This research was carried out to evaluate the effect of organic loading rate to the performance of anaerobic co-digestion digester treating organic fraction of food waste (FW) and sludge waste (SW) from wastewater treatment plant. The experiment was conducted in two runs: Run S50, substrate contained 50 % of FW and 50 % of SW in term of volatile solid (VS) concentration; Run S100 (control run) contained 100 % SW in the influent substrate. | Effect of organic loading rate on the performance of anaerobic co-digestion digester treating food waste and sludge waste Vietnam Journal of Science and Technology 56 (2A) (2018 ) 37-42 EFFECT OF ORGANIC LOADING RATE ON THE PERFORMANCE OF ANAEROBIC CO-DIGESTION DIGESTER TREATING FOOD WASTE AND SLUDGE WASTE Dinh Thi Nga1, *, Tran Thi Minh Ngoc2 1 Research Institute for Sustainable Development, Hochiminh City University of Natural Resources and Environment, 236B Le Van Sy, Ward 1, Tan Binh District, Hochiminh City 2 Faculty of Chemical Engineering, HoChiMinh City University of Technology, 268 Ly Thuong Kiet Street, District 10, Hochiminh City * Email: dtnga@ Received:17 March 2018; Accepted for publication: 12 May 2018 ABSTRACT This research was carried out to evaluate the effect of organic loading rate to the performance of anaerobic co-digestion digester treating organic fraction of food waste (FW) and sludge waste (SW) from wastewater treatment plant. The experiment was conducted in two runs: Run S50, substrate contained 50 % of FW and 50 % of SW in term of volatile solid (VS) concentration; Run S100 (control run) contained 100 % SW in the influent substrate. The experiment was performed in a 3L working volume reactor at ambient temperature with three levels of organic loading rate (OLR) as 2; 4; 6 kgVS/m3/day, the duration of experiment was 18 days for each level of OLR. As results, the average of biogas production rate (BPR) at OLR 2;4;6 kgVS/m3/day,in Run S50 and Run S100 was 390 – 520; 860 – 1220; 1140 - 2440 ml/day and 160 – 300; 560 – 640; 700 - 1400 ml/day, respectively. The maximum methane yield (mlCH4/gVSadded/day) of organic loading rate 2; 4; 6 kgVS/m3/day was ; ; for Run S50 and; ; ; for Run S100, respectively. In conclusion, Run S50 always produced higher biogas production rate and higher methane yield at all 3 OLR levels. The higer OLR .