Thallium-containing heavy metal wastewater advanced treatment method

Abstract

The invention belongs to a thallium-containing heavy metal wastewater advanced treatment method. The method comprises the following steps: (1) pretreating thallium-containing heavy metal wastewater: adjusting the pH value of wastewater to 9.5-11.5 with alkaline, and adding a chemical thallium removing agent according to the mass ratio of the chemical thallium removing agent to thallium of (0.5-1.5):1; (2) medicating according to the mass ratio of the chemical thallium removing agent to wastewater after the reaction in step (1) for 15-30 minutes, and carrying out mixed reaction for 15-30 minutes; (3) adding liquid alkaline into the solution obtained from the step (2), adjusting the pH value to 11.0-11.5, reacting for 10-20 minutes, adding 5-50g / m<3> of flocculating agents, reacting for 10-20 minutes, carrying out solid-liquid separation by oblique plate deposition or plate frame press filtration, standing for 1-2 hours, and discharging or recycling supernate. The thallium contained heavy metal wastewater treatment method is simple in process, has no secondary pollution, is high in treatment efficiency, runs stably and low in cost, and has very high practicability.

Description

Technical field: [0001] The invention belongs to the technical field of water treatment, in particular to the technical field of industrial wastewater treatment of thallium-containing heavy metals, and specifically relates to a method for advanced treatment of thallium-containing heavy metal wastewater. Background technique: [0002] Thallium (Tl) is a typical dispersed element, which is widely used in important fields such as national defense, aerospace, electronics, communication, and health. At present, 56 kinds of thallium minerals have been reported in the world. The annual production and use of thallium in the world is less than 15 tons, while the annual discharge of thallium by industry is about 2000-5000 tons, which has brought about such as soil thallium pollution, water body thallium pollution, human and animal chronic thallium A series of environmental pollution problems such as poisoning. The abundance of thallium is very low (0.75mg / kg). Relatively speaking, th...

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Problems solved by technology

[0003] At present, the main treatment processes of thallium-containing wastewater: (1) chemical oxidation precipitation method: (the State Intellectual Property Office authorized and announced a "thallium-containing wastewater treatment method" on December 23, 1992) (public number: 1067229) mainly in Under oxidative and alkaline conditions, thallium is converted from monovalent to trivalent, and oxidants and alkaline substances (such as lime) can be added to polluted water to form precipitates and remove thallium; sulfidation precipitation method: (State Intellectual Property Office, 2007 On May 23, a "thallium-containing wastewater treatment method" was authorized and announced) (public number: 1317205c) to introduce sulfur and iron by adding powdered pyrite. The main principle is that under alkaline reducing conditions (pH>7.4, Eh+ Can form Tl 2 S precipitation, thallium in wastewater can be reduced to 2.0μg / L, which is limited to the solubility product limit of sediment, but cannot meet the requirements of 0.1μg / L "Environmental Quality Standards for Surface Water" (GB3838-2002); Chlorination precipitation Method: Saturated NaCl solution can promote Tl in wastewater + Effective precipitation in the form of TlCl, the concentration of thallium in wastewater can be reduced to 2μg / L, which cannot be further treated and cannot meet the discharge requirements; the precipitation method is simple in process and has a good treatment effect, but the sulfur content in the treated wastewater > 1mg / L, can not be discharged, there is secondary pollution, it is difficult to meet the standard stably

(2) Adsorption method: The adsorption method can be divided into general adsorption and ion selective adsorption. Taking advantage of the property that thallium is easily adsorbed by "sponge adsorbents", add adsorbents such as MnO (solid) to the polluted water body to reduce the activity of thallium. rate and make it precipitate; the US EPA recommends the use of active Al purification and ion exchange methods to treat drinking water with a low content (<10μg / L), and the thallium content of drinking water treated with this method can be reduced to 2ug / L The drinking standard of L, but the cost of this method is relatively high ($81.321 / kg thallium), and it is only suitable for the treatment of low concentration (<10μg / L) thallium-containing wastewater, and it is difficult to popularize and apply it in the treatment of large amounts of thallium-containing wastewater

(3) Membrane method: Membrane methods mainly include ultrafiltration, reverse osmosis and electrodialysis. These methods can only play the role of separation and concentration, and it is difficult to completely remove thallium-containing pollutants from water