Effects of long-lasting nitrogen and organic shock loadings on an engineered biofilter treating matured landfill...

The decentralized bioreactor is a promising process for landfill leachate (LL) treatment, however, it is often confronted with various forms of shock loadings. To explore the robustness of bioreactors to the long-lasting substrate shocks, a long-term study of over 90 days was carried out to investigate the effects of nitrogen (mainly ammonium nitrogen, NH₄-N) and organic (in terms of chemical oxygen demand, COD) shock loading on an engineered zeolite-based biofilter with alternative soil-mixed block (SMB) (EZS-biofilter) for treating matured LL. The low-, mid-, and high-strength intensity of matured LL was theoretical defined mainly according to the content of total nitrogen (TN) and COD. The experiment proved that the EZS-biofilter could effectively absorb the substrate shocks in a range of 104, 408, and 1357 mg/L as TN and 178, 590, and 1050 mg/L as COD, corresponding to the low-, medium-, and high-strength LL, respectively. A modified sensitivity index reflected that the nitrogen shock loadings exerted much more predominant influence than COD shock due to the great variation of nitrification/denitrification. The provided information in this study are beneficial for the practical engineered operation of biofilters for treating matured LL.