The lime neutralization method generally has one neutralization method, two secondary neutralization methods, and three neutralization methods:
First, a neutralization method
This kind of neutralization method is currently used in China. The advantage is that the equipment is less and the operation is convenient; the disadvantage is that the dosage is difficult to control and the treatment effect is poor. It is best to control the dosage by pH.
Second, secondary neutralization
This method is generally applicable to low pH value, a divalent iron more salts of the acidic waste water. The advantage of the secondary neutralization method is that the lime milk is added twice, the pH value is easy to control, the pH value of the primary neutralization tank is 4-5, the pH of the secondary neutralization tank is controlled at 6.5-8.5; the ferrous iron in the wastewater After the salt reacts with the lime milk, Fe(OH) 2 is formed . After aeration, it is oxidized to form Fe(OH) 3 , which is easy to precipitate and precipitate, and the effluent quality can reach the discharge standard. The disadvantage is that there are more equipment and a large investment in infrastructure.
Three or three neutralization methods
This method is used for a low pH, a large variation, the acid waste water containing various metal ions. In order to precipitate the metal ions in the wastewater, the pH is adjusted to 7 to 9 in one neutralization tank, and the pH is adjusted to 9.5 to 11 in the secondary neutralization tank. After separation by precipitation, the pH is adjusted to 6.5-8.5 in three neutralization tanks, and the discharge is discharged after reaching the discharge standard.
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