Sulfide issues in the wastewater from flue gas desulfurization
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Dear colleagues, I have recently encountered a problem with my unit: the sulfur content in the wastewater resulting from flue gas desulfurization in the catalytic cracking unit is above the allowed levels. After reviewing numerous sources of information, it should be that all sulfur compounds in the flue gas generated by coke combustion are oxidized to SO2 or SO3. Through flue gas desulfurization and reaction with sodium hydroxide, sodium sulfite should be produced, and upon further oxidation, only sodium sulfate or sodium sulfite should remain, with no sulfur compounds present. Tests using the iodometric method in other plants also detect sulfur compounds. I would like to ask if you have encountered similar issues and whether you also control the sulfur compound levels
Is the amount of alkali added during the oxidation process appropriate? What is the pH value of the external drainage water? The oxidation process releases hydrogen ions, causing the effluent solution to become acidic
The gas absorption rate using the absorption method can’t possibly reach 100% anyway; it’s understandable that it can still be detected{:9006:}
Sulfides? We don’t test for them; it’s all sodium sulfite and sodium sulfate. Sulfides have an impact on wastewater treatment plants; I wonder what level you have reached?
Well, it’s really hard to figure out where the sulfides come from. The SO2 and SO3 present in the flue gas should, through flue gas desulfurization, produce only sodium sulfite and sodium sulfate; no other substances should be formed. Our laboratory analysis shows that the level of sulfides ranges from 50 to 400 mg/L.
Personally, I recommend using highly active calcium hydroxide for SDS treatment; it yields the same results as baking soda, and the waste solids generated can be recycled free of charge. Feel free to contact me if you need more information