Innovative Nitrogen and Carbon Removal

The aerobic systems have been the most widely biological treatment used for municipal and industrial wastewater but show serious problem with sludge sedimentation, high energy demand and microbial inhibition. On the other hand, the anaerobic digestion (AD) of wastewater is considered the best alternative to remove the organic compounds and to recover energy via methane production. Nevertheless, AD has a problem: the treatment of industrial wastewater with high organic nitrogen content reaches high free ammonia (NH3) concentrations due to the protein degradation. NH3 inhibits the methanogenic process and is toxic to the environment, and then, it must be removed before its final disposition. Several physicochemical processes have been evaluated for the recovery or/and treatment of ammonium from wastewater. The most frequent treatments are gas stripping and magnesium ammonium phosphate precipitation. These methods are effective, but they are very expensive compared to biological treatments. Moreover, these techniques usually require more power consumption than the biological process. The technologies based on partial nitrification and Anammox (PN‐A) are the ones with better performance. Thus, this chapter mainly focuses on biological processes based on AD, denitrification and PN‐A for the removal of carbon and nitrogen from industrial wastewater with recovery of energy and water

LIVING BIOMASS SUPPORTED ON A NATURAL-FIBER BIOFILTER FOR LEAD REMOVAL

Living biomass biofilters constitute an excellent alternative for heavy metal bioremediation. In situ biomass and exopolysaccharides production involve a crucial advantage over other bioremediation alternatives such as lignocellulosic biomass-based materials. In this study, a biofilm-forming bacterium was isolated from an ambient exposed to heavy metals. Bacterial biomass was inoculated on a biofilter packed with Furcraea andina fibers. The goal was to develop a continuous low-cost biofilter to remove low-to-moderate concentrations of Pb2+. Adsorption equilibrium and kinetics were determined for the fibers and the biofilm developed on the fibers. Biofilm presence had positive effects on the maximum adsorption capacity and the process kinetics. Biofilters packed with 20 g of F. andina fibers, with and without living biomass biofilm, were evaluated under continuous inflow of Pb2+ (325mg/day) at a concentration of 50 mg/L. The best results were obtained with the biofilm- fiber biofilter where total adsorption on Pb2+ were observed for 72 h. Maximum absorption capacity was 48.75 mg/g at pH=7

Effect of the bench scale extraction conditions on Pinus radiata bark extract yield, antioxidant properties and composition

Many pine bark extracts have antioxidant properties. This work examined bench scale extraction on the yield, the composition and antioxidant properties of Pinus radiata. Acetone solvent (98.7% w/w at 120 °C) yielded maximum phenols concentration, tannins concentration, anti-radical activity (DPPH) and reducing activity (FRAP), although its extraction yield was the lowest. When the organic solvent in the mixture decreased, the chelating activity increased (ICA) and antiradical and reducing activities decreased. The extract largest yield was obtained with water at 120ºC, but the antioxidant properties were relatively poor. Taxifolin (dihydroquercetin) and catechin were the main extract components detected by RP-HPLC. The best extraction conditions for high extractive yield and antioxidant properties was achieved with ethanol/water at 120 °C

The Prediction of Partial-Nitrification-Anammox Performance in Real Industrial Wastewater based on Granular Size

To date, the partial nitrification-Anammox (PN-A) granular sludge size has been exclusively analyzed in synthetic substrates. In this work, different ranges of granular size of PN-A sludge were studied at low oxygen concentration using real industrial wastewater as, well as a synthetic substrate. The granular sludge was characterized by the specific nitrification activity (SNA), specific anammox activity (SAA), and granule sedimentation rate. The relative abundance of the bacterial consortium was assessed for each range of diameters through the fluorescence in situ hybridization (FISH) technique. SNA exhibits a direct association with the specific surface of granules, which proves the importance of the outer layer in the nitrification process. Even more critical, the flocculent sludge allowed the stability of the nitrifying activity. The SAA showed different performances faced the real industrial and synthetic substrates. With the synthetic substrate, the SAA decreased at higher diameter ranges, whereas with the industrial substrate, the SAA increased at higher diameter ranges. This situation is explained by the oxygen protection in the sludge maintained with industrial wastewater. The relative abundance of heterotrophic bacteria increased from 9.6 to 22%, due to the presence of organic matter in the industrial substrate. The granular sedimentation rate increased with the diameter of the granules with a linear correlation (R2>0.98). Thus, granular sizes can be selected through sedimentation rate control. A linear correlation between SAA and granular sludge diameter ranges was observed. With this correlation, an error of less than 11% in the prediction of SAA was achieved. The use of diameter measurement and granular sedimentation rate as routine techniques could contribute to the control and start-up of PN-A reactors. In the same sense, organic matter present in defined concentrations, can be beneficial for the granular sludge stability, and thus, for nitrogen removal

