Heavy metal settling agent for treating mercury-containing wastewater

The invention relates to a heavy metal settling agent for treating mercury-containing wastewater. The technical scheme of the invention comprises the following steps: adding the heavy metal settling agent formed by mixing 20-60 parts of reactant Na2S, 10-20 parts of flocculating agent Fe3 , 1-20 parts of coagulant aid polyacrylamide and 10-40 parts of water into the mercury-containing wastewater; adding Hg and the heavy metal settling agent into the treated water according to the mass concentration ratio of 1:5-1:20 to enable the Hg in the treated water to react to generate HgS precipitates; adsorbing micro HgS suspended particles into flocculent precipitates for precipitating under the action of the flocculating agent and the coagulant aid; and filtering and adsorbing the obtained materials to enable the HgS flocculent precipitates to be separated from the treated water to obtain the qualified water solution. The invention has better effect on removing high-concentration mercury-containing wastewater and low-concentration mercury-containing wastewater, the precipitates after treatment can be separated easily and can not cause secondary pollution, and the invention especially can achieve the effect on removing more than 95% of high-concentration mercury-containing wastewater.