This bachelor’s thesis focuses on the possibilities of using small hydroelectric power plant in wastewater treatment plant. The first part is theoretical and describes the theory of wastewater treatment plants, small hydro power plants, turbines and generators. The seconds part focus is to describe the design of small hydro power plant. It begins with description of location then continues with calculation of Banki turbine and ends with generator selection. The last part deals with an economic evaluation, which includes estimating of the investment costs, the price of saved electricity and determining the estimated return on investment. In conclusion the thesis compares the ways of using the produced electricity