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A variety of test procedures have been reported in the literature for determination of the specific methanogenic activity profile of anaerobic sludges and for screening synthetic organic chemicals for anaerobic biodegradability. This paper reviews the methods developed and presents data obtained in the authors' laboratory using test procedures based on pressure transducer measurement of gas pressures in sealed anaerobic vials. Data on the feasibility of freeze-drying granular sludge are also presented as part of a wider study concerning the development of a standard reference sludge for anaerobic biodegradability testing. The use of the methanogenic activity test method to assess the relative toxicity of compounds, known to inhibit methanogenesis, against individual trophic groups involved in the overall digestion process is also described.

A novel, high temperature solid absorbent based on lithium orthosilicate (Li(4)SiO(4)) has shown promise for postcombustion CO(2) capture. Previous studies utilizing a clean, synthetic flue gas have shown that the absorbent has a high CO(2) capacity, >25 wt %, along with high absorption rates, lower heat of absorption and lower regeneration temperature than other solids such as calcium oxide. The current effort was aimed at evaluating the Li(4)SiO(4) based absorbent in the presence of contaminants found in typical flue gas, specifically SO(2), by cyclic exposure to gas mixtures containing CO(2), H(2)O (up to 25 vol. %), and SO(2) (up to 0.95 vol. %). In the absence of SO(2), a stable CO(2) capacity of ∼ 25 wt % over 25 cycles at 550 °C was achieved. The presence of SO(2), even at concentrations as low as 0.002 vol. %, resulted in an irreversible reaction with the absorbent and a decrease in CO(2) capacity. Analysis of SO(2)-exposed samples revealed that the absorbent reacted chemically and irreversibly with SO(2) at 550 °C forming Li(2)SO(4). Thus, industrial application would require desulfurization of flue gas prior to contacting the absorbent. Reactivity with SO(2) is not unique to the lithium orthosilicate material, so similar steps would be required for other absorbents that chemically react with SO(2).