Biogas production from wet olive mill wastes pretreated with hydrogen peroxide in alkaline conditions

AbstractIn this study, the influence of alkaline hydrogen peroxide (H2O2) pretreatment of the three different plant sources: Miscanthus giganteus, Sorghum Moench, and Sida hermaphrodita, for biogas production was investigated. The influence of temperature, reaction time, and H2O2 concentration on the efficiency of biomass degradation and on the further methanogenic fermentation were studied. The results obtained after chemical pretreatment indicate that using H2O2 at alkaline conditions leads to the decomposition of three major structures: lignin, hemicellulose, and cellulose. The best results were achieved for the process performed at 25°C for 24 h with the use of a 5 mass % H2O2 solution. Although the degradation level was very high for all three plant sources, the biogas production from the energy crops pretreated chemically was strongly inhibited by byproducts and the residual oxygen formed after H2O2 decomposition. This fact indicates that alkaline H2O2 pretreatment is a very promising method for plant material degradation for further biogas production, but pretreated biomass must be separated from supernatant before the fermentation process because of the high concentration of inhibitors in the hydrolysates. The best results were obtained for Sida with biogas and methane production of 2.29 Ndm3 and 1.06 Ndm3, respectively.

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Adaptation of Methanogenic Communities to the Cofermentation of Cattle Excreta and Olive Mill Wastes at 37°C and 55°C

Applied and Environmental Microbiology ◽

10.1128/aem.00961-10 ◽

2010 ◽

Vol 76 (19) ◽

pp. 6564-6571 ◽

Cited By ~ 63

Author(s):

Marta Goberna ◽

Maria Gadermaier ◽

Carlos García ◽

Bernhard Wett ◽

Heribert Insam

Keyword(s):

Steady State ◽

Biogas Production ◽

Fold Increase ◽

Rrna Gene ◽

Two Phase ◽

Methanogenic Activity ◽

Gene Copies ◽

Olive Mill Wastes ◽

Uncultured Archaea ◽

Olive Mill

ABSTRACT The acclimatization of methanogens to two-phase olive mill wastes (TPOMW) was investigated in pilot fermenters started up with cattle excreta (37°C) and after changing their feed to excreta plus TPOMW (37°C or 55°C) or TPOMW alone (37°C) until a steady state was reached (28 days). Methanogenic diversity was screened using a phylogenetic microarray (AnaeroChip), and positive targets were quantified by real-time PCR. Results revealed high phylogenetic richness, with representatives of three out of the four taxonomic orders found in digesters. Methanosarcina dominated in the starting excreta (>96% of total 16S rRNA gene copies; over 45 times more abundant than any other methanogen) at high acetate (0.21 g liter−1) and ammonia N concentrations (1.3 g liter−1). Codigestion at 37°C induced a 6-fold increase of Methanosarcina numbers, correlated with CH4 production (r Pearson = 0.94; P = 0.02). At 55°C, the rise in temperature and H2 partial pressure induced a burst of Methanobacterium, Methanoculleus, Methanothermobacter, and a group of uncultured archaea. The digestion of excreta alone resulted in low but constant biogas production despite certain oscillations in the methanogenic biomass. Unsuccessful digestion of TPOMW alone was attributed to high Cu levels inducing inhibition of methanogenic activity. In conclusion, the versatile Methanosarcina immediately adapted to the shift from excreta to excreta plus TPOMW and was responsible for the stimulated CH4 production at 37°C. Higher temperatures (55°C) fostered methanogenic diversity by promoting some H2 scavengers while yielding the highest CH4 production. Further testing is needed to find out whether there is a link between increased methanogenic diversity and reactor productivity.

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Increase of the anaerobic biodegradability of olive mill wastewaters through a pre-treatment with hydrogen peroxide in alkaline conditions

Desalination and Water Treatment ◽

10.1080/19443994.2014.928797 ◽

2014 ◽

Vol 55 (7) ◽

pp. 1735-1746 ◽

Cited By ~ 10

Author(s):

A. Siciliano ◽

M.A. Stillitano ◽

S. De Rosa

Keyword(s):

Hydrogen Peroxide ◽

Anaerobic Biodegradability ◽

Olive Mill Wastewaters ◽

Alkaline Conditions ◽

Pre Treatment ◽

Olive Mill

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Impact of Emerging Technologies on Virgin Olive Oil Processing, Consumer Acceptance, and the Valorization of Olive Mill Wastes

Antioxidants ◽

10.3390/antiox10030417 ◽

2021 ◽

Vol 10 (3) ◽

pp. 417

Author(s):

Maria Pérez ◽

Anallely López-Yerena ◽

Julián Lozano-Castellón ◽

Alexandra Olmo-Cunillera ◽

Rosa M. Lamuela-Raventós ◽

...

Keyword(s):

Olive Oil ◽

Electric Fields ◽

Emerging Technologies ◽

Virgin Olive Oil ◽

Consumer Preference ◽

Extra Virgin Olive Oil ◽

Microwave Treatment ◽

Olive Mill Wastes ◽

Minor Compounds ◽

Olive Mill

There is a growing consumer preference for high quality extra virgin olive oil (EVOO) with health-promoting and sensory properties that are associated with a higher content of phenolic and volatile compounds. To meet this demand, several novel and emerging technologies are being under study to be applied in EVOO production. This review provides an update of the effect of emerging technologies (pulsed electric fields, high pressure, ultrasound, and microwave treatment), compared to traditional EVOO extraction, on yield, quality, and/or content of some minor compounds and bioactive components, including phenolic compounds, tocopherols, chlorophyll, and carotenoids. In addition, the consumer acceptability of EVOO is discussed. Finally, the application of these emerging technologies in the valorization of olive mill wastes, whose generation is of concern due to its environmental impact, is also addressed.

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A review of lignin hydrogen peroxide oxidation chemistry with emphasis on aromatic aldehydes and acids

Holzforschung ◽

10.1515/hf-2020-0165 ◽

2021 ◽

Vol 0 (0) ◽

Author(s):

Ajinkya More ◽

Thomas Elder ◽

Zhihua Jiang

Keyword(s):

Hydrogen Peroxide ◽

Oxidative Degradation ◽

Reaction Medium ◽

Dicarboxylic Acids ◽

Aromatic Aldehydes ◽

Product Distribution ◽

Reaction Conditions ◽

Alkaline Conditions ◽

The Stability ◽

Oxidation Chemistry

Abstract This review discusses the main factors that govern the oxidation processes of lignins into aromatic aldehydes and acids using hydrogen peroxide. Aromatic aldehydes and acids are produced in the oxidative degradation of lignin whereas mono and dicarboxylic acids are the main products. The stability of hydrogen peroxide under the reaction conditions is an important factor that needs to be addressed for selectively improving the yield of aromatic aldehydes. Hydrogen peroxide in the presence of heavy metal ions readily decomposes, leading to minor degradation of lignin. This degradation results in quinones which are highly reactive towards peroxide. Under these reaction conditions, the pH of the reaction medium defines the reaction mechanism and the product distribution. Under acidic conditions, hydrogen peroxide reacts electrophilically with electron rich aromatic and olefinic structures at comparatively higher temperatures. In contrast, under alkaline conditions it reacts nucleophilically with electron deficient carbonyl and conjugated carbonyl structures in lignin. The reaction pattern in the oxidation of lignin usually involves cleavage of the aromatic ring, the aliphatic side chain or other linkages which will be discussed in this review.

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