The use of Anaerobic batch reactors (ABRs) for the anaerobic digestioninvolves several metabolic reactions from different functional microbialgroups. The relevance of using an ABR take root in contributing toresolve the solid waste disposal and fossil fuels dependence problems.We developed two ABRs; for ABRa we selected an anaerobic microbialcommunity (AMC) with functional roles of collagen degradation coupledwith methanogenesis, and for ABRb we selected and mixed two AMCs;one with the functional role of collagen degradation, and the other withthe role of syntrophic volatile fatty acid (VFAs) degradation. In thisresearch, we tested which ABR biotransformed more efficiently thecollagen based on methane production, the VFAs production orconsumption, and by comparing the bacterial and methanogenicpopulation among the ABRs using Denaturing Gradient Gelelectrophoresis (DGGE). Our results showed that ABRa biotransform11% of the waste in to methane generating 2.7 Watts while ABRbbiotransform only 4.4% of the waste in to methane generating 3.7 Watts.DGGE analysis showed similarity on the ABRs bacterial population,suggesting a parallel selecting process in these populations regardlessof their origin. However, differences were detected between the ABRsmethanogenic populations through time. It appears that the ABRsconverged on the same hydrogenotropic methanogen Methanospirillumhungatei. Furthermore, the accumulation of acetate, the most abundantintermediary, in ABRb suggests that an acetoclastic methanogen isabsent. In conclusion, using a single AMC in an ABR is more efficient tobiotranform collagen to methane.

The use of anaerobic batch reactor for the bioconve rsion of an Industrial solid waste to methane Luis A. Piñero García* and Luis A. Ríos Hernández

University of Puerto Rico at Mayagüez, Biology Depa rtment, Anaerobic Solutions Lab B256

SB medium

Anaerobic chamber

Inoculation of the Anaerobic batch

reactors

DGGE HPLC GC

AbstractAbstractAbstract MethodologyMethodologyMethodology

Blended

A LCH4

Waste

anaerobic solutions lab

biotranform collagen to methane.

H0: The ABR developed with an AMC with functional roles of collagendegradation coupled with methanogenesis will biotransform moreefficient the collagen into methane than the ABR developed with amixture of different AMCs.

H1: The ABR developed with an AMC with functional roles of collagendegradation coupled with methanogenesis will not biotransform moreefficient the collagen into methane than the ABR developed with amixture of different AMCs.

Finstein, M. (2010). Anaerobic digestion variants in the treatment of solid wastes. Microbe, 5(4):151-155.

Jain M., and Zeikus J. (1989). Bioconversion of Gelatin to Methane by a Coculture of Clostridium collagenovoransand Methanosarcina barkeri. Applied and Environmental Microbiology, 55:366-371.

Watanabe T., Asakawa S., Nakamura S., Nagaoka K., Kimura M. (2004). DGGE method for analyzing 16S rDNA of methanogenic archaeal community in paddy field soil. Elsevier, 232:153-163.

• Industrial solid wastes such collagen can be biotransformed to methane.

• The bacterial diversity within the reactors were similar as showed by DGGE.

•DGGE analysis showed that Methanospirillum hungatei was the onlyhydrogenotrophic methanogen responsible for the production of methane.

•An accumulation of the most abundant intermediary (acetate) in ABRb suggests lowefficiency in the degradation of this intermediary possibly suggesting syntrophicmetabolism.

• The use of one anaerobic microbial community with functional roles of collagendegradation coupled with methanogenesis is more efficient that using a mixture ofAMCs.

DGGE Bact 16SDGGE Bact 16S

A- ARBa (1 day)

B- ABRb (1 day)

C-ABRa (45 day)

D-ABRb (45 days)

E-ABRa (90 days)

F-ABRb (90 days)

G- Syntrophus aciditrophicus

A B C D E F G

DGGE HPLC GC

IntroductionIntroductionIntroduction

HypothesisHypothesisHypothesis

Results Results Results ConclusionConclusionConclusion

ReferencesReferencesReferences

In natural environments, the anaerobic digestion of organic matter suchas proteins, carbohydrates, and lipids involves a complicated processof several metabolic reactions from at least three different functionalmicrobial groups that constitutes as a whole an anaerobic microbialcommunity (Ward, A. J. 2008). The heart of the digester depends onthe bioconversion potential reflected in the amount of methaneproduced and the stability of the remaining digestate (Finstein, M.2010). The main objective of this research was to prove that anindustrial solid waste (collagen) could be transformed into a renewableenergy source using an anaerobic batch bioreactor. For our goal, itwas essential to develop two ABRs with selected functional anaerobicmicrobial communities. In this study, we determined which ABRbiotransformed more efficiently the collagen into methane, based on theproduction of methane and VFA’s; the subsequent consumption of theVFA’s, and by comparing the stability of the bacterial and methanogenicpopulation within the ABRs.

8% acrylamide, 12h, 60ºC,100v (30-50%)

DGGE Archea 16SDGGE Archea 16S

A B C D E F G H I A- ARBa (1 day)

B- ABRb (1 day)

C-ABRa (45 day)

D-ABRb (45 days)

E-ABRa (90 days)

F-ABRb (90 days)

G- Empty

H- Empty

I- Methanospirillum hungatei8% acrylamide, 12h, 60ºC,100v (50-70%)