Influence of hydrothermal pretreatment conditions, typology of anaerobic digestion system, and microbial profile in the production of volatile fatty acids from olive mill solid waste

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.

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Performance evaluation of mesophilic semi-continuous anaerobic digestion of high-temperature thermally pre-treated olive mill solid waste

Waste Management ◽

10.1016/j.wasman.2019.02.003 ◽

2019 ◽

Vol 87 ◽

pp. 250-257 ◽

Cited By ~ 10

Author(s):

Antonio Serrano ◽

Fernando G. Fermoso ◽

Bernabé Alonso-Fariñas ◽

Guillermo Rodríguez-Gutiérrez ◽

Sergio López ◽

...

Keyword(s):

Performance Evaluation ◽

High Temperature ◽

Anaerobic Digestion ◽

Solid Waste ◽

Olive Mill Solid Waste ◽

Olive Mill

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Long-Term Evaluation of Mesophilic Semi-Continuous Anaerobic Digestion of Olive Mill Solid Waste Pretreated with Steam-Explosion

Energies ◽

10.3390/en12112222 ◽

2019 ◽

Vol 12 (11) ◽

pp. 2222 ◽

Cited By ~ 4

Author(s):

Antonio Serrano ◽

Fernando G. Fermoso ◽

Bernabé Alonso-Fariñas ◽

Guillermo Rodríguez-Gutiérrez ◽

Sergio López ◽

...

Keyword(s):

Anaerobic Digestion ◽

Phenolic Compounds ◽

Solid Waste ◽

Steam Explosion ◽

Loading Rates ◽

Microbial Inhibitors ◽

Olive Mill Solid Waste ◽

Term Evaluation ◽

Olive Mill

Steam-explosion is a promising technology for recovering phenolic compounds from olive mill solid waste (OMSW) due to its high impact on the structure of the fibre. Moreover, the recovery of the phenols, which are well-known microbial inhibitors, could improve the subsequent biomethanization of the dephenolized OMSW to produce energy. However, there is a considerable lack of knowledge about how the remaining phenolic compounds could affect a long-term biomethanization process of steam-exploded OMSW. This work evaluated a semi-continuous mesophilic anaerobic digestion of dephenolized steam-exploited OMSW during a long operational period (275 days), assessing different organic loading rates (OLRs). The process was stable at an OLR of 1 gVS/(L·d), with a specific production rate of 163 ± 28 mL CH4/(gVS·d). However, the increment of the OLR up to 2 gVS/(L·d) resulted in total exhaust of the methane production. The increment in the propionic acid concentration up to 1486 mg/L could be the main responsible factor for the inhibition. Regardless of the OLR, the concentration of phenolic compounds was always lower than the inhibition limits. Therefore, steam-exploited OMSW could be a suitable substrate for anaerobic digestion at a suitable OLR.

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Biogas Potential of the Side Streams Obtained in a Novel Phenolic Extraction System from Olive Mill Solid Waste

Molecules ◽

10.3390/molecules25225438 ◽

2020 ◽

Vol 25 (22) ◽

pp. 5438

Author(s):

África Fernández-Prior ◽

Ángeles Trujillo-Reyes ◽

Antonio Serrano ◽

Guillermo Rodríguez-Gutiérrez ◽

Claudio Reinhard ◽

...

Keyword(s):

