## 3 Results
### Removal of TBC from Drinking Water by Filtration
#### 3.1.1 Filtration at a Flow Rate of 1 L/min (Flow Velocity 18 m/h; Retention Time 0.67 min)  
In Tables 1 and 2, the efficiency of removal of TBC by the ordinary complex was compared with that of an enriched complex in which the amounts of ODTMA added during the preparation of the granulated complex (enriched) were increased. Two columns (D = 6.5 cm \(\bullet\) L = 20 cm) exclusively containing granules of each type were fed with water from a container filled continuously with tap water. The filtration flow rate for 3 h per day was 1 L/min, which corresponds to a flow velocity of 18 m/h. This flow regime is quite demanding for a domestic filter, where a flow of several liters is usually followed by a period of rest, and the total amount filtered rarely exceeds 30 L per day. Samples were taken in the morning and afternoon except on the first day in each case. In the morning, the first filtered volume of 0.25 L was spilled, and then a sample of 1 L was taken; after that, the flow proceeded for 3 h, and another sample was taken. This procedure was in accordance with certain tests on domestic filters in Israel. A criterion was set that the number of bacteria in the filtered water should not exceed 1000/mL for an acceptable quality of drinking water. The first experiment (Table 1) started on 19 February when the reproduction rate of bacteria in water is relatively minimal, whereas in Table 2, the starting day was on 3 June, towards the end of spring season. The total filtered volumes were 1630 L and 1270 L, in Tables 1 and 2, respectively. Sampling columns 1 and 2 in Table 1 indicated that filters filled with the enriched complex yielded in all cases a small number of emerging bacteria, whereas in the case of the filters filled with the ordinary complex, four samples exceeded the criterion of 1000 TBC/mL from one of the columns. Larger observed numbers were sampled in the morning, i.e., 20 h or 47 h after a halt of the flow. \begin{table}
\begin{tabular}{c c c c c c c} \hline \hline \multicolumn{6}{c}{**Total Count of Bacteria Emerging from Filters per mL**} \\ \hline \multicolumn{2}{c}{**Enriched Granules**} & \multicolumn{2}{c}{**Ordinary Granules**} & \multicolumn{2}{c}{**Bacteria per mL at Entry to Filters**} & \multicolumn{2}{c}{**Volume Filtered**} & \multicolumn{1}{c}{**Day**} \\ \hline
1 & 2 & 1 & 2 & (CFU/mL) & (L) & \\ \hline \(<\)1 & \(<\)1 & 5 & \(<\)1 & 180 & Mon. \\
2 & 8 & 1 & \(<\)1 & 28 & & Tue. M \\ \(<\)1 & \(<\)1 & \(<\)1 & 1 & 360 & Tue. \\ \(<\)1 & \(<\)1 & \(<\)1 & \(<\)1 & & Wed. M \\ \(<\)1 & \(<\)1 & \(<\)1 & \(<\)1 & 540 & Wed. \\ \(<\)1 & 3 & \(<\)1 & 3 & 140 & & Thu. M \\ \(<\)1 & \(<\)1 & \(<\)1 & \(<\)1 & 720 & Thu. \\ \(<\)1 & 8 & \(<\)1 & 1600 b  & 370 & & & Sun. M \\ \(<\)1 & \(<\)1 & \(<\)1 & 3 & 220 & 900 & Sun. \\ \(<\)1 & 8 & 2 & 42,000 a  & 630 & & Mon. M \\ \(<\)1 & \(<\)1 & \(<\)1 & 16 & 10 & 1080 & Mon. \\ \(<\)1 & 2 & \(<\)1 & 240 c  & 210 & & Tue. M \\ \(<\)1 & \(<\)1 & 68 c  & 2 & 16 & 1260 & Tue. \\ \(55\) c  & \(<\)1 & \(<\)1 & 88,000 a  & 6 & & Wed. M \\ \(<\)1 & \(<\)1 & \(<\)1 & 85 c  & 95 & 1440 & Wed. \\ \(37\) c  & 32 c  & 1 & 150,000 a  & 120 & & Thu. M \\ \(<\)1 & \(<\)1 & \(<\)1 & 190 c  & 110 & 1630 & Thu. \\ \hline \end{tabular}
\end{table} 
Table 1: Removal of bacteria from drinking water by filters containing an ordinary or enriched granular complex (10% increased amount of cation during preparation of complex).