A method of processing landfill leachate by use of a membrane separation process is disclosed. Specifically, the following steps are taken to process landfill leachate: collecting landfill leachate in a receptacle suitable to hold said landfill leachate; treating said landfill leachate with one or more water soluble polymers, wherein said water soluble polymers are selected from the group consisting of: amphoteric polymers; cationic polymers; zwitterionic polymers; and a combination thereof; optionally mixing said water soluble polymers with said landfill leachate; passing said treated landfill leachate through a membrane, wherein said membrane is an ultrafiltration membrane or a microfiltration membrane; and optionally back-flushing said membrane to remove solids from the membrane surface.