130
M. S. Miswan et al.
The above equation is identical to the equation for biological oxidation of organic
matter with the exception that NO 3
− is used as an electron acceptor instead of O 2 :
O 2 + Organic matter → CO 2 + OH
−
+ H 2 O
( 8 . 2 )
A large variety of heterotrophic bacterias can use nitrate in lieu of oxygen for the
degradation of organic matter under anoxic conditions. If O 2 is present, however,
the bacteria will preferentially select it instead of NO 3
− (US EPA 1993). Thus, it is
very important that anoxic conditions exist so that NO 3
− will be used as electron
acceptor. Autotrophic denitrification is also possible with either elemental sulphur
or hydrogen gas used as electron donor by autotrophic bacteria as shown in the
following unbalanced equation (Li et al. 2016):
NO
−
3 + CO 2 + Inorganic Electron Donor → N 2 + Oxidized Electron Donor
(8.3)
8.5 Selection of Tilapia (Oreochromis Niloticus)
for Aquaponic Biofilter System
The type of fish used in an aquaponic system is dependent on the surrounding climate.
The temperature shall be able to maintain: the types of fish which local fisheries
department has specified as legal (there are sometimes restrictions on the cultivation
of fish that are not native to the region), the type of fish desired for consumption by
consumers and the type of fish feeds available to the grower (Yavuzcan et al. 2017).
The hybrid striped bass is one species that has been reported as cannot perform well
in aquaponic systems because it cannot tolerate high potassium levels which are
common supplements used for plant growth (Dediu et al. 2012).
Tilapia is the second most cultured freshwater finfish species after carps. It has
the potential to be the most important farmed fish in the twenty-first century (Mahieu
2015). The worldwide production of tilapia fish in 2015 was estimated at 6.4 million
metric tonnes (MMT), (FAO 2017a). Tilapia is considered to be relatively resistant
to a few numbers of diseases encountered in other cultured fishes (Del-Pozo et al.
2017). One of the specialties of tilapia is hypoxia tolerance (ability to live in critically
low level of oxygen). The hypoxia tolerance of tilapia is higher than other aquatic
organisms, and tilapia can tolerate a hypoxia environment with dissolved oxygen
below than 0.5 mg/L for a short period (Lim et al. 2006). This makes it a suitable
model fish to be used in studying ammonia removal in an aquatic habitat. Other than
that, tilapia is selected by studies due to the availability of its genome database (Chen
et al. 2017).
M. S. Miswan et al.
The above equation is identical to the equation for biological oxidation of organic
matter with the exception that NO 3
− is used as an electron acceptor instead of O 2 :
O 2 + Organic matter → CO 2 + OH
−
+ H 2 O
( 8 . 2 )
A large variety of heterotrophic bacterias can use nitrate in lieu of oxygen for the
degradation of organic matter under anoxic conditions. If O 2 is present, however,
the bacteria will preferentially select it instead of NO 3
− (US EPA 1993). Thus, it is
very important that anoxic conditions exist so that NO 3
− will be used as electron
acceptor. Autotrophic denitrification is also possible with either elemental sulphur
or hydrogen gas used as electron donor by autotrophic bacteria as shown in the
following unbalanced equation (Li et al. 2016):
NO
−
3 + CO 2 + Inorganic Electron Donor → N 2 + Oxidized Electron Donor
(8.3)
8.5 Selection of Tilapia (Oreochromis Niloticus)
for Aquaponic Biofilter System
The type of fish used in an aquaponic system is dependent on the surrounding climate.
The temperature shall be able to maintain: the types of fish which local fisheries
department has specified as legal (there are sometimes restrictions on the cultivation
of fish that are not native to the region), the type of fish desired for consumption by
consumers and the type of fish feeds available to the grower (Yavuzcan et al. 2017).
The hybrid striped bass is one species that has been reported as cannot perform well
in aquaponic systems because it cannot tolerate high potassium levels which are
common supplements used for plant growth (Dediu et al. 2012).
Tilapia is the second most cultured freshwater finfish species after carps. It has
the potential to be the most important farmed fish in the twenty-first century (Mahieu
2015). The worldwide production of tilapia fish in 2015 was estimated at 6.4 million
metric tonnes (MMT), (FAO 2017a). Tilapia is considered to be relatively resistant
to a few numbers of diseases encountered in other cultured fishes (Del-Pozo et al.
2017). One of the specialties of tilapia is hypoxia tolerance (ability to live in critically
low level of oxygen). The hypoxia tolerance of tilapia is higher than other aquatic
organisms, and tilapia can tolerate a hypoxia environment with dissolved oxygen
below than 0.5 mg/L for a short period (Lim et al. 2006). This makes it a suitable
model fish to be used in studying ammonia removal in an aquatic habitat. Other than
that, tilapia is selected by studies due to the availability of its genome database (Chen
et al. 2017).