Effects of volatile fatty acids in biohydrogen effluent on biohythane production from palm oil mill effluent under thermophilic condition

Background: Biohydrogen effluent contains a high concentration of volatile fatty acid (VFA) mainly as butyric, acetic, lactic and propionic acids. The presence of various VFAs (mixture VFAs) and their cooperative effects on two-stage biohythane production need to be further studied. The effect of VFA concentrations in biohydrogen effluent of palm oil mill effluent (POME) on methane yield in methane stage of biohythane production was investigated. Results: The methane yield obtained in low VFA loading (0.9 and 1.8 g/L) was 15­20% times greater than that of high VFA loading (3.6 and 4.7 g/L). Butyric acid at high concentrations (8 g/L) has the individual significantly negative effect the methane production process (P b 0.05). Lactic, acetic and butyric acid mixed with propionic acid at a concentration higher than 0.5 g/L has an interaction significantly negative effect on the methanogenesis process (P b 0.05). Inhibition condition had a negative effect on both bacteria and archaea with inhibited on Geobacillus sp., Thermoanaerobacterium thermosaccharolyticum, Methanoculleus thermophilus and Methanothermobacter delfuvii resulting in low methane yield. Conclusion: Preventing the high concentration of butyric acid, and propionic acid in the hydrogenic effluent could enhance methane production in two-stage anaerobic digestion for biohythane production.

Biomethane production from vinasse in upflow anaerobic sludge blanket reactors inoculated with granular sludge

ABSTRACT The main objective of this study was to evaluate the anaerobic conversion of vinasse into biomethane with gradual increase in organic loading rate (OLR) in two upflow anaerobic sludge blanket (UASB) reactors, R1 and R2, with volumes of 40.5 and 21.5 L in the mesophilic temperature range. The UASB reactors were operated for 230 days with a hydraulic detection time (HDT) of 2.8 d (R1) and 2.8-1.8 d (R2). The OLR values applied in the reactors were 0.2-7.5 g totalCOD (L d)−1 in R1 and 0.2-11.5 g totalCOD (L d)−1 in R2. The average total chemical oxygen demand (totalCOD) removal efficiencies ranged from 49% to 82% and the average conversion efficiencies of the removed totalCOD into methane were 48-58% in R1 and 39-65% in R2. The effluent recirculation was used for an OLR above 6 g totalCOD (L d)−1 in R1 and 8 gtotalCOD (L d)−1 in R2 and was able to maintain the pH of the influent in R1 and R2 in the range from 6.5 to 6.8. However, this caused a decrease for 53-39% in the conversion efficiency of the removed totalCOD into methane in R2 because of the increase in the recalcitrant COD in the influent. The largest methane yield values were 0.181 and 0.185 (L) CH4 (gtotal COD removed)−1 in R1 and R2, respectively. These values were attained after 140 days of operation with an OLR of 5.0-7.5 g totalCOD (L d)−1 and total COD removal efficiencies around 70 and 80%.

Residuos agroindustriales con potencial para la producción de metano mediante la digestión anaerobia / Agroindustrial wastes methanization and bacterial composition in anaerobic digestion

Las toneladas de residuos orgánicos que se generan anualmente en la agroindustria pueden aprovecharse como materia prima para la producción de metano. Para que los residuos orgánicos se puedan convertir a metano a gran escala, es importante que previamente se realicen sobre ellos pruebas de biodegradabilidad; un parámetro importante que conviene establecer es su potencial bioquímico de metano. En el presente trabajo se estudió la biodegradabilidad, la producción de metano y el comportamiento de poblaciones de eubacterias y arqueobacterias durante la digestión anaerobia de residuos de plátano, mango y papaya provenientes de la agroindustria, adicionando un inóculo microbiano. Los residuos de mango y plátano tenían mayor contenido de materia orgánica (94 y 75 %, respectivamente) que el residuo de papaya con base en su relación sólidos volátiles/sólidos totales. Después de 63 días de tratamiento, la mayor producción de metano se observó en la digestión anaerobia del residuo de plátano: 63,89 ml de metano por g de demanda química de oxígeno del residuo. Los resultados del potencial bioquímico de metano demostraron que el residuo de plátano tiene el mejor potencial para ser usado como materia prima en la producción de metano. A través de un análisis por PCR-DGGE con oligonucleótidos específicos se logró evaluar el tamaño y la composición de las poblaciones de eubacterias y arqueobacterias presentes en la digestión anaerobia de residuos agroindustriales a lo largo del proceso.

