# Water Supply Systems for Settlements with Arsenic-Contaminated Groundwater--Making the Right Choice
## 3 Results and Discussion  
### Drinking Water Requirements and Socioeconomic Position of the Investigated Area  
Socioeconomic and water supply data from 2021 for the municipalities Kanjiza and Senta are provided in Table 2. The data provide a comparison between the municipalities of Kanjiza and Senta with the larger region of Vojvodina, as well as the country of Serbia. These statistics show that Kanjiza and Senta are smaller and less densely populated compared to the Vojvodina region as a whole. The municipalities are located in a region that boasts a gross domestic product greater than the national average, whilst Kanjiza and Senta are among the top 20 municipalities in Serbia with a level of development above the national average [22]. However, a more detailed look at the data reveals a less favourable picture. For instance, the average age of the inhabitants in Kanjiza and Senta is slightly higher than the national average, while the average salary before taxes and contributions per employee is slightly lower than both the state and Vojvodina averages. \begin{table}
\begin{tabular}{c c c} \hline
**Scheme** & **Technologies Required \({}^{\ddagger}\)** & **Treated Parameters** \\ \hline B & degasification/aeration, filtration, disinfection & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn \\ C & degasification/aeration, filtration, adsorption, disinfection & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, organic \\  & degasification/aeration/oxidation, & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, organic \\ D & filtration, adsorption on granulated & matter \(<\) 20 mg KMnO\({}_{4}\)/L, \\  & activated carbon (GAC), disinfection & As \(<\) 50 \(\mu\)g/L \\  & degasification/aeration/oxidation, & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, \\ E & separation of floccelles, GAC & As \(>\) 50 \(\mu\)g/L \\  & degasification/aeration/oxidation, & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, organic \\ F & separation of floccules, GAC & matter \(<\) 20 mg KMnO\({}_{4}\)/L, \\  & adsorption, disinfection & As \(>\) 50 \(\mu\)g/L \\  & degasification/aeration/oxidation, & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, As, Ba, \\ G & filtration, membrane & electrical conductivity \(>\) 1000 \(\mu\)s/cm, \\  & separation, disinfection & organic matter \(<\) 20 mg KMnO\({}_{4}\)/L \\  & degasification/aeration/oxidation, & CH\({}_{4}\), CO\({}_{2}\), NH\({}_{3}\), Fe, Mn, As, Na, B, \\ H & separation of floccules, membrane & electrical conductivity \(>\) 1000 \(\mu\)s/cm, \\  & separation, disinfection & organic matter \(>\) 20 mg KMnO\({}_{4}\)/L \\ \hline \end{tabular} \({}^{\ddagger}\) Technologies defined in the Strategy of water supply and water protection in AP Vojvodina [21].  
\end{table} 
Table 1: Water treatment schemes [21]. In terms of water supply, Kanjiza has approximately 10,097 households connected to the water supply network, representing approximately 1.5% of the total number of households connected in the province of Vojvodina. Similarly, Senta has approximately 8195 households connected, accounting for around 1.2% of the total households connected in the province. It is clear from the data in Table 2 that both Kanjiza and Senta capture a relatively small amount of water compared to the provincial and national levels. The same trend can be observed in terms of delivered drinking water, realisation of investments in new fixed assets in the field of water supply and wastewater management, and the number of individuals employed in the field of water supply and waste management. The small size of these municipalities suggest that the expected benefits from the economies of scale achieved by centralisation may be relatively small--the costs per connection in these systems will still be higher than the costs achieved in large urban areas. In these settlements, groundwater is abstracted almost exclusively from water-bearing layers of basic aquifer complex at depths of 60 m to 220 m, with significant differences in the important hydrogeological parameters.