Approximately 20% of the mineral coal ash (MCA) generated worldwide, during the combustion of this fossil fuel, has been used to produce Portland cement. Other applications include soil improvement, ceramic industry, catalysis, and an application with special interest for this work which is the synthesis of zeolites. A hospital effluent clarification system was developed using MCA as an adsorbent for substances responsible for the color of the effluent generated by the laundry. A perfect mix tank promotes intimate contact between MCA and the effluent. At the exit of the mixing tank, a pH sensor correlated the value of this variable with the concentration of MCA in the mixture inside the tank. The information about the pH of the mixture was then sent to a programmable logical controller (PLC), which regulated the motor speed of a screw conveyor, with the aid of a frequency inverter. A color removal efficiency of the order of 99.8% was achieved. The proposed clarification system can operate both in batch and continuous. In the first case, the ideal operating conditions can be set. The strategy for adjusting operating conditions is to obtain an adequate nominal capacity for the system by reducing or increasing the number of cyclones per battery or the number of cyclone batteries.

Este artigo de revisão aborda estratégias biotecnológicas sustentáveis para a conversão de compostos de sulfato e resíduos lignocelulósicos, com foco na utilização de bactérias redutoras de sulfato (BRS) e na valorização de resíduos agroflorestais e esgoto sanitário. As BRS demonstram potencial no tratamento de efluentes, drenagem de minas e remoção de sulfato e metais pesados de águas residuais, sendo sua atividade metabólica influenciada por fatores como pH, temperatura e relação demanda química de oxigênio/sulfato — DQO/SO4=. No contexto de uma bioeconomia sustentável, o desafio de converter resíduos lignocelulósicos em produtos de valor agregado é abordado por meio de técnicas de pré-tratamento físico, como moagem, extrusão, irradiação por micro-ondas e ultrassom, eficientes na valorização de resíduos de poda de árvores urbanas. O artigo destaca a importância dos biorreatores na transformação de matérias-primas em produtos bioquímicos, discutindo diferentes tipos de biorreatores, como batelada, tanque agitado contínuo, airlift, leito fluidizado, reator anaeróbio de fluxo ascendente (UASB) e coluna de bolhas, e suas vantagens e desvantagens específicas. A redução sustentável do sulfato é o foco central, integrando a aplicação de BRS e a conversão de resíduos lignocelulósicos de maneira a complementar os objetivos do trabalho e promover um fluxo mais coeso no resumo. Assim, enfatiza-se a inter-relação entre as estratégias de tratamento de efluentes e a valorização de resíduos em uma perspectiva de sustentabilidade ambiental, destacando-se a relevância deste estudo no contexto mais amplo de uma bioeconomia sustentável.

This work investigates the hydrodynamics of a circulating fluidized-bed riser by combining CFD simulations with noninvasive gamma-radiation transmission measurements. Two drag models, Gidaspow and EMMS, were evaluated. The computational setup underwent mesh-independence verification using the Grid Convergence Index, and model performance was quantified against experiments with RMSE and NRMSE. The analysis shows that EMMS generally provides closer agreement with measured solids volume-fraction profiles, particularly in the dilute core and in regions prone to particle clustering, while both models reproduce the principal axial and radial trends. In some sections with lower local solids concentration, Gidaspow tends to underestimate the solids holdup. Predictions of axial pressure variation are consistent with experimental tendencies for both closures. The integrated use of gamma-radiation diagnostics and CFD is shown to be effective for validating model predictions and for guiding model selection in riser simulations, balancing accuracy and computational cost. These results provide a documented, reproducible basis for simulations of gas–solid flows in circulating fluidized-bed systems and inform design and optimization decisions where reliable estimates of cross-sectional solids distribution are required.

This work investigates the fluid dynamic behavior of a circulating fluidized bed riser through CFD simulations and experimental measurements using gamma radiation. The main objective was to compare the accuracy of the Gidaspow and EMMS drag coefficient models in predicting the distribution of solids along the riser. The simulations were conducted using ANSYS Fluent software, which focused on predicting the volumetric fraction of solids and the pressure variation along the riser height. The results showed that the EMMS model, which considers interactions at multiple scales, provided more accurate predictions of solids concentration, especially in less dense regions. In contrast, the Gidaspow model presented underestimation in some sections. The experimental analysis reinforces the importance of considering the effects of particle clustering on flow behavior, highlighting the superiority of the EMMS model in simulating circulating fluidized beds. It is concluded that the EMMS model is more suitable for this type of application due to its greater accuracy in representing the interactions between the solid and gas phases.

Microorganisms are promising sources of biopigments, many of them with antioxidant, antimicrobial, anticancer and antimutagenic properties, and can be applied in food, pharmaceutical, and textile industries, among others. Among them, bicaverine, which is produced by Fusarium species and which has proven antitumor and antimicrobial properties. The objective of this work was to evaluate different strains of Fusarium oxysporum species in the production of this polycaferid and to analyze the influence of variables such as agitation, temperature and pH on the production of biomass, intracellular and extracellular bicaverin. For this, three strains of this fungus were tested: UCP 1624, UCP 1137 and UCP 0119. The results revealed that all species were able to produce pigment in both solid and liquid mediums, but with different yields. Due to obtaining a higher yield of biomass and bicaverine, the species Fusarium oxysporum UCP 1624 was subjected to a complete factorial design 23 that showed that high levels of agitation significantly influence all dependent variables: biomass production and extracellular and intracellular production of bicaverine. However, high pH levels showed a negative effect, indicating that low values contribute to the production of pigment and biomass. To confirm the presence of bicaherin, Infrared Spectroscopy (FT-IR) was performed, which demonstrated the presence of quinones, oxygenated polycyclic aromatic hydrocarbons, as well as the pigment bicaverin, which has in its molecule an oxygen interposed between two carbon atoms (C-O-C) in aromatic chains (benzoxanthone).