Method for treating leachate wastewater of arsenic-containing waste residue landfills and waste mines

Abstract

The invention discloses a method for treating leachate wastewater of arsenic-containing waste residue landfills and waste mines. The method comprises: 1, aerating: aerating collected arsenic-containing leachate wastewater for 1-2 h, and oxidizing a part of arsenic (III) into arsenic (V) by using air; 2, oxidizing: adding an oxidizing agent ferrate into a solution obtained in step 1 to further oxidize arsenic (III) into arsenic (V), continuously aerating for 25-45 min while oxidizing, and controlling the pH value of the system to be 4-7; 3, precipitating and separating: adding lime milk and a flocculating agent into a solution obtained in step 2, continuing aeration for 20-30 min, controlling the pH value of the system to be 9-10, performing a flocculation reaction to form large particles convenient to settle and separate, allowing the large particles and Fe<3+> subjected to strong oxidative decomposition of ferrate to form a lime-ferric salt system and a Fe(OH)3 colloid which has a good flocculation and adsorption effect and can further quickly remove arsenic in the solution, standing the precipitate for 3-6 h, separating, and discharging the obtained supernatant in a standard-reaching manner.

Description

technical field [0001] The invention specifically relates to the technical field of sewage treatment, in particular to a treatment method for arsenic-containing waste residue landfill and abandoned mine leachate wastewater. Background technique [0002] Arsenic and arsenic-containing compounds are highly toxic, and the toxicity of As(Ⅲ) is much higher than that of As(Ⅴ), which can damage human liver, kidney and nerves. Once the pollution of arsenic to the environment is formed, it will be difficult to eliminate in the environment, especially the pollution of water and soil, which can eventually enter the human body through the food chain or surface water and groundwater and endanger human health, causing human and animal poisoning incidents from time to time occur. The environmental pollution and harm caused by the arsenic slag produced in the smelting process and the arsenic-containing waste slag produced in the treatment of waste water and waste acid have not yet been com...

AI Technical Summary

Problems solved by technology

Lime precipitation method, iron salt precipitation method, and iron salt-lime co-precipitation method need to add a large amount of chemical agents, which are precipitated in the form of sediment, resulting in a large amount of waste residue and secondary pollution problems

For example, the method of Chinese patent (CN 102234160B) for treating low-concentration arsenic-containing wastewater adopts pH neutralization adjustment, gypsum precipitation separation, arsenic pre-oxidation of wastewater, arsenic slag air flotation separation and clear liquid membrane filtration, etc. The treatment process is simple and suitable for automation It can be widely applied to various industrial arsenic-containing wastewater, but there are many kinds of chemical agents added, and the dosage is large, so the treatment cost is high

Chinese patent (CN 103964601B) uses scorodite crystals (FeAsO4 2H2O) to remove arsenic in wastewater at high temperature. Reaction at 70-95°C, high energy consumption, long reaction time, uneconomical

The Chinese patent (CN 103408162B) adopts two-stage "chelation-flocculation-pH adjustment-filtration" for treatment, which has high treatment efficiency and the concentration of arsenic in the effluent is lower than 0.5ppm required by the national discharge standard, but the treatment process is lengthy and the operation is cumbersome

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