Chicken Manure Methanogenesis.

Abstract

Thermophilic (55 C) methanogenesis of chicken manure was examined after prolonged acclimatization procedures. Unusual steady state parameters were obtained in quasi-continuous operations: volatile solids = 24 to 96 g/L, retention time = 5 to 20 days, in which methane was continuously formed (.5 to .7 L-L~'-day~'), H 2 was not present, but acetate (19 to 222 mM), other fatty acids, and ammonia nitrogen (800 to 2,830 mg/L) levels were very high. Tracer (2-[ l4 C]acetate) studies showed that acetate accumulation resulted from inhibition of acetate conversion to methane. Enumeration of H 2 -oxidizing methanogenic populations as well as acetate-degrading methanogens indicated adequate populations in chicken manure relative to cow manure. Thus, measurement of acetate degradation activities indicated its inhibition, whereas bacterial enumeration studies indicated no lack of methanogenic bacterial populations. These findings are in disagreement with the uninhibited fast rate of aceticlastic methanogenesis in cow manure. Therefore, it may be concluded that the methanogenic populations are unchanged, but their capacity to decarboxylate acetate is somehow blocked, which would lead to concomittant accumulation of acetate in addition to the formation of C0 2 and H 2 /C0 2 -derived methane as the major fermentation end products. (

Chicken Manure Methanogenesis.

“…Results indicated the presence in the extract of similar inhibitory substances which also fail to interfere with the conversion of H 2 /C0 2 to methane. Furthermore, the correlation appeared quantitative in that the inhibition caused by a given amount of extract added was similar to that found at the corresponding chicken manure concentration in the digesters (Dosoretz and Lamed, 1986). The inhibitory substance(s) present in broiler litter can be extracted by organic solvents, in contrast to what would be expected of inorganic salts in general and of NH 3 /NH 4 + in particular.…”

“…The resemblance between the selective inhibitory effect of ionophores on the enrichment culture and the inhibition found in chicken manure fermentation (Dosoretz and Lamed, 1986) prompted the reexamination of the effect of chicken manure components on the relatively well defined acetate enrichment culture. Using either 2-[ 14 C]acetate or H 2 /C0 2 as a methanogenic substrate, sterilized water extract of broiler litter (100 g manure extracted per L) was added either at full strength or diluted in PB medium as indicated ( Figure 5).…”

“…In contrast, the sub-stance^) recovered from the two main fractions that migrated faster (CHM extract 1) and slower than monensin (CHM extract 2), did not affect (P>.05) methane formation by the acetate-enriched culture (Table 1). DISCUSSION Inhibition of acetate conversion to methane, a phenomenon which persists despite lengthy acclimatization procedures implemented in chicken manure fermentors (Dosoretz and Lamed, 1986), is one of the major obstacles which hinder the successful application of methane fermentation as a potential solution to the problem of chicken manure disposal. In order to identify the specific component(s) of chicken manure responsible for this problem, an approach was selected in which an acetate-enriched methanogenic culture is used as a model for the more complex natural system.…”

“…In previous work (Dosoretz and Lamed, 1983), the nature of thermophilic fermentation of chicken manure was examined, and a peculiar inhibition pattern was characterized (Dosoretz and Lamed, 1986). Preferential inhibition of aceticlastic methanogenesis over hydrogenophilic methanogenesis was observed with increasing manure concentration.…”