Search results for "METHANE"
showing 10 items of 1763 documents
Batch dark fermentative hydrogen production from grass silage: The effect of inoculum, pH, temperature and VS ratio
2008
Abstract The potential for fermentative hydrogen (H2) production from grass silage was evaluated in laboratory batch assays. First, two different inocula (from a dairy farm digester and digested sewage sludge) were studied with and without prior heat treatment and pH adjustment. Only the inoculum from the dairy farm digester produced H2 from grass silage. Without heat treatment, methane (CH4) was mainly produced, but heat treatment efficiently inhibited CH4 production. pH adjustment to 6 further increased H2 production. The effects of initial pH (4, 5 and 6), temperature (35, 55 and 70 ∘ C ) and the substrate to inoculum volatile solids (VS) ratio (henceforth VS ratio) (1:1; 1.5:1 and 2:1) …
Supercritical water gasification of microalgae and their constituents in a continuous reactor
2016
The supercritical water gasification of Nannochloropsis gaditana microalgae has been studied in term of process development at 24 MPa and 663 °C. Gasification has been investigated using a 200 cm3 down flow reactor working continuously. The effect of microalgae slurry concentration, with or without alkali catalysts, was studied. Moreover, the role played by different constituents of microalgae on gasification was investigated. Particularly, gasification of amino acids, carbohydrates and model mixtures among them was studied. Nannochloropsis gaditana was successfully gasified up to 97.4 wt% as gasification efficiency and 86.0 wt% as carbon efficiency. The product gas is mainly composed of hy…
Co-production of Hydrogen and Methane From the Organic Fraction of Municipal Solid Waste in a Pilot Scale Dark Fermenter and Methanogenic Biofilm Rea…
2018
The co-production of biohydrogen and methane from the organic fraction of municipal solid waste was investigated using a two-stage AD system, composed of a pilot scale dark fermenter (DF) and a continuous methanogenic biofilm reactor. From the DF process, a biohydrogen yield of 41.7 (± 2.3) ml H2/gVSadded was achieved. The liquid DF effluent (DFE) was rich in short chain volatile fatty acids, i.e., mainly acetic and butyric acid. The DFE was valorized by producing methane in the methanogenic biofilm reactor. Two methanogenic biofilm reactors were used to assess the biotic and abiotic role of the DFE on the performance of the reactors. Regardless of the different DFE feeding (i.e., biotic an…
Capturing Hydrophobic Trifluoroiodomethane in Water into an M 4 L 6 Cage
2016
Synthetically important trifluoroiodomethane (CF3I) was trapped in water by using a metal–organic supramolecular anionic cage. Under ambient conditions, nearly 1:1 encapsulation of the hydrophobic, gaseous CF3I substrate with the cage was observed, and its binding constant was calculated by relative comparison with benzene encapsulation.
The operating cost of an anaerobic membrane bioreactor (AnMBR) treating sulphate-rich urban wastewater
2014
The objective of this study was to evaluate the operating cost of an anaerobic membrane bioreactor (AnMBR) treating sulphate-rich urban wastewater (UWW) at ambient temperature (ranging from 17 to 33 degrees C). To this aim, energy consumption, methane production, and sludge handling and recycling to land were evaluated. The results revealed that optimising specific gas demand with respect to permeate volume (SGDp) and sludge retention time (for given ambient temperature conditions) is essential to maximise energy savings (minimum energy demand: 0.07 kW h m(-3)). Moreover, low/moderate sludge productions were obtained (minimum value: 0.16 kg TSS kg(-1) CODRemoved), which further enhanced the…
A plant-wide energy model for wastewater treatment plants: application to anaerobic membrane bioreactor technology
2016
[EN] The aim of this study is to propose a detailed and comprehensive plant-wide model for assessing the energy demand of different wastewater treatment systems (beyond the traditional activated sludge) in both steady- and unsteady-state conditions. The proposed model makes it possible to calculate power and heat requirements (W and Q, respectively), and to recover both power and heat from methane and hydrogen capture. In order to account for the effect of biological processes on heat requirements, the model has been coupled to the extended version of the BNRM2 plant-wide mathematical model, which is implemented in DESSAS simulation software. Two case studies have been evaluated to assess t…
Environmental impact of submerged anaerobic MBR (SAnMBR) technology used to treat urban wastewater at different temperatures
2013
[EN] The objective of this study was to assess the environmental impact of a submerged anaerobic MBR (SAnMBR) system in the treatment of urban wastewater at different temperatures: ambient temperature (20 and 33 degrees C), and a controlled temperature (33 degrees C). To this end, an overall energy balance (OEB) and life cycle assessment (LCA), both based on real process data, were carried out. Four factors were considered in this study; (1) energy consumption during wastewater treatment; (2) energy recovered from biogas capture; (3) potential recovery of nutrients from the final effluent; and (4) sludge disposal. The OEB and LCA showed SAnMBR to be a promising technology for treating urban…
Economic and environmental sustainability of an AnMBR treating urban wastewater and organic fraction of municipal solid waste
2016
[EN] The objective of this study was to evaluate the economic and environmental sustainability of a sub- merged anaerobic membrane bioreactor (AnMBR) treating urban wastewater (UWW) and organic fraction of municipal solid waste (OFMSW) at ambient temperature in mild/hot climates. To this aim, power requirements, energy recovery from methane (biogas methane and methane dissolved in the effluent), consumption of reagents for membrane cleaning, and sludge handling (polyelectrolyte and energy consumption) and disposal (farmland, landfilling and incineration) were evaluated within different operating scenarios. Results showed that, for the operating conditions considered in this study, AnMBR tec…
Organocatalytic enantioselective aminoalkylation of pyrazol-3-ones with aldimines generated in situ from α-amido sulfones
2019
Herein, an efficient asymmetric aminoalkylation of pyrazolones with α-amido sulfones catalyzed by a quinine-derived squaramide in dichloromethane/aqueous media has been established. A variety of chiral amines were obtained with high yields (up to 98%) and excellent enantioselectivities (up to 99% ee). The corresponding products are transformed into optically active acetylated pyrazoles after treatment with Ac2O/Et3N, because of the instability of some adducts. The reaction tolerates a wide range of α-amido sulfones and different pyrazolones.
Hydroxy-Directed Enantioselective Hydroxyalkylation in the Carbocyclic Ring of Indoles
2017
[EN] A Cinchona-derived squaramide catalyzes the reaction between hydroxyindoles and isatins leading to enantioenriched indoles substituted in the carbocyclic ring. The reaction proceeds efficiently with differently substituted isatins, yielding the desired products with excellent regioselectivity, good yields, and high enantiocontroi. Moreover, every position of the carbocyclic ring of the indole can be functionalized by using the appropriate starting hydroxyindole. The OH group was removed smoothly upon hydrogenolysis of the corresponding triflate.