How to remove fluoride ions from SHELL gasification wastewater
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The wastewater generated by my SHELL gasification process contains fluoride ions, which are removed through chemical reactions in a cyanide-destruction and fluoride-removal unit (by adding calcium chloride); however, the fluoride removal efficiency is poor and the results vary greatly. This is reflected in insufficient dosing of chemicals, poor dissolution of the PAM used for sedimentation, and inadequate amounts of calcium chloride added. Could you please provide information on systems that are similar to this? What types of chemicals such as PAM should be used, how should their concentration be determined, and what should be the control parameters for the dosage?
This aspect involves two things: one is the removal of fluoride ions, and the other is the sedimentation and removal of other substances.
This aspect involves two things: one is the removal of fluoride ions, and the other is the sedimentation and removal of other substances. Removing fluoride ions and adding calcium chloride is a good approach, but it’s better to adjust the pH of the wastewater to which calcium chloride is added to a slightly acidic level, around pH 6.5, before adding calcium chloride; this may yield better results. After the reaction is complete, the wastewater is treated by adding PAC and PAM to increase the size of the particles, thereby facilitating sedimentation. I’m not entirely clear about your specific processes, but the addition of PAC and PAM later on requires adjustment experiments to determine the optimal ratio. There is a certain range within which these substances can be diluted; however, once a ratio has been established, it should not be changed arbitrarily. Only when all aspects are appropriate can a good treatment effect be achieved