Apparatus for the biological purification of waste water

摘要

An apparatus is provided for the multistage biological purification of waste water containing organic substances including carbohydrates and proteins. The apparatus comprises an at least substantially closed first tank for holding waste water while maintaining the waste water at least substantially free from contact with air so as to prevent further oxygen from becoming dissolved in the waster water. The apparatus also includes a second tank including an aerator for dissolving oxygen in waste water contained in the said tank, the second tank being located inside the first tank and including a conical bottom portion for receiving sludge produced by aerobic degradation of the waste water in the second tank.