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Introducing:
with for High Density Prawn & Fish Culture
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Basic Info
WHAT IS NITRIFICATION & DENITRIFICATION?
When fish and prawns are cultured and fed protein-rich feeds, uneaten food particles and by-products like amino acids and proteins, become major sources of organic compounds that accumulate on the pond bottom. These wastes are ultimately metabolized by bacteria to ammonia. Bacteria in NS Series SPO use dissolved organic sources of carbon from proteins, fats, and carbohydrates to build their body components. Conversion of dissolved organic material by these bacteria is a precursor to nitrification. The wastes excreted by fish are in the form of ammonia and urea. Their amounts accelerates as stocking and feeding rates increase. Most of the ammonia is taken up directly by the algae. When nitrate is used, it must first be reduced to ammonia (the reverse of nitrification). However, most of the ammonia will be converted by nitrifying bacteria to nitrite, and then nitrate.
Excess ammonia is toxic to fish and must be removed or converted
into non-toxic substances. It exists as a
mixture of two forms, unionized ammonia (NH3) and ionized ammonia (NH4+).
They are converted from one to the other at an equal rate depending upon
the pH and temperature of the water. Ammonia, consumed by the bacteria in
NS Series SPO, is initially converted it
into nitrite and subsequently into nitrate. Nitrite (NO2) is
toxic to fish and can reduce growth and adversely affect fish
health with high mortalities. Nitrate (NO3) is the end product
of nitrification and is normally not toxic to fish even in high concentrations.
Nitrate is tolerated by some fish species however, ideally it should be maintained
below 20 ppm. Nitrate accumulation can be controlled by regular water
changes and can also be converted to nitrogen gas.
In properly balanced
aquaculture environment, ammonia and nitrite levels
should always be zero.
Their presence is an indication that something in the system is out of balance
and s an indication for you to start corrective action. Even If low levels of these
persist in the aquaculture environment, they will cause problems for your prawns
and fishes, resulting in increased susceptibility to other diseases.
When oxygen is absent, denitrification can occur when
certain anaerobic bacteria obtain their oxygen by removing it from the nitrate
(NO3-) ion, finally leaving nitrogen gas or organic nitrogen
compounds. Nitrogen gas is then either volatilized to the atmosphere or
converted by biological fixation to ammonia. NS Series SPO can reduce nitrate. Nitrate
is used as a nitrogen
source by reducing it and incorporating the nitrogen atoms into organic
molecules. Denitrification generally requires anoxic conditions and adequate
soluble organic carbon. This combination of conditions is usually lacking in
many aquaculture environments and this prevents the complete removal of nitrate.
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Nitrification involves the conversion of ammonia into nitrite by the
Nitrosomonas bacteria. Nitrite is then converted to nitrate by Nitrobacter. Simultaneously, denitrification occurs wherein nitrate is converted to nitrite then to ammonia which when acted upon by
Bacillus, Psuedomonas and Clostridium, are converted into nitrogen gas, nitrous oxide and nitric oxide, all nontoxic, and are released in the process.