vermifiltration can provide efficient treatment of dairy wastewater. Furthermore, for
the treatment of voluminous wastewater by vermifiltration, economic optimization
of these processes must be worked out (Natarajan et al. 2015). The combination of
horizontal subsurface flow vermifilter system and vertical down flow vermifilter
system planted with various macrophytes and the earthworm, Eisenia fetida was able
to significantly reduce organics, nutrients, and solids from dairy wastewater (Samal
et al. 2018a, b). Vermibed height is considered a significant variable in the process of
vermifiltration.
3.3.3 Swine Wastewater Treatment
Vermifiltration can be used to treat diluted swine manure. The wastewater can be
reused to flush the manure, inducing a reduction in ammonia emissions compared to
rearing on a slatted floor with slurry accumulation (Li et al. 2008). Earthworms have
a simple, although indirect, effect on gaseous emissions during pig fresh slurry
vermifiltration. The abundance of earthworms can be used as a bioindicator to verify
low-energy consumption and low greenhouse gas and ammonia production in fresh
water recycled manure systems (Luth et al. 2011). The variable levels of pollutants in
the influential hybrid constructed wetland (HCW) were measured. This may result
from differences in the composition of pig waste, farm management, and storage
conditions but may also be related to inefficiencies in the pretreatment used on the
wastewater of raw piggery. This fluctuation may have had an impact on the HCW
performance (Borin et al. 2013).
3.4 Limitations
In spite of being an effective technology in treatment of wastewater by
vermifiltration, this technology still has some limitations. Among the species of
earthworms, not all are reported to be equally efficient in the treatment of wastewater. Earthworms are categorized as epigeic (found on top surface of soil), endogeics
(found in 10–30 cm of soil layer), and anecic (that burrow deep in the soil). Among
the three, only the epigeic group of earthworms have been reported to be efficient in
conversion of organic waste to vermicompost. Similarly, the process of
vermifiltration is also reported to work efficiently when epigeic group of earthworms
are used for treatment of wastewater. Among the epigeic group also, different
species have varying capacity to remediate the pollutants from the wastewater. It
has been reported that Eisenia fetida is more efficient than other worm in removal of
pollutants from wastewater (Gupta 2015). At present, vermifiltration is not very
efficient in removal of nutrients particularly nitrogen and phosphorus. A
bio-vermifilter used by Nie et al. (2015) showed fluctuations in removal of nitrogen
due to low ratio of C:N (carbon to nitrogen) in the biofilter. Thus, this requires an
3 Treatment of Wastewater by Vermifiltration Integrated with Plants
45
the treatment of voluminous wastewater by vermifiltration, economic optimization
of these processes must be worked out (Natarajan et al. 2015). The combination of
horizontal subsurface flow vermifilter system and vertical down flow vermifilter
system planted with various macrophytes and the earthworm, Eisenia fetida was able
to significantly reduce organics, nutrients, and solids from dairy wastewater (Samal
et al. 2018a, b). Vermibed height is considered a significant variable in the process of
vermifiltration.
3.3.3 Swine Wastewater Treatment
Vermifiltration can be used to treat diluted swine manure. The wastewater can be
reused to flush the manure, inducing a reduction in ammonia emissions compared to
rearing on a slatted floor with slurry accumulation (Li et al. 2008). Earthworms have
a simple, although indirect, effect on gaseous emissions during pig fresh slurry
vermifiltration. The abundance of earthworms can be used as a bioindicator to verify
low-energy consumption and low greenhouse gas and ammonia production in fresh
water recycled manure systems (Luth et al. 2011). The variable levels of pollutants in
the influential hybrid constructed wetland (HCW) were measured. This may result
from differences in the composition of pig waste, farm management, and storage
conditions but may also be related to inefficiencies in the pretreatment used on the
wastewater of raw piggery. This fluctuation may have had an impact on the HCW
performance (Borin et al. 2013).
3.4 Limitations
In spite of being an effective technology in treatment of wastewater by
vermifiltration, this technology still has some limitations. Among the species of
earthworms, not all are reported to be equally efficient in the treatment of wastewater. Earthworms are categorized as epigeic (found on top surface of soil), endogeics
(found in 10–30 cm of soil layer), and anecic (that burrow deep in the soil). Among
the three, only the epigeic group of earthworms have been reported to be efficient in
conversion of organic waste to vermicompost. Similarly, the process of
vermifiltration is also reported to work efficiently when epigeic group of earthworms
are used for treatment of wastewater. Among the epigeic group also, different
species have varying capacity to remediate the pollutants from the wastewater. It
has been reported that Eisenia fetida is more efficient than other worm in removal of
pollutants from wastewater (Gupta 2015). At present, vermifiltration is not very
efficient in removal of nutrients particularly nitrogen and phosphorus. A
bio-vermifilter used by Nie et al. (2015) showed fluctuations in removal of nitrogen
due to low ratio of C:N (carbon to nitrogen) in the biofilter. Thus, this requires an
3 Treatment of Wastewater by Vermifiltration Integrated with Plants
45