Fouling and Cleaning

Fouling manifests itself as a decline in flux with time under constant operating conditions. The sieving properties of the membrane may also change. This is owing to irreversible interactions between feed components and the membrane, causing a layer of foulant on the membrane, blinding of the pores and an increased resistance to fluid flow through the membrane. Many membrane materials listed earlier are relatively hydrophobic (e.g. polysulfone, poly-vinylidene fluoride) and tend to foul more than hydrophilic membrane materials (e.g. cellulosics, cer amics). Many feed components interact strongly with membranes, e.g. oils through hydrophobic interactions with hydrophobic membranes, proteins by hydrogen bonding, charge interactions or hydrophobic interactions, and salts by precipitation or charge interaction.

A fouled membrane has to be cleaned according to the nature of the foulant. Proteins can be effectively cleaned with alkaline solutions, salts are removed with acid cleaners. The quality of the water is very important in ensuring a membrane can be effectively cleaned in the shortest time possible.

Flux can be enhanced by periodic backwashing, pulsating Sows, uniform transmembrane pressure or co-current permeate Sow techniques. These have been found to be effective in maintaining high Suxes with feed streams containing colloidal or suspended matter and less effective with foulants that are in solution.

Solar Panel Basics

Solar Panel Basics

Global warming is a huge problem which will significantly affect every country in the world. Many people all over the world are trying to do whatever they can to help combat the effects of global warming. One of the ways that people can fight global warming is to reduce their dependence on non-renewable energy sources like oil and petroleum based products.

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