Water and Wastewater.com Help Forums

heffer YaBB Newbies Offline I love Water and Wastewater.com Posts: 5 Company or Organization: municipal	MLVSS May 24^th, 2012, 10:40am I am at a conventional wwtp, and our ammonias have gone kinda higher. I have decreased waste at moment to build mass, but want to know more with regards to the MLVSS test. I want to try the MLVSS test, and know where it should be. I am having issues trying to find the area of target that i am looking for, can someone help?
Back to top	IP Logged

The sludge judge

God Member

Offline

Posts: 649
Wisconsin
Gender: male

Company or Organization: private

Re: MLVSS
Reply #1 - May 24^th, 2012, 11:45am

This depends on the amount of inorganic material in the flocs. A typical number would be around 80% of the MLSS for MLVSS. Less isn't necessarily bad (may help weigh down flocs) provided there's enough active biomass to remove the BOD/ ammonia etc. Keep in mind though a lower MLVSS may help point to hydraulic overloading/ short circuiting etc of a primary clarifier as well.

Back to top

IP Logged

heffer YaBB Newbies Offline I love Water and Wastewater.com Posts: 5 Company or Organization: municipal	Re: MLVSS Reply #2 - May 24^th, 2012, 12:16pm i think this may still be a bit over my head at this moment....
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: MLVSS
Reply #3 - May 24^th, 2012, 8:09pm

Actually, you may have too young of a sludge in the aeration basin if you have too much NH₃-N in the discharge. To determine the sludge age, you must calculate the ratio of the mass of sludge in the aeration basin daily divided by the mass of sludge wasted daily:

(MLSS)(volume in basin)/[(volume of wasted sludge daily)(TSSs in wasted sludge) + (Effluent TSSs)(Effluent Flow)] = sludge age

The sludge age is in days; and a minimum sludge age for conversion of NH₃-N to NO_3^- would be greater than 7 days.

Take the time to search "sludge age" and "biological nitrification" for a better understanding of these terms.

grrun

Back to top

IP Logged

The sludge judge

God Member

Offline

Posts: 649
Wisconsin
Gender: male

Company or Organization: private

Re: MLVSS
Reply #4 - May 24^th, 2012, 8:39pm

It sounds like you're on the right track with wasting less. 70-80% of the MLSS as MLVSS is pretty normal. This may vary depending on some factors (for example plants without primary clarifiers will have a lower MLVSS%)

You'll need a muffle furnace for this. You'll find the procedure with a google search of a look in Standard Methods book. Basically you run a normal MLSS, ignite it at around 550 degrees for an hour or so and weigh the ash portion once it's cooled. The ash is your inorganic fraction. The MLVSS is the difference between the MLSS and the ash weight. (I may be off on the time and temp of the muffle furnace- haven't had to run one of these in a long time.)- If anyone knows the correct temp and time please jump in.... too lazy right now to look it up!

best regards,

Ryan

Back to top

IP Logged

heffer YaBB Newbies Offline I love Water and Wastewater.com Posts: 5 Company or Organization: municipal	Re: MLVSS Reply #5 - May 25^th, 2012, 2:30pm ok, if i did this right i came up with a 1.25.....? I looked into the range and i thought it was supposed to be in the .2 to .5 range??
Back to top	IP Logged