Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions

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Summary

Anaerobic digestion of residual materials from animals and crops offers an opportunity to simultaneously produce bioenergy and plant fertilizers at single farms and in farm communities where input substrate materials and resulting digested residues are shared among member farms. A surplus benefit from this praxis may be the suppressing of propagules from harmful biological pests like weeds and animal pathogens (e.g. parasites). In the present work, batch experiments were performed, where survival of seed of seven species of weeds and non-embryonated eggs of the large roundworm of pigs, Ascaris suum, was assessed under conditions similar to biogas plants managed at meso- (37 °C) and thermophilic (55 °C) conditions. Cattle manure was used as digestion substrate and experimental units were sampled destructively over time. Regarding weed seeds, the effect of thermophilic conditions (55 °C) were very clear as complete mortality, irrespective of weed species, was reached after less than two days. At mesophilic conditions, seeds of Avena fatua, Sinapsis arvensis, Solidago canadensis had completely lost germination ability, while Brassica napus, Fallopia convolvulus and Amzincki amicranta still maintained low levels (~1%) of germination ability after one week. Chenopodium album was the only weed species which survived one week at substantial levels (7%) although after 11 d germination ability was totally lost. Similarly, at 55°C, no Ascaris eggs survived more than 3 h of incubation. Incubation at 37 °C did not affect egg survival during the first 48 h and it took up to 10 days before total elimination was reached. In general, anaerobic digestion in biogas plants seems an efficient way (thermophilic more efficient than mesophilic) to treat organic farm wastes in a way that suppresses animal parasites and weeds so that the digestates can be applied without risking spread of these pests.

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• Survival of animal parasites and weed seeds as affected by anaerobic digestion at meso- and termophilic conditions. (deposited 29 Jun 2011 09:16)
  • Survival of weed seeds and animal parasites as affected by anaerobic digestion at meso- and thermophilic conditions. (deposited 06 Feb 2012 10:58) [Currently Displayed]