Metabolic Pathway Analysis of Nitrogen and Phosphorus Uptake by the Consortium between C. vulgaris and P. aeruginosa.

Anthropogenic activities have increased the amount of urban wastewater discharged into natural aquatic reservoirs containing a high amount of nutrients such as phosphorus (Pi and PO 4 - 3 ), nitrogen (NH 3 and NO 3 - ) and organic contaminants. Most of the urban wastewater in Mexico do not receive any treatment to remove nutrients. Several studies have reported that an alternative to reduce those contaminants is using consortiums of microalgae and endogenous bacteria. In this research, a genome-scale biochemical reaction network is reconstructed for the co-culture between the microalga Chlorella vulgaris and the bacterium Pseudomonas aeruginosa. Metabolic Pathway Analysis (MPA), is applied to understand the metabolic capabilities of the co-culture and to elucidate the best conditions in removing nutrients. Theoretical yields for phosphorus removal under photoheterotrophic conditions are calculated, determining their values as 0.042 mmol of PO 4 - 3 per g DW of C. vulgaris, 19.43 mmol of phosphorus (Pi) per g DW of C. vulgaris and 4.90 mmol of phosphorus (Pi) per g DW of P. aeruginosa. Similarly, according to the genome-scale biochemical reaction network the theoretical yields for nitrogen removal are 10.3 mmol of NH 3 per g DW of P. aeruginosa and 7.19 mmol of NO 3 - per g DW of C. vulgaris. Thus, this research proves the metabolic capacity of these microorganisms in removing nutrients and their theoretical yields are calculated.

Evaluation of nutrients removal (NO3-N, NH3-N and PO4-P) with Chlorella vulgaris, Pseudomonas putida, Bacillus cereus and a consortium of these microorganisms in the treatment of wastewater effluents.

In this research removal of NH3-N, NO3-N and PO4-P nutrients from municipal wastewater was studied, using Chlorella vulgaris, Pseudomonas putida, Bacillus cereus and an artificial consortium of them. The objective is to analyze the performance of these microorganisms and their consortium, which has not been previously studied for nutrient removal in municipal wastewater. A model wastewater was prepared simulating the physicochemical characteristics found at the wastewater plant in Chapala, Mexico. Experiments were carried out without adding an external carbon source. Results indicate that nutrient removal with Chlorella vulgaris was the most efficient with a removal of 24.03% of NO3-N, 80.62% of NH3-N and 4.30% of PO4-P. With Bacillus cereus the results were 8.40% of NO3-N, 28.80% of NH3-N and 3.80% of PO4-P. The removals with Pseudomonas putida were 2.50% of NO3-N, 41.80 of NH3-N and 4.30% of PO4-P. The consortium of Chlorella vulgaris-Bacillus cereus-Pseudomonas putida removed 29.40% of NO3-N, 4.2% of NH3-N and 8.4% of PO4-P. The highest biomass production was with Bacillus cereus (450 mg/l) followed by Pseudomonas putida (444 mg/l), the consortium (205 mg/l) and Chlorella vulgaris (88.9 mg/l). This study highlights the utility of these microorganisms for nutrient removal in wastewater treatments.

Monitoreo ambiental en un laboratorio quimico y su sistema de extracción / Environmental monitoring in a chemical laboratory and its air extraction system

Introducción. La volatilidad de los compuestos orgánicos usados en los laboratorios químicos los hace ser peligrosos para el ambiente y para la salud de las personas. Objetivo: Evaluar la calidad del aire del interior del laboratorio para compararla con el sistema de extracción en funcionamiento. Material y método: En esta investigación se consideró como indicador de calidad de aire interior la concentración de compuestos orgánicos volátiles (COV) provenientes del uso de alcoholes y disolventes. Mediante un muestreo puntual que comprendió 9 puntos, distribuidos en la superficie total dl laboratorio químico en un centro universitario de Jalisco, México, se midieron los COV por medio de un equipo portátil con detector de ionización de llama, probando con los sistemas de extracción funcionando y sin funcionar . Resultados: Se registraron concentraciones de COV de hasta 9,62 ppm, observándose que el sistema de extracción no siempre resulta funcional. Conclusiones: Se concluye que e s relevante revisar los sistemas de ventilación y extracción para mejorar la calidad del aire en el ambiente interno de los espacios donde se hacen demostraciones para la enseñanza de las ciencias químicas, específicamente en aquellos ambientes de interiores como aulas, laboratorios de práctica o talleres(AU)

Wetland plant uptake of desorption-resistant organic compounds from sediments.

Wetland plant uptake of 14C-labeled phenanthrene and chlorobenzene was investigated in greenhouse studies using sediment prepared to contain only the desorption-resistant fraction of the contaminant. Measurements of contaminant distribution in the plants and root-contaminant partition coefficients were conducted as well as estimates of the transpiration stream concentration of chlorobenzene and phenanthrene. Plant uptake of desorption-resistant phenanthrene and chlorobenzene occurred primarily in the root zone with total uptake ranging from 3.8 to 5.7% of the initial concentration in the sediment. Observed uptake of the compounds was remarkably similar despite wide differences in contaminant properties. A biphasic sorption isotherm was combined with a simple translocation model to predict plant uptake from two processes: root sorption and translocation. The model predicted the observed uptake well and may serve as an important tool for estimating plant uptake in sediments containing a desorption-resistant fraction. The potential implications of the existence of a finite, desorption-resistant pool of contaminants on phytoremediation of sediments are discussed.