×
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

Primary clarifier

Primary clarifier

Primary clarifier

(OP)
Is a primary clarifier ahead of the aeration tank a must for an extended aeration wastewater treatment plant? The screens are 6 mm bar screens. This is for municipal wastewater.

RE: Primary clarifier

Primary clarifiers are rarely used for wastewater treatment plants sized for less than 10 mgd. In the past, primary clarifiers were widely used. Part of the reason that primary clarifiers are not widely used anymore is that aerobic digesters are now more common than anearobic digesters.

If you use screening in the front of the plant, it will help to minimize downstream problems with flotable solids.

 

RE: Primary clarifier

Is there a grit trap before the ditch and if so what type? Found a plant last year with 6mm screens, pista type grit trap and dicth that had been passing fine grit since it was built. The ditch had gone from 10" deep to <2" in some places, and they wondered why it wasn;t meeting consent!

RE: Primary clarifier

(OP)
Thanks folks for the feedbacks. Yes we do have an aerated grit chamber. We want to convert this to a vortex grit chamber.

bmir: why do we need a PST for an anearobic digester?  

RE: Primary clarifier

Primary and secondary biosolids have different compositions. Secondary biosolids generally consists of microorganisms.  Because of the different compositions, it is more difficult to operate an digester (aerobic or anerobic) with combinded primary and secondary biosolids.

Anaerobic digesters are better suited for operating with primary biosolids than with secondary biosolids. Aerobic digestion of primary solids or a mixture of primary and waste-activated solids is not recommended.

Reference the NATIONAL MANUAL OF GOOD PRACTICE FOR BIOSOLIDS:
http://www.google.com/url?sa=t&source=web&amp;cd=2&amp;sqi=2&amp;ved=0CB0QFjAB&url=http%3A%2F%2Fwww.wef.org%2FWorkArea%2Flinkit.aspx%3FLinkIdentifier%3Did%26ItemID%3D2103&rct=j&q=national%20biosolids%20manual&amp;ei=hfybTen_Noa-sAOho8WVBA&amp;usg=AFQjCNFP94b4sJP0EGiOcFnaT6O-cG_zvg

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