Centrifugation has routinely been used for the dewatering of municipal digested sludges to produce a cake and centrate.  However, the centrates are often high in suspended solids which reduces the capture rate of the process.  This study was set out to look for causes for the high suspended solids in the centrates.  The study linked the suspended solids concentrations in the centrates to the volatile solids contents of the cakes.  Further study showed that the gas contents of the feed sludge to be the main factor in centrates fluctuations.  Bench tests showed that eliminating the gas in the feed sludge would minimize centrate suspended solids in the decanter-type centrifuge in particular, and centrifuges in general.