Performance of Nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO) Membranes in the Removal of Fluorine and Salinity from Brackish Drinking Water

Abstract

Certain areas in Senegal have a serious problem of high fluoride and salinity in underground water because of soil properties. This water currently used for drink has a bad taste on consumption and caused diseases like dental fluorosis and skeletal fluorosis. A membrane filtration plant constructed by Pall Corporation was improved through nanofiltration (NF) and Low Pressure Reverse Osmosis (LPRO). Both NF and LPRO membranes were shown applicable for salinity and fluoride ions removal from brackish and high fluorinated drinking water in a remote community. The NF membrane has given a fluorine retention rate varying between 63.3% and 71% while the LPRO membrane allow to reach 97 to 98.9% for fluorine rejection. Highest salinity rejection rates expressed through conductivity measurements are around 46% and 97% for respectively NF and LPRO

Efficiency of Nanofiltration Membrane TFC-SR3 and SelRo MPF-34 for Partial Elimination of Fluoride and Salinity from Drinking Water

“…While for SelRo MPF-34 membrane, the flux remains constant from 1 to 24 hours beyond it decreases to 9 L/m 2 •h at 61 hours functioning. The decrease in flux may be due to fouling membrane [3]. It emerges from these results that the permeability of SelR MPF-34 membrane is higher and that fouling phenomena happen very quickly with the TFC-SR3 membrane.…”

“…The difference on the rejection of salts and fluoride between TFC-SR3 and SelRo MPF-34 membranes was due to difference of intrinsic properties of these membranes. The decline of the rejection rate for fluoride was assumed to be due to the membrane fouling [3] ( Figure 5), beyond 30 hour the permeate flux decreases gradually from 13 to 8 L/m 2 •h for TFC-SR3 membrane and 19 to 9 L/m 2 •h for SelRo MPF-34 membrane. In general, the rejection of ions in NF membrane process can be explained by Donnan exclusion and electrostatic repulsion.…”

“…Fluoride concentrations above 1.5 mg/L are known to cause dental fluorosis while those greater than 4 mg/L can cause crippling skeletal fluorosis [1] [2]. In Senegal, fluorosis is among the most common diseases due to water quality [3]. The problem not only affects public health, but also hinders rural activities such as agriculture and economic activities.…”

Fluorine in the Water Environment - Hazards and Removal Methods

“…Diawara i in. [26] stosowali niskociśnieniową RO do usuwania fluorków z zasolonych wód podziemnych, uzyskując 97÷98,9% usunięcia fluorków. Gedam i in.…”

Nanofiltration Technology for Toxic or Harmful Ions Removal from Groundwater: Characteristics and Economic Analysis

“…Nanofiltration (NF) membrane process is a lower pressure needed and less pressure loss technology than Reverse Osmosis (RO), while it still has a higher rejecttion efficiency for (in)organic compounds than Ultrafiltration (UF) [3]. Especially, NF has the characteristic of selectively removing ions as the result of the combination effects of Donnan exclusion (membrane surface), steric-resistance or solution-diffusion [4,5], which means that some ions beneficial for human body are kept, as well as the fluoride, arsenic and other harmful ions are effectively removed [6][7][8][9][10][11][12][13][14][15][16].…”