A method for the treatment of lignocellulose-containing materials wherein such lignocellulose-containing materials, normally resistant to biotreatment, are first subjected to pyrolysis to produce pyrolysis products including pyrogas and char. Exemplary applications of the method include pyrolytic pre-treatment of wastewater sludges, cellulosic wastes, wood, peat, plant residues, low-grade coal, and the like. The pyrogas is introduced into digester sludge in an anaerobic digester.