Role of ozone for reducing fouling due to pharmaceuticals in MF (microfiltration) process

Nanofiltration processes applied to the removal of phenyl-ureas in natural waters

“…In effect, the total hydraulic resistance R t found by the solution can be determined from the permeate flux values, by applying the general Darcy's law [21,22]:…”

The use of ultrafiltration and nanofiltration membranes for the purification of cork processing wastewater

“…The R ef resistance is due to concentration polarization and deposition of solids (cake layer) on the membrane surface, and therefore, it can be removed by cleaning with water after the filtration experiment of the wastewater, as was described in Section 2.3. On the contrary, the R if resistance is due to pore blocking and adsorption of materials onto the membrane surface and pores, which cannot be removed by water cleaning [24]. All the mentioned resistances were determined from permeate flux data obtained in the filtration experiments and by using Eqs.…”

Combination of chemical oxidation‐membrane filtration processes for the elimination of phenyl‐ureas in water matrices

“…Similar effects have been described in the ozone treatment of permeates from hydrophobic membranes. 9 However, the ozonation of permeates from NF pretreatment (Expts G-FO-3 and R-FO-3), resulted in an almost total elimination of the herbicides, with an enhancement in the conversions in comparison with the single ozonation experiments, as could be expected. The absence of organic matter in the NF permeate led to a decrease of ozone consumption (higher ozone stability), and also, to its decomposition into OH radicals, both factors favouring the oxidation of herbicides.…”

“…Thus, researchers have recently proposed the use of sequences of treatments, comprising chemical oxidation stages followed by membrane treatment stages. 8,9 The application of a pre-treatment step with ozone or AOP was able to reduce membrane fouling. 9 In addition, the NF membrane process is one of the best available technologies for removing disinfection byproducts such as THMs.…”

“…8,9 The application of a pre-treatment step with ozone or AOP was able to reduce membrane fouling. 9 In addition, the NF membrane process is one of the best available technologies for removing disinfection byproducts such as THMs. 10 In recent years, several studies have demonstrated that phenylurea herbicides can be readily removed from natural waters by ozonation 11 -13 and by membrane procedures, mainly NF 1,14 -15 when individually applied.…”