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Separating earthworms from organic media using an electric field [Erratum: 2009 July, v. 103, issue 3, p. 395.]

Chaoui, Hala, Keener, Harold M.
Biosystems engineering 2008 v.100 no.3 pp. 409-421
earthworms, vermicomposting, biodegradation, separation, electrical treatment, mathematical models, mortality, electrostatic interactions
Earthworms have been shown to be effective in processing biodegradable organic waste. Typically, they are mechanically separated from the resulting vermicompost before it is marketed. Electric currents have been shown to repel earthworms and could be used to separate them from processed waste. This study investigated the effectiveness of an electric current at repelling earthworms from a soil slab of organic media as a function of the voltage created across the worms. This voltage is itself a function of electrode depth, spacing, earthworm diameter and its resistance, and electric current. The effectiveness of the electric field was significantly affected by each of these factors and was logarithmically proportional to the voltage generated across earthworms at a given electrode spacing, up to the onset of earthworm mortality, after which effectiveness decreased exponentially. The time period over which earthworms left the soil slab increased exponentially up to peak electric field effectiveness and then decreased exponentially afterwards. Mathematical models were derived from this study and could ultimately be used for preliminary designs of an electric earthworm separator.