Cattle slaughtering produce large amounts of wastewater containing high concentrations of organic matter and nutrients and requires significant treatment before disposal or reutilization. However, the nutrients contained can be valued as a medium for microalgal biomass generation. In this work, hydrodynamic cavitation (HC) followed by membrane filtration or biological (microalgae cultivation) treatment in continuous mode were performed. From cattle slaughterhouse wastewater (CSW), by the effect of HC treatment with air injection in batch mode, more than 20% of the chemical oxygen demand (COD) was removed. In a continuous HC process, the COD content in output was 324 mg O₂/L, which is 68% lower than the supplied CSW. After that, 76% of residual COD was removed by filtration through a tubular alumina membrane (600 nm). Finally, 85% of residual COD after HC treatment in 24 h in a batch mode was removed by microalgae. On the other hand, the COD concentration in the output was around 59 mg O₂/L in continuous mode, which represents 85–93% COD removal. The process involving HC and microalgae growing looks promising since in addition to water treatment, the microalgae produced could be valued in a biorefinery concept.

The aim of this research was to explore the removal of Red G and Bordeaux B dyes from water using a packed bed column with conventional carbon (C_-conv) and iron-modified activated carbon $(C{{}_{\text{-}}}_{FeC{l}_3}$). The bands increased in $C{{}_{\text{-}}}_{FeC{l}_3}$, corresponding to groups already existing in C_-conv, such as C = C and C-C, and the appearance of new groups, such as C-O, C-Cl, Fe-Cl and Fe-O. The total ash content (C_T) was C_T = (10.53 ± 0.12 and 8.98 ± 0.21)% for C_-conv and $C{{}_{\text{-}}}_{FeC{l}_3}$, respectively. A molecular structure in the shape of a cross was noticed in Bordeaux B, which was less complex and smaller than the one in Red G. For fixed-bed columns, the carbon fraction was (0.43 and 0.85) mm. The pH of the adsorbents was 8.55 for C_-conv and 4.14 for $C{{}_{\text{-}}}_{FeC{l}_3}$. Breakthrough curves were obtained and the Thomas model (TM) and Yoon–Nelson model (YNM) were applied. The sorption capacity of Bordeaux B on C_-conv and $C{{}_{\text{-}}}_{FeC{l}_3}$ was $q_{TH}$: (237.88 and 216.21) mg/g, respectively, but the one of Red G was $q_{TH}$: (338.46 and 329.42) mg/g. The dye removal (R_T) was over 55%.

Los hidrocarburos aromáticos BTEX (benceno, tolueno, etilbenceno y xileno) son contaminantes persistentes y tóxicos provenientes de actividades industriales y derrames de petróleo que afectan significativamente la calidad del agua, del suelo y la salud humana. Dadas las limitaciones de los métodos fisicoquímicos para la remediación de estos contaminantes, la biorremediación, particularmente mediante el uso de microalgas como Chlorella sp., emerge como una alternativa eficiente y sostenible debido a su capacidad para biodegradar compuestos orgánicos contaminantes y adaptarse a diversas condiciones ambientales. Es por eso que este estudio evaluó la eficiencia de biodepuración de hidrocarburos BTEX utilizando la microalga Parachlorella kessleri, aislada y caracterizada morfológica y molecularmente. Se determinó su cinética de crecimiento, obteniendo una fase exponencial de 120 horas, una velocidad específica de crecimiento μ=0,0230 h⁻¹ y un tiempo de generación G=30,15 h. La medición de BTEX mediante cromatografía de gases FID mostró alta precisión y selectividad, con concentraciones mínimas detectables para benceno de 0,4 mg/L, tolueno 1,7 mg/L, etilbenceno 4,7 mg/L y xilenos entre 1,4-7,2 mg/L. Parachlorella kessleri demostró una notable capacidad de biorremediación, eliminando hasta 93,6% de benceno, 78,1% de tolueno, 66,0% de etilbenceno y 73,7% de xilenos en cinco días. Estos resultados destacan el enorme potencial de las microalgas en la mitigación de la creciente contaminación ambiental e invita a revalorar el papel de la biotecnología para enfrentar de manera sostenible los desafíos ambientales globales contemporáneos.