Biochemical Oxidation – A Pathway for Ammonia Removal from Aquatic Systems

The river network in the Republic of Moldova is the final receptor of most runoff and wastewater with insufficient treatment level. About 1/3 of pollutants, including ammonia compounds, still persist after treatment, is discharged into natural waters. In the preceding thousand years the course of all small rivers was straighten and basins where drainage. The self-purification process and oxidation of ammonia to nitrate by microorganisms has in their waters a low rate. This paper presents the results of researches that include laboratory modelling of the role of diverse substrates in biochemical oxidation of ammonia as a Pathway for Ammonia Removal from Aquatic Systems. The biomineralization process of ammonium ions was simulated in small rivers water in the presence of diverse substrates (polyethylene film, sandy soil, stone, gravel, active carbon). Biochemical transforming of nitrite produced by ammonia oxidation is reduced to nitric oxide, nitrous oxide and possibly to nitrogen gas. Particularly the gravel accelerates the rate of process more than 2-3 times.