IMPACT OF ETHANOL, METHANOL AND SULFIDES ON THE NITRIFICATION PROCESS OF AMMONIUM IONS IN NATURAL WATERS

Maria Sandu,Elena Moșanu,Anatol Tărîţă,Tudor Lupaşcu,Galina Dragalina

doi:10.15551/pesd2020142013

Abstract

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.

Highlights

Inorganic nitrogen compounds (NH4+, NH3, NO2, NO3-) are present practically in all natural waters, the content of which is conditioned by their amount in existing sources of pollution: wastewater discharged into the environment, the presence of industrial, agricultural, household waste illegallyMaria Sandu, Anatol Tărîţă, Tudor Lupaşcu, Galina Dragalina, Elena Moșanu stored, atmospheric deposits and surface runoff and as a result of their biochemical transformation [3].As a result of the discharge of wastewater from Chisinau municipality into the water of Bâc river were detected 119 mg/L NH4+, and in Cogâlnic district, downstream of Hânceşti city - 24.2 mg/L NH4+ [12]
An example is the information in Council Directive 78/659 / EEC of 18.07.1978 on the permissible concentration of ammonium ions, ammonia and nitrites in water for the maintenance of fish life: salmon waters: 0,005 mg/L NH3; 0,04 mg/L NH4+; 0,01 mg/L NO2-; cyprinoid waters: 0,005 mg/L NH3; 0,2 mg/L NH4+; 0,03 mg/L NO2- [4] and limited allowance of 0,5 mg/L NH4+ and NO2- for drinking water [9]
Denitrification research into reactors that simulate effluents from domestic wastewater treatment plants using methanol, ethanol and methane as electron donors based on kinetic parameters [20] has shown that the most efficient electron donor was ethanol, which completely removed nitrogen and nitrates in 50 min, the same efficiency being obtained by feeding the reactors with methanol and methane for 120 and 315 min, respectively

Summary

Introduction

Inorganic nitrogen compounds (NH4+, NH3, NO2-, NO3-) are present practically in all natural waters, the content of which is conditioned by their amount in existing sources of pollution: wastewater discharged into the environment, the presence of industrial, agricultural, household waste illegallyMaria Sandu, Anatol Tărîţă, Tudor Lupaşcu, Galina Dragalina, Elena Moșanu stored, atmospheric deposits and surface runoff and as a result of their biochemical transformation [3].As a result of the discharge of wastewater from Chisinau municipality into the water of Bâc river were detected 119 mg/L NH4+, and in Cogâlnic district, downstream of Hânceşti city - 24.2 mg/L NH4+ [12]. Nitrites and nitrates ions have different toxicity for hydrobionts, and surface waters are classified into 5 quality classes according to their concentration: for nitrates from 1,0 to >11,3 mg N/L; nitrites from 0,01 to >0,3 mg N/L and for ammonium from 0,2 to >3,1 mg N/L [8]. Their presence in water determines the excessive growth of algae causing eutrophication of the aquatic basin [5], and by deteriorating the ecological balance of the aquatic ecosystem; the water quality is diminished. Sulfides (S2-, H2S) are present in wastewater from various economic fields, including domestic, and cause an unpleasant odor already at a concentration of 0,05 mg/L in drinking water [7], but are missing in the list of pollutants to be monitored by the regulation on environmental quality requirements for surface waters [8]

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