Anaerobic Digestion ◽

Phenolic Compounds ◽

Olive Oil ◽

Solid Waste ◽

Suspended Solids ◽

Extraction Process ◽

Methane Yield ◽

Yield Coefficient ◽

Olive Mill Solid Waste ◽

Olive Mill

The olive oil production is an important industrial sector in many Mediterranean areas, but it is currently struggled by the necessity of a proper valorisation of the olive mill solid waste or alperujo. The alperujo is the main by-product generated during the two-phase olive oil extraction, accounting for up to 80% of the initial olive mass. The alperujo is a source of valuable compounds, such as the pomace olive oil or highly interesting phenolic compounds. In the present research, a novel biorefinery approach has been used for phenolic compounds recovery. However, the extraction of these valuables compounds generates different exhausted phases with high organic matter content that are required to be managed. This study consists of the evaluation of the anaerobic biodegradability of the different fractions obtained in a novel biorefinery approach for the integral valorisation of alperujo. The results show that the different phases obtained during the biorefinery of the alperujo can be effectively subjected to anaerobic digestion and no inhibition processes were detected. The highest methane yield coefficients were obtained for the phases obtained after a two-months storages, i.e., suspended solids and liquid phase free of suspended solids, which generated 366 ± 7 mL CH4/g VS and 358 ± 6 mL CH4/g VS, respectively. The phenol extraction process reduced the methane yield coefficient around 25% due to the retention of biodegradable compounds during the extraction process. Regardless of this drop, the anaerobic digestion is a suitable technology for the stabilization of the different generated residual phases, whereas the high market price of the extracted phenols can largely compensate the slight decrease in the methane generation.

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Batch culture growth of Chlorella zofingiensis on effluent derived from two-stage anaerobic digestion of two-phase olive mill solid waste

Electronic Journal of Biotechnology ◽

10.2225/vol11-issue2-fulltext-1 ◽

2008 ◽

Vol 11 (2) ◽

pp. 0-0 ◽

Cited By ~ 7

Author(s):

Lissette Travieso Cordoba ◽

Alma Rosa Dominguez Bocanegra ◽

Barbara Rincon Llorente ◽

Enrique Rincon Llorente ◽

Francisco Benitez Echegoyen ◽

...

Keyword(s):

Anaerobic Digestion ◽

Solid Waste ◽

Batch Culture ◽

Two Stage ◽

Two Phase ◽

Chlorella Zofingiensis ◽

Olive Mill Solid Waste ◽

Culture Growth ◽

Olive Mill

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Effect of alkaline pretreatment on anaerobic digestion of olive mill solid waste

Waste Management ◽

10.1016/j.wasman.2016.08.008 ◽

2016 ◽

Vol 58 ◽

pp. 160-168 ◽

Cited By ~ 22

Author(s):

Frantseska-Maria Pellera ◽

Sofia Santori ◽

Raffaella Pomi ◽

Alessandra Polettini ◽

Evangelos Gidarakos

Keyword(s):

Anaerobic Digestion ◽

Solid Waste ◽

Alkaline Pretreatment ◽

Olive Mill Solid Waste ◽

Olive Mill

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Limiting factors for anaerobic digestion of olive mill wastewater blends under mesophilic and thermophilic conditions

Journal of Agricultural Engineering ◽

10.4081/jae.2018.792 ◽

2018 ◽

Vol 49 (2) ◽

pp. 130-137

Author(s):

Demetrio Antonio Zema ◽

Giovanni Zappia ◽

Souraya Benalia ◽

Giuseppe Zimbalatti ◽

Enzo Perri ◽

...

Keyword(s):

Fatty Acids ◽

Anaerobic Digestion ◽

Volatile Fatty Acids ◽

Biogas Production ◽

Olive Mill Wastewater ◽

Limiting Factors ◽

Citrus Peel ◽

Thermophilic Conditions ◽

High Concentrations ◽

Olive Mill

Experimental trials of anaerobic digestion of olive mill wastewater (OMW) blended with other agro-industrial by-products were carried out to evaluate biogas production and sensitivity of the process to inhibiting compounds. Blends containing different percentages of OMW, digested liquid manure, and citrus peel were subjected to a batch anaerobic digestion process under both mesophilic and thermophilic conditions. The results showed that blends with percentages of OMW higher than 20% (v/v) had low methane yields due high concentrations of polyphenols (PPs) and/or volatile fatty acids (concentrations above 0.8 g kg–1 and 2.4 g L–1, respectively). The addition of other substrates such as citrus peel may have induced synergic inhibiting effects of PPs and essential oils (EO) on microbial growth. Thermophilic processes were more sensitive to these inhibiting compounds than mesophilic processes. The results of this study suggest that reducing PPs and EO concentrations in blends subject to anaerobic digestion below the inhibiting concentrations of 0.6 g L–1 and 0.5 g kg–1, respectively, is suitable. Additionally, it is advisable to maintain the volatile fatty acids content below 2 g L–1 to avoid its evident toxic effects on the growth of microorganisms in biochemical processes.

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