×
INTELLIGENT WORK FORUMS
FOR ENGINEERING PROFESSIONALS

Log In

Come Join Us!

Are you an
Engineering professional?
Join Eng-Tips Forums!
  • Talk With Other Members
  • Be Notified Of Responses
    To Your Posts
  • Keyword Search
  • One-Click Access To Your
    Favorite Forums
  • Automated Signatures
    On Your Posts
  • Best Of All, It's Free!
  • Students Click Here

*Eng-Tips's functionality depends on members receiving e-mail. By joining you are opting in to receive e-mail.

Posting Guidelines

Promoting, selling, recruiting, coursework and thesis posting is forbidden.

Students Click Here

Jobs

Secondary effluent filtration

Secondary effluent filtration

Secondary effluent filtration

(OP)
I would like to hear forum members experience on using single media rapid sand filtration unit (polishing) to filter municipal extended aeration secondary effluent. If a coagulant (Alum)is added, is settling before the filter a must? What is the type, size and the uniformity coefficient of the filter media used?

Thanks is advance

RE: Secondary effluent filtration

Absolutely, settlement is a must. At normal RGF flow rates of 10m3/m2 per hour at a MLSS of 3000mg/l thats 30kg of solids loading per m2 per hour. Your filter will last a matter of minutes rather than hours between washes, especially if operating contact filtration through.

RE: Secondary effluent filtration

Secondary effluent is the effluent from the secondary clarifier.

Filters used for secondary effluent are operated at lower flow rates than rapid sand filters, typically 1/3 less gpm/sq ft.

If you add alum, you can add the alum prior to the secondary clarifier.

You would not add an additional clarification step between the secondary clarifier and the tertiary filter.

RE: Secondary effluent filtration

Misunderstood in thinking you were going straight from ASP to filter with no settlement in between. Assuming a post FST solids loading of 20mg/l + whatever your hydroxide loading will be, it will work without pre-settlement, but your washing will be increased.  

RE: Secondary effluent filtration

Suggest you should consider dual media filters(coal/sand). The coal will hold a larger quantity of solids between backwashes.

Yes you will need a coagulant if you are going to comply with PEA discharge regulations.

"Sharing knowledge is the way to immortality"
His Holiness the Dalai Lama.

http://waterhammer.hopout.com.au/

Red Flag This Post

Please let us know here why this post is inappropriate. Reasons such as off-topic, duplicates, flames, illegal, vulgar, or students posting their homework.

Red Flag Submitted

Thank you for helping keep Eng-Tips Forums free from inappropriate posts.
The Eng-Tips staff will check this out and take appropriate action.

Reply To This Thread

Posting in the Eng-Tips forums is a member-only feature.

Click Here to join Eng-Tips and talk with other members!


Resources