This study aims at investigating the effects of micro-nano municipal solid waste (MSW) incinerator (MSWI) fly ash (FA) and bottom ash (BA) on the MSW anaerobic digestion. Results showed that suitable micro-nano and non micro-nano MSWI ashes addition (FA/MSW 3, 6, 18 and 30 g g(-1) VS and BA/MSW 12, 36,60 and 120 g g(-1) VS) could enhance the biogas production compared to the control. It was particularly found to have the highest biogas production at the micro-nano MSWI BA/MSW ratio of 36 g g(-1) VS (similar to 193 mL g(-1) VS MSW, similar to 3.5 times to the control). Micro-nano MSWI FA and BA added bioreactors had the higher biogas production than the corresponding non micro-nano MSWI FA and BA added ones. Suitable MSWI ashes addition could improve the biogas production due to the released metals levels suitable for the MSW anaerobic digestion particularly found in the micro-nano added bioreactors. (C) 2012 Elsevier Ltd. All rights reserved.