In my design I will be thickening the WAS by a gravity thickener and I'd like to know some typical solids loading rate i.e. kgTSS/m2.d. I'd be thickening the solids to 6% solids conc. (60000 mgTSS/l). otherwise, I do have typical loading rate for primary sludge gravity thickening but it's different.
Gravity thickening of WAS really needs pilot trials. A high loading may not thicken to what you want. A low loading may gas and lift through biological activity from the bacteria. Centrifuges are preferred for this application for a reason - and even then you usually need a trial to determine the settings.
The metric you want is 20 - 40 kg TSS/m2.d
http://www.wefnet.org/mopnew/Operation_of_Municipal_Wastewater_Treatment_Plants/Chapter%2029%20Revised_6th%20Edition.pdf
Gravity thickening of WAS really needs pilot trials. A high loading may not thicken to what you want.
Thank you for your response, and Jeremy for the resource. indeed I will be using floatation for the other two options in my design. I thought I could use gravity thickening given that my system is just an activated sludge MLE with only N-removal. so using gravity thickener would not give room for phosphorus release as the plant is not an N&P removal plant.
Centrifugation does the work of concentration of wastes. Too much thickened or concentrated waste may not have enough air spaces for bacteria too act on.
Flotation will keep the system aerobic, and will mean that any biological activity creating gases within the sludge will not matter. A common failure with thickening of WAS is the biological activity, so that in summer you may hydraulically overload your downstream process because of the poor performance. But really you need pilot plant trials.
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