Agriculture Reference
In-Depth Information
but later expanded into producing vermicomposts from food, brewery, paper, and animal wastes.
Research in the U.K. at Rothamsted Experimental Station, Harpenden, focused initially on pro-
cessing animal and vegetable wastes (Edwards 1988) but now has expanded to vermicomposting
other organic wastes.
The current leading research programs into vermiculture and vermicomposting are at the Soil
Ecology Laboratory at The Ohio State University (OSU) in Columbus; at the University of Vigo
in Spain, led by Jorge Dominguez (see
Chapter 20
this volume); at the University of Agricultural
Sciences in Bangalore, India, led by Dr. Radha Kale (see
Chapter 19
this volume); and at the
Instituto de Ecologia, Mexico, led by Dr. Isabelle Barois and Dr. Aranda.
As public interest in vermiculture and vermicomposting increases, so does interest by farmers
and commercial organizations, and U.S. journals such as
Biocycle
,
Compost Science and Utilization
,
and
are beginning to publish many articles on vermiculture; there are
sessions at waste management and composting meetings that frequently address vermicomposting
issues. Vermiculture newsletters, such as ÑCasting CallÒ and ÑWorm Digest,Ò published in the United
States proliferate and attract a broad readership. There is also considerable interest in vermicom-
posting domestic organic garbage and food waste from schools in the United States, which is
promoted by Mary AppelhofÔs best-selling book,
Bioresource Technology
(1997). At the same time,
earthworm growers associations have proliferated in New Zealand, Australia, the United States, and
Europe, as have Web sites, which provide ready access to vermiculture information and publication
(Edwards and Steele 1997).
Worms Eat My Garbage
BREAKDOWN OF SEWAGE WASTES BY EARTHWORMS
Sewage sludges and biosolids were two of the first organic wastes to attract interest and funding
for research into vermiculture at SUNY Syracuse in the late 1970s (Hartenstein 1978). Quite
early, they showed, on a laboratory scale, that aerobic sewage sludges can be readily ingested
by earthworms such as
and egested as finely divided casts; in the process, the
sludge is decomposed and stabilized (i.e., rendered innocuous) much faster than non-earthworm-
ingested sludge, probably because of the dramatic increases of microbial populations in the
casts resulting from earthworm activity. During this process, relative to non-earthworm-ingested
sludge, objectionable odors disappear from the wastes very quickly, and there is a rapid reduction
in populations of human pathogenic microorganisms such as
Eisenia fetida
Salmonella enteriditis, Escherichia
coli,
and other Enterobacteriaceae, human viruses, and even helminth ova (Eastman et al. 2001),
which has been confirmed by other workers. Although most of the sludges produced in sewage
plants are anaerobic and, when fresh, can be toxic to
after
becoming aerobic they are readily acceptable to this earthworm species and others (see Chapter
20 this volume).
It has been found that mixing sewage sludge with other bulking materials (e.g., garden wastes,
paper pulp sludge, or other lignin-rich wastes) before composting the mixtures using earthworms
can accelerate the rates of decomposition. During passage through the earthworm gut, there is
maceration and mixing of such materials and finely divided materials with high microbial activity
in the casts (Dominguez et al. 1999). There are many possibilities for the utilization of garden,
paper, and timber mill wastes and other materials as bulking agents for simultaneous disposal of
these materials together with municipal sewage sludges and conversion into vermicomposts. The
use of earthworms in organic waste or sludge management has been termed
E. fetida,
when they are dewatered
vermicomposting
or
vermistabilization
Loehr et al. 1984; Neuhauser et al. 1988), and although there is now a large
database, many aspects of vermicomposting still need to be researched, evaluated, and resolved to
ensure the consistent success of such a process for a wide range of wastes.
Factors involved in vermicomposting sludges about which additional information is needed
include the following: (1) how earthworms are affected by sludge characteristics, (2) the comparative
