, as well as the evaluation of product quality and employment of optimization tools in GW composting. These studies help position GW composting as a suitable option for the management of the lignocellulosic fraction present in municipal solid waste (MSW).