sludge-free, and the resulting vermifiltered water is clean enough to be reused for
farm irrigation and in parks and gardens. They inhibit the action of anaerobic
microorganisms creating an aerobic condition in the waste materials by their
burrowing actions. Vermifiltration process satisfies multiple requirements, like
zero-sludge generation, odour-free, simple design, simple equipment and comparatively lower operating and capital costs. Therefore, the application of a simple,
efficient, low-cost and environment-friendly technology to treat wastewaters can
solve the problems of sanitation issues in the rural areas in the long run.
2.3.1 Vermifiltration Mechanism
In the vermifiltration process, earthworms work in symbiosis with the microbes to
treat the wastewater. In addition to the microbiological degradation, earthworms
perform many beneficial activities by grinding of ingested soil along with the
ingested organics, addition of gut microbes and excretion of soil plus organics as
castings (Sinha et al. 2008; Xing et al. 2014). It acts as an aerator, grinder, crusher,
chemical degrader and biological stimulator while promoting the growth of ‘beneficial decomposer bacteria’ in wastewater (Sinha et al. 2002). Earthworms improve
aeration by the burrowing action and accelerate microbial activity by increasing the
population of soil microorganisms. Earthworms host millions of decomposer
(biodegrader) microbes in their gut and excrete them in soil along with nutrients
nitrogen and phosphorus in their excreta called ‘vermicast’ (Singleton et al. 2003).
The nutrients are further used by the microbes for multiplication and vigorous action.
Singleton et al. (2003) also studied the bacterial flora associated with the intestine
and vermicasts of the earthworms and found species like Pseudomonas, Mucor,
Paenibacillus, Azoarcus, Burkholderia, Spiroplasma, Alcaligenes and
Acidobacterium which has potential to degrade several categories of organics.
Suspended solids are trapped on top of the vermifilter and processed by earthworms
and fed to the soil microbes immobilized in the vermifilter (Komarowski 2001).
Earthworms granulate the clay particles thereby increasing the ‘hydraulic conductivity’ of the system which further intensifies the organic loadings of wastewater in
the vermifilter. The grinding activity of the earthworms leads to high total specific
surface area to the filter media, enabling the absorption of the organic and inorganic
from the wastewater. Such process is found ideal for diluted wastewater like sewage
(Bhawalkar 1995). Earthworms devour the surplus harmful and ineffective microbes
in the wastewater selectively, resulting to a pathogen-free vermifiltered effluent. The
earthworms also prevent choking of the medium due to their burrowing nature and
maintain a culture of effective biodegrader microbes to function. Individual households or a cluster of homes in cities can also treat their domestic wastewater with
such decentralized system so as to reduce the burden on the sewage treatment plants
down the sewer system.
2 Vermifiltration for Rural Wastewater Treatment
25
farm irrigation and in parks and gardens. They inhibit the action of anaerobic
microorganisms creating an aerobic condition in the waste materials by their
burrowing actions. Vermifiltration process satisfies multiple requirements, like
zero-sludge generation, odour-free, simple design, simple equipment and comparatively lower operating and capital costs. Therefore, the application of a simple,
efficient, low-cost and environment-friendly technology to treat wastewaters can
solve the problems of sanitation issues in the rural areas in the long run.
2.3.1 Vermifiltration Mechanism
In the vermifiltration process, earthworms work in symbiosis with the microbes to
treat the wastewater. In addition to the microbiological degradation, earthworms
perform many beneficial activities by grinding of ingested soil along with the
ingested organics, addition of gut microbes and excretion of soil plus organics as
castings (Sinha et al. 2008; Xing et al. 2014). It acts as an aerator, grinder, crusher,
chemical degrader and biological stimulator while promoting the growth of ‘beneficial decomposer bacteria’ in wastewater (Sinha et al. 2002). Earthworms improve
aeration by the burrowing action and accelerate microbial activity by increasing the
population of soil microorganisms. Earthworms host millions of decomposer
(biodegrader) microbes in their gut and excrete them in soil along with nutrients
nitrogen and phosphorus in their excreta called ‘vermicast’ (Singleton et al. 2003).
The nutrients are further used by the microbes for multiplication and vigorous action.
Singleton et al. (2003) also studied the bacterial flora associated with the intestine
and vermicasts of the earthworms and found species like Pseudomonas, Mucor,
Paenibacillus, Azoarcus, Burkholderia, Spiroplasma, Alcaligenes and
Acidobacterium which has potential to degrade several categories of organics.
Suspended solids are trapped on top of the vermifilter and processed by earthworms
and fed to the soil microbes immobilized in the vermifilter (Komarowski 2001).
Earthworms granulate the clay particles thereby increasing the ‘hydraulic conductivity’ of the system which further intensifies the organic loadings of wastewater in
the vermifilter. The grinding activity of the earthworms leads to high total specific
surface area to the filter media, enabling the absorption of the organic and inorganic
from the wastewater. Such process is found ideal for diluted wastewater like sewage
(Bhawalkar 1995). Earthworms devour the surplus harmful and ineffective microbes
in the wastewater selectively, resulting to a pathogen-free vermifiltered effluent. The
earthworms also prevent choking of the medium due to their burrowing nature and
maintain a culture of effective biodegrader microbes to function. Individual households or a cluster of homes in cities can also treat their domestic wastewater with
such decentralized system so as to reduce the burden on the sewage treatment plants
down the sewer system.
2 Vermifiltration for Rural Wastewater Treatment
25