| 摘要 |
In a biological water purification process polluted water, including surface water to be made potable, sewage water or industrial water, is percolated through a submerged fixed bed of granular material such as activated carbon, chamottes, raw clays, etc., with an oxygenated gas being upwardly injected at an intermediate level of the bed. The water and gas delivery rates are controlled to satisfy the following relations: <IMAGE> (1) <IMAGE> (3) and simultaneously: <IMAGE> (4) wherein Q1 is the delivery of oxygenated gas in m3/hr, Q2 is the delivery of water to be treated in m3/hr, epsilon is the porosity of the granular material bed, alpha is the maximum fraction of the volume that can be occupied by the gas without affecting the effectiveness of the treatment, S is the bed section in m2, h is the height of the bed in meters, v is the vertical component of the average speed of the ascending gas bubbles in m/hr, K1 is a constant corresponding to the fraction of volume of bed occupied by immobilized gas pockets in m3, K2 is the concentration of gas in oxygen in kg/m3, K3 is the value of the demand for oxygen that 1 m3 of granular material can satisfy in 1 hour under operating conditions of the process (in kg/m3/hr), R is the total transfer yield (or the fraction: weight of oxygen effectively dissolved/weight of oxygen injected in the bed), and OD is the demand for oxygen to be met, in kg per unit of volume of water to be treated.
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