| 摘要 |
<p>PURPOSE:To stably carry out the removal of ammonia compounds and phosphorus compounds by controlling a return sludge flow rate adjusting valve installed in a return sludge pipeline based on the difference between a standard oxidoreduction potential and the oxidoreduction potential detected by ORP meters. CONSTITUTION:In an activated sludge treatment apparatus to treat sewage biologically, a first anaerobic tank 3 where sewage from a pipeline 1 and return sludge from a return sludge pipeline 14 are stirred and NOx-N are reduced into nitrogen gas in a denitrification reaction is installed. A second anaerobic tank 4 where the mixed liquid flowing out of the tank 3 is stirred to release phosphorus compounds is installed, the mixed liquid from the anaerobic tank 4 is introduced into an aerobic tank 9 and nitrogen are oxidized to NOx-N by aeration and, at the same time, the phosphorus compounds are absorbed in an activated sludge, and the resultant mixed liquid coming out of the aerobic tank 9 is treated for solid-liquid separation in a final precipitation pond 12. At that time, the degree of the difference between the oxidoreduction by ORP meters 7, 8 set in the anaerobic tanks 3, 4 and the standard oxidoreduction potential is computed and based on the difference degree, a return sludge flow rate adjusting valve 18 in the pipeline 14 is controlled.</p> |
