| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a treatment method for an organic-containing alkaline waste liquid whereby the increase in the COD and SS of a treated liquid is prevented and the COD and BOD of a treated liquid can be decreased by adding an acidic solution containing Fe2+ to the waste liquid before subjecting the liquid to aeration with an activated sludge. SOLUTION: Ammoniacal liquor 52 from which the most part of free ammonia compounds, cyanate compounds, and hydrogen sulfide are removed in advance by distillation is supplied from an ammoniacal liquor storage vessel 51 to an adjustment vessel 1, and diluting water 53, waste hydrochloric acid 11 generated in the step of pickling steel sheets as an acidic solution containing Fe2+, and phosphoric acid 54 as a nutrition source are supplied. The ammoniacal liquor having a pH adjusted to about 7.0 is led into an aeration vessel 2 to be aerated, and organic substances are oxidatively decomposed by an activated sludge into water and carbon dioxide. The treated liquid is led to a precipitation vessel 3, and a part 55 thereof is returned to the aeration vessel 2. An overflowing treated liquid 56 comes into a neutralization vessel 57, where, if necessary, ferric chloride 61 is added to the liquid 56. The liquid is then sent to a sedimentation vessel 62 to sediment activated sludge, or the like, and the liquid overflowing the vessel 62 is clarified and discharged 66.</p> |
