2.3.2 Earthworms
Out of the 3000 species of earthworms in the world and about 500 species are
available in India (Julka 1986). Earthworms are good decomposer and soil eater, and
they have over 600 million years of experience in waste and environmental management. No wonder then, Charles Darwin called them as the ‘unheralded soldiers of
mankind’, and the Greek philosopher Aristotle called them as the ‘intestine of earth’,
meaning digesting a wide variety of organic materials including the waste organics,
from earth (Darwin and Seward 1903; Martin 1976). Earthworms are long, cylindrical, narrow, bilaterally symmetrical, segmented animals without bones consisting
of 100–200 almost cylindrical rings or segments, each covered with the minute
bristles weighing around 1400–1500 mg after 8–10 weeks. Depending on the type of
species and the ecological situation, the life span of an earthworm is practically
3–7 years. It is learned from the studies that their reproduction rate is high and within
60–70 days, they are able to double their number (Sinha et al. 2008). The gut of the
earthworms is home to millions of good microbes like ‘nitrogen-fixing’ and ‘decomposer microbes’. Availability of organic matter, soil moisture and pH of the soil
plays an important role in the distribution of earthworms in soil. They breathe
through their skin, and they prefer environment which is dark and moist. They can
tolerate a temperature range between 5 and 29
C. Earthworms can flourish comfortably in habitats with a temperature of 20–25
C and moisture of 60–75% (Hand
1988). Their activity is reduced in low temperatures, but high temperature can dry
them out killing them instantly. Earthworms are bisexual animals, and their multiplication rate is very high. Earthworms can multiply by 28, i.e. 256 worms every
6 months from a single individual if provided the optimal conditions of temperature,
moisture and feeding materials. In their life cycle, they have the ability to produce
300–400 young ones (Hand 1988). Earthworms carry out the grinding of soil, debris,
food, etc. with their muscular gizzard to a size of 2–4 microns. Earthworms play an
important role in the vermifiltration system by consuming organic solids present in
wastewater at a high rate. Therefore, their population density, maturity and health of
the worms in the vermifiltration bed play an important role in the treatment process.
For an efficient functioning of a vermifiltration system, maintaining an optimum
worm density is very crucial (Li et al. 2008). Definitely the number of worms per unit
area in the vermifilter bed affects the treatment efficiency of vermifiltration process.
Therefore, initially enough worms should be added to vermicompost the incoming
wastes and produce a suitable humus filter. From studies an estimate of at least
15,000–20,000 worms/m
3 of the vermifiltration system is required to start a
vermifiltration system (Sinha et al. 2008).
26
M. Khwairakpam
Out of the 3000 species of earthworms in the world and about 500 species are
available in India (Julka 1986). Earthworms are good decomposer and soil eater, and
they have over 600 million years of experience in waste and environmental management. No wonder then, Charles Darwin called them as the ‘unheralded soldiers of
mankind’, and the Greek philosopher Aristotle called them as the ‘intestine of earth’,
meaning digesting a wide variety of organic materials including the waste organics,
from earth (Darwin and Seward 1903; Martin 1976). Earthworms are long, cylindrical, narrow, bilaterally symmetrical, segmented animals without bones consisting
of 100–200 almost cylindrical rings or segments, each covered with the minute
bristles weighing around 1400–1500 mg after 8–10 weeks. Depending on the type of
species and the ecological situation, the life span of an earthworm is practically
3–7 years. It is learned from the studies that their reproduction rate is high and within
60–70 days, they are able to double their number (Sinha et al. 2008). The gut of the
earthworms is home to millions of good microbes like ‘nitrogen-fixing’ and ‘decomposer microbes’. Availability of organic matter, soil moisture and pH of the soil
plays an important role in the distribution of earthworms in soil. They breathe
through their skin, and they prefer environment which is dark and moist. They can
tolerate a temperature range between 5 and 29
C. Earthworms can flourish comfortably in habitats with a temperature of 20–25
C and moisture of 60–75% (Hand
1988). Their activity is reduced in low temperatures, but high temperature can dry
them out killing them instantly. Earthworms are bisexual animals, and their multiplication rate is very high. Earthworms can multiply by 28, i.e. 256 worms every
6 months from a single individual if provided the optimal conditions of temperature,
moisture and feeding materials. In their life cycle, they have the ability to produce
300–400 young ones (Hand 1988). Earthworms carry out the grinding of soil, debris,
food, etc. with their muscular gizzard to a size of 2–4 microns. Earthworms play an
important role in the vermifiltration system by consuming organic solids present in
wastewater at a high rate. Therefore, their population density, maturity and health of
the worms in the vermifiltration bed play an important role in the treatment process.
For an efficient functioning of a vermifiltration system, maintaining an optimum
worm density is very crucial (Li et al. 2008). Definitely the number of worms per unit
area in the vermifilter bed affects the treatment efficiency of vermifiltration process.
Therefore, initially enough worms should be added to vermicompost the incoming
wastes and produce a suitable humus filter. From studies an estimate of at least
15,000–20,000 worms/m
3 of the vermifiltration system is required to start a
vermifiltration system (Sinha et al. 2008).
26
M. Khwairakpam