Abstract:
In order to reduce the ultra-high concentration of ammonia nitrogen in the waste water during the etching solution treatment, 3000 mg/L ammonia nitrogen solution was prepared to simulate the waste water by using the struvite precipitation method. The effects of pH value, pH regulation order, additive order and
n (N)∶
n (Mg)∶
n (P) on the denitrification effect of the three groups of agents were studied. The results showed that the nitrogen removal efficiency of the three groups reached 98.64% (MgSO
4+NaH
2PO
4), 97.73% (MgCl
2+Na
2HPO
4) and 85.69% (MgO+H
3PO
4) when the pH value was 10.5 and the molar ratio was
n (N)∶
n (Mg)∶
n (P)=1∶1.4∶1.2. The order of adding agents has great influence on ammonia nitrogen removal rate. The reaction process leads to the decrease of pH, so it is difficult to get the ideal effect of nitrogen removal only by adjusting the initial pH value of wastewater. The verification results of the actual production wastewater showed that the nitrogen removal efficiency of (MgSO
4+NaH
2PO
4) could reach 95.5% under the optimal conditions.