Kinetics of cross-inhibited denitrification of a high load wastewater

Batch denitrification of a synthetic saline medium at 37 degrees C, pH 7.5 was studied. A kinetic expression and an inhibition function which adequately expresses inhibition and cross-inhibition by nitrate and nitrite in denitratation and denitritation steps occurring in high organic and nitrate load wastewater treatment was determined. Denitratation and denitritation rates were measured independently. Monod- and Haldane-type kinetics were used for denitratation and denitritation, respectively. The maximum specific rate, kNO(3) = 12.7 ing NO3-N/g VSS h, and the saturation constant, K-SNO3 = 0.47 mg NO3-N/L were calculated for denitratation. The maximum specific rate, kNO(2) = 13.8 mg NO2-N/g VSS h, the saturation constant K-SNO2 = 0.36 mg NO2-N/L and the inhibition constant KI-NO2 = 906 mg NO2-N/L were calculated for denitritation. Among other functional forms the Levenspiel inhibition model for denitratation and denitritation kinetics was proposed. The Levenspiel constants were SNO2-M = 1149.4 mg NO2-N/L, SNO3-M = 34.7 mg NO3-N/L, beta(1) = 1.578 and beta(2) = 1.005, respectively. The fitted experimental values show a good representation of the denitrification of effluents with high nitrogen load containing both nitrate and nitrite. Parametric sensitivity analysis show that inhibition functions (f(i)) and dimensionless constants (beta(i)) greatly affect predicted nitrite and nitrate consumption rates. (C) 2006 Elsevier Inc. All rights reserved

La acreditación ABET en ingeniería: ¿problema u oportunidad?

El Departamento de Ingeniería Química de la Universidad de Concepción ha presentado su carrera de Ingeniería Civil Química al proceso de acreditación ante la agencia norteamericana ABET. El eje de la acreditación se centra en un proceso de mejoramiento continuo que requiere ajustar el proceso de enseñanza a nuevas formas de medición, control y evaluación. Se presenta un modelo que implica cambios en la cultura de medición y evaluación en las asignaturas, hacia uno centrado en el logro de resultados de aprendizaje (RAs) por parte de los estudiantes. Dentro de la estrategia adoptada por el Departamento se realizaron actividades de perfeccionamiento docente y se instauraron trabajos en etapas para establecer el proceso de mejoramiento continuo: (1) creación de carpetas para cada asignaturas con sus respectivos syllabus, instrumentos de evaluación y pautas; (2) talleres para definir los RAs de todas las asignaturas de la carrera; (3) planillas para todas las asignaturas, con porcentaje de cumplimiento de los RA; (4) definición de índices clave de desempeño y su relación con cada RAs; (5) rúbricas como método de evaluación; y (6) trabajo de una Comisión de Mejoramiento Continuo. El proceso de acreditación significa instalar un proceso de mejoramiento continuo en la docencia, recoger evidencias claves sobre tipo de docencia que se imparte y resultados de aprendizaje, e incorporar a los planes de mejoramiento la percepción de los propios estudiantes además de titulados y empleadores, lo que permite finalmente considerar en el proceso de enseñanza las necesidades de la industria y la sociedad.Doi: 10.21703/rexe.20212043roeckel2

Effect of the bench scale extraction conditions on "Pinus radiata" bark extract yield, antioxidant properties and composition

Many pine bark extracts have antioxidant properties. This work examined bench scale extraction on the yield, the composition and antioxidant properties of Pinus radiata. Acetone solvent (98.7% w/w at 120 °C) yielded maximum phenols concentration, tannins concentration, anti-radical activity (DPPH) and reducing activity (FRAP), although its extraction yield was the lowest. When the organic solvent in the mixture decreased, the chelating activity increased (ICA) and antiradical and reducing activities decreased. The extract largest yield was obtained with water at 120ºC, but the antioxidant properties were relatively poor. Taxifolin (dihydroquercetin) and catechin were the main extract components detected by RP-HPLC. The best extraction conditions for high extractive yield and antioxidant properties was achieved with ethanol/water at 120 °C