Pretreatment of municipal waste activated sludge for volatile sulfur compounds control in anaerobic digestion
https://doi.org/10.1016/j.biortech.2010.12.020
Abstract: The effect of combination of mechanical and chemical pretreatment of municipal waste activated sludge (WAS) prior to anaerobic digestion was studied using a laboratory scale system with an objective to decrease volatile sulfur compounds in biogas and digested sludge. Mechanical pretreatment was conducted using depressurization of WAS through a valve from a batch pretreatment reactor pressurized at 75 ± 1 psi, while combined pretreatments were conducted using six different dosages of hydrogen peroxide (H2O2) and ferrous chloride (FeCl2) along with mechanical pretreatment. About 37–46% removal of H2S in biogas occurred for different combined pretreatment conditions. Sludge solubilization achieved due to the mechanical pretreatment increased total cumulative methane production by 8–10% after 30 days during the biochemical methane potential (BMP) test. The pretreatment also improved dewaterability in terms of time to filter (TTF), and decreased methyl mercaptan generation potential of the digested sludge
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Nitrogen and Phosphorus in Water, An Annotated Selected Bibliography of ...
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Nitrogen N% dry weight is 1.5-4.0 for Primary Sludge, 3.5-8.5 for WAS and 1.6-6.0 for combined digested sludge.
Phosphorus P% dry weight is 0.8-2.8 for Primary Sludge, 2.0-2.7 for WAS and 1.4-4.0 for combined digested sludge.
Potash in % dry weight is 1.0-1.0 for Primary Sludge, 0.2-0.5 for WAS and 0.1-3.0 for combined digested sludge.
These values are given in literature and can be safely considered.
While designing thickener, I think you don't need these values.
what you need to know is solids loading rate. The guideline values are 47 kg/m2/d. Thus you will be able to find total surface area. Then hydraulic loading can be determined Sludge Volume/d divided by surface area.
I think this should suffice your need Mam
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