[Pilot scale research on impacts of leachate recirculation on its ultimate treatment].

Two pilot scale simulated columns, with and without leachate recirculation, were erected to study impacts of leachate recirculation of traditional anaerobic bioreactor landfill on leachate ultimate treatment methods. The results indicate that recirculation can remove organic pollutants visibly, but it isn't effective to inbiodegradable components, nitrogen (N) and phosphorus (P) pollutants. After recircualted for 44 weeks, test column has a BODs removal ratio of 98.5%. BOD5/COD value of outflow is only 0.07. BOD5/TN and BOD5/TP are 0.13 and 11 respectively, which are much lower than the adequate value for anaerobic microorganisms. It's difficult to treat this kind of leachate by traditional biological methods. When a bioreactor landfill is being designed, leachate characteristics after recirculated should be well considered and adequate leachate treatment, landfill and recirculation schemes should be chosen to take full advantage of waste stack decontamination effects.