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Separating earthworms from organic m...

Chaoui, Hala I.

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Separating earthworms from organic media using an electric field.

紀錄類型:	書目-語言資料,印刷品 : Monograph/item
正題名/作者:	Separating earthworms from organic media using an electric field./
作者:	Chaoui, Hala I.
面頁冊數:	124 p.
附註:	Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6096.
Contained By:	Dissertation Abstracts International66-11B.
標題:	Engineering, Agricultural. -
電子資源:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3197827
ISBN:	9780542421532

Separating earthworms from organic media using an electric field.
Chaoui, Hala I.

Separating earthworms from organic media using an electric field. - 124 p.

Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6096.

Thesis (Ph.D.)--The Ohio State University, 2005.

Earthworms have been shown to effectively process biodegradable organic waste and increase the availability of nutrients to plants in the final product, earthworm casts (or vermicompost), compared to the raw material. After processing earthworms are typically mechanically separated from the vermicompost and used for processing more waste or sold. This study investigated whether an electric field could be used to separate earthworms from vermicompost. Results showed that electric current does repel earthworms, at levels as low as 3 mA. Results also showed that an electric field generated across electrodes inserted in a medium (such as soil) inhibits earthworm migration along a nitrate gradient. The effectiveness with which an electric field repels earthworms is a function of the voltage created across earthworms which in turn is a function of electrode depth, spacing, earthworm species (and resulting diameter and resistance) and electric current level. Each factor was shown to significantly affect the effectiveness with which earthworm were repelled. This was concluded through a set of experiments where earthworms were placed in a 2.8 x 2.8 x 7.5 cm soil slab at a density corresponding to 150 earthworms per liter, and effectiveness of the electric field was calculated as a function of the number of earthworms that exited the soil slab. Spatial voltage values were evaluated in each replicate in order to identify the voltage drops in the soil slab and derive the corresponding threshold electric current (current at the edge of the soil slab).

ISBN: 9780542421532Subjects--Topical Terms:

1019504
Engineering, Agricultural.

Separating earthworms from organic media using an electric field.
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500 $a Source: Dissertation Abstracts International, Volume: 66-11, Section: B, page: 6096.
500 $a Adviser: Harold M. Keener.
502 $a Thesis (Ph.D.)--The Ohio State University, 2005.
520 $a Earthworms have been shown to effectively process biodegradable organic waste and increase the availability of nutrients to plants in the final product, earthworm casts (or vermicompost), compared to the raw material. After processing earthworms are typically mechanically separated from the vermicompost and used for processing more waste or sold. This study investigated whether an electric field could be used to separate earthworms from vermicompost. Results showed that electric current does repel earthworms, at levels as low as 3 mA. Results also showed that an electric field generated across electrodes inserted in a medium (such as soil) inhibits earthworm migration along a nitrate gradient. The effectiveness with which an electric field repels earthworms is a function of the voltage created across earthworms which in turn is a function of electrode depth, spacing, earthworm species (and resulting diameter and resistance) and electric current level. Each factor was shown to significantly affect the effectiveness with which earthworm were repelled. This was concluded through a set of experiments where earthworms were placed in a 2.8 x 2.8 x 7.5 cm soil slab at a density corresponding to 150 earthworms per liter, and effectiveness of the electric field was calculated as a function of the number of earthworms that exited the soil slab. Spatial voltage values were evaluated in each replicate in order to identify the voltage drops in the soil slab and derive the corresponding threshold electric current (current at the edge of the soil slab).
520 $a Results showed that the effectiveness of the electric field was logarithmically proportional to the voltage generated across earthworms, at a given electrode spacing, up to the point where earthworm mortality started to occur. At higher voltages the electric field effectiveness decreased exponentially due to mortality. The time where all potential earthworms exited a soil slab increased exponentially up to peak effectiveness, and decreased exponentially after that. Testing the derived model on different soil types showed that soil properties including salinity, moisture content and porosity are accounted for in the model by soil resistance that is indirectly expressed in the electric current term, and that the results apply to any soil type. A comparison between alternating and direct current showed an increased effectiveness of the model when alternating current was used, which suggests that an AC voltage source would increase the effectiveness with which an electric field repels earthworms. A model of electric current diffusion in earthworm casts suggested that as increasing voltage levels are used, the distance from the electric field at which an optimal electric current level can be found converges to a single value. The mathematical models derived from this study can be used for the preliminary design of an electric earthworm separator consisting of an array of current-conducting rods connected to a power or voltage source.
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