in the concentration of conducting ions leaving just the sodium and
chloride ions as the ions responsible for conductivity in the cells. The
internal resistance also further increased because of loss of water from
the soil which was used as the proton ex-change membrane. Initially
the soil is saturated with the sewage sample and the conductivity of
the soil is higher than 160 S at 22.8°C (Table 1). The ions responsible
for conductivity at this point are those contained in the soil, the
added sodium chloride and the salts contained in the sewage. When
the soil moisture content decreased, this meant that the migration of
ions across the soil membrane from the anode to the cathode became
more difficult. Resistance was highest during the times of low moisture
content and the resistance greatly varied with moisture content. It was
expected that the internal resistance would in-crease with time but this
was not the case (Figure 8). During the early times of ion migration
across the soil towards the cathode compartment, there was slow
accumulation of ions in the soil (membrane). This accumulation of
ions led to an increase in the ion concentration thus an increase in
E.C. The increase in ion concentration by far surpasses the effect of
moisture content variation. This led to an increase of E.C of the cells or
a decrease in electrical resistance of the cells. The E.C increased from
160 S on day 0 to 243 mS on day 55 (Table 1).