TY  - JOUR
T1  - Clarification of Fluoride Suspensions by <I>Grewia</I> sp. Extracts
AU - Ndi, K.S. AU - Kofa, G.P. AU - Tekem, G. AU - Ngnie, N.P. AU - Amba, E.V. AU - Kayem, G.J. 
JO  - Journal of Engineering and Applied Sciences
VL  - 8
IS  - 4
SP  - 104
EP  - 108
PY  - 2013
DA  - 2001/08/19
SN  - 1816-949x
DO  - jeasci.2013.104.108
UR  - https://makhillpublications.co/view-article.php?doi=jeasci.2013.104.108
KW  - Grewia sp.
KW  -natural flocculant
KW  -sand filtration
KW  -laterite
KW  -adsorption
AB  - Fluoride removal using adsorbents require clarification steps 
  during which the adsorbate is removed from the suspension. In this study, powders 
  of <I>Grewia</I> sp. (Gs) were used as flocculants in the clarification of laterite-fluoride 
  suspensions resulting from the adsorption of fluoride onto laterite. Clarification 
  experiments consisted in adsorption, coagulation, decantation and filtration 
  steps. Experiments were carried out in a settling tank (34.6 cm<SUP>2</SUP>) 
  and in a glass column of 0.4 inner diameter, at different pH (5, 7, 9) and Gs 
  concentration (0.25-1 g L<SUP>-1</SUP>) with constant laterite concentration 
  (1 g L<SUP>-1</SUP>) and adsorption contact time (30 min). Sedimentation was 
  realized for 30 min, prior to sand filtration of the resulted supernatant. Sand 
  beds of granular particle size 400-500 &#956;m and 10 cm high were used for 
  filtration experiments at a fixed flow rate (5 m h<SUP>-1</SUP>). Results show 
  that the best removal efficiency was obtained at pH 5 for fluoride and at pH 
  9 for suspended material. Using Gs extracts alone gave fluoride removal efficiencies 
  greater than what obtained with laterite. The combined process of decantation 
  and filtration was found suitable in the removal of suspended particles and 
  the sedimentation step was the more efficient process under the tested conditions.
ER  -