Removal of F- and organic matter from coking wastewater by coupling dosing FeCl3 and AlCl3

Coagulation and precipitation is a widely applied method to remove F- from wastewater. In this work, the effect of coagulation on the removal of F- and organic matter from coking wastewater was studied using AlCl3 and FeCl3 as compound coagulants. The removal rates of F- and organic matter under different coagulant doses and pH conditions were investigated. The results show that the highest removal rates of F- by AlCl3 and FeCl3 are 94.4% and 25.4%, respectively; when the dosage is 10 mmol/L, the TOC removal rates of FeCl3 and AlCl3 reach 20.4% and 34.7%, respectively. Therefore, the removal rate of F- by AlCl3 is higher than that of FeCl3, but the removal rate of organic matter by FeCl3 is relatively higher. The addition of Ca2+ can promote the removal of F-, but the removal rate of organic matter decreases. In addition, by investigating the effects of different pH and Fe-Al ratio on the removal rate, the removal effect of adding FeCl3 and AlCl3 at the same time was discussed. The results show that the most suitable working condition for the removal of organic matter and F- is that the pH is 6.5 and the molar ratio of Al/Fe is 8:2. Overall, the removal mechanism of F- and organic matter in coking wastewater by FeCl3 and AlCl3 was explored in this study. The experimental results can provide reference for the advanced treatment of coking wastewater. (c) 2021TheResearch Center for Eco-Environmental Sciences, Chinese Academy of Sciences. Published by Elsevier B.V.

Automated summary

In this study, the removal of F- and organic matter from coking wastewater using AlCl3 and FeCl3 as compound coagulants was investigated. The results showed that AlCl3 had a higher removal rate for F- while FeCl3 had a higher removal rate for organic matter. The addition of Ca2+ was found to promote the removal of F- but decrease the removal rate of organic matter.