The anaerobic
filter effluents reached 2.2
0.7 mg L1 of
average phosphorus concentration (Table 5). The hydraulic loading
rate of 300 L m2 day1 was the
first where the effluents generated
did not present a statistically significant difference compared to anaerobic effluents, which points to a weaker removal of this
compound by the sand bed. Comparatively, USEPA (1999) states
that the decrease in concentration can be higher than 50% in newly
installed
filters; however, there is loss of efficiency with bed
maturation. Nielsen et al. (1993) found removals that ranged from
40 to 60%, while Guilloteau et al. (1993) ascertained a drop of
almost 50% in the concentration.