The paper presents the results of the study on the feasibility of using combustible wastes from the wood processing industry for energy purposes. We have established that efficient combustion of hydrolytic lignin, which is a waste of biochemical production, is possible in the furnace of the boiler. Based on the low-temperature swirl combustion method, a furnace structure has been developed that is characterized by reliability, simplicity and allows minimizing costs during the reconstruction, modernization or new construction of power plants. In order to confirm compliance with the current requirements for the protection of the air basin from harmful gaseous pollutants, a quantitative assessment of the nitrogen oxide emission level under low-temperature swirl combustion was performed for the TP-35U boiler of the biochemical plant using the developed methodology, algorithm and calculation program. Numerical studies of the combustion process for the model of the boiler reconstructed confirmed the high technical, economic and environmental indicators of the proposed method. Involving lignin in the energy balance, in turn, frees up the territories occupied by waste, eliminates dumps, and improves the natural environment.