Comparison of temperature-phased and two-phase anaerobic co-digestion of primary sludge and municipal solid waste.
Characterization of the similarities and differences between two-phase and temperature-phased systems treating primary wastewater sludge (PS) and the organic fraction of municipal solid waste (OFMSW) as substrate was performed by comparing the rates of key steps, including hydrolysis and methanogenesis. Aceticlastic methanogenic rates were determined using batch respirometric tests with inocula from operating two-phase and temperature-phased systems. The initial methane production rates ranged from 0.32 to 0.93 mL methane/g volatile solids (VS)h for all systems, with the greatest rates observed from the first stage of the temperature-phased system. Hydrolysis rates were determined from particulate chemical oxygen demand destruction. The first stage of the temperature-phased system had greater specific hydrolysis rates than the first stage of the two-phase system at each operating condition. The temperature-phased system outperformed the two-phase system in terms of methane production and VS destruction when treating a mixed OFMSW-PS stream at OFMSW-to-PS ratios of 0:100, 20:80, and 40:60. When the feed ratios were 60:40 and 80:20 OFMSW-PS, there was no significant difference in the performance of the two systems. The overall methane yield and VS destruction of the temperature-phased system ranged from 0.299 to 0.418 L/g VS fed and 47.5 to 71.6%, respectively. The overall methane yield and VS destruction of the two-phase system ranged from 0.281 to 0.332 L/g VS fed and 39.6 to 69.3%, respectively.
Schmit
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Environmental Engineering Program at Iowa State University, Ames 50011-3232, USA.
Ellis
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D001421:Bacteria, Anaerobic / Q000502:physiology*; D006868:Hydrolysis; D008697:Methane / Q000032:analysis; D012037:Refuse Disposal; D012722:Sewage / Q000382:microbiology*; D013696:Temperature
D012722:Sewage; D008697:Methane