| Popis: |
The objective of this study was the comparison between two filtration systems, being one composed of a boulder pre-filter followed by a slow filter with sand as filtration media and a non-woven synthetic fabric in the upper part, and the other one composed of a boulder pre-filter followed by a slow filter with sand as filtration media and granular activated charcoal and a non-woven synthetic fabric in the upper part, for the purification of household effluents treated in cultivated beds, to be applied in fertigation. The filtration systems were compared to assess the efficiency in the removal of the parameters: suspended solids, turbidity, apparent color, chemical oxygen demand, dissolved oxygen, iron, manganese, total coliforms and E. coli. The two systems operated 24 hours a day, with the same application rate, treating a total final flow of 1.5 m3 day-1, while the application rate for the pre-filtration unit was 8.4 m3 m-2 day-1 on average and for each of the slow filtration units it was 2.7 m3 m-2 day-1 on average. The pre-filtration and slow filtration units were efficient in the reduction of suspended solids concentrations, turbidity, apparent color and COD, for the purification of previously treated domestic sewage. The use of granular activated charcoal combined with sand in the slow filter allowed a higher efficiency in the removal of suspended solids, color, turbidity, total coliforms and E. Coli., without increasing the initial head loss. The use of effluents is possible in the fertigation practice, where the disinfection process may be necessary or not, depending on the cultivation and the irrigation system adopted. |
