Revistas
Revista:
JOURNAL OF CLEANER PRODUCTION
ISSN 0959-6526
Vol. 280
N° P2
Año 2021
Págs.124479
Lignocellulosic residues are a widely available energy resource, but their conversion into biogas through biomethanation may be hindered by a chemical structure with strong bonds. A strategy based on temperature-phased anaerobic digestion (TPAD) is here applied to optimize anaerobic digestion of artichoke as a representative lignocellulosic waste. The experiments consist of a first thermophilic stage conducted at 55 °C (7 and 5 days), followed by a second mesophilic stage at 35 °C. In addition, for comparison, single-stage temperature trials are carried out within the most common conditions for biomethanation (mesophilic at 35 °C, and thermophilic at 55 °C), as well as at the intermediate range (42 °C). In general, biomethanation of artichoke residues under TPAD configuration provides better performance than single-stage systems. Particularly, the best performance is observed for the TPAD arrangement using a thermophilic phase of 7 days. Thus, at this optimal configuration, volatile solids (VS) removal of 54%, and biogas and methane yields of 442 mL/g-VS and 375 mL-CH4/g-VS were reached, respectively. Moreover, a kinetic model coupling biogas generation and substrate consumption has been applied. Good agreement is found for both variables in each system tested. The calculated non-biodegradable substrate (S¿) is lower in TPAD systems (mean 49.6%) compared with that of single-stages (average 53.9%).
Revista:
FUEL
ISSN 0016-2361
Vol. 245
Año 2019
Págs.240 - 246
In this paper, the use of techniques such as TGA, FTIR-ATR and XRD has provided valuable information about the lignocellulosic wastes in anaerobic digestion (AD) processes. A deep study of their break-down in solid state could improve the management of these recalcitrant substrates. Representative wastes (artichoke -ART-, asparagus -ASP-, the co-digestion of both -AcoD-and pure cellulose -CELL-) were assessed in batch. The main obtained results were related to biochemical parameters. As the biomethanization progressed, hemicellulose, cellulose and lignin were weakened as shown by TGA, and cellulose crystallinity decreased as demonstrated by XRD. Additionally, results from FTIR-ATR allowed hypothesizing that the formation of acetate in solid state did not always lead to its solubilisation, thus hindering biogas formation. AcoD and CELL were the most successful in releasing the newly formed acetate from the solid fraction to the aqueous medium, increasing its bioavailability, which was supported by the higher biogas production.
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 334
Año 2018
Págs.650 - 656
Barley malt and sloe are two raw materials used in the production of beer and pacharan (a Spanish spirit drink), respectively. These organic wastes have been used as substrate of anaerobic digestion to assess the effect of temperature (35 degrees C and 55 degrees C) and thermal pretreatment (80 degrees C for 1.5 h). Viable microbiological isolates have also been identified through metabolic tests and a kinetic model which includes biogas generation and volatile solids (VS) removal has been proposed. Temperature studies on barley malt yielded higher productivities at 55 degrees C (the ratio of produced biogas volume per VS consumed was 119% higher than that at 35 degrees C), but similar VS removal (0.9% less elimination at 55 degrees C). On the other hand, sloe digestion was more effective at 35 degrees C (biogas/VS-consumed ratio 252% higher than that at 55 degrees C), while VS elimination can be considered the same. Attending to the effect of thermal pretreatment on productivity, barley malt showed no improvement while sloe was enhanced (144% at 35 degrees C and 160% at 55 degrees C). Kinetic modelling fits to the experimental results, showing differences in maximum specific growth rate of biomass according with the temperature conditions. In all cases the adjustment was good (R-2 > 0.96). Microbiological characterization identified bacterial population, both strict and facultative anaerobes.
Revista:
FOOD AND BIOPRODUCTS PROCESSING
ISSN 0960-3085
Vol. 110
Año 2018
Págs.120 - 125
Different wastes treated together can be the supplement of nutritional deficiencies for the microorganisms involved in anaerobic codigestion (AcoD). In this study, the presence of macromolecules and trace elements on AcoD of agricultural waste was assessed. An extra nutrients solution that plays a key role in the microbiological metabolism was used at three different conditions: mesophilic (35 degrees C), intermediate (42 degrees C) and thermophilic (55 degrees C). The main results showed that at 35 degrees C in the presence of nutrients, biogas production reached 1.5-fold the production of biogas without them. Additionally, productivity was 1.9 times higher than that for the process without nutrients. Also, 42 degrees C without nutrients posed an interesting approach due to the uncommon use of this intermediate temperature, which has been demonstrated to be worth considering (55% of VS removal and 7.4 L-biogas). The AcoD at 55 degrees C showed that biogas production also surpassed 10.2 L with nutrients and that mL-CH4/g-VS were 1.2-fold of that obtained for the process without extra solution. Results for each temperature indicate that the nutrients solution contributes to AcoD. Furthermore, 35 degrees C, the most widespread temperature range at industrial scale, was the temperature at which the impact of nutrients was more remarkable. A deeper knowledge of AD nutritional limitations according to temperatures can optimize the industrial process in order to get better biogas yields and biomass removal. (C) 2018 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.
