| 摘要 |
<p>For the anaerobic purification of waste water it is difficult to maintain good operative contact between sludge particles with bacteria and water to be purified, i.e. sufficiently freely floating sludge particles, which means avoiding the formation of a dense settled layer of active sludge and avoiding easy washing away of sludge with the water in the usual upward flow thereof. The invention proposes the generation of a downward flow of the water to be purified in a reaction chamber and the introduction of an oxygen-free gas to contact the active sludge particles so that gas bubbles adhere thereto and keep them buoyant as much as possible notwithstanding said downward flow. Any sludge moving downwards with the water too much enters a flotation device near the top of the reaction chamber, from which it overflows to be returned wholly or partially to the reaction chamber. Preferably, the reaction chamber has a central riser pipe leading water with some sludge from the bottom of the reaction chamber upwardly to the flotation device.</p> |
