A review on slurry bioreactors for bioremediation of soils and sediments

The aim of this work is to present a critical review on slurry bioreactors (SB) and their application to bioremediation of soils and sediments polluted with recalcitrant and toxic compounds. The scope of the review encompasses the following subjects: (i) process fundamentals of SB and analysis of advantages and disadvantages; (ii) the most recent applications of SB to laboratory scale and commercial scale soil bioremediation, with a focus on pesticides, explosives, polynuclear aromatic hydrocarbons, and chlorinated organic pollutants; (iii) trends on the use of surfactants to improve availability of contaminants and supplementation with degradable carbon sources to enhance cometabolism of pollutants; (iv) recent findings on the utilization of electron acceptors other than oxygen; (v) bioaugmentation and advances made on characterization of microbial communities of SB; (vi) developments on ecotoxicity assays aimed at evaluating bioremediation efficiency of the process

Growth of Chlorella vulgaris and Nannochloris oculata in effluents of Tilapia farming for the production of fatty acids with potential in biofuels

The use of microalgae in wastewater treatment and its biotechnological exploitation for the production of biofuels is a potential environmental application. Some species of microalgae are notable due to their lipid composition and fatty acid profile suitable for biofuel production. During the present study, a factorial 23 experimental design was conducted, which assessed three factors: i) two species of microalgae (Chlorella vulgaris and Nannochloris oculata), ii) two types of culture media [wastewater of tilapia farming (WTF) and bold’s basal medium (BB)], and iii) two types of lighting (multi-LED lamps and white light). Microalgae were inoculated in photobioreactors in 6 L of medium (WTF or BBM) at an initial concentration of 1.0 × 106 cells ml-1 at 20 ± 2°C. The highest average cell density as well as the highest productivity of biomass observed in the treatments was C. vulgaris treatment in BBM and multi-LED lighting (8.83 × 107 cells ml-1 and 0.0854 g l-1 d-1, respectively). Although the majority of lipid productivity was obtained in the exponential phase of N. oculata cultivated in multi-LEDs in both treatments (BBM with 58% and WTF with 52%), cultivation of both species was generally maintained in WTF and were those that presented the major lipid productivity (2-18 mg l-1 d-1) in comparison with those cultivated in BBM. Palmitic, stearic, oleic, linoleic, linolenic and eicosanoic (C16–C20) fatty acids were present in both species of microalgae in concentrations between 26 and 74%. Based on the results of the present study, we conclude that cultivation of N. oculata and/or C. vulgaris in WTF illuminated with multi-LEDs is an economic and sustainable alternative for biodiesel production because it can represent up to 58% of lipids with a fatty acid profile optimal up to 74% of the total fatty acids.Key words: Chlorella vulgaris, Nannochloris oculata, production of fatty acids, wastewater of tilapia farming, production of biofuels

Ambiente y bioenergía

El número especial “Ambiente y Bioenergía” es una compilación de 15 artículos de investigación seleccionados con estricto rigor científico a partir de más de 100 trabajos de investigación presentados durante el Simposio Ambiente y Bioenergía (SAB2020), llevado a cabo el 17 y 18 de septiembre del año 2020. Este simposio se realizó de manera virtual como consecuencia de la pandemia del SARS-CoV-2 (COVID-19) y fue transmitido vía Zoom, Youtube y Facebook. El simposio estuvo organizado por la Asociación de Biotecnología, Ingeniería Ambiental y Energías Renovables, Asociación Civil (ABIAER AC), una asociación sin fines de lucro y de carácter internacional con sede en Méxic

Impactos ambientales de biorrefinería integrada con etapa de sacarificación ácida

El objetivo de este trabajo fue evaluar los impactos ambientales producidos en una biorrefinería que procesa la fracción orgánica de residuos sólidos urbanos para la obtención de bioenergías y productos de valor agregado tales como concentrado de ácidos orgánicos y solventes, concentrado de enzimas celulolíticas y xilanolíticas conocida como HMZS. Se utilizó la técnica de Análisis de Ciclo de Vida. La etapa S de sacarificación consistió en la hidrólisis ácida de residuos donde se desdobla los polisacáridos a azúcares reductores dando licores hidrolizados (HL). Se encontró que el uso de carbón activado en la detoxificación de los HL de la sacarificación contribuyó notablemente a los impactos ambientales. A su vez, esos impactos se relacionaron también con la minería de carbón y su procesamiento para convertirlo en carbón activado. Desde el punto de vista energético global, la biorrefinería resultó deficitaria en carga térmica y productora neta de energía eléctrica.The objective of this work was to evaluate the environmental impacts of a biorefinery that processes the organic fraction of municipal solid waste. The biorefinery is known as HMZS. This is crucial because it can produce bioenergy’s and value-added products such as organic acids, solvents, cellulolytic, and xylanolytic enzymes. The Life Cycle Analysis technique was used. Stage S consisted of acid hydrolysis of residues where the polysaccharides are splitted into reducing sugars giving hydrolyzed liquors (HL). It was found that the use of activated carbon in the detoxification of HL contributed significantly to environmental impacts. In turn, these impacts were also related to coal mining and its processing into activated carbon. From the overall energy point of view, the biorefinery was found to be deficient in thermal load and net producer of electrical energy

Contribution à la technologie durable pour la remédiation des sols et sédiments pollués avec pesticides - réacteur électro-biochimique de nouveau type

L\u27objectif de cette recherche est d\u27étudier la remédiation d\u27un sol pollué par le lindane couplée à la génération simultanée d\u27électricité en utilisant un réacteur électrobiochimique de sols en suspension (REBC), puis de comparer la performance de bioréacteurs de sols en suspensions à celles des REBC

A side-by-side comparison of two systems of sequencing coupled reactors for anaerobic digestion of the organic fraction of municipal solid waste

The objective of this work was to compare the performance of two laboratory-scale, mesophilic systems aiming at the anaerobic digestion of the organic fraction of municipal solid wastes (OFMSW). The first system consisted of two coupled reactors packed with OFMSW (PBR1.1-PBR1.2) and the second system consisted of an upflow anaerobic sludge bed reactor (UASB) coupled to a packed reactor (UASB2.1-PBR2.2). For the start-up phase, both reactors PBR 1.1 and the UASB 2.1 (also called leading reactors) were inoculated with a mixture of non-anaerobic inocula and worked with leachate and effluent full recirculation, respectively. Once a full methanogenic regime was achieved in the leading reactors, their effluents were fed to the fresh-packed reactors PBR1.2 and PBR2.2, respectively. The leading PBR 1.1 reached its full methanogenic regime after 118 days (T m, time to achieve methanogenesis) whereas the other leading UASB 2.1 reactor reached its full methanogenesis regime after only 34 days. After coupling the leading reactors to the corresponding packed reactors, it was found that both coupled anaerobic systems showed similar performances regarding the degradation of the OFMSW. Removal efficiencies of volatile solids and cellulose and the methane pseudo-yield were 85.95%, 80.88% and 0.109 NL CH4 g-1 VSfed in the PBR-PBR system; and 88.75%, 82.61% and 0.115 NL CH4 g-1 VSfed in the UASB-PBR system [NL, normalized litre (273oK, 1 ata basis)]. Yet, the second system UASB-PBR system showed a faster overall start-up