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Clarification and Purification of Drinking Water

In addition, bacterias need to be removed from well, river or lake water before water can be rendered potable. A properly selected microfiltration ceramic membrane is effective for bacteria decontamination. When used preceding a reverse osmosis or an ion-exchange unit, the microflltiaiion membrane protects the downstream separation process from bacteria contamination and possible fouling due to colloids. [Pg.203]

Furthermore, ultrafiltration ceramic membranes have been found to be effective in removing some heavy metal pollutants. [Pg.203]

Surface water can also be processed to become drinking water but it requires some pretreatment prior to the microfiltration step. A filtrate flux of 1,000-1,500 L/hr-m can be realized [Guibaud, 1989]. [Pg.204]

Both microfiltration (02 m) and ultrafiltration (4 nm) alumina membranes are very effective in removing bacterias. For example, the bacteria level of a lagoon water is reduced from 1,000-5,000/cm to 0.03-0.4/cm and 0.03-0.1/cm with the microHltration and ultrafiltration membrane, respectively [Castelas et al., 1984]. The total coliform level drops from 50-500/cm to zero for both types of membranes. The accompanying permeate flux is 600-1,200 L/hr-m for 70 hours for the microfiltration membrane when the water contains a low level of colloids and only 200 L/hr-m for 20 hours when the concentrations of colloids and organic materials are high. The ultrafiltration flux varies between 100 and 250 L/hr-m for 1,000 hours of operation. [Pg.204]

In addition to bacteria decontamination, the ultrafiltration membranes also reduce some ions such as sulfates (118 to 1.5 mg/L) and nitrites (0.22 to 0.02 mg/L). This is attributable to complexation of these ions with the humic and fulvic acids which are retained by the membranes. On the other hand, the non-complexed ammonium and chloride ion concentrations are essentially the same before and after ultrafiltration. [Pg.204]


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