| 摘要 |
<p>PURPOSE:To regulate easily the nitrous nitrogen concn. in water to be treated to a value close to the critical concn. by treating water in the vicinity of the oxidation- reduction potential inflection point of the water to be treated in the water treatment wherein harmful substances contained in the water to be treated are decomposed and removed biologically. CONSTITUTION:The water treatment is carried out in the vicinity of the oxidation- reduction potential inflection point of the water to be treated in the water treatment wherein the water to be treated is brought under aerobic conditions into contact with activated sludge to decompose and remove biologically harmful substances in the water to be treated. Namely, as the activated sludge treatment proceeds, the oxidation-reduction potential of the water to be treated is gradually increased, the nitrous nitrogen concn. is increased to a value higher than the critical concn., and hence the biological treatment is hindered. Accordingly, when the inflection point of the oxidation-reduction potential of an oxidation-reduction potentiometer 7 in a settling tank 3 is reached, the amt. of air to be sent from a blower 4 to an aeration pipe 6 is reduced by controlling a motor-operated valve 5 with an air volume controller 8. Consequently, the nitrous nitrogen concn. is kept at a value close to the critical concn. by using the oxidation-reduction potential which can be measured easily and accurately as the index, and the treatment is continued.</p> |
