Odorous gaseous emissions as influence by process condition for the forced aeration composting of pig slaughterhouse sludge.
Compost sustainability requires a better control of its gaseous emissions responsible for several impacts including odours. Indeed, composting odours have stopped the operation of many platforms and prevented the installation of others. Accordingly, present technologies collecting and treating gases emitted from composting are not satisfactory and alternative solutions must be found. Thus, the aim of this paper was to study the influence of composting process conditions on gaseous emissions. Pig slaughterhouse sludge mixed with wood chips was composted under forced aerationin 300 L laboratory reactors. The process conditions studied were: aeration rate of 1.68, 4.03, 6.22, 9.80 and 13.44 L/h/kg of wet sludge; incorporation ratio of 0.55, 0.83 and 1.1 (kg of wet wood chips/kg of wet sludge), and; bulking agent particles size of <10, 10<20 and 20<30 mm. Out-going gases were sampled every 2 days and their composition was analysed using gas chromatography coupled with mass spectrometry (GC-MS). Fifty-nine compounds were identified and quantified. Dividing the cumulated mass production over 30 days of composting, by odour threshold, 9 compounds were identified as main potential odour contributors: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone, 1-propanol-2-methyl, dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide and acetophenone. Five gaseous compounds were correlated with both aeration rate and bulking agent to waste ratio: hydrogen sulphide, trimethylamine, ammonia, 2-pentanone and 1-propanol-2-methyl. However, dropping the aeration rate and increasing the bulking agent to waste ratio reduced gaseous odour emissions by a factor of 5-10, when the required threshold dilution factor ranged from 10(5) to 10(6), to avoid nuisance at peak emission rates. Process influence on emissions of dimethyl sulphide, dimethyl disulphide, dimethyl trisulphide were poorly correlated with both aeration rate and bulking agent to waste ratio as a reaction with hydrogen sulphide was suspected. Acetophenone emissions originated from the wood chips. Olfactory measurements need to be correlated to gaseous emissions for a more accurate odour emission evaluation.
Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes, France. Electronic address: vincent.blazy@irstea.fr.
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Blazy
Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes, France. Electronic address: amaury.de-guardia@irstea.fr.
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de Guardia
Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes, France.
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Benoist
Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes, France.
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Daumoin
Laboratoire Sciences Chimiques de Rennes - équipe Chimie et Ingénierie des Procédés, UMR 6226 CNRS, ENSCR, Avenue du Général Leclerc, 35700 Rennes, France.
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Lemasle
Laboratoire Sciences Chimiques de Rennes - équipe Chimie et Ingénierie des Procédés, UMR 6226 CNRS, ENSCR, Avenue du Général Leclerc, 35700 Rennes, France.
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Wolbert
Irstea, UR GERE, 17 Avenue de Cucillé, CS 64427, F-35044 Rennes, France; Concordia University, Department of Building, Civil and Environmental Engineering, 1455 de Maisonneuve, Montréal, QC H3G 1M8, Canada. Electronic address: suzellebarrington@sympatico.ca.
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Barrington
D000393:Air Pollutants / Q000032:analysis*; D000818:Animals; D002849:Chromatography, Gas; D009812:Odorants / Q000032:analysis*; D010316:Particle Size; D012037:Refuse Disposal; D012722:Sewage / Q000737:chemistry*; D012987:Soil / Q000737:chemistry; D034421:Sus scrofa; D018505:Waste Management; D014934:Wood / Q000032:analysis
D000393:Air Pollutants; D012722:Sewage; D012987:Soil
Composting; Forced aeration; Gaseous emissions; Odour; Pig slaughter house sludge