ABSTRACT
The objective of this study is to investigate the impacts of anionic polymer as a flocculant aid on the coagulation/flocculation performance with a saline solution of Moringa oleifera as a coagulant to provide larger flocs and decrease the time sedimentation. For the tests, raw water was used from Pirapó River Basin (Maringá, Paraná, Brazil). Optimization of coagulation/flocculation tests was initially performed in a jar-test with a dosage of M. oleifera Lam (crude extract--MO, oil-extracted with ethanol--MO (et) and hexane--MO (hex) 1% m/v) as the coagulant that ranged from 10 to 60 mg L(-1) and of the anionic polymer 0.1% as a flocculant aid with a dosage that ranged from 0 to 0.4 mg L(-1). The parameters analysed were colour, turbidity and compounds with absorption in UV254nm. In view of the statistical analysis results, MO (hex) with a dosage of 30 mg L(-1) was chosen as a coagulant for the next tests of coagulation/flocculation. When anionic polymer was used alone (0.0 mg L(-1) of MO (hex)), parameters were not removed and there was no generation of heavy flocs as compared with the combination of MO (hex) with the anionic polymer. Statistical analysis showed that MO (hex) obtained the highest removals of the parameters analysed in lower dosages and no significant increase in parameters removal was observed when the polymer dosage was increased. The efficacy of the coagulant +/- anionic polymer was optimal when 30mg L(-1) of MO (hex) was used as a coagulant and 0.1 mg L(-1) of the anionic polymer was used as a flocculant aid, decreasing the time sedimentation from 1 h to 15 min.