Supercritical water treatment method for arsenic-containing wastewater

Abstract

The invention relates to a supercritical water treatment method for arsenic-containing wastewater, belonging to the field of wastewater treatment. The supercritical water treatment method comprises the following steps of: adding an oxidizing agent, the arsenic-containing wastewater and additives to a high-temperature and high-pressure reaction kettle to obtain a reaction system, heating and pressurizing the reaction system under a closed condition until the reaction system reaches a supercritical state, and reacting for 8 to 115 minutes to obtain the reaction product system; when the temperature in the supercritical state is 460-630 DEG C, quickly releasing the pressure, carrying out gas-solid-liquid separation on the reaction product system, wherein a solid product in the kettle body is metal oxide, a gaseous product is cooled, and arsenic trioxide is converted from a gas into a solid to be settled, and a liquid product is a solution of nitric acid; and when the temperature in the supercritical state is 385-460 DEG C (excluding 460 DEG C), cooling the reaction product system in the high-temperature and high-pressure reaction kettle to be below 100 DEG C, introducing sulfur dioxidewaste gas and reacting to obtain a solid product and a liquid product, carrying out solid-liquid separation to obtain the arsenic trioxide solid and the liquid product, wherein the liquid product isa mixed acid solution containing metal cations.

Description

technical field [0001] The invention relates to a supercritical water treatment method for arsenic-containing wastewater, which belongs to the field of wastewater treatment. Background technique [0002] Arsenic and its compounds are common environmental pollutants and are highly toxic carcinogens. If they are not controlled, they will easily pollute the environment, and once the pollution is formed, it will be difficult to eliminate. It has been recognized by the US Centers for Disease Control and National Defense. Cancer Research Institute identified as the first class of carcinogens. Arsenic will enter the human body through the food chain or surface water and groundwater, seriously damaging human health. In recent years, with the massive development of metal mines and the wide application of arsenic in industry, the amount of arsenic-containing wastewater and waste residues is increasing day by day, and the environmental pollution caused by arsenic is becoming more and ...

AI Technical Summary

Problems solved by technology

Chinese patent CN102234160B discloses a low-concentration arsenic-containing wastewater treatment method, using plaster of paris (milk of lime) to adjust pH, oxidizing agent to oxidize, adding inorganic coagulant, heavy metal scavenger, caustic soda, organic flocculant, surfactant in sequence, Reuse flotation and clear liquid membrane filtration have reached the standard, and failed to effectively recover arsenic resources

Chinese patent CN103112974B discloses a treatment method for arsenic-containing wastewater. The pH is adjusted by acid, sulfide is added in multiple stages, precipitation is separated, alkali is added to adjust, electrolytic coagulation, electrolytic air flotation, electrolytic redox, aeration and precipitation, and finally solidification Liquid separation, but the technical scheme of the present invention is complex and involves many devices, and the input cost is large