6.3.2.3 Secondary Treatment
Secondary treatment is also referred to as biological treatment as this involves the
use of aerobic microorganisms for the removal of additional suspended solids and
biochemical oxygen demand, beyond what can be accomplished through basic
sedimentation. The microorganisms use these organic impurities as a food source
and convert them into carbon dioxide, water, and energy for their own growth. The
basic biological treatments used are trickling filters, activated sludge treatment,
oxidation ponds, rotating biological contactors, and membrane bioreactors. Secondary treatment plants remove about 90 percent of the biochemical oxygen demand and
90 percent of the suspended solids (Masters and Ela 2004).
6.3.2.4 Tertiary Treatment
If the intended water supply is highly sensitive to the effects of pollution, many
tertiary processes may further treat secondary water effluent. Advanced waste
treatment methods in use or in implementation vary from microbial treatment
capable of removing nitrogen and phosphorus to physicochemical extraction strategies such as filtration, carbon adsorption, distillation, and reverse osmosis. Such
wastewater treatment systems, alone or in conjunction, may attain almost any degree
of pollution control required; waste effluent treated by such application can be used
for commercial, agricultural, or recreational purposes or even for drinking water.
6.3.2.5 Vermifiltration
The utilization of earthworms in wastewater or sludge treatment is called
vermifiltration. According to Aguilera (2003), it was first advocated by Prof. Jose
Toha at the University of Chile in 1992. Vermifiltration is a treatment method that
incorporates traditional treatment and vermicomposting methods for the treatment of
wastewater. It is an environmentally sustainable and economically viable wastewater
treatment system (Singh et al. 2019a, b). The body of earthworms acts as biofilter as
it contains different types of enzymes, decomposers, and nitrogen-fixing bacteria
that helps in elimination of 5-day BOD (BOD5) by over 90%, COD by 80–90%,
total dissolved solids (TDS) by 90–92%, and the total suspended solids (TSS) by
90–95% from wastewater by the process of ingestion, absorption, and biodegradation of organic wastes, heavy metals, and solids from wastewater (Sinha et al. 2008).
Additionally, earthworms convert mineralized nitrogen to ammonium which is then
transformed to nitrates by microbes and is then more readily available for plant
uptake. The wastewater solids composted by earthworms can be useful soil additives
that help in improving its fertility (Sinha et al. 2008).
6 Vermitechnology: A Sustainable Approach in the Management of Solid and Liquid. . .
95
Secondary treatment is also referred to as biological treatment as this involves the
use of aerobic microorganisms for the removal of additional suspended solids and
biochemical oxygen demand, beyond what can be accomplished through basic
sedimentation. The microorganisms use these organic impurities as a food source
and convert them into carbon dioxide, water, and energy for their own growth. The
basic biological treatments used are trickling filters, activated sludge treatment,
oxidation ponds, rotating biological contactors, and membrane bioreactors. Secondary treatment plants remove about 90 percent of the biochemical oxygen demand and
90 percent of the suspended solids (Masters and Ela 2004).
6.3.2.4 Tertiary Treatment
If the intended water supply is highly sensitive to the effects of pollution, many
tertiary processes may further treat secondary water effluent. Advanced waste
treatment methods in use or in implementation vary from microbial treatment
capable of removing nitrogen and phosphorus to physicochemical extraction strategies such as filtration, carbon adsorption, distillation, and reverse osmosis. Such
wastewater treatment systems, alone or in conjunction, may attain almost any degree
of pollution control required; waste effluent treated by such application can be used
for commercial, agricultural, or recreational purposes or even for drinking water.
6.3.2.5 Vermifiltration
The utilization of earthworms in wastewater or sludge treatment is called
vermifiltration. According to Aguilera (2003), it was first advocated by Prof. Jose
Toha at the University of Chile in 1992. Vermifiltration is a treatment method that
incorporates traditional treatment and vermicomposting methods for the treatment of
wastewater. It is an environmentally sustainable and economically viable wastewater
treatment system (Singh et al. 2019a, b). The body of earthworms acts as biofilter as
it contains different types of enzymes, decomposers, and nitrogen-fixing bacteria
that helps in elimination of 5-day BOD (BOD5) by over 90%, COD by 80–90%,
total dissolved solids (TDS) by 90–92%, and the total suspended solids (TSS) by
90–95% from wastewater by the process of ingestion, absorption, and biodegradation of organic wastes, heavy metals, and solids from wastewater (Sinha et al. 2008).
Additionally, earthworms convert mineralized nitrogen to ammonium which is then
transformed to nitrates by microbes and is then more readily available for plant
uptake. The wastewater solids composted by earthworms can be useful soil additives
that help in improving its fertility (Sinha et al. 2008).
6 Vermitechnology: A Sustainable Approach in the Management of Solid and Liquid. . .
95