unstable throughout the experiment. Subsequently, the
removal efficiency of COD of columns S continued to
improve until reaching 99.58% while at the same time,
the elimination of COD by SP was varying, and
remained above 90%. The removal efficiency of P
remained low. Broussard (1985) related poor pozzolana
result to preferential pathways created by water.
Statistical analysis of the weekly abatement result by
the SPSS software with tukey test showed that S and
SP abatement were not significantly different and that
they differed significantly from those of P Elimination
of COD which was mainly due to sedimentation and
particular filtration phenomena. The S treatment led to
the most important abatement. Thus, our results were
consistent with those of Pell and Nyberg (1989), who
obtained 91% of the reduction after 7 days of column
operation. From the 2nd week the output COD value for
all treatment was below 60 mg/L O2
, which was the
guide value of the French decree of August 31, 2010 of
form COD of treated wastewater for irrigation of crops
to be eaten raw. However, for the P columns, the
abatement was more unstable and collapsed at the 7th
week.
Fig. 2b below shows the change in the reduction
of BOD7
during the period of the experiment. The filter
pilot treatment led to the important abatement in BOD7
after only 2 weeks of operation. All treatment reached
abatement above 95%, for an average value of 185.48
mg/L O2
at the input. The BOD7
concentration of output
effluent was in the range of 1.42±0.24 – 7.15±0.86 mg/L
O2
by S and 3.18±0.69 – 7.59±0.3 mg/L O2
by SP
treatment. The BOD7
removal by P treatment fluctuated
but still averaged over 90%. From the results presented
above it can be concluded that the aerobic reactor
columns have great potential in biodegrading organic
pollutants present in municipal wastewater.