Water and Wastewater.com Help Forums - DSVI (Diluted Sludge Volume Index)

namsac

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DSVI (Diluted Sludge Volume Index)
Apr 30^th, 2004, 11:47pm

Dear member
I am a 3rd year student in Leeds university Envionmental School. my final year project is based on tests to determine the sludge deposites. Eventhough this may not seem profetional, I could realy use your help in this matter.
My question is about DSVI(diluted sludge volume index), what is it and how the test is carried out I really hope you can provide me with some information about this.
Thank you for your time in this matter
Yours Sincerely
Namal Senaratne

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greg

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Re: DSVI (Diluted Sludge Volume Index)
Reply #1 - May 1^st, 2004, 4:49am

Sludge volume index is a measurement that can be used to characterize the settling rate for sludge. Activated sludge solids have a specific gravity almost the same as water, so settling is tedious and can vary depending on changing solids and temperature during the four seasons. Readings of the settling rate can be taken at various intervals to confirm proper settling. These readings can also be used to verify proper sizing of settling tanks.

The test is performed using a 1000 ml graduated cylinder and recording the value of settled solids after 30 minutes.

Thanks, Greg

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Sewer_Doc Junior Member Offline Microorganisms are in Control! Posts: 99 Canada Gender: Company or Organization: Rothsay, Div. Maple Leaf Foods	Re: DSVI (Diluted Sludge Volume Index) Reply #2 - May 3^rd, 2004, 1:17am You can find good explanation of the diluted SVI test procedure in "Manual on the Causes and Control of Activated Sludge Bulking, Foaming, and Other Solids Separation Problems" by Jenkins, Richard & Daigger. Sewer_Doc
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sobisch

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Re: DSVI (Diluted Sludge Volume Index)
Reply #3 - May 3^rd, 2004, 4:20am

Dear Namal Senaratne,

Diluted Sludge Volume Index is used, when determination of the sludge volume index (undiluted) results in values above a certain limit. This means that above these values determination will give huge scattering, normaly one can observe water channels or layers inside the bulk sludge. Sludge volume is used as a rough prediction of sludge quality.
If your intend is to obtain information about consolidation of sludges the function of packing density via excess pressure of sludge solids has to be investigated up-to high sludge concentrations. This can be done by investigations in a centrifugal field or in filtration cells under pressure. Diluted sludge volume index seems not to be very useful in this respect.

Kind regards
T. Sobisch

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T. Sobisch
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Tom Keenan - nesa

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Re: DSVI (Diluted Sludge Volume Index)
Reply #4 - May 4^th, 2004, 8:10am

Hi namsac,
Sludge Volume Index, (SVI), is a measure of the volume occupied by 1 gram of activated sludge following a 30 minute settling period in an Imhoff Cone.
The SVI is determined by taking the result of the mixed liquor suspended solids test, (measured in grams per litre), and dividing that value into the result obtained for the 30 minute sludge settling test, (measured in mls/litre and carried out on the same sludge).
The result is therefore reported on mls per gram for that particular activated sludge.
The diluted sludge volume index is determined as follows:
a) Dilute the activated sludge sample, taken from the aeration basin, with treated effluent until the result of the 30 minute sludge settling test is found to be 250 mls/litre or less.
b) Determine the MLSS concentration in this diluted sample in grams per litre,
c) Use these two results to calculate the DSVI .
Hope that this helps.

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tomkeenan@nesa.ie
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www.nesa.ie

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