Comparison of Temperature Phased and Other State of the Art Processes for Anaerobic Digestion of Municipal Solid Waste

The temperature-phased anaerobic digestion (TPAD) process was used for the anaerobic digestion of the source separated biodegradable organic fraction of municipal solid waste (OFMSW). The TPAD process was used to co-digest OFMSW with primary wastewater solids (PS) at ratios of 20:80, 40:60, 60:40, and 80:20 O FM SW :PS. Th e OF MS W/P S feed mixtu re wa s slurrie d at co ncen trations up to 5.2% TS. T he TP AD p roces s con sisted o f two c omp letely mixed reactors operating in series. The first stage temperature was maintained at 55°C while the second stage temperature was maintained at 35°C. The purpose of this research was to compare TPAD performance with the performance of both slurry and dry digestion processes reported in the literature for the digestion of MSW. The TPAD system exhibited volati le solids (VS) removals between 58.2 ± 3.1 and 71.6 ± 2.9% and methane yields between 0.299 ± 0.017 and 0.418 ± 0.014 L/g VS fed at STP. The temperaturephased system performed comparably to other slurry processes reported in the literature with the exception that the TPAD process provides increased pathogen destruction due to the high temperature first stage. The VS reduction and methane yields for the slurry processes used for comparison range from 41 to 78% and 0.17 to 0.49 L/g VS fed, respectively. The TPAD system outperformed dry digestion proce sses. T he V S red uction and m ethan e yield s repo rted in the literature for dry digestion processes ranged from 27 to 60% and from 0.13 to 0.30 L/g VS fed, respectively.