Thermophilic anaerobic fermentation of olive pulp for hydrogen and methane production: modelling of the anaerobic digestion process

2006 ◽  
Vol 53 (8) ◽  
pp. 271-279 ◽  
Author(s):  
H.N. Gavala ◽  
I.V. Skiadas ◽  
B.K. Ahring ◽  
G. Lyberatos

The present study investigates the thermophilic biohydrogen and methane production from olive pulp, which is the semi-solid residue coming from the two-phase processing of olives. It focussed on: a) production of methane from the raw olive pulp; b) anaerobic bio-production of hydrogen from the olive pulp; c) subsequent anaerobic treatment of the hydrogen-effluent with the simultaneous production of methane; and d) development of a mathematical model able to describe the anaerobic digestion of the olive pulp and the effluent of hydrogen producing process. Both continuous and batch experiments were performed. The hydrogen potential of the olive pulp amounted to 1.6 mmole H2 per g TS. The methane potential of the raw olive pulp and hydrogen-effluent was as high as 19 mmole CH4 per g TS suggesting that: a) olive pulp is a suitable substrate for methane production; and b) biohydrogen production can be very efficiently coupled with a subsequent step for methane production.

2005 ◽  
Vol 52 (1-2) ◽  
pp. 209-215 ◽  
Author(s):  
H.N. Gavala ◽  
I.V. Skiadas ◽  
B.K. Ahring ◽  
G. Lyberatos

The present study investigates the potential for thermophilic biohydrogen and methane production from olive pulp, which is the semi-solid residue coming from the two-phase processing of olives. It focussed on: a) production of methane from the raw olive pulp, b) anaerobic bio-production of hydrogen from the olive pulp, and c) subsequent anaerobic treatment of the hydrogen-effluent with the simultaneous production of methane. Both continuous and batch experiments were performed. The hydrogen potential of the olive pulp amounted to 1.6 mmole H2 per g TS. The methane potential of the raw olive pulp and hydrogen-effluent was as high as 19 mmole CH4 per g TS. This suggests that olive pulp is an ideal substrate for methane production and it shows that biohydrogen production can be very efficiently coupled with a subsequent step for methane production.


Fermentation ◽  
2021 ◽  
Vol 7 (4) ◽  
pp. 284
Author(s):  
Xiaojue Li ◽  
Naoto Shimizu

To enhance anaerobic fermentation during food waste (FW) digestion, pretreatments can be applied or the FW can be co-digested with other waste. In this study, lipase addition (LA), hydrothermal pretreatment (HTP), and a combination of both methods (HL) were applied to hydrolyze organic matter in FW. Furthermore, the effects of crude glycerol (CG), which provided 5%, 10%, and 15% of the volatile solids (VS) as co-substrate (denoted as CG5, CG10, and CG15, respectively), on the anaerobic digestion of FW were assessed. With an increasing proportion of CG in the co-digestion experiment, CG10 showed higher methane production, while CG15 negatively affected the anaerobic digestion (AD) performance owing to propionic acid accumulation acidifying the reactors and inhibiting methanogen growth. As the pretreatments partially decomposed hard-to-degrade substances in advance, pretreated FW showed a stronger methane production ability compared with raw FW, especially using the HL method, which was significantly better than co-digestion. HL pretreatment was shown to be a promising option for enhancing the methane potential value (1.773 NL CH4/g VS) according to the modified Gompertz model.


Author(s):  
D. de la Lama-Calvente ◽  
M. J. Fernández-Rodríguez ◽  
J. Llanos ◽  
J. M. Mancilla-Leytón ◽  
R. Borja

AbstractThe biomass valorisation of the invasive brown alga Rugulopteryx okamurae (Dictyotales, Phaeophyceae) is key to curbing the expansion of this invasive macroalga which is generating tonnes of biomass on southern Spain beaches. As a feasible alternative for the biomass management, anaerobic co-digestion is proposed in this study. Although the anaerobic digestion of macroalgae barely produced 177 mL of CH4 g−1 VS, the co-digestion with a C-rich substrate, such as the olive mill solid waste (OMSW, the main waste derived from the two-phase olive oil manufacturing process), improved the anaerobic digestion process. The mixture improved not only the methane yield, but also its biodegradability. The highest biodegradability was found in the mixture 1 R. okamurae—1 OMSW, which improved the biodegradability of the macroalgae by 12.9% and 38.1% for the OMSW. The highest methane yield was observed for the mixture 1 R. okamurae—3 OMSW, improving the methane production of macroalgae alone by 157% and the OMSW methane production by 8.6%. Two mathematical models were used to fit the experimental data of methane production time with the aim of assessing the processes and obtaining the kinetic constants of the anaerobic co-digestion of different combination of R. okamurae and OMSW and both substrates independently. First-order kinetic and the transference function models allowed for appropriately fitting the experimental results of methane production with digestion time. The specific rate constant, k (first-order model) for the mixture 1 R. okamurae- 1.5 OMSW, was 5.1 and 1.3 times higher than that obtained for the mono-digestion of single OMSW and the macroalga, respectively. In the same way, the transference function model revealed that the maximum methane production rate (Rmax) was also found for the mixture 1 R. okamurae—1.5 OMSW (30.4 mL CH4 g−1 VS day−1), which was 1.6 and 2.2 times higher than the corresponding to the mono-digestions of the single OMSW and sole R. okamurae (18.9 and 13.6 mL CH4 g−1 VS day−1), respectively.


