5 replies to this topic

[Ayok]

Does anyone know how to calculate settling time properly? I want to precipitate Fe(OH)₃ from backwash water of my Iron Removal Filter. Actually i know a formula to calculate settling velocity from book for sedimentation, but i dont know about diameter of Fe(OH)3, so i'm stuck on it. I cannot do diameter measure test and i cant found diameter of Fe(OH)3 in book and internet. So, does anyone know how to calculate settling velocity with other way? Or should i do settling time test?

[Bobby Strain]

I think you answered your own query.

 

Bobby

[breizh]

Ayok

You should perform Jar test ! this is the only way to get reliable data and this is the method used by Chemicals supplier looking after sedimentation and coagulation processes.

 

Breizh

[Ayok]

Mr Breizh, i dont have proper equipment to do jar test since i'm only student and i dont have access lab. Is there any simple way to do jar test sir?

Thanks Mr Breizh and Mr Bobby. I really apprecite your help

[kan_gou_lai]

1 particle Fe(OH)3 in dispersed form, also called colloid, is of dimension around 0.1 um will take forever to settle. in water treatment, it will be a group of thoses colloids Fe(OH)3 and other suspended solids (created after flocculation which make the particules biggers) will settle at less than 2 m/s.

 

Very good design of flocculation & settling tank (without polymer aid) can function at 6 - 8 m/h

[breizh]

Ayok ,

Consider reading this general paper :http://www.rpi.edu/d.../sedsettle.html

 

Probably a good resource could be any Books dealing with Waste water treatment .

 

Good luck

Breizh