Textile printing and dyeing wastewater is alkaline. Why should lime be added after ferrous sulfate is used for flocculation and precipitation?

See what your treatment process is like. Generally, adding lime to flocculation precipitation can help precipitation and reduce precipitation at the same time, but printing and dyeing wastewater itself is alkaline. If the flocculating agent precipitates quickly, there is no need to add lime. I wonder what the landlord means by adding ferrous sulfate after flocculation. Is it Fenton oxidation with hydrogen peroxide? The optimal ph value of Fenton oxidation is about 3, so the wastewater itself is alkaline, so the waste cost needs to be adjusted. You can directly adjust the acid to find the flocculant under acidic conditions.