# The Use of Chalcogenite as a Biosorption Bed in the Treatment of Groundwater
## 3 Results  
Based on the obtained results, it can be concluded that purification of groundwater on chalcogenite beds is an effective process in terms of ammonium nitrogen removal. In the case of single-stage filtration (water 1) in the first days of the experiment, the reduction of NH\({}_{4}\)\({}^{+}\) content was due to the sorption properties of chalcogenite with an average effectiveness of 16.5%, however, already from day 31, it was due to the biochemical processes (Figure 2). The process efficiency was maintained at a high level of 60 to 100%. During this period, values in the range 0-0.7 N-NH\({}_{4}\)\({}^{+}\) were obtained in the filtrate, with a standard deviation of 0.22. The ammonium nitrogen was removed to a level below the permissible norm of 0.39 g N- NH\({}_{4}\)\({}^{+}\)/m\({}^{3}\) as early as the 23 rd day of the experiment (Figure 2). From day 31, an \begin{table}
\begin{tabular}{c c c c c c} \hline \hline \multicolumn{2}{c}{**Physical Properties**} & \multicolumn{4}{c}{**Chemical Composition**} \\ \hline Parameter & Unit & Range & Parameter & Unit & Range \\ Specific density & t/m\({}^{3}\) & 2.62–2.67 & SiO\({}_{2}\) & \% & 94.0–99.0 \\ Bulk density & t/m\({}^{3}\) & 1.0–2.0 & Al\({}_{2}\)O\({}_{3}\) & \% & 0.4–3.6 \\ Porosity & \% & 15–30 & Fe\({}_{2}\)O\({}_{3}\) & \% & 0.1–0.8 \\ Impregnability & \% & 4–10 & CaO & \% & 0.1–1.2 \\ Compressive strength & MPa & 60–120 & MgO & \% & 0.0–0.3 \\ Abrasion in the Devala drum & \% & 6–15 & Na\({}_{2}\)O & \% & 0.04–0.2 \\ Oil number & g/100 g meal & 26 & K\({}_{2}\)O & \% & 0.1–0.5 \\ \hline \hline \end{tabular}
\end{table} 
Table 4: Properties of chalcogenite [34; 35]. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameter** & **Min** & **Max** & **Mean** & **Median** & **SD** & **N** \\ \hline Ammonium Nitrogen & 0.50 & 3.70 & 2.49 & 2.50 & 0.62 & 57 \\ Nitrite Nitrogen & 0.00 & 2.26 & 0.37 & 0.06 & 0.61 & 57 \\ Nitrate Nitrogen & 0.02 & 3.58 & 2.01 & 2.00 & 0.85 & 57 \\ Manganese & 0.86 & 1.80 & 1.06 & 1.03 & 0.18 & 57 \\ Iron & 0.78 & 1.17 & 1.02 & 1.00 & 0.08 & 57 \\ Dissolved Oxygen & 5.10 & 10.84 & 8.26 & 8.45 & 1.31 & 55 \\ pH & 7.13 & 7.70 & 7.43 & 7.46 & 0.16 & 55 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: The physicochemical quality of water directed to biofilters. \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Parameter** & **Unit** & **Analytical Method/Standard** \\ \hline Ammonium nitrogen & g N-NH\({}_{4}\)\({}^{+}\)/m\({}^{3}\) & \begin{tabular}{c} Colorimetric method with Nessler’s reagent using UV-Vis Spectrophotometer (DR 5000, Hach-Lange, Germany, Europe), method number 8155 \\ \end{tabular} \\ \hline Nitrite nitrogen & g N-NO\({}_{2}\)\({}^{-}\)/m\({}^{3}\) & \begin{tabular}{c} Colorimetric method by Nitrite Test Merck 1.14408 \\ (Germany, Europe), method number 8507 \\ \end{tabular} \\ \hline Nitrate nitrogen & g N-NO\({}_{3}\)\({}^{-}\)/m\({}^{3}\) & \begin{tabular}{c} Colorimetric method with sodium salicite using UV-Vis Spectrophotometer (DR 5000, Hach-Lange, Germany, Europe), method number 8039 \\ \end{tabular} \\ \hline Dissolved oxygen & g O\({}_{2}\)/m\({}^{3}\) & \begin{tabular}{c} Electrochemical method using a HQ30D Dissolved Oxygen Meter (Hach-Lange, Germany, Europe) \\ \end{tabular} \\ \hline Manganese & g Mn/m\({}^{3}\) & \
\begin{tabular}{c} Colorimetric method using UV-Vis Spectrophotometer \\ (DR 5000, Hach-Lange, Germany, Europe), method number 8149 \\ \end{tabular} \\ \hline Iron & g Fe/m\({}^{3}\) &
\begin{tabular}{c} Spectrophotometric method by the rhododendron method using UV-Vis Spectrophotometer (DR 5000, Hach-Lange, Germany, Europe), method number 8008 \\ \end{tabular} \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Methodology of physicochemical determinations of water parameters. increase in the nitrite nitrogen content in purified water was observed, indicating the beginning of the first phase of the nitrification process.