Title: Evaluation of anaerobic digestate as a substrate for vermicomposting

Authors: Karthika Krishnasamy; Jaya Nair; Richard Bell

Addresses: School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia ' School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia ' School of Veterinary and Life Sciences, Murdoch University, South Street, Murdoch, Western Australia 6150, Australia

Abstract: Vermicomposting is an established process to convert organic wastes into vermicastings suitable for plant growth. This research investigated the vermicomposting of anaerobic digestate with four different ratios of sawdust as a bulking material, for 75 days. The optimum proportion of anaerobic digestate to sawdust was identified as 70:30 based on worm growth and reproduction. Vermicomposting process increased the conversion of ammonium into nitrate when compared with control (p = 0.05). Vermicastings produced at the end of this experiment had significantly high N, NO₃-N, P and K than the control (p = 0.05). There was significant reduction in pathogen levels by the worms (99%), and also a germination test undertaken showed an 83% increase in radish seed germination after vermicomposting when compared to raw digestate. The results indicated that vermicomposting with Eisenia fetida is a sustainable technology to convert the anaerobic digestate into nutrient-rich, safe to handle vermicastings, which otherwise is a secondary pollutant.

Keywords: pre-stabilisation; anaerobic digestate; Eisenia fetida; germination index; sawdust; vermicomposting; ammonium; nitrate.

DOI: 10.1504/IJEWM.2014.064084

International Journal of Environment and Waste Management, 2014 Vol.14 No.2, pp.149 - 164

Accepted: 23 Sep 2013
Published online: 30 Aug 2014 *

Full-text access for editors Full-text access for subscribers Purchase this article Comment on this article