Landfill leachate treatment method and system

Abstract

The invention discloses a landfill leachate treatment method and system. The landfill leachate treatment method comprises the following steps: S1, pretreating landfill leachate to remove suspended solids, heavy metals, sulfate ions, calcium ions and magnesium ions so as to obtain clarified liquor; S2, performing pH regulation and filtration on the clarified liquor, and removing the residual suspended solids so as to obtain filtrate with SDI less than 3; S3, performing electrodialytic treatment on the filtrate so as to obtain electrodialytic concentrated water and electrodialytic fresh water; S4, performing biochemical and membrane filtration treatment on the electrodialytic fresh water so as to obtain membrane filtration concentrated water and membrane filtration produced water; and S5, performing evaporative crystallization treatment on the electrodialytic concentrated water and membrane filtration concentrated water, thereby obtaining crystalline salt and recycled water. According tothe method disclosed by the invention, the landfill leachate is subjected to treatments such as concentration and solid-liquid separation by virtue of a process combining pretreatment, filtration, electrodialysis, biochemical treatment and evaporative crystallization, so as to obtain the recyclable crystalline salt and the recycled water, zero wastewater emission and resource reutilization are realized, and the landfill leachate treatment method is environmental-friendly and has wide application prospects.

Description

technical field [0001] The invention relates to the technical field of wastewater treatment, in particular to a landfill leachate treatment method and system for realizing zero discharge and resource utilization of crystalline salt. Background technique [0002] At present, with the improvement of national discharge standards, zero discharge treatment of landfill leachate is gradually implemented. The existing landfill leachate zero discharge treatment process generally includes anaerobic digestion (reducing the concentration of organic matter), biochemical treatment (removal of ammonia nitrogen), membrane concentration and filtration (using various types of membranes to perform concentration treatment to obtain high-salt concentrate) and Evaporation, concentration and crystallization treatment, the crystallized concentrated solution and crystal particles undergo solid-liquid separation, the mother liquor returns to the original solution pool or continues to evaporate and cr...

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Problems solved by technology

[0003] However, the above process has the following disadvantages: (1) The biochemical system for biochemical treatment has clear requirements on the salt concentration of the influent, and the biochemical system cannot effectively treat high-salt landfill leachate, making the wastewater treatment system unable to operate stably for a long time; Dilution and other methods to reduce the salt content of biochemical influent will greatly increase the operating cost of subsequent processes

(2) The operating pressure of the reverse osmosis membrane concentration system is high, and the salt content (TDS) can only be concentrated to about 50,000mg / L. The recovery rate of water is low and the energy consumption is large.

(3) The COD removal efficiency is low, and the evaporation stock solution contains organic matter, which affects the quality of the product salt

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