Page 150 - Membranes for Industrial Wastewater Recovery and Re-Use

124 Membranes for Industrial Wastewater Recovery and Re-use

I 3 5 7 9 11
Volm Reduction Faetor
Figure 3.27 Effect of pH on nunofiltration flux with two different membranes, US-5 and PVD-1
(Hydranautics: Nuortila-lokinen, 1997). aCF = acidic clearfiltrate, nCF = neutral clearfiltrate, VSEPfilter

(a) CaC03 Talc Clay Latex
WS)

Figure 3.28 (a) Microfiltration of coating colour components; VSEP L, 465 cm2, Teflon Typar 0.1 pm
(Tetratec),pressure 6.9-20.7 bar, amplitude2-2.5 cm. (b) Concentrationofwet offset (WO) coatingcolour.
VSEP L. 465 cm2, various membranes, pressure 6.9-27.6 bar, amplitude 1.9-3.2 cm. Fluxes recalculated
to 40°C (Nuortila-Jokinen and Nystrom, 2000)

the normal paper process operating conditions. This is due to the hydrophobic-
hydrophobic interaction between the talc and the Teflon membrane: i.e.
repulsion between the hydrophobic particle and surface. However, when
these particles are mixed with other coating colour raw materials, the effect of
charge and hydrophobicity are greatly ameliorated, presumably because
of aggregation and adsorptive reactions between of particles and solutes
(Fig. 3.28b).
As with almost all industrial effluents, the variability of the water quality
presents a significant challenge to the membrane material and module. This
demands that the membrane technology must be robust to extreme conditions
of, in particular, temperature and pH, as well as being tolerant of shock loads. It