The influence of leachate composition on anaerobic digestion stability and biogas yields

In this paper the leachate composition influence on anaerobic digestion stability and biogas production was presented. Co-digestion of Sewage Sludge (SS) and landfill Leachate (L) requires an adequate period of microorganisms acclimatization. The results show that addition of old leachate as a co-substrate to anaerobic digestion process requires longer acclimatization time about 75 days, while using leachate of medium age, 60-day acclimatization is adequate. The addition of medium leachate (landfill aged from 5 to 10 years) to anaerobic digestion process of sewage sludge in ratio SS:L = 20:1 and 10:1 provided the growth of biogas yield for about 50 and 15% respectively, compared with biomethanization process of only sewage sludge. In this case biogas yield was 1.55 m(3) kg(-1)VS(rem) (20:1) and 1.18 m(3) kg(-1)VS(rem) (10:1). Application of leachate obtained from long age landfill (>10 years) in ratio 20:1 and 10:1 resulted in biogas yield decrease for about 30%, despite achieving fermentation stable conditions.