Fixation of ammonium-N and nitrate-N with olive oil mill wastewaters

The present work evaluates whether ammonium and nitrate ions become linked with diluted olive oil mill wastewaters (OOMW). From a laboratory experiment it was concluded that the ammonium ion linked with OOMW in the presence of carbonates or hydroxides and OOMW could block up to a third of the present ammonium-N ion. On the other hand, OOMW are capable of joining with the nitrate ion, in a sulphuric diluted medium at room temperature, retaining up to 80% of nitrate-N. These complexes could be useful for recycling OOMW as new OOMW-N fertilizers. In soils treated with OOMW-N fertilizers, the nitrate-N emissions were reduced by 90% for two months. So, inorganic-N fertilizers mixed with OOMW could produce new organic fertilizers with a higher efficiency index for N.