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Bourgel C.,French National Center for Scientific Research | Bourgel C.,University of Orleans | Veron E.,French National Center for Scientific Research | Veron E.,University of Orleans | And 5 more authors.
Energy and Fuels | Year: 2011

The context of the present study is the gasification of dried sludge at high temperature. The aim of this work is to shed new light on the impacts of sludge ashes on gasification process. The purification sludge can contain up to 50% inorganic matter. The objective of this study is to understand the role of these inorganics, especially phosphorus, during the heat treatment. Several techniques are used to solve this problem. First, using thermodynamic calculations (FactSage), the evolution of the volatility of the inorganics is observed and the condensed phases formed during the heat treatment are determined. The simulations are done under atmospheric pressure, from 500 to 1500 °C. Second, to compare with the calculus, XRD and TGA experiments are carried out on model samples, with composition close to the real sludge, to determine which species volatilize and to compare the experimental results with the thermodynamic calculations. © 2011 American Chemical Society.


Sigot L.,INSA Lyon | Ducom G.,INSA Lyon | Benadda B.,INSA Lyon | Laboure C.,CIRSEE
Fuel | Year: 2014

Biogas can be used as a fuel for electricity conversion. However, volatile organic silicon compounds (including siloxanes) in biogas severely damage combustion engines or solid oxide fuel cells. Three adsorbents of different nature were tested for octamethylcyclotetrasiloxane (D4) removal and silica gel (SG) proved to be the most efficient. It was shown that SG adsorption capacity is in the order of 250 mgD4/gSG and the adsorbent bed height has little influence on this adsorption capacity. In the presence of water (relative humidity of 70%), the adsorption capacity was lowered by 90% due to competitive effects and preferential adsorption of water. An increase of the temperature of roughly 20 °C also lowered the adsorption capacity but the decrease was less than 15%. Moreover, SG regeneration by heating was only partial, probably due to siloxane polymerization on SG. © 2014 Elsevier Ltd. All rights reserved.


Gabet-Giraud V.,IRSTEA | Miege C.,IRSTEA | Choubert J.M.,IRSTEA | Ruel S.M.,CIRSEE | Coquery M.,IRSTEA
Science of the Total Environment | Year: 2010

This study aims at evaluating occurrence and treatment efficiency of five estrogenic hormones and ten beta blockers in wastewater treatment plants (WWTP). The use of consistent sampling procedures, analytical techniques and data processing enabled to achieve an accurate comparison of the performances of the different treatment processes. First, the occurrence of molecules was evaluated in fourteen rural and urban WWTP located in France. Free and total estrogens were analyzed showing that more than 84% of estrogens in the dissolved phase of influent samples are in the free form. In effluent samples, comparable mean values but higher variation are underlined (RSD from 13 to 54% depending on the estrogen, compared to 11-21% for influents). Most of the target molecules are quantified in 30 influent and 31 effluent samples. Similar occurrence frequencies are obtained for influents from rural (6 WWTP) and urban areas (8 WWTP), except for betaxolol which is only quantified in urban wastewaters. Removal efficiencies of 8 biological treatments were studied: suspended growth biomass (activated sludge) and attached growth systems (biofilter, rotating biological contactor, reed-bed filter, trickling filter). Biological treatments are efficient to remove estrogens from the dissolved phase, with removal rate around 90%. For beta blockers, acebutolol and nadolol are efficiently removed (mean removal rate of 80%), whereas sotalol and propranolol are hardly impacted by biological treatments (removal rate below 20%). Finally, 9 tertiary treatment processes were evaluated. Ozonation, reverse osmosis and activated carbon filtration prove a high removal efficiency for beta blockers (above 80%). On the contrary, high speed chemical settler, sand filtration, silex filtration, microfiltration and UV present generally removal rates below 30% for all beta blockers. The polishing pond studied presents variable removal performances depending on the molecules (up to 75% for propranolol). The role of the hydraulic retention time on the removal efficiencies is confirmed. © 2010 Elsevier B.V.


Choubert J.-M.,IRSTEA | Pomies M.,IRSTEA | Martin Ruel S.,CIRSEE | Coquery M.,IRSTEA
Water Science and Technology | Year: 2011

This extensive study aimed at quantifying the concentrations and removal efficiency of 23 metals and metalloids in domestic wastewater passing through full-scale plants. Nine facilities were equipped with secondary biological treatment and three facilities were equipped with a tertiary treatment stage. The metals investigated were Li, B, Al, Ti, V, Cr, Fe, Ni, Co, Cu, Zn, As, Se, Rb, Mo, Ag, Cd, Sn, Sb, Ba, Tl, Pb and U. Particulate and dissolved metals were measured using 24 h composite samples at each treatment stage. In influents, total concentrations of Cd, Sb, Co, Se, U, Ag, V were below a few μg/L, whereas at the other extremity Zn, B, Fe, Ti, Al were in the range of 0.1 to >1 mg/L. It was demonstrated that secondary treatment stage (activated sludge, biodisc and membrane bioreactor) were efficient to remove most metals (removal rate > 70%), with the exception of B, Li, Rb, Mo, Co, As, Sb and V due to their low adsorption capacities. With the tested tertiary stages (polishing pond, rapid chemical settler, ozonation), a removal efficiency was obtained for Ti, Cr, Cd, Cu, Zn, Sn, Pb, Fe, Ag and Al, whereas a little removal (<30%) was obtained for other metals. © IWA Publishing 2011.


Raich-Montiu J.,Centro Tecnologico Del Agua | Ribas-Font C.,Ramon Llull University | de Arespacochaga N.,Centro Tecnologico Del Agua | Roig-Torres E.,Ramon Llull University | And 4 more authors.
Analytica Chimica Acta | Year: 2014

Siloxanes and trimethylsilanol belong to a family of organic silicone compounds that are currently used extensively in industry. Those that are prone to volatilisation become minor compounds in biogas adversely affecting energetic applications. However, non-standard analytical methodologies are available to analyse biogas-based gaseous matrixes. To this end, different sampling techniques (adsorbent tubes, impingers and tedlar bags) were compared using two different configurations: sampling directly from the biogas source or from a 200L tedlar bag filled with biogas and homogenised. No significant differences were apparent between the two sampling configurations. The adsorbent tubes performed better than the tedlar bags and impingers, particularly for quantifying low concentrations. A method for the speciation of silicon compounds in biogas was developed using gas chromatography coupled with mass spectrometry working in dual scan/single ion monitoring mode. The optimised conditions could separate and quantify eight siloxane compounds (L2, L3, L4, L5, D3, D4, D5 and D6) and trimethylsilanol within fourteen minutes. Biogas from five waste water treatment plants located in Spain, France and England was sampled and analysed using the developed methodology. The siloxane concentrations in the biogas samples were influenced by the anaerobic digestion temperature, as well as the nature and composition of the sewage inlet. Siloxanes D4 and D5 were the most abundant, ranging in concentration from 1.5 to 10.1 and 10.8 to 124.0mgNm-3, respectively, and exceeding the tolerance limit of most energy conversion systems. © 2013 Elsevier B.V.

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