Revista:
BIORESOURCE TECHNOLOGY
ISSN 0960-8524
Vol. 264
Año 2018
Págs.140 - 147
Microbial dynamics in an upgrading biogas reactor system undergoing a more than two years-period at stable operating conditions were explored. The carbon dioxide generated during biomass degradation in the first reactor of the system was converted to methane into the secondary reactor by addition of external hydrogen. Considering the overall efficiency, the long-term operation period resulted in an improved biogas upgrading performance (99% methane content). However, a remarkable accumulation of acetate was revealed, indicating the enhancement of homoacetogenic activity. For this reason, a shift in the anaerobic digestion microbiome was expected and evaluated by 16S rRNA amplicon analysis. Results demonstrated that the most abundant archaeal species identified in the first time point, Candidatus Methanoculleus thermohydrogenotrophicum, was replaced by Methanothermobacter thermautotrophicus, becoming dominant after the community adaptation. The most interesting taxonomic units were clustered by relative abundance and six main long-term adaptation trends were found, characterizing functionally related microbes (e.g. homoacetogens).
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 285
Año 2016
Págs.409 - 416
The optimization of anaerobic digestion of organic wastes is a challenge to maximize energy production through biogas production process. In this study, semicontinuous TPAD (Temperature Phased Anaerobic Digestion) process has been used for the treatment of the Organic Fraction of Municipal Solid Waste (OFMSW) coming from a mechanical-biological-treatment (MBT) plant. TPAD combines the advantages of operating in different temperature ranges getting better efficiencies of organic matter removal and higher methane productivities than single-stage anaerobic digestion. In this study, the configuration used in the overall process was a thermophilic reactor (55-57 °C) for the first phase followed by a mesophilic one (35-37 °C) for the second phase. Two TPAD conditions have been tested in this paper: 4:10 and 3:6. The first digit means the SRT used in the first thermophilic phase while the second digit is related to the SRT used in the second mesophilic phase. Moreover, the performance of TPAD processes was compared with those from single-stage digesters operating at similar SRT (i.e., mesophilic and thermophilic reactors operating at 15 days SRT and thermophilic reactor operating at 10 days).
The results showed that achievement reached in TPAD 4:10 was better than the corresponding one in TPAD 3:6, obtaining higher productivity of methane (35-45%) and removal of organic matter (6-19%).
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 270
Año 2015
Págs.597 - 604
Anaerobic digestion of the Organic Fraction of Municipal Solid Wastes from non-selective collection systems is widely implemented at industrial scale. Classically, single-temperature anaerobic digestion systems (mesophilic or thermophilic) have been used although some limitations were found in the processes performance. However, the specific advantages of the two processes could be exploited by using a temperature-phased anaerobic digestion (TPAD). Thus, in this paper, the application of a TPAD process without microbiological separation (thermophilic 55 °C-mesophilic 35 °C) to the biomethanation of OFMSW has been studied.
The TPAD assays were carried out in batch reactors. The processing times for the thermophilic (55 °C) stage have been located in the range from 12 to 3 days. After the first stage, the waste treatment was continued in a second mesophilic reactor (35 °C) until completing the degradation process.
The higher values for the organic matter removal (VS removal 82-85%) and the maximum specific growth rates of microorganisms (0.31-0.43 days-1), were obtained for thermophilic phase operation at 5 and 4 days, respectively. Lower operation times, namely 3-days, for thermophilic first-phase are viable and the methane productivity obtained was comparable with respect to that obtained in the above mentioned conditions (0.6 L/gVSremoved).
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 251
Año 2014
Págs.435 - 440
The thermophilic temperature has showed operational advantages in the Anaerobic Digestion process (AD). The increasing of the rate of hydrolysis, which suppose an acceleration of the overall process, and a higher hygienization of the final digestate are one of them. Dealing with OFMSW (Organic Fraction of Municipal Solid Waste) from non-selective collection systems involves additional difficulties due to their heterogeneity. The AD process of OFMSW is conducted usually in the range of 20-35% TS (dry AD).
The main objective of this study was to determine the optimum Solids Retention Time (SRT) for the dry thermophilic AD of OFMSW operating in semi-continuous regime. Thus, the following SRTs have been tested: 15, 10, 8, 6, 5, 4 and 3 days.
