This paper includes the results of laboratory modeling of ethyl and methyl alcohol and sulfide ions impact on the biochemical process of ammonium ions nitrification in water from the Dniester River, Palanca village, Stefan Voda district (august 2019). An insignificant influence of ethyl and methyl alcohol (0,5 ml/L) was established in both stages of the process. In the comparison test, the stage NH 4 + → NO 2 - lasted 12 days, and in the presence of ethyl alcohol - 14 days and in the presence of methyl alcohol - 16 days. The NO 2 - → NO 3 - stage in the comparison test lasted 16 days and in the presence of ethyl alcohol 2 days less (14 days) and in the presence of methyl alcohol - 16 days, so without any influence. The study showed a significant influence of sulfur ion in both stages at a concentration of 0.1 mg/L with and without the presence of ethyl and methyl alcohol. In the comparison test, the NH 4 + → NO 2 - stage lasted 12 days, in the presence of the S 2- ion it lasted 18 days, and in the presence of alcohols and sulfur ion - more than 20 days, the synergism of the impact being obvious. In the NO 2 - → NO 3 - step of the process for 20 days the NO 2 - concentration did not decrease in the presence of the S 2- ion, and in the presence of ethyl, methyl alcohol and S 2- only 15-35% of the NO 2 - ions were oxidized, in comparison with the witness test.