# Water Quality Changes in Cement-Lined Water Pipe Networks
## 3 Results
### Determination of Trace Element Content in Water Contacting Cement-Mortar Coating  
On the basis of the results of the analysis of a sample cement coating covering the interior surface of the pipeline in the experimental setup using the Inductively Coupled Plasma--Optical Emission Spectrometer (ICP-OES), it was found that, besides the primary cement components (including such elements as potassium, sodium, magnesium, calcium, zinc, aluminium) it also contained numerous trace elements such as iron, manganese, barium, chromium, lead, nickel and cobalt. Analyses of \begin{table}
\begin{tabular}{c c c c} \hline \hline
**Parameter** & **Unit** & **Water Feeding the Setup** &
\begin{tabular}{c} **Water Flowing Out** \\ **from the Setup** \\ \end{tabular} \\ \hline temperature & \({}^{\circ}\)C & 11.0 & 11.2 \\ colour & mg Pt/L & 1 & 1 \\ turbidity & NTU & 0.89 & 0.93 \\ pH & - & 7.53 & 7.58 \\ alkalinity & mV/L & 6.3 & 6.4 \\ hardness & mval/L & 7.8 & 8.2 \\ calcium & mg Ca/L & 104 & 114 \\ iron & mg Fe/L & 0.10 & 0.055 \\ manganese & mg Mn/L & 0 & 0 \\ chlorides & mg Cl/L & 32.0 & 39.0 \\ sulphates & mg SO\({}_{4}\)/L & 86 & 86 \\ oxygen consumption & mg O\({}_{2}\)/L & 1.84 & 1.12 \\ ammonium ion & mg NH\({}_{4}\)/L & 0.09 & 0.09 \\ nitrates & mg NO\({}_{3}\)/L & 15.8 & 15.8 \\ free CO\({}_{2}\) & mg/L & 50.6 & 39.6 \\ oxygen & mg O\({}_{2}\)/L & 6.70 & 6.93 \\ dry residue & mg/L & 494 & 519 \\ Langelier saturation index (IL) & - & 0.23 & 0.38 \\ Ryznar stability index (IR) & - & 7.07 & 6.82 \\ AWWA index & - & 12.64 & 12.67 \\ \hline \hline \end{tabular}
\end{table} 
Table 5: Quality of the water flowing through the experimental set-up at the velocity of 0.1 m/s (series III). chlorinated and non-chlorinated water contacting the cement-mortar coating conducted at the initial stage of setup operation (preliminary research) allowed to make a general statement that majority of trace elements found in the cement were successfully immobilized and significant amounts failed to penetrate the water that contacted the coating. It should be stressed however, that leaching of trace elements from the cement was less intense in the case of chlorinated water [25]. As part of the research presented herein, an attempt was made to analyse the phenomenon of trace element penetration into the water after long-term use of the setup. To that end, after eight months of using the setup, another test for trace element water content was performed. The analysed sample consisted of water feeding the setup and water stagnant in the setup for 32 h. The results are presented in Table 6. The majority of trace elements (including those detectable in the water at the initial stage of setup operation) were below the detection limit of the spectrometer. As regards elements detected in the stagnant water on the other hand, there was an insignificant increase in their concentration when compared to the water feeding the experimental setup, which was reported for sodium, magnesium, iron and barium. A slightly larger increase of about 19% was reported only in the case of boron concentration whereas there was a slightly lower increase of about 12% in the case of gallium. A large (three-fold) increase was reported for zinc on the other hand, although its final concentration in the stagnant water (0.027 mg/L) is still found to be rather low. It should be stressed that zinc content in drinking water is not limited by any Polish, American or international provisions. All final concentrations of elements detected in the water after its contact with the coating were considerably below limit values for drinking water set out in relevant legal provisions. The reported small increases in their concentration is likely to occur for a number of reasons. The first one is the effective immobilisation of trace elements in the structure of the cement (their presence is confirmed, therefore their possible low content should be excluded).