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 NH4 + → NO2- lasted 12 days, and in the presence of ethyl alcohol - 14 days and in the presence of methyl alcohol - 16 days. The NO2- → NO3- 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 NH4+ → NO2- stage lasted 12 days, in the presence of the S2- 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 NO2- → NO3- step of the process for 20 days the NO2- concentration did not decrease in the presence of the S2- ion, and in the presence of ethyl, methyl alcohol and S2- only 15-35% of the NO2- ions were oxidized, in comparison with the witness test.