primary sludge thickening performance
primary sludge thickening performance
(OP)
Primary sludge thickening performance at gravity thickeners at a WWTP decreased significantly in 1998. Prior to 1998 typical thickened primary sludge concentrations were around 5-6 %D.S. Since 1998, thickened sludge concentrations have decreased to around 3-4% D.S. Several tests conducted suggest that the decrease thickening performance is primarily due to changes in the primary sludge thickening characteristics (as opposed to thickener operation).
Prior to 1998, the plant added "pickle liquor" (ferrous) to precipitate phosphorus. In 1998, they switched to ferric chloride. Do you think this change could potentially affect primary sludge thickening characteristics?
Prior to 1998, the plant added "pickle liquor" (ferrous) to precipitate phosphorus. In 1998, they switched to ferric chloride. Do you think this change could potentially affect primary sludge thickening characteristics?





RE: primary sludge thickening performance
RE: primary sludge thickening performance
Higgins and Novak did a study several years ago that showed when the ratio of Sodium and Potassium to Magnesium and Calcium is above 1:1, sludge settling problems are increased. Can your lab do an analysis of this?
You can try a bench scale test of ferrous and ferric and see how they compare, that may give you an indication of whether the chemical is to blame or if the problem lies elsewhere.
Mike Bensema
www.dutchmenservices.com
RE: primary sludge thickening performance
BobPE