Side-stream filtration possibly with in-line coagulation

1 Side stream filtration possibly with in-line coagulation 

Filtration of a fraction of the circulating flow is highly recommended because it allows part of the suspended solids (SS) to be retained and eliminated from the system. The SS ratio in the system can thus be held to below 5 to 25 mg l depending on the system. 

Generally speaking, the flow rate for side-stream filtration is set at 5 to 10% of the total flow of the recirculated water. It corresponds to one-tenth of the volume of the system. Of course, if the system is prone to specific pollution (sand storms, processes, etc.), the percentage must be much higher. 

If the water has a tendency to clog, then cationic organic coagulants should be used upstream from the filter. The aim is to coagulate the colloidal matter in the water, retain it on the filter and thereby eliminate it from the system. 

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