Filtration Grade
The filtration grade defines in microns the size of the particles that are retained by the filter.
There are Two Basic Definitions:
Absolute Filtration Grade:
The filter removes 100% of the particles larger than the declared size.
Nominal Filtration Grade:
Depending on the manufacturer's definitions, the filter removes 80-99% of the particles larger than the declared size.
Particle Removal in Arkal Filters
Independent tests have shown that Arkal filters remove 85-99% of the suspended particles at the declared filtration grade,
depending on specific particle characteristics.
Flow Rate
The system design should consider the maximum flow rate that may run through the filtration unit at the required filtration
grade and water quality.
Water Quality
Clogging Factors:
1.
Suspended mineral solids, such as sand, silt and clay.
2.
Large Microorganisms such as zooplankton and macro-algae.
3.
Colonies and agglomerations of small microorganisms such as bacteria, micro-algae and protozoa.
4.
Deposits of dissolved minerals such as calcium carbonates, oxidized iron or manganese.
DESIGN PARAMETERS
Water Quality Determination:
Water quality is directly related to the water source. The
main types of water sources and water quality levels are
generally as follows:
A. Good Quality
Municipal supply.
Well water from a steadily flowing aquifer, with the
well being properly maintained, no presence of iron or
manganese.
B. Average Quality
Clear surface water (lakes and ponds, slow flowing rivers
and canals).
Treated wastewater after tertiary or quaternary treatment.
Circulated cooling water.
C. Poor Quality
Well water from a poor quality aquifer.
Surface water (lakes and ponds, rivers and canals) in
hot climates with increased biological growth and no
chemical treatment.
Treated wastewater after secondary (biological)
treatment.
Industrial process waste water.
D. Very Poor Quality
Water from a well, which has collapsed, or with high
concentrations of iron or manganese.
Surface water affected by floods and storm water without
sedimentation facilities.
Raw municipal and industrial wastewater.
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