2000 ◽  
Vol 42 (10-11) ◽  
pp. 247-255 ◽  
Author(s):  
J. Paing ◽  
B. Picot ◽  
J. P. Sambuco ◽  
A. Rambaud

Sludge accumulation and the characteristics of anaerobic digestion in sludge had been investigated in a primary anaerobic lagoon. Methanogenic potential of sludge was evaluated by an anaerobic digestion test which measured the methane production rate. Sludge was sampled at several points in the lagoon to determine spatial variations and with a monthly frequency from the start-up of the lagoon to observe the development of anaerobic degradation. Maximum amounts of sludge accumulated near the inlet. The mean methane production of sludge was 2.9 ml gVS–1 d–1. Sludge near the outlet presented a greater methanogenic activity and a lesser concentration of volatile fatty acids than near the inlet. The different stages of anaerobic degradation were spatially separated, acidogenesis near the inlet and methanogenesis near the outlet. This staged distribution seemed to increase efficiency of anaerobic fermentation compared with septic tanks. Methane release at the surface of the lagoon was estimated to be very heterogeneous with a mean of 25 l m–2 d–1. The development of performance and sludge characteristics showed the rapid beginning of methanogenesis, three months after the start-up of the anaerobic lagoon. Considering the volume of accumulated sludge, it could however be expected that methanogenic activity would further increase.


2006 ◽  
Vol 54 (4) ◽  
pp. 149-156 ◽  
Author(s):  
H. Kalfas ◽  
I.V. Skiadas ◽  
H.N. Gavala ◽  
K. Stamatelatou ◽  
G. Lyberatos

The management of the wastewater originating from olive oil producing industries poses a serious environmental problem. Recently, two-phase production of olive oil has been developed, leading to almost complete elimination of the bulk of the generated wastewater and, is thus regarded as an environmentally friendly technology. However, the main waste stream (olive pulp) is a slurry material characterized by high solids concentration (∼30%), requiring stabilisation before its final disposal. The anaerobic digestion of olive pulp is studied in this work under mesophilic and thermophilic conditions in CSTR-type digesters. The digesters were fed with water-diluted (1:4) olive pulp at an HRT of 20 days and an OLR of 3.94 kg COD m−3 d−1. In order to study the process kinetics, the digesters were subjected to impulse disturbances of different substrates. The IWA anaerobic digestion model was used to simulate the reactors' response. Some key process parameters, such as the specific maximum uptake rate constants and the saturation constants for the volatile fatty acids degradation were estimated and compared with the standard values suggested by the ADM1.


2011 ◽  
Vol 356-360 ◽  
pp. 2510-2514 ◽  
Author(s):  
Ming Fen Niu ◽  
Sai Yue Wang ◽  
Wen Di Xu ◽  
An Dong Ge ◽  
Hao Wang

In order to improve the rate of degradation of cellulose in corn straw, the study has an important significance that compost corn straw with inoculating high-efficient microbe agents. The experiment inoculated a cellulose-degrading strain F2 which was screened from compost into compost pretreatment, the VS of corn straw reduced from 93.14% to 71.69% after 15 days, the content of cellulose reduced from 34.12g·kg-1 to 25.66g·kg-1, the rate of degradation was 24.79% which was 10.60% higher than those without the strain. An anaerobic fermentation experiment was carried out with the two groups of composted corn straw and mixed pig feces with a certain ratio, and investigations of biogas production, pH, content of volatile fatty acids(VFA) and rate of methane production were conducted. The results were that the corn straw composted with the cellulose-degrading strain peaked 4 days earlier, the maximal daily biogas production was 1470mL, the cumulative biogas production reached 23641mL which was 16.87% higher and operated stably earlier. The study showed that the cellulose-degrading strain had a strong capacity to degrade cellulose in corn straw, and then improved the performance of anaerobic digestion.


2020 ◽  
Vol 14 (4) ◽  
pp. 551-557
Author(s):  
Yongku Li ◽  
Xiaomin Hu ◽  
Lei Feng

The changing parameters, as the biogas production rate, the methane production rate, the cumulative biogas amount, the cumulative methane amount, the biogas composition, pH etc. in high temperature anaerobic fermentation of chicken manure and stalks were analyzed by experiments with different mass ratios of chicken manure or livestock manure and stalks with a high C/N ratio. The methane production mechanism of high temperature anaerobic digestion of chicken manure and stalks was discussed in detail. It showed that not only the biogas production rates but also the methane production rates of R1–R7 demonstrated the trend of initial increase and then decrease after 50 d of high temperature anaerobic digestion. Besides, the gas production of R1 with pure chicken manure stopped on the 30th d of the reaction. The gas production of other groups R2–R7 also stopped on the corresponding 34th, 36th, 36th, 37th, 37th, and 37th day, respectively. At the end of the reaction, the cumulative biogas amounts and the cumulative methane amounts of R1–R7 were 411.58 and 269.54, 459.91 and 314.41, 425.32 and 294.11, 401.85 and 272.54, 382.63 and 257.07, 363.04 and 218.16, and 257.15 and 160.10 N ml/(g VS). The biogas slurry pH of R1–R7 all demonstrated a trend of initial decrease and then increase, e. g., pH of R2 reached the minimum of 5.94 on the 5th day. pH values of other groups were between 6.01 and 6.39. After the addition of 4 g of sodium bicarbonate on the 7th day, biogas slurry pH of R1–R7 all increased. pH was maintained between 7.16 and 7.44 until the end of the reaction.


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