Sulfur containing wastewater is a kind of toxic wastewater containing sulfide, which has strong sulfide flavor and corrosiveness. Chemical flocculation is suitable for all kinds of wastewater treatment, with high removal rate of suspended solids in wastewater. The typical chemical treatment method is to add ferrous sulfate, which is not only a flocculant but also a reducing agent. So, is ferrous sulfate used as flocculant or reducing agent in the treatment of wastewater containing sulfur?

Unlike polyferric sulfate, ferrous sulfate will produce a large number of divalent iron ions after dissolving in water. These ions will react with negatively charged trivalent sulfur ions in water to produce ferrous sulfide precipitate, which will be oxidized by air to produce ferric sulfide precipitate. Then, the solid-liquid separation treatment is carried out for these precipitates, so as to achieve the purpose of desulfurization.

When ferrous sulfate is used for desulfurization treatment, it is generally required to add excessive ferrous sulfate. When the sulfur ion content in wastewater is 0.8 mg / L, the dosage of ferrous sulfate is 30 mg / L, and the desulfurization rate of wastewater can reach 99%.

When ferrous sulfate is used as precipitant to treat sulfur-containing wastewater, ferrous sulfate can react with sulfur ion to form insoluble sulfide precipitation. However, this method has one disadvantage, that is, the sodium sulfate alum produced by the reaction is relatively small, so auxiliary flocculant needs to be added, otherwise the dosage of ferrous sulfate will be increased and the cost will be wasted.

In addition to ferrous sulfate and other precipitants, there are neutralization method, chlorination method, stripping method, aeration method, oxidation method and so on. According to the concentration of sulfur content in the wastewater, which method is more suitable and economical is determined.