• Blog
  • Wastewater Testing
  • Bioaugmentation Applications
  • Useful Information
  • About Us
BIOLOGICAL WASTE TREATMENT EXPERT
Contact Us

Are SV30 & SVI important in MBR (membrane) wastewater treatment systems?

9/4/2018

2 Comments

 
Picture
Image from www.ovivo.com - installed MBR unit.
MBR systems use membrane separation instead of a DAF or clarifier to remove biological solids from effluent wastewater. MBR systems are becoming more common as membrane technology has improved and overall costs are lower when compared with larger foot print activated sludge systems. When compared with extended aeration activated sludge units, MBR systems typically have the following differences:
  • Higher MLSS/MLVSS 
  • Smaller aeration basin & overall foot print
  • Better control of F/M & MCRT
  • Fewer problems with solids in effluent
The MBR is technologically superior to older clarifier systems, but they still have issues that require operator attention. First since a membrane separates solids from discharged water, settling rates and floc formation would not seem as critical - however biological polymers are just as important for good MBR function as they are in systems with conventional clarification. Why do I say that floc formation is just as important in an MBR with advanced membrane technology?

Pores in the membrane allow for water to pass with solids being retained. As pores become clogged with solids - both biological & particulate - the system goes into a backwash cycle to clear the pores and restore membrane function. The problem is that backwashing is not perfect, overtime pores deteriorate with accumulated solids. Even with cleaning technologies that include oxidants, acids, or enzymes - the pores will eventually become plugged. 

A leading cause of plugged pores in biological waste treatment units is the accumulation of high molecular weight and "sticky" biological polymers. Organisms that thrive in the low F/M conditions found in MBR systems also tend to excrete copious amounts of extracellular polymeric substances (EPS). While some EPS is good and improves separation potential, the wrong EPS and overabundance of EPS can both create blinding conditions in membrane pores. 

The easiest ways to monitor EPS in a biological treatment unit is to run SV30, SVI, and microscopic exam on at least a daily basis. Additional monitoring with molecular testing is equally important - including both Microbial Community Analysis (MCA) and qPCR for specific problem or good organisms which gives earlier warnings for EPS blinding potential. When you have a buildup of problematic EPS, do not just assume that it cannot be corrected. Multiple control methods exist, it is just best to address the EPS problem before membrane issues start to compromise unit performance.


2 Comments
EWALT TECHNOLOGIES PVT.LTD link
10/6/2020 09:05:21 pm

how we can improve SVI in 150 KLD MBR STP unit.
Presently SSV - 250 PPM
MLSS - 5274 PPM
SVI - 47.4

Reply
Erik Rumbaugh
10/7/2020 10:34:28 am

At first glance, it looks like you are running a low MLSS at 5,274 mg/L for MBR systems. Usually, I see MBR systems running at 8,000 - 12,000 MLSS.

And for MBR systems don't look at settling rates as much as how well the membrane is performing - pressure, backflushing, and fouling parameters.

Reply



Leave a Reply.

    Author

    Erik Rumbaugh has been involved in biological waste treatment for over 20 years. He has worked with industrial and municipal wastewater  facilities to ensure optimal performance of their treatment systems. He is a founder of Aster Bio (www.asterbio.com) specializing in biological waste treatment.

    View my profile on LinkedIn

    RSS Feed

    Click to set custom HTML

    Archives

    July 2019
    June 2019
    May 2019
    April 2019
    March 2019
    February 2019
    January 2019
    December 2018
    November 2018
    October 2018
    September 2018
    August 2018
    July 2018
    June 2018
    May 2018
    April 2018
    March 2018
    February 2018
    January 2018
    December 2017
    November 2017
    October 2017
    September 2017
    August 2017
    July 2017
    June 2017
    May 2017
    April 2017
    March 2017
    February 2017
    January 2017
    December 2016
    November 2016
    October 2016
    September 2016
    August 2016
    July 2016
    June 2016
    May 2016
    April 2016
    March 2016
    February 2016
    January 2016
    December 2015
    November 2015
    October 2015
    September 2015
    August 2015
    July 2015
    June 2015
    May 2015
    April 2015
    March 2015
    February 2015
    January 2015
    December 2014
    November 2014
    October 2014
    September 2014
    August 2014
    July 2014
    June 2014
    May 2014
    April 2014
    March 2014
    February 2014

Proudly powered by Weebly
Photos used under Creative Commons from Picturepest, marcoverch, perzonseowebbyra, Picturepest, Picturepest, dsearls, dungodung, Massachusetts Office of Travel & Tourism, aqua.mech, vastateparksstaff, hile, Aaron Volkening, amishsteve, Neil DeMaster, mklwong88, KOMUnews, Picturepest, kaibara87