Abstract

FERNANDEZ, Javier; MONTENEGRO, Susana; LEDEZMA, Cristina  and  YANZA, Jeffrey. Sedimentability of Flocculent Particles in Highly Colored Low Turbidity Water Coagulated with FeCl3 + PAC Versus PAC. TecnoL. [online]. 2021, vol.24, n.51, pp.32-42.  Epub Oct 12, 2021. ISSN 0123-7799.  https://doi.org/10.22430/22565337.1789.

Highly colored low turbidity water, which is characteristic of high mountain sources, can limit the process of water treatment plants because it generates a low sedimentation rate of the flocs formed in the coagulation process. This article compares the sedimentation produced by the combination of ferric chloride (FeCl3) and polyaluminium chloride (PAC) used as primary coagulant and coagulation auxiliary, respectively, versus PAC as primary coagulant. This study was conducted at laboratory level using jar tests and natural water with the aforementioned characteristics. The sedimentation curves of each treatment option were determined and adjusted to linear regressions, which were statistically compared. For each curve, efficiency and theoretical turbidity were determined using three sedimentation rates: 1.3 cm/s, 0.9 cm/s, and 0.6 cm/s. The results indicate that the two processes were different (p=0.000), and the use of FeCl3+PAC generated higher sedimentation rates and lower theoretical residual turbidities, which improves the efficiency of the sedimentation process. In conclusion, the use of FeCl3 in combination with PAC represents a better technical option than PAC as primary coagulant because, in addition to optimizing the sedimentation process, it could help to increase the filtration run and reduce the consumption of water for filter washing.

Keywords : Low turbidity; sedimentability of particles; ferric chloride; polyaluminium chloride.

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