BIO-METHANE POTENTIAL TEST FOR ANAEROBIC CO-DIGESTION OF FAECAL SLUDGE AND SEWAGE SLUDGE

Faecal sludge (FS) samples taken in Hanoi urban area had COD values ranging from 2.83 g/L to 83.83 g/L,TN values from 0.18 g/L to 3.95 g/L, and VS/TS ratio from 47.5 % to 87.7 %. Sewage sludge (SS) samples taken from sewage treatment plants in Hanoi had COD values ranging from 2.22 g/L to 24.97 g/L, TN from 0.16 g/L to 1.24 g/L, VS/TS ratio from 53.5 % to 69.5 %. Bio-methane potential (BMP) tests at mesophilic anaerobic condition (35 oC) provided results of methane production from FS, primary sewage sludge (PSS), waste activated sludge (WAS1 and WAS2) and mixture of primary and secondary sewage sludge at sludge thickener (WAS) as much as 242.3 NmL/gVS, 310.5 NmL/gVS, 294 NmL/gVS, 228.2 NmL/gVS and 282.3 NmL/gVS, respectively. Co-digestion of FS and WAS at different mixing ratios provided from 269.3 NmL to 294.8 NmL CH4 per gram of fed substrate VS. The values of methane yield have shown promising sludge-to-energy option with FS-SS co-digestion. FS-SS co-digestion in anaerobic digesters built at municipal sewage treatment plants which are often working under capacity provides chance to combat with FS and SS challenges, utilizing infrastructure facilities efficiently.