Nitrate
Nitrate is a stable compound, which is an end-product of nitrification. Nitrate,
although is far less toxic than ammonium and nitrite, can become toxic towards tilapia
when its concentration exceeds 70 mg N/L (Van Rijn, 1996). Nitrate is poisonous to
human especially in baby under 4 to 6 months old because it can bind with hemoglobin
to form methamoglobin. Discharge of nitrate into natural water resources can cause
eutrophication, which is a natural aging of freshwater reservoir such as lakes to become
organically rich, thereby leading to domination of weeds and eventually transforming
into mash land (Tchobanoglous, et al., 2003). Discharge of nitrate into natural water
resource quickly accelerates eutrophication by stimulating the growth of microalgae.