Effect of volumetric organic loading rate (OLR) on H 2 and CH 4 production by two-stage anaerobic co-digestion of food waste and brown water.

•The effect of change in OLR by HRT in H2 and CH4 production.•Household generated food waste (FW) and brown water (BW) was used for codigestion.•The highest H2 production and yield was observed in acidogenic reactor at HRT of 8h with OLR of 106gVS/L·d.•The highest CH4 production and yield was observed in methanogenic reactor at HRT of 20days with OLR of 1.24gVS/L·d.•Longer HRT is favorable for higher lactate degradation.