Abstract: A method for treating sludge in an anaerobic digester includes the steps of providing a pit in the ground that is lined with a seal and then forming cells in the pit into which a mixture of vegetal waste and sludge that has optionally undergone a pre-acidification stage is provided. After a sealing cover is placed over the digester, an optional trigger is provided that enhances formation of biogas that is recovered from the digester to be utilized for the production of energy and the digested mixture recovered at the end of the use of the digester is utilized as an organic fertilizer.