The main results have showed that the process is feasible in SRTs lower that those found in literature. Probably the history of the reactor, joined to the lower organic content in the waste, can be a key factor and the progressive decreasing of SRT is a strategy that permits to maintain stable conditions for lower SRT. The best operating conditions for thermophilic semicontinuous systems ranged in 8-5 days, with a yield of 0.33-0.34 LCH4/gVSadded and a concentration of Volatile Fatty Acids (VFA) around 100 mg HAc/L.
Revista:
POLISH JOURNAL OF CHEMICAL TECHNOLOGY
ISSN 1509-8117
Vol. 15
N° 2
Año 2013
Págs.99 - 106
The main objective of this study was to analyse the development of dry anaerobic digestion process of OFMSW in batch reactors under two temperature ranges, thermophilic (55°C) and mesophilic (35°C). The experimental results lead to the conclusion that the thermophilic range has a greater rate of hydrolysis and is therefore more effective to degrade wastes, shortening the overall operating time. For example, the hydrolytic step in the thermophilic (T) process lasted an average of 8 days versus 14 days in the mesophilic (M) range. The methanogenic phase lasted for 18 and 29 days in the T and M processes, respectively. The mesophilic range showed higher removal of the organic effluent but with greater uptime requirements. Moreover, the thermophilic range showed greater productivities than the mesophilic range, and the productivities were approximately doubled in terms of the produced biogas from a given amount of consumed organic matter.
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 232
Año 2013
Págs.59 - 64
Temperature is a significant variable in anaerobic digestion (AD) since it determines the values of the main kinetic parameters for the process and, hence, the rate of the microbiological process. Thus, in this study, batch AD experiments were carried out, at mesophilic (35 °C) and thermophilic (55 °C) conditions, with the aim to compare the kinetic of both processes. Tests were performed in dry conditions (concentration of Total Solids (TSs) of 20%) using the Organic Fraction of Municipal Solid Waste (OFMSW) as feedstock.
Romero model [1] was used to fit the experimental results from both, the organic matter consumption and the biogas production. This model has been used extensively in the analysis of results of AD process in a wide range of experimental conditions [2], [3], [4].
The values of the maximum specific growth rate of microorganisms (¿MAX) are 27¿60% higher for thermophilic process than for mesophilic ones and, therefore, the same level of organic matter degradation and methane production can be achieved in a shorter operating time, 20 days in thermophilic instead of 40 days in mesophilic. Moreover, the yield coefficient for methane production (¿P/S) and the initial amount of active microorganisms (XV0/YX/S) show values 107% and 129% higher, respectively, in thermophilic processes.
Revista:
CHEMICAL ENGINEERING JOURNAL
ISSN 1385-8947
Vol. 193 - 194
Año 2012
Págs.10 - 15
Dry mesophilic anaerobic digestion of the organic fraction of municipal solid waste (OFMSW) is a widespread technology. However, OFMSW is a very heterogeneous waste and therefore specific studies are needed to optimise the AD process with each type of OFMSW that will be used. The main operational variables to optimise are the solids retention time (SRT) and the organic loading rate (OLR), which are closely related to each other when the concentration of organic matter of OFMSW remains relatively constant. In this work three different experimental conditions (corresponding to the SRT of 30, 20 and 15 days) were tested in a semi-continuous stirred tank reactor, operating at mesophilic range (35 °C) and high solids concentration (20% TS). The OLR corresponding to the above mentioned SRT were 22.8, 27.3 and 35.9 mg DOC/Lreactor/d, respectively.
The results obtained in this study indicate that 20 days is the optimum SRT for the dry mesophilic anaerobic digestion of the OFMSW used. Thus, in general, all the parameters analysed show better performance for 20-day SRT with regard to 30-day and 15-day SRT. More specifically, it can be pointed out than at SRT of 20 days (27.3 mg DOC/Lreactor/d), both the highest productivity of methane (0.11 L CH4/g waste-fed) and the highest organic matter removal rate (66.3% DOC removal) were reached.
