Filterability Index Unit
The Atico Filterability Index Unit enables a water quality test to be made on a suspension to be filtered through sand or similar granular media. It can therefore be used in routine control at waterworks, or at a sewage treatment works which employs tertiary filtration.
- measurement of filterability of a given suspension performance of a standard water quality testprocedure
- procedure for filtrationbasic principles of filter operation for student study
- basic principles of filter operation for student study
The use of deep beds of porous granular media to filter liquids to improve their clarity is widespread in municipal and industrial practice. Predominant is the filtration of drinking water and industrial water, although the filtration of sewage as a tertiary stage of treatment is increasing. Other liquids are filtered through granular media in the processing of beverages and food products for example.
The Filterability Index Unit utilises a bed of granular material, normally sand, which can be chosen by the investigator to suit his own purposes. The measurements taken with this apparatus enable a filterability number to be calculated which has significance in deep bed filter performance.
It must be stressed that the Filterability Index Unit is not intended for filter design purposes. That requires pilot filter column equipment such as the Deep Bed Filter Column. However preliminary assessment of pre-treatment processes, and possible filter media with the Filterability Index Unit will reduce the amount of testing required with pilot filter columns.
A particular application of the Filterability Index Unit is in the process control of existing deep bed filter operation. The effects of changing pre-treatment dosing (for example poly-electrolyte dose) can be rapidly tested before making changes on the operating plant.
Flow is controlled by a needle valve and observed on a variable area meter. Head loss is measured directly by a water manometer. The filter unit can be readily demounted to change the sand. This unit and all tubing connections are transparent so that the operation can be observed and air bubbles avoided. Metal fittings are corrosion resistant.
Test filter cell diameter: 38mm
Height of filter: 60mm maximum
Variable area meter range: 20-280m/min
Water manometer length: 0.5m
Equipment consists of a metal framework supporting a 1 litre vessel connected by transparent tubing to a 60mm high filter unit. A needle valve controls flow which is observed on a Rotameter. A 0.5m water manometer measures head loss. Test filter cell diameter: 38mm. Flow meter range: 20-280ml/min.
1 litre Measuring cylinder
Triple beam top loading balance:
capacity: 2610g; sensitivity: 0.1g; tare: 225g
100ml Measuring cylinder
Laboratory drain or 1 litre receiving vessel
Gross weight: 60kg