A simple method for temporal collection of tissue and microbial samples from static composting systems.
Reuter, T.R., Xu, W., Alexander, T.W., Baker, B.C., Larney, F.J., Stanford, K.I.M., and McAllister, T.A. (2008). "A simple method for temporal collection of tissue and microbial samples from static composting systems.", Canadian Biosystems Engineering / Le génie des biosystèmes au Canada, 50, pp. 6.17-6.20.
Composting is being seriously considered as a means of disposal of livestock moralities in Canada, in part as a result of the enhanced feed ban implemented by the Canadian Food Inspection Agency in 2008. Information on the fate of pathogens and animal tissues during composting is essential to assess its suitability as a means of carcass disposal. This report describes a simple system for the implantation and temporal retrieval of microbial and tissue samples from field-scale static composting systems. A metal device, termed the Baker Retrieval Pyramid (BRP), with an internal volume of ≈3600 cm3 was constructed to enable the implantation and removal of samples, with minimal disturbance, from depths of 0.8 and 1.6 m within composting piles. Polyester bags with a pore size of 50 µm were placed in BRP and used to introduce known amounts of Escherichia O157:H7, Newcastle disease virus, brain tissue and keratin into the composting pile. Thermocouples were attached to the BRP’s to enable temperature to be monitored directly at the site of implantation. The BRP’s allowed for temporal removal of both microbial and tissue samples during a static composting period of 148 days. Microbial samples were shown to be non-viable within a period of 3 weeks and over 80% (dry matter basis) of brain tissue and keratin were decomposed after 148 days of composting. Whole carcasses were decomposed to a similar extent, suggesting that the microbial ecology within the BRP was similar to that of the outer composting matrix. It was concluded that the BRP system could be used to temporally examine the decomposition of a variety of substrates and the fate of microorganisms, without altering the efficacy of static composting as a means of carcass disposal.