Landfill recirculation of leachate concentrates from evaporation treatment process

Abstract

It is established that landfill leachate recirculation (i) speeds up waste biodegradation, (ii) reduces leachate pollution and (iii) increases biogas production by enhancement of waste moisture content and consecutive activated biological degradation. To evaluate the impact of leachate concentrate recirculation on leachate quantity and quality and biogas production, CReeD has conducted a laboratory study in co-operation with Cemagref. Two columns have been filled with a reconstituted typical waste; check column received only water whereas test column received water and concentrates. Present results (after 400 days of monitoring) show that methanogenesis has installed later in test column than in check column. The concentrate seems to hinder bacterial development as shown by the smaller biogas production of the test column (29% smaller than the check one in volume). The organic load of concentrate appears totally restituted. The hydric balance shows that 97% of the recirculated volumes are immediately restituted whereas restitution of the mineral load of concentrate is delayed but also nearly total (70 to 100% of restitution). The main conclusion is that concentrate recirculation has not the same beneficial effects as the leachate one. Future results of the still on-going study will allow knowing if actual trends are confirmed.