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The pros and cons, fiber filtration vs. sand filtration
(filtration volume: 100m3/hr)

Type

       Description

Item

Conventional sand filtration

Fiber filtration

Filtration rate

(LV linear velocity)

10 m/hr

Normal filtration: 30m/hr

High speed filtration: 60~100 m/hr

Filtering surface area

10 m2  large location area

(LV=10)

Normal filtration: 3.3m2  (LV=30)

High speed filtration: 1.25m2 (LV=80)

Backwash time

20~30 minutes

20~30 minutes

Backwash water volume

2~3 times the standard outlet water (filtered) volume.

100m3/hrx2x30min/cycle=100m3/cycle

0.36~0.48 m3/m2min

Normal filtration:

0.42m3/m2minx3.3m2x30min/cycle=42m3/cycle

High speed filtration:

0.42m3/m2minx1.25m2x30min/cycle=16m3/cycle

Total backwash water volume

If washed once a day, the total backwash water volume per year will reach 36500m3, which is a huge consumption.

If washed once a day, the total backwash water volume per year is 15330/5840m3, a much smaller consumption.

Filtration capacity

Shallow bed filtration, low capacity, and relatively high backwash frequency.

Deep bed filtration, high capacity, and relatively low backwash frequency.

Filtration accuracy

Only capable of removing suspended solids of 10μm diameter and above.

The removing rate of suspended solids:

100% for 10μm diameter

80% for 2μm diameter

Filtering material replacement

Once every 1 to 3 years, depending on fouling condition.

Last for more than 10 years under normal operation.

Treatment for colloid and iron

Not effective for colloid, iron, and manganese.

Capable of removing colloid, iron, and manganese.

Agglomeration

Microorganisms and pollutants will agglomerate on the filtering material to cause short circulating current during filtration.

No agglomeration impairing filtration effect.

Filtration for oil

The filtering material will be fouled by oil.

Capable of removing oil.

Power requirement

Much more backwash water volume (several times as much as raw water) and higher water head loss is needed, which requires larger power.

Less backwash water (lesser than outlet water (filtered) is required, which can be mixed with air to clean the fibers.

Small power requirement.

Filtration water head loss

Initial pressure depends on the diameter of filtering material. Normally 0.5kg/cm2

Backwash if pressure difference is 0.5kg/cm2.

Initial pressure is 0.2~0.4 kg/cm2.

Backwash if pressure difference is 0.5~1.0kg/cm2.

Options for different applications

No.

High efficiency fiber filter.

High speed fiber filter.

High accuracy fiber filter.

High capacity fiber filter.

Oil-bearing wastewater fiber filter.

Open type fiber filtering basin.

Wet weight

Heavy gross weight

Light gross weight

 

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