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Communication Dans Un Congrès Année : 2012

Influence of aeration rate on composting gaseous emissions with pig slaughterhouse sludge

Résumé

This study investigated the influence of composting aeration rate on emission concentrations in terms of ammonia, hydrogen sulphide, mercaptan, and Volatile Organic Compounds (VOCs). The influence of the aeration on the gaseous emission was the first process conditions investigated. Organic waste composting generates emissions resulting in a significant level of nuisance often leading to conflicts closing or preventing the installation of treatment plants. Ammonia, hydrogen sulphide and VOCs are the main contributors to compost odours. Conventional solutions are designed to confine the odours or apply a biological or chemical treatment. By establishing the relationship between aeration rate and compost gaseous emission characteristics, preventive control techniques can be introduced. The project investigated the influence of the aeration rate on compost emissions from pig slaughterhouse sludge, using 300 L pilots reactors under forced aeration. Five different rates were tested: 1.68, 4.03, 6.22, 9.80 and 13.04 L/h/kg of wet waste. The aeration treatment was applied to the same waste mixture consisting of Pig Slaughter house Sludge (PSS) and Wood Chips (WC), mixed at a dry mass ratio of 1.2:1(PSS:WC). The Wood Chips (WC) came from the same plot of calibrated 20-40 mm particle size. All experimental materials were analyzed and weighed before starting the experiment. Composting treatments were aerated during 30 to 60 days, and the material was turned every 10 days. The aeration rate was maintained constant while monitoring the compost temperature. The incoming and outgoing ventilation air streams were monitored for O2, CO2 and CH4. A portion of the outgoing ventilation air stream was also bubbled into chemical traps for NH3, H2S and mercaptan quantification. Every two days, another portion of the outgoing ventilation air stream was collected using Tedlar bag and its gases trapped on activated carbon trap to analyze its VOC by Gas Chromatography coupled with a Mass Spectrometry (GC/MS); qualification and quantification of VOCs were obtained by chromatogram processing. At the end of the experiment, all reactors were emptied, to weigh and sample their content for a mass balance analysis. In terms of composting emissions, over 45 VOCs were identified and classified based on their concentration: major constituents (nitrides, sulphides, ketones and alcohols); average constituents (nitride and sulphide compounds, aromatic hydrocarbons and aliphatic hydrocarbons), and minor constituents (terpenes, alkanes, and acids). The concentration of these compounds was based on the concentration over time per kg organic matter of initial wet PSS waste within the air flow rate. The analysis of emission concentrations indicated that higher aeration rates increased emissions, but had no influence on the final waste stability simply because low rates resulted in a longer treatment period and more turning operations. Thus, higher aeration rate enhanced the stripping of gases from the compost matrix. Nevertheless, increasing the aeration rate changed the emission profile with higher rate producing emission peaks rather than an even profile associated with the lower aeration rates. As a result, an aeration strategy must be considered to optimize the treatment of gaseous emissions from pig slaughterhouse sludge composting plant.
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Dates et versions

hal-02605573 , version 1 (16-05-2020)

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V. Blazy, A. de Guardia, M. Daumoin, J.C. Benoist, M. Lemasle, et al.. Influence of aeration rate on composting gaseous emissions with pig slaughterhouse sludge. 8th International Conference ORBIT: Global assessment for organic resources and waste management, Jun 2012, Rennes, France. pp.9. ⟨hal-02605573⟩
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