Changes in the Removal Efficiency of Total Phosphorus by the Basicity of Al(III) Coagulant

The analysis of Al (III) hydrolysis species with PACls prepared by different basicity showed that mononmeric Al species were reduced while precipitate Al species were increased with an increase in basicity for PACls. In the case of the PACl with 13.6% basicity, monomeric Al species were 81%, polymeric Al (III) species 19%, precipitate Al (III) species was 0%, as showing the dominant monomeric Al species. The PACl with 13.6% basicity showed above 80% of turbidity removal efficiency without any restabilization. In addition, the PACl with 13.6% basicity showed higher organic removal expressed by $UV_{254}$ which was caused by lower coagulation pH. The PACl containing the higher amount of monomeric Al species was the most beneficial for T-P and $PO_{4}-P$ removal.

Al(III) 응집제의 염기도에 따른 총인 제거효율의 변화

염기도를 달리하여 제조된 PACl에 대한 Al(III)종 분포는 염기도가 높을수록 monomeric Al(III)종은 적어지고, precipitate Al(III)종은 증가하는 것으로 나타났다. 염기도 13.6%의 경우에서는 monomeric Al(III)종이 81%, polymeric Al(III)종이 19%, precipitate Al(III)종은 0%로 monomeric Al(III)종이 주종을 이루고 있었다. 염기도 13.6%의 경우에서 재안정화 없이 80% 정도의 탁도제거 효율을 유지하고 있었으며, $UV_{254}$ 제거효율이 향상되는 것은 낮은 응집 pH 범위에서 유기물 응집효과가 우수하게 나타나기 때문으로 판단된다. 그리고 13.6% 염기도를 가진 PACl이 T-P 제거효율 및 $PO_{4}-P$의 제거효율이 가장 우수한 것으로 나타났으며 이는 높은 monomeric Al 성분에 기인하리라 판단된다.