Revista:
BIORESOURCE TECHNOLOGY
ISSN 0960-8524
Vol. 101
N° 16
Año 2010
Págs.6322 - 6328
The anaerobic mesophilic degradation of municipal waste has been studied in discontinuous lab-reactors with two different initial concentrations of OFMSW: R20, with 931.1 mg DOC/L (20% TS), and R30, with 1423.4 mg DOC/L (30% TS). The anaerobic digestion process was favoured when it was carried on material with a total solids content of 20% in comparison to a similar process with 30% TS. A higher level of organic matter, in terms of DOC and VFA, 18.18% and 8.09% respect, was removed in the system with the lower amount of solids. The kinetics parameters showed higher active biomass and a higher coefficient for the production of methane at the lower loading. The highest maximum specific growth rate for the microorganisms (Mi-MAX) in the reactors with 20% TS, a value of 0.192 d-1, was achieved in comparison to 0.131 d-1 in the reactors with 30% TS. The inverse of the F:M ratio was higher in the R20 system with a value of 0.0104 (cf. 0.0006 in R30) and, as a result, the R30 system required longer hydrolytic and acidogenic stages. and the yield coefficient for product generation (alpha P/S) were higher, by around 53%, for the R20 digester.
Capítulos de libros
Libro:
Clean energy and resources recovery: biomass waste based biorefineries
Editorial: ELSEVIER
Año 2021
Págs.155 - 202
Agricultural lignocellulosic waste can generate serious environmental problems if not properly managed. Biodegradation, through anaerobic digestion (AD), is a cost-effective strategy for biogas production. However, studies on the biodegradation of lignocellulose show that the substrate is recalcitrant to microbiological hydrolysis, which reduces the efficiency of converting organic matter into biogas. The main reasons are its complex structure and slow biodegradation. The appropriate performance of biomethanization suggests a deep knowledge of substrate composition. Typically, the composition is about 10% to 25% lignin, 20% to 30% hemicellulose, and 40% to 50% cellulose. This book chapter will summarize the AD process and rate-limiting steps, compositional properties (focusing especially on pretreatment strategies applied to lignocellulosic biomass to improve methane yield), and overall AD performance. The most common pretreatments applied to organic substrates will be studied: physical, chemical, biological, and a combination of them. Additionally, the new trends in pretreatments will be exposed.
Libro:
Book of proceedings : VIII international scientific agriculture symposium AGROSYM 2017
Lugar de Edición: Bosnia y Herzegovina
Editorial: University of East Sarajevo
Año 2017
Págs.1892 - 1896
Anaerobic codigestion has shown to be feasible to manage organic waste. Different wastes treated together can be the supplement of nutritional deficiencies for the microorganisms involved. In this study, the presence of acromolecules and trace elements on anaerobic codigestion of agricultural waste has been assessed. An extra nutrients solution containing elements, which play a key role in the anaerobic microbiological metabolism, was used at three different temperature conditions: mesophilic (35°C), intermediate (42°C) and thermophilic (55°C). The main results showed that at 35°C in the presence of nutrients, biogas production reached 6.2L, almost 1.5-fold the production of biogas without them. Additionally, productivity was 359.3mL-CH4 / g-VS, which is 1.9 times higher than that for the process
without nutrients. At 42°C up to 55% of VS were eliminated and more than 10.0L-biogas were produced, while biomethanization without extra nutrients solution only reached 7.4L. The anaerobic codigestion at 55°C showed that biogas production also surpassed 10.2L in the presence of nutrients and 146.99mL-CH4 / g-VS were obtained, being these results 1.2-fold those obtained for the process without extra solution. Results for each temperature showed
that the nutrients solution could contribute to the biomethanization process of codigestion waste. Furthermore, 35°C was the temperature range at which the impact of nutrients was more remarkable.
Libro:
Book of proceedings : VIII international scientific agriculture symposium AGROSYM 2017
Lugar de Edición: Bosnia y Herzegovina
Editorial: University of East Sarajevo
Año 2017
Págs.1886 - 1891
Anaerobic digestion (AD) is becoming one of the most feasible and efficient options for agroindustrial waste management. However, this kind of waste can contain certain substances from the industrial activity, which could potentially inhibit or, at least, modify the biomethanization process. Pesticides are widely used in agricultural activities. Mancozeb is an ethylene dithiocarbamate fungicide with broad spectrum used in crops. It reacts with and inactivates sulfhydryl groups of aminoacids and enzymes of fungal cells, disrupting of respiration, lipid metabolism and production of energy. Tefluthrin is a synthetic pyrethroid insecticide used to control a wide range of soil pests. It causes neurotoxicity and is a sodium channel modulator. This paper assesses the influence of the presence of mancozeb and
tefluthrin on thermophilic (55°C) anaerobic co-digestion (carrot, cabbage, green pea, artichoke and fava and broad bean) of synthetic agroindustrial waste. The main results show that the pesticides improve the biomethanization process referred to generation of biogas (123%), consumption of volatile solid -VS- (18%), removal of chemical oxygen demand (5%) and yield of biogas measured like mL biogas/ VS consumed (117%), between other parameters. Anaerobic codigestion on presence of pesticides seems feasible and improved in comparison with the codigestion without these substances.
