| 摘要 |
<p>A method of treating polluted effluents such as domestic and industrial waste water comprising at least one stage of biological treatment leading to the formation of sludge mixtures comprising organic sludges and water which comprises a stage of control of bacterial growth in at least part of the sludge mixtures and at least part of the raw effluents. The method comprises a stage of aerobic treatment of the effluent, a clarification stage, which may be replaced by a membrane filtration stage, and a thickening stage. It may further comprise stages of (1) anaerobic treatment; (2) a second aerobic treatment. The outputs of any or all of these stages may be fed to the control stage or recycled upstream of it into the raw effluent. Control of bacterial growth is achieved by regulating the oxido-reduction potential of the sludge mixture. The potential is regulated to between -50mV and +50mV and more preferably -20mV to +20mV with respect to a normal hydrogen electrode. The potential is measured by use of a platinum or gold measurement electrode and a Ag/AgCl or Hg/HgCl 2 (calomel) reference electrode. The measurement system is connected to an automatic control system. Regulation of the potential is achieved by (1) regulation of the feed of raw effluents into the bacterial growth control basin; (2) regulation of the flow of sludge mixtures into the control basin; (3) regulation of the evacuation of liquor from the control basin to an aerobic or anaerobic basin; (4) aeration of the basin with air or oxygen. The bacterial growth control stage may further comprise (1) the addition of reagents such as sodium hydroxide, acid or oxidant; (2) the injection of steam; (3) raising the temperature of the medium; (4) application of mechanical shear.</p> |
