A process for treating a sludge of biological solids has the steps of mixing an oxide-containing chemical with a pozzolanic material, reacting the mixture with the sludge so as to elevate a temperature of the sludge to between 40° C. and 140° C., pressurizing the blended sludge to a pressure of greater...http://www.google.com.au/patents/US7771601?utm_source=gb-gplus-sharePatent US7771601 - Treatment of waste sludge with recycling
