SVI is a key factor when it comes to the clarifier design so that a clear wastewater discharge can be obtained without significant carry over of sludge. Basically what the value represents is the settling characteristics that have profound effect on the return rates and also the Mixed Liquor Suspended Solids (MLSS) value.

Typically a healthy sludge aeration pond basin should have the value registered within 80 to 150 mL/g and the MLSS concentration between 3000 – 5000ppm with the wastewater temperature less than 20degC. With this value in mind, generally the clarifier or settling basin has to be designed to accept higher solid loadings so that loss or carry over of sludge due to hydraulic displacement can be minimized.The SVI is the volume, in milliliters, occupied by 1 gram of settled activated sludge, and it is a measure of the settling characteristics of the sludge.

http://waterfacts.net/Formulas/SVI/svi.html

http://www.tpomag.com/online_exclusives/2013/04/process_control_using_sludge_volume_index_svi

http://www.owp.csus.edu/glossary/sludge-volume-index.php

Hi Dushyant,

Here are some useful links for your persual.

http://www.owp.csus.edu/glossary/sludge-volume-index.php

http://waterfacts.net/Formulas/SVI/svi.html

http://www.wastewatersystem.net/2010/10/correlation-between-sludge-volume-index.html

http://www.jstor.org/stable/25045011?seq=1#page_scan_tab_contents

Good Luck

Dear Dushyant,

SVI is defined as 'the volume (in ml) occupied by 1 gram of activated sludge after settling the aerated liquor for 30 minutes'.

SVI (ml/gm) = settled sludge volume/sample volume (ml/l) * 1000 (mg/g)/ suspended solid concentration (mg/l)

http://www.owp.csus.edu/glossary/sludge-volume-index.php 

With my best regards

Prof. Bachir ACHOUR

Sir,I read somewhere that is

SVI = H30/H0*SS

where is H30 is the sludge height after 30 min settling time (cm)

H0 is the initial height of the electrocoagulated waste in the settling column (cm)

SS is the initial sludge concentration after electrocoagulation treatment (gml-1)

Now i am confused about both of H0 and SS how i find them ??

Plz explain 

Generally, the SVI is the most appropriate parameter to express the settling characteristics of sludge. Higher SVI values suggest poorer sludge compaction characteristics. A good sludge should have an SVI less than 80 ml/g and a very good one around 50 ml/g

It is the volume in milliliters occupied by 1.0 g of a suspension after 30 minutes settling.

See the attached files for details.

Thank u sir to all of you

SVI =  Vs . 1000/MLSS

here what you are looking for,

http://www.tpomag.com/editorial/2010/03/what-the-heck-is-svi

http://www.owp.csus.edu/glossary/sludge-volume-index.php

60-80

https://chemtech-us.com/how-to-calculate-and-control-sludge-volume-index-svi/

Very important question, that pertains to my design of settling tanks.

https://www.calculatoratoz.com/en/sludge-volume-index-calculator/Calc-20046