Water and Wastewater.com Help Forums - Just a question about Tertiary treatment...

crackcrack

Ex Member

Just a question about Tertiary treatment...
Mar 23^rd, 2012, 3:21am

Can anyone shed any light pease.

A typical plant...

Screen
Settle
Aerate
Settle
inject sanitation such as chlorine Clo2 etc.

The tertiary sanitation process theoretically destroys any remaining bacteria and/or pathogens remaining in the effluent stream.

My question...

If there is still a small amount of organic matter remaining at this point will bacteria eventually re-populate after tha sanitation has been expended and simply increase BOD once again?

Back to top

IP Logged

grrun

God Member

Offline

WaterandWastewa
ter.Com is the best!

Posts: 3525
Pekin, IL
Gender: male

Company or Organization: Freelance Environmental Engine

Re: Just a question about Tertiary treatment...
Reply #1 - Mar 23^rd, 2012, 12:14pm

The remaining organic material is the BOD and does not depend on the bacteria present. However, since the BOD is still present; bacteria may repopulate the remaining water. It is the organic material in the water that creates the BOD rather than the presence of bacteria. Disinfection does not remove BOD. You are confusing two different phenomema.

grrun

Back to top

IP Logged

NorCal_Wastewater1

God Member

Offline

"Wastewater
rules! Give sludge a
chance!!!"

Posts: 1780
CA.
Gender: male

Company or Organization: Wastewater

Re: Just a question about Tertiary treatment...
Reply #2 - Mar 23^rd, 2012, 3:52pm

It also depends on what is the driver of the Tertiary filtration requirement.

If it is Title 22 specifications such as here in California then a sand filter or a cloth media filter can perform that required step. With the cloth filters they are usually preceeded by an RO unit or a UF system to remove the remaining bacterial element. Tertiary filtration is a "polishing" filtration step much like nature.

Dallas

Back to top

Have a great day,

Dallas

IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #3 - Mar 23^rd, 2012, 10:41pm Thanks Grun, I gathered as much... If this is the case, why would we treat with ClO2 or chlorine prior to discharge when the bacteria will repopulate anyway? Why not just discharge with minimal leftover BOD? Why disinfect in the first place?
Back to top	IP Logged

grrun

God Member

Offline

WaterandWastewa
ter.Com is the best!

Posts: 3525
Pekin, IL
Gender: male

Company or Organization: Freelance Environmental Engine

Re: Just a question about Tertiary treatment...
Reply #4 - Mar 23^rd, 2012, 11:33pm

There are bacteria and there are bacteria. Not all bacteria belong to the same species. After disinfection, water can be contaminated by external as well as internal sources. The bacteria of concern are the ones leaving the bowels of warm blooded animals. If these are ingested, then bad things happen in the guts of people so that this is the reason that we attempt to kill most of these little critters before they have a chance to multiply. Would you feel like drinking the discharge from a wastewater treatment plant with or without disinfection? What kind of pinch penney are you?

grrun

Back to top

IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #5 - Mar 24^th, 2012, 3:48am Mmmm No pinch penny, I am used to treating Winery waste and forget about the other pathogens. You have answered my question. Thanks.
Back to top	IP Logged

crackcrack

Ex Member

Re: Just a question about Tertiary treatment...
Reply #6 - Mar 24^th, 2012, 3:53am

grrun wrote on Mar 23^rd, 2012, 12:14pm:

The remaining organic material is the BOD and does not depend on the bacteria present. However, since the BOD is still present; bacteria may repopulate the remaining water. It is the organic material in the water that creates the BOD rather than the presence of bacteria. Disinfection does not remove BOD. You are confusing two different phenomema.

grrun

Disinfection does reduce BOD results temporarirly though as the bacteria are destroyed???

This would be the case?

Back to top

IP Logged

WWT Disinfection Pro YaBB Newbies Offline I love Water and Wastewater.com Posts: 18 Menifee Gender: Company or Organization: City of Corona	Re: Just a question about Tertiary treatment... Reply #7 - Mar 26^th, 2012, 1:38pm Keep in mind that tertiary treatment is to minimize to the discharge of pathogens and is monitored by analyzing for coli-form bacteria.
Back to top	IP Logged

sobisch God Member Offline Posts: 1777 Gender: Company or Organization: L.U.M. GmbH	Re: Just a question about Tertiary treatment... Reply #8 - Mar 27^th, 2012, 1:00am BOD is lowered by oxidation when ClO2 is added, with and without bacteria.
Back to top	T. Sobisch for@appliedcolloidssurfactants.info http://AppliedColloidsSurfactants.blogspot.com http://www.AppliedColloidsSurfactants.info http://www.lum-gmbh.com IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #9 - Mar 27^th, 2012, 2:52am sobisch wrote on Mar 27^th, 2012, 1:00am: BOD is lowered by oxidation when ClO2 is added, with and without bacteria. Thanks Sobisch... Is this permanent reduction by oxidation or will the BOD return once the ClO2 has dispersed? Thanks
Back to top	IP Logged

sobisch God Member Offline Posts: 1777 Gender: Company or Organization: L.U.M. GmbH	Re: Just a question about Tertiary treatment... Reply #10 - Mar 27^th, 2012, 3:20am it is permanent reduction.
Back to top	T. Sobisch for@appliedcolloidssurfactants.info http://AppliedColloidsSurfactants.blogspot.com http://www.AppliedColloidsSurfactants.info http://www.lum-gmbh.com IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #11 - Mar 27^th, 2012, 5:47am sobisch wrote on Mar 27^th, 2012, 3:20am: it is permanent reduction. Very good to know... Can you explain the action the ClO2 has on the Organics ? Thanks
Back to top	IP Logged

sobisch God Member Offline Posts: 1777 Gender: Company or Organization: L.U.M. GmbH	Re: Just a question about Tertiary treatment... Reply #12 - Mar 27^th, 2012, 5:59am The ClO2 is a very strong oxidizing agent. This how it kills the micros. This way it itself reduces to chloride. Most organic matter is broken down to CO2 and water. Kind regards T. Sobisch
Back to top	T. Sobisch for@appliedcolloidssurfactants.info http://AppliedColloidsSurfactants.blogspot.com http://www.AppliedColloidsSurfactants.info http://www.lum-gmbh.com IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #13 - Mar 27^th, 2012, 6:27am Thank you Sobisch! Very helpful
Back to top	IP Logged

WWT Disinfection Pro YaBB Newbies Offline I love Water and Wastewater.com Posts: 18 Menifee Gender: Company or Organization: City of Corona	Re: Just a question about Tertiary treatment... Reply #14 - Mar 27^th, 2012, 11:10am Do keep in mind that if the is any free ammonia left in the Eff. and you store the water in tank for a long period of time the bacteria can continue to start the nitrification process in the water. That is one way a BOD demand could start again.
Back to top	IP Logged

crackcrack Ex Member	Re: Just a question about Tertiary treatment... Reply #15 - Mar 27^th, 2012, 1:17pm That would be unlikely after aeration at 2.0 D.O???
Back to top	IP Logged