The document provides instructions for cleaning an anaerobic digester tank. Key steps include isolating the digester, removing as much material as possible, ventilating the space, following strict safety protocols like lock out tag out and confined space entry procedures, and pumping out remaining sludge and inert materials. The pumped sludge can be sent to grit removal, screening, storage tanks for dewatering, or direct land application depending on the disposal option selected. Reseeding from another source or slowly building up biomass over time are described as options for restarting digestion after cleaning is complete.