The tons of organic waste that are annually generated by agro-industry, can be used as raw material for methane production. For this reason, it is important to previously perform biodegradability tests to organic wastes for their full scale methanization. This paper addresses biodegradability, methane production and the behavior of populations of eubacteria and archaeabacteria during anaerobic digestion of banana, mango and papaya agroindustrial wastes. Mango and banana wastes had higher organic matter content than papaya in terms of their volatile solids and total solid rate (94 and 75 % respectively). After 63 days of treatment, the highest methane production was observed in banana waste anaerobic digestion: 63.89 ml CH4/per gram of chemical oxygen demand of the waste. In the PCR-DGGE molecular analysis, different genomic footprints with oligonucleotides for eubacteria and archeobacteria were found. Biochemical methane potential results proved that banana wastes have the best potential to be used as raw material for methane production. The result of a PCR- DGGE analysis using specific oligonucleotides enabled to identify the behavior of populations of eubacteria and archaeabacteria present during the anaerobic digestion of agroindustrial wastes throughout the process.

Quantification of ruminal microbiota and production of methane and carbonic dioxide from diets with inclusion of glycerin / Quantificação da microbiota ruminal e produção de metano e gás carbônico de dietas com inclusão de glicerina

The aim of this study was to quantify the liquid-associated bacteria and protozoa of the rumen and to evaluate the potential of in vitro production of gases CH4 and CO2 of diets with inclusion of glycerin for sheep. Two diets were formulated with a roughage:concentrate ratio of 20:80, according to the presence or absence of glycerin: G0 - control, without glycerin; and G10 - 10% glycerin as part of the concentrate. To quantify the liquid-associated bacteria and protozoa from the rumen and production of CH4 and CO2 gases, a completely randomized design was used. The diets had no effect (P>0.05) on production and composition of liquid-associated protozoa and bacteria from the rumen of lambs. Likewise, a (P>0.05) diet effect was not observed on production of CH4 and CO2 in vitro, which presented average concentrations of 24.55mL/g MS and 51.52mL/g MS, respectively. The use of 10% glycerin did not alter production or composition of ruminal microflora, and moreover, did not negatively impact the production of CH4 and CO2 gases in vitro.

Objetivou-se com este estudo quantificar as bactérias e protozoários líquido-associados do rúmen e avaliar o potencial de produção dos gases CH4 e CO2 in vitro de dietas com inclusão de glicerina para ovinos. Duas dietas foram formuladas, na proporção volumoso:concentrado de 20:80, conforme a presença ou ausência de glicerina: G0 - controle sem glicerina, G10 - 10% glicerina como parte do concentrado. Para a quantificação das bactérias e protozoários líquido-associados do rúmen e produção dos gases CH4 e CO2, utilizou-se o delineamento inteiramente ao acaso. Não foi observado efeito de dieta (P>0,05) sobre a produção e composição de protozoários e bactérias líquido-associados do rúmen de cordeiros. Da mesma forma, não houve efeito de dieta (P>0,05) sobre a produção de CH4 e CO2 in vitro, os quais apresentaram concentrações médias de 24,55mL/g MS e 51,52mL/g MS, respectivamente. O uso de 10% glicerina não altera a produção ou composição da microflora ruminal, e também não impacta negativamente a produção dos gases CH4 e CO2 in vitro.

Effect of sediment composition on methane concentration and production in the transition zone of a mangrove (Sepetiba Bay, Rio de Janeiro, Brazil) / Efeito da composição do sedimento sobre a concentração e a produção do metano na zona de transição de um mangue tropical, na Baía de Sepetiba-RJ, Brasil

The aim of this research was to evaluate the effect of sediment composition on methane (CH4) dynamics in sediments of different areas in the transition zone between a mangrove and the sea. This research was conducted in a mangrove at Coroa Grande, on the southern coast of Rio de Janeiro. Samples were collected at three stations: (1) region colonised by Rhizophora mangle L. on the edge of the mangrove, (2) region colonised by seagrasses and (3) infra-littoral region without vegetation. Samples were collected from the surface layer of the sediment to determine the concentrations of nutrients (C, N and P) and CH4 concentration and production. We observed that concentrations of CH4 and carbon (C) were significantly higher (p < 0.05) in station 1 than station 3. The molar ratios (C:N, C:P and N:P) suggest that the origin of the substrate is mainly autochthonous. Methanogenesis was initially low, possibly due to competition between methanogens and sulfate reducers, and increased significantly (p < 0.05) on the twenty-sixth day in the sediment of station 1, probably due to higher organic matter (OM) availability in this region. Results indicate that methanogenic activity observed herein is not regulated by the amount or quality of OM, but by other factors. The concentration of CH4 in the sea-land ecotone at Mangrove Coroa Grande is a function of available OM suggesting a possible inhibition of methanotrophy by intense oxygen consumption in the soil surface covered by detritus of Rhizophora mangle vegetation.

