Landfill leachate concentrated water treatment method

The invention discloses a landfill leachate concentrated water treatment method which comprises the following steps: (S1) preliminary flocculent precipitation: adding a first flocculating agent into leachate, regulating the pH value of the system to be neutral, stirring and mixing uniformly, and carrying out flocculent precipitation for 2 hours to obtain a supernatant and a precipitate, wherein the first flocculating agent is a mixed solution of 3% of PAM, 5% of PAC and 5% of ferric sulfate; and the first flocculating agent can also comprise 12% of fatty amine modified sodium alginate nanoparticles or 15% of a composition of nano silicon dioxide and polyferric sulfate; (S2) electroreduction treatment: taking the supernatant for electroreduction treatment, selecting iron and graphite as electrode materials, and obtaining primary filtrate after 8 hours; (S3) carrying out electric flocculation treatment to obtain secondary filtrate; and(S4) secondary flocculent precipitation: mixing the secondary filtrate with a