The topic to Diploma Thesis is design of Biological Wastewater Treatment for 450 PE in Hvozd Commune (Region Olomoucký). First part is dedicated to description of multiple possible variants of design. In the following part is more detailed described chosen technology. Except from description of technology are also shown parameters calculations proposal. Some of the main reasons for preference of Biological Wastewater Treatment are low maintenance requirements, independence of energy supply or possibility of future sludge treatment. Foundational materials for the design were first, Local Zoning Plan which describes current and future drainage and wastewater disposal situation. Second, study aims at parameters calculations of French system. Project documentation is part and parcel of this thesis. Documentation will also be a basis for planning building permission.