O objetivo desta pesquisa foi avaliar a dinâmica do metano (CH4) no sedimento em diferentes áreas na região de transição entre a borda do manguezal e o mar, em função da composição do sedimento. A pesquisa foi realizada no Manguezal de Coroa Grande, no litoral sul do Estado do Rio de janeiro. Foram coletadas amostras em três estações: (1) região colonizada por Rhizophora mangle L. na borda do mangue, (2) região colonizada por macrófitas, e (3) região sem vegetação, permanentemente inundada pelo mar. Foram coletadas amostras da fração superficial do sedimento para determinação da concentração de nutrientes (C, N e P), e da concentração e da produção de CH4. Foi observado que as concentrações de CH4 e carbono (C) foram significativamente maiores (p < 0,05) na estação 1, em relação à estação 3. Com relação às razões molares (C:N, C:P e N:P), estas indicam que a origem da composição do substrato é principalmente autóctone. Quanto à metanogênese, foram observados, inicialmente, baixos valores de CH4 produzido, indicando provável competição entre metanogênicos e sulfatorredutores. Seguiu-se, então, um significativo aumento (p < 0,05) da metanogênese no 26º dia, no sedimento da estação 1, provavelmente em função da maior disponibilidade de matéria orgânica (MO) nessa região. Os resultados mostram que a atividade metanogênica observada pela presente pesquisa não é regulada pela quantidade e a qualidade da MO e sim por outros fatores. A concentração de CH4 no ecótono mar-terra no manguezal de Coroa Grande, ocorre em função da MO disponível, sugerindo possível inibição da metanotrofia, em razão de intenso consumo de oxigênio na superfície do solo coberto pelo detrito da vegetação de Rhizophora mangle.

Monensin effect on rumen metabolic profile, methane production and protozoal population in buffalo-heifers

Thirteen propuberal buffalo-heifers aged 10-14 months were kept on the experimental farm on National Research Center, to investigate the effects of monensin on rumen metabolic profile, mithane production and protozoal population. The experimental animals were radomly allotted into two groups: control group of 5 heifers fed a pelleted concentrate and monensin group of 8 heifers which received the same concentrate after milling and mixing with 100 mg monensin head daily. Rumen samples were taken from buffalo-heifers of both groups 8 and 10 months after the beginning of treatment, before and 2 hours post-feeding. The rumen juice was subjected for determination of pH value, ammonia production, total and individual volatile fatty acids. Methane was also calculated and derect smears from the whole rumen contents were made for detection of protozoal density. pH values were not affected by neither feeding nor monensin and ammonia production was increased significantly by feeding, while monensin administration lowered the amonia production. The values of total volalille fotty avds [TVFAS] were elevated significantly by control feeding regime while monensin had no significant effects on the TVFAS concentrations. The production of acetic acid decreased in the rumen of monensin treated heifers. Monensin supplementation resulted in increasing the propionic acid production. The concentration of butyric acid was not affected by adding monensin. The molar prportions of acitic: propionic: butyric acids were 53.82: 26.34:19.75 under feeding of basal diet, and 41.82: 38.64: 19.53 on monensin administration. Monensin lowered the production of mentane in the rumen. Moreover, the density of protozoal population decreased in the rumen liquor of buffalo-heifers receiving monensin. In conclusion, monensin acts as a propionate enhancer and methane inhibitor. Thus, use of monensin as a feed additive may be profitable and incentive in buffalo production

Methane biogenesis at low pH and null alkalinity conditions: I. Perspectives of a new operational concept in the anaerobic treatment of industrial wastewaters

Propöe-se novo conceito operacional para tratamento anaeróbio de efluentes industriais com vistas ta metanogênese, sob condiçöes de pH ácido, elevada acidez volátil e alcalinidade total nula. Fundamenta-se na elevada capacidade de adaptaçäo dos microrganismos ao ambiente e visa diminuir custos de operaçäo e controle bem como, minimizar as consequências de desequilíbrio entre a acidogênese e metanogênese. Utilizou-se reatores de laboratórios ligados em série, alimentados em fluxo contínuo ascendente, com temperatura controlada e reciclagem de lodo. O substrato foi água residuária da indústria de chapas de fibras da madeira com correçäo da relaçäo DQO:N:P à razäo de 40:0:0,2, e adiçäo de CaCO3 à base de 100mg/. Ressalte-se que näo foi adotado nenhum outro tipo de controle para balancear a relaçäo acidez volátil/alcalinidade total. Duas fontes de inóculo foram testadas: uma oriunda de digestor operado com lodo de esgoto urbano e outra, de digestor operado em fase ácida, com água servida. Os resultados obtidos ao longo de 201 dias de operaçäo do protótipo de laboratório confirmaram a hipótese central do trabalho, para ambas as fontes de inóculo. Entretanto, tendo em vista que o teor de metano no biogás raramente superou 50% (em média 20 a 25%), o novo conceito deverá ser submetido a estudos de otimizaçäo visando alcançar rendimento similar à metanogênese em pH neutro convencional