Master’s thesis deals with the possibilities of streamlining the operation of wastewater treatment plant in Zvolen. The focus is on the production of biogas – sludge gas and its valorisation as fuel. The production of sludge on the sludge treatment unit, its characteristics as secondary raw material and its material evaluation options. The essence of the proposed method of increasing the efficiency of the biogas combustion process should be to improve its properties as fuel which affects the combustion process in the production of energy in the piston combustion engine of the combined heat and power unit. Environmental aspects of the management of the sludge and the proposal for its valorisation in accordance with legislation and long-term sustainability. The proposals should be assessed from the environmental and economic point of view of the WWTP application in Zvolen.