Effects of char from biomass gasification on carbon retention and nitrogen conversion in landfill simulation...

The application of char from biomass gasification as a filling material in landfill simulation reactors was investigated to evaluate the effect of char on carbon retention and nitrogen leaching, nitrogen denitrification, and waste stabilization. Landfill simulation columns filled with fine fraction of aged refuse (AR) and solid fraction of digestate (SFD) were used, with two char application methods: embedding a char layer between AR and SFD layers and mixing char with the SFD. The experimental results show that char application increased the biodegradable organic matter content as the respiration index (RI₄) of the mixture char-SFD increased up to 37.7%, which could enhance the heterotrophic denitrification. Moreover, 12.3% of ammonia leaching was avoid by applying the SFD mixed with char. These results indicate that char from biomass gasification poses a significant enhancement on nitrogen and carbon retention which might increase the denitrification capacity of the SFD in the long run. Although high nitrogen removal rates were achieved (up to 23.1 mg N/kg-TS day), the addition of char from biomass gasification has little effect on the nitrate removal.