How often should sludge be removed?
Sludge removal should be done every 4-28 days depending on the application. In some cases sludge removal would be possible only once every year or two in the case of pre-treatment of industrial wastewaters for sewer discharge. Sludge cannibalisation can be optimised by transferring the sludge to a holding tank on the Monday and returning the decant to the aerobic system on the Sunday (quiet day) to digest the soluble nutrients released during autolysis during the week.
