# The Use of Chalcogenite as a Biosorption Bed in the Treatment of Groundwater
## 3 Results
Over time, not only was the efficiency of manganese  
Figure 4: Change in the content of nitrate nitrogen compounds after biofiltration on the chalcogenite bed in the analyzed systems. Figure 5: Change in the content of manganese compounds after biofiltration on the chalcogenite bed in the analyzed systems. removal reduced but more manganese was introduced into the treated water (Figure 5). The reason for this phenomenon could have been the reaction of the produced manganese dioxide with the nitrites generated in the nitrification process. A similar relationship was observed in the single-stage biofiltration system (water I). After the biofiltration process on the chalcogenite beds, iron concentrations in the analyzed water did not exceed the permissible value of 0.2 g Fe/m\({}^{3}\)[12] (Figure 6). The exception was one sample taken from system I and II on the first working day of the filter, for which a value of 1.2 and 1.087 g Fe/m\({}^{3}\) was recorded. The values of iron on the outflow from biofilters ranged from 0 to 0.15 (average standard deviation was 0.03). The obtained results indicate that the chemical activation of the bed and the number of filtration stages did not affect the efficiency of the iron removal process (Figure 6). Research on the biofiltration process on sand beds carried out by [PERSON] et al. [3] also showed a high efficiency of iron removal (below 0.2 g /m\({}^{3}\)) from the first days of the experiment. Iron in the form of Fe\({}^{2+}\) at pH > 5 could also be chemically oxidized with the oxygen present in the water [1]. Values < 0.5 NH\({}_{4}\)\({}^{+}\) were obtained on the 10 th day of the filter's operation and the removal of Mn maintained at a constant low level was observed after the 56 th day of the filter's operation. On the basis of the results depicted in Figures 5 and 6, the capacity of the bed in relation to iron was estimated at approximately 0.7 g/dm\({}^{3}\) chalcedonite and filtration was not carried out to the point of exhaustion. In the case of manganese, the capacity of the bed was only 0.19 g /dm\({}^{3}\) chalcedonite. In comparison with other chemically-active sorption deposits on the basis of silicate media, chalcedonite has a lower level of sorption capacity (Table 6). However, it is necessary to indicate that the values of this parameter were determined by the producers of deposits for model solutions in the optimum conditions of filtration. In the case of catalytic deposits on the basis of manganese ores, i.e., G1, Defeman, Multiman 3M, Pyroolx Filox-R, MetalEase, the sorption capacity is not determined because their properties are not exhausted. Yet, the producers of filtration deposits determine the maximum contents of iron and manganese in the water supplied to the filter, thus indicating the scope of the effective use of a catalytic ore [40; 41; 42; 43; 44; 45]. \begin{table}
\begin{tabular}{c c c c} \hline \multirow{2}{*}{**Filtration Materials**} & \multicolumn{2}{c}{**The Sorption Capacity**} & \multirow{2}{*}{**References**} \\ \cline{2-3}  & **g Fe /dm\({}^{3}\) deposits** & & \\ \hline
**MTM\({}^{\circledR}\)** & 1,3 & 0,6 & [36; 37] \\
**GreensandPlusTM** & 1,3 & 0,6 & [38; 39] \\ \hline \end{tabular}
\end{table} 
Table 6: The of chemically active filtration materials based on silica carriers. Figure 6: Change in the content of iron compounds after biofiltration on the chalcedonite bed in the analyzed systems. Dissolved oxygen is a very important factor affecting the growth rate of microorganisms, as well as the efficiency, type, and rate of metabolite production. Changes to the oxygen content in the biofiltration process in the analyzed systems are shown in Figure 7. The oxygen consumption in water I and II was in the range 0.1-5.2 g O\({}_{2}\)/m\({}^{3}\) and from the 51 st day of the experiment, a greater reduction in the content of O\({}_{2}\) in the treated water was noted.