Worms in waste: Putting their work to the test

Breadcrumbs

One of the key challenges of biowaste re-use is to ensure that the processed biowaste is safe, acceptable and poses no health hazards, particularly if it contains human waste. To help protect New Zealand’s health, guidelines [PDF, 845 KB] have been developed for the safe application of biowaste to land.

Worms have been shown to reduce concentrations of some disease-causing organisms or ‘pathogens’ in compost1,2, in addition to their widely known ability to recycle nutrients and improve soil structure. 

The interdisciplinary team of scientists at CIBR is currently investigating the potential of vermicomposting to treat biowaste. CIBR social scientists are looking at the economic and cultural viability of vermicomposting as a biowaste re-use option for small rural communities. 

Meanwhile, our soil scientists and ecotoxicologists are hard at work exploring just how effective worms are at killing pathogens, and testing how well they are able to eliminate pathogens in combinations of agricultural, dairy, and human waste – all locally sourced from a small Māori settlement near Taupō. Results to date show that vermicomposting can stabilise the nutrient content of septic tank waste and go some way to removing microbial contamination. However, this appears to be quite a selective process – not all microorganisms of concern are greatly impacted by vermicomposting. 

Other experts at the CIBR are assessing the potential of vermicomposted biowaste as a fertiliser in forestry by applying it to tree saplings in pot trials. You can find updates on this research and more in our regular newsletters.

References:

[1] Eastman, B.R., Kane, P.N, Edwards, C.A., Trytek, L., Gunadi, B., Stermer, A.L, Mobley, J.R. 2001. The effectiveness of vermiculture in human pathogen reduction for USEPA biosolids stabilization. Compost Science & Utilization 9: 38-49.

[2] Monroy, F., Aira, M., Domínguez, J. 2009. Reduction of total coliform numbers during vermicomposting is caused by short-term direct effects of earthworms on microoganisms and depends on the dose of application of pig slurry. Sci. Total Environ. 407: 5411-5416.