Method of pyrolyzing sewage sludge to produce activated carbon

A method of transforming wet sewage sludge to a solid carbonaceous material that is at least partially activated carbon which includes the steps of:

• a. providing an elongate first confined space within a rotatable cylindrical shell that has first and second ends and a longitudinal axis, said shell defined by a rigid material that has substantial heat conductivity;
• b. rotating said cylindrical shell about said longitudinal axis;
• c. initially heating said cylindrical shell from a first source to a first temperature at which a mixture of said wet sewage sludge and hot carbonaceous material will be transformed to char in traversing the length of said first confined space;
• d. delivering a mixture of wet sewage sludge and hot carbonaceous material to said first confined space adjacent said first end of said shell;
• e. moving said mixture longitudinally through said first confined space at such a rate that said sewage sludge is transformed to char prior to reaching said second end of said cylindrical shell;
• f. continuously discharging wet sewage sludge at a first rate into a second confined space;
• g. continuously mixing said hot char and wet sewage sludge in said second confined space to obtain a substantially dry mixture thereof, with a substantial portion of the water in said wet sewage sludge being transformed to water vapor;
• h. discharging said water vapor from said second confined space;
• i. heating said water vapor to transform the latter to steam that is directed into said first confined space;
• j. continuously discharging said dry mixture from said second confined space to said first confined space adjacent said first end of said shell at a second rate that is so selected that said dry mixture is substantially transformed to pyrogas and char that is at least partially activated carbon in traversing the length of said confined space;
• k. continuing to discharge a first portion of said char from said second end of said cylindrical shell into said second confined space;
• l. recovering a second portion of said char from said second end of said cylindrical shell, which char is at least partially in the form of activated carbon for use apart from said method;
• m. providing a source of air under pressure;
• n. mixing said pyrogas with said air under pressure, and burning said air-pyrogas mixture to heat, said shell and first confined space to provide a second source of heat;
• and
• o. using said heat from said second source of such heat as may be necessary from said first source to maintain said shell and first confined space at a temperature to transform said dry mixture from said second confined space to pyrogas and to char at least partially in the form of activated carbon as said dry mixture traverses the length of said first confined space.