Anaerobic Treatment of Municipal Wastewater at Mesophilic and Psychrophilic Temperatures Using Bench Scale Upflow Anaerobic Sludge Blanket (UASB) Reactors

Abstract

The limitation of high TSS wastewater treatment is hydrolysis. At low temperatures, the hydrolytic rate limitation is exacerbated. This project investigates the operational conditions required to improve the hydrolytic rate of mesophilic wastewater at 16℃ and the potential for psychrophilic wastewater treatment at 2.5℃. Parameters studied in this thesis include Methane Production rate, Methane Yield, COD Removal, VFA removal and Upflow velocity. At 16℃ OLRs between 2.5 and 6.4 gCOD/L∙d were investigated as well as upflow velocities of 23, 42 and 68 m/d. Maximum CODRE and Methane Yield were 44% and 68% respectively. Average CODRE was low at 33% and this was attributed to granule-substrate incompatibility.

The possibility of anaerobic wastewater treatment at 2.5℃ was tested and confirmed with an average sCODRE of 31% and an average Methane Yield of 83% was achieved during an average OLR of 5.42gCOD/L∙d. The organic loading limit for treatment of Grødaland wastewater was below 8gCOD/L∙d. A mixture of granules from different sources was more effective at treating wastewater than singly sourced granules. Optimal sCODRE was 32% and occurred at an OLR of 2.45gCOD/L.d