What are the main parameters that influence (growth or decreasing) on the Sludge Volume Index in Wastewater treatment plant?
Agree with Xiangsheng in reality SVI is controlling whether your settler can still work with the sludge you generate. If the sludge is too voluminous it can no longer settle and will be in your effluent- serious malfunctioning of the WWTP.
Operationally one could add floccolation agents, increase shear forces, or ozonate if the sludge gets to voluminous
Dear Dr Messaoud
you can find your answer within this attached lecture.
with my best regards
Randa Osman
factors such as low SRT, low nutrient load (COD and phosphorus), out of range operating temperatures, dissolved oxygen levels, pH, etc. could all affect sludge volume index.
good luck
DO, nutrient load, SBR cycle configuration. can do the optimization study first.
Dear Messaoud,
There are three main parameters that influence the Sludge Volume Index in the activated sludge process.
Firstly the mixed liquor solids concentration: a high MLSS in essence results in false information on settleability properties because the sludge sticks to the cylinder wall causing a high SVI. The problem is resolved by using either a diluted or stirred settleability test.
A high abundance of filamentous bacteria (sludge bulking) will give a high SVI result.
A very low sludge age (dispersed floc) or very high sludge age (pin-point, over-aerated floc) often result in very low SVI values.
The most important is the age of Sludge (SRT). This provides an opportunity for filamentous growth, DO reduction, nutrient variations and other possibilities. Obviously, the sludge age is controlled by F/M ratio or returning sludge.
For SVI you should consider the cations of wastewater. if the concentration of some ions such as Ca or Mg are high, the SVI will reduce. The latter is not good because it does not show whether the operation is good or not and hides weaknesses.
Look for filamentous counts and floc sizes as well. These directly relates to SVI and bulking problem. Microbial analysis in AS usually speaks to the operators much more fluently than design parameters.
Also add the degree of mixing - look for the work of Brian Chambers and Eddie Tomlinson. 'Plug flow' is regarded as promoting lower SVI; complete mixed reactors as promoting higher SVI.
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