| 摘要 |
<p>A method for the treatment of waste liquids originating from plants for the treatment of aluminum and comprising a first alkaline eluate (B) that contains sodium hydroxide (NaOH) and sodium aluminate (NaAlO 2 ), and a second acid eluate (A) which contains sulfuric acid (H 2 SO 4 ) and aluminum sulfate (Al 2 (SO 4 ) 3 ), which comprises the steps of:
a) supplying the alkaline eluate (B) in a reactor and the acid eluate (A) in a storage tank;
b) performing volumetric titration of the alkaline eluate (B) and the acid eluate (A), providing respectively an alkalinity value and an acidity value thereof;
c) heating the alkaline eluate (B) in the reactor to a temperature comprised between 40 and 50°C;
d) maintaining the temperature within said range, dispersing in the reactor the acid eluate (A) in a quantity that depends on the alkalinity and acidity values detected in step b), by injecting the acid eluate (A) into the alkaline eluate (B) in the reactor with an hourly injection flow-rate that does not exceed one fifth of the total volume of the reactor, so as to achieve the forming of an aluminum hydroxide precipitate (Al(OH) 3 ) on the bottom of said reactor;
e) simultaneously with step d), recirculating continuously the content of the reactor, drawing from the lower part and reintroducing from the upper part of the reactor, so that the volume of the content of the reactor that is recirculated in 1 hour is equal to at least 5 times the total volume of the reactor;
f) ending step e) upon reaching a pH value of the content of the reactor between 7,5 and 9.0;
g) removing the aluminum hydroxide precipitate (Al(OH) 3 ) from the bottom of said reactor.</p> |
