Aged leachate treatment method and system

The invention discloses an aged leachate treatment method and system. The method comprises the steps: carrying out the multistage filtering of leachate raw water to obtain a filtrate; carrying out material membrane treatment on the filtrate to obtain first produced water and first concentrated water; carrying out biochemical A/O-MBR treatment on the first produced water to obtain second produced water; carrying out solidification treatment on the first concentrated water; and carrying out nanofiltration treatment on the second produced water to obtain final produced water. The method and the system aim at wastewater which is poor in biodegradability and difficult to treat, such as an aged refuse landfill or stock refuse leachate. Macromolecular humic acid which is difficult to biochemically degrade in leachate can be separated, the B/C ratio of biochemical inlet water is increased, the system can stably operate, the produced water is stably discharged in a standard reaching manner, anda reliable technical sch