This study investigates the use of a sodium sulfite tracer analysis to assess
the amount of gas bubbles trapped in a porous media. The objective was to contribute to the
development of a new diagnostic tool to be used in waterworks to characterize and
quantify air bubbles in rapid sand filters. This new method was developed and tested in
laboratory column experiments. The experimental set up was designed to reproduce the formation of bubbles in the
porous media during rapid sand filtration. In this set of experiments, particle and soluble
contaminant filtration was neglected and distilled water was used as inlet water. To
simplify further the phenomenon taking place in the column during bubble formation,
inlet water was saturated with oxygen. The bubbles forming in the column are therefore
oxygen bubbles.
Experiments were conducted in a 63x63x313 mm<sup>3</sup> transparent column packed
with 1 mm diameter glass beads. The porous medium (total pore volume of 522 ml) was
water saturated at the start of the experiment by flushing the column with carbon dioxide
and then filling it with boiled water cooled to room temperature. Conclusions indicate that the observed conductivity breakthrough curves showed an increase of longitudinal
dispersivity, in accordance with the literature, caused by the supersaturation of the inlet
water. The conductivity, dissolved oxygen and pH curves evolved with time and with the
presence of oxygen bubbles in the column which were controlled by pictures and
weighing of the column.
The new tracer method developed in this study is useful to monitor the
development of oxygen bubbles in the column; and, could therefore be a useful tool for
investigating the presence of air bubbles in the filter bed of rapid sand filters at
waterworks. Includes 6 references, figures.
| Edition : | Vol. - No. |
| File Size : | 1
file
, 860 KB |
| Note : | This product is unavailable in Ukraine, Russia, Belarus |
| Number of Pages : | 5 |
| Published : | 11/01/2009 |
