External drainage from the flue gas desulfurization tower of the catalytic unit

The principle behind the change from an alkaline to an acidic pH of the wastewater discharged from the flue gas desulfurization tower, after being oxidized by air injection in an oxidation tank, relates primarily to the oxidation process of sulfides (such as disulfides HS^- or hydrogen sulfide H2S) in water. When the oxidation tank introduces air into alkaline water containing sulfides, the oxygen in it reacts with the dissolved sulfides, oxidizing them into sulfates (such as sulfuric acid or sodium sulfate). This oxidation process produces sulfuric acid, a strong acid, which causes the pH of water to drop, changing it from alkaline to acidic. The specific reaction can be expressed as follows: The H^+ ions produced lower the pH value of water, resulting in an acidic condition. .

I was wondering, is the high level of heavy metals in this wastewater due to the large amount of catalysts present in it?

The high level of heavy metals in the wastewater discharged from flue gas desulfurization towers can be caused by various factors, including: 1. **Catalyst carryover**: If the catalysts used in the catalytic devices contain heavy metals, or if the materials used in the flue gas desulfurization process (such as absorbents) contain heavy metals, these metals may be washed away by water during the treatment process and end up in the discharged wastewater. These heavy metals mainly originate from the wear or corrosion of catalysts. 2. **Heavy metals in flue gas**: Flue gas may contain a certain amount of heavy metals, which are absorbed by the absorbent liquid in the flue gas desulfurization tower and then end up in the wastewater. 3. **Corrosion products**: The equipment and pipelines in the desulfurization system may, due to physical and chemical corrosion, cause heavy metal elements present in the equipment to be released into the wastewater. Therefore, although catalyst carryover is a possible factor, other potential sources should also be considered comprehensively in order to fully assess and manage the heavy metal content in wastewater. For such problems, detailed water quality analysis and system inspections are usually required to identify the specific sources of pollution and the types of pollutants involved. .