scholarly journals Effects of Freezing-Thawing Pretreatment on Anaerobic Digestion of Wheat Straw and its Kinetics Analysis

2021 ◽  
Author(s):  
QIANRU ZHANG ◽  
Yiqing Yao ◽  
Xinming Xi
Keyword(s):  
Anaerobic Digestion ◽  
Wheat Straw ◽  
Methane Production ◽  
Freezing Temperature ◽  
Logistic Function ◽  
Lag Phase ◽  
Model Parameters ◽  
Freezing Time ◽  
Function Model ◽  
Phase Time

Abstract In this study, freezing-thawing (FT) pretreatment of different freezing time and freezing temperatures was investigated to find the effect on anaerobic digestion of wheat straw (WS). The freezing temperature gradient is -10, -20, -40 and -80℃, and the freezing time gradient is 12 h, 24 h, 48 h and 96 h. Total methane production exhibited a mere distance among all samples. Morphology change sculptured by SEM showed this method broken the structure of WS leaving fragments and pores in varying degrees. Three kinetic models were performed on WS to represent the behavior of experimental data. Kinetic model parameters of total methane production and lag phase time showed that logistic function model had the best fit, followed by modified Gompertz model, yet transfer function model lost efficacy in this experiment. Logistic function model was then used to reveal the influence on lag phase caused by freezing time and freezing temperature, the results implied that FT pretreatment can shorten the lag phase time of anaerobic digestion (AD), providing a 21.39% improvement under the optimal conditions of -20℃ 96 h. The analysis of response surface regression shows that the freezing temperature has more effect on the lag phase time of anaerobic digestion than freezing time. Warmer freezing temperature of -20℃ do better than -80℃ on lag time, which can be achieved in most cold regions, so this treatment can occur naturally in such area without additional energy input.In this study, freezing-thawing (FT) pretreatment of different freezing time and freezing temperatures was investigated to find the effect on anaerobic digestion of wheat straw (WS). The freezing temperature gradient is -10, -20, -40 and -80℃, and the freezing time gradient is 12 h, 24 h, 48 h and 96 h. Total methane production exhibited a mere distance among all samples. Morphology change sculptured by SEM showed this method broken the structure of WS leaving fragments and pores in varying degrees. Three kinetic models were performed on WS to represent the behavior of experimental data. Kinetic model parameters of total methane production and lag phase time showed that logistic function model had the best fit, followed by modified Gompertz model, yet transfer function model lost efficacy in this experiment. Logistic function model was then used to reveal the influence on lag phase caused by freezing time and freezing temperature, the results implied that FT pretreatment can shorten the lag phase time of anaerobic digestion (AD), providing a 21.39% improvement under the optimal conditions of -20℃ 96 h. The analysis of response surface regression shows that the freezing temperature has more effect on the lag phase time of anaerobic digestion than freezing time. Warmer freezing temperature of -20℃ do better than -80℃ on lag time, which can be achieved in most cold regions, so this treatment can occur naturally in such area without additional energy input.

scholarly journals Modelling of Biphasic Biogas Production Process from Mixtures of Livestock Manure Using Bi-logistic Function and Modified Gompertz Equation

2021 ◽  
pp. 116-129
Author(s):  
Christian C. Opurum ◽  
Christian O. Nweke ◽  
Christopher E. Nwanyanwu ◽  
Nkemakolam A. Nwogu
Keyword(s):  
Anaerobic Digestion ◽  
Biogas Production ◽  
Logistic Function ◽  
Model Parameters ◽  
Cow Dung ◽  
Organic Substrates ◽  
Livestock Manure ◽  
Function Model ◽  
Biogas Yield ◽  
Significant Difference

In this study, anaerobic digestion (AD) of three livestock manure: (poultry manure (PM), pig dung (PD), and cow dung (CD) was conducted at different mixed ratios under mesophilic (25-35°C) conditions. Two kinetic models, the modified Gompertz and bi-logistic function model were used to simulate the cumulative biogas yield from the experiments, and model parameters simultaneously obtained. The biogas production profile appeared diauxic-like or biphasic with multiple peaks, revealing the complexity and multi-component nature of the substrates. There was an increase in biogas yield from the treatments, PD/CD 1:1; 37.25 dm3 (3.47%), PD/CD 3:1; 38.41 dm3 (6.96%), CD/PM 1:1; 26.76 dm3 (16.80%) and CD/PM 3:1 24.31 dm3 (6.11%), whereas PD/CD 2:1 (15.41 dm3) and CD/PM 2:1 (22.57 dm3) exhibited inhibitory effect. However, statistical analysis (ANOVA) indicated a significant difference in biogas yield from PD alone (36 dm3) compared to CD alone (22.91 dm3). The two models showed good performance in the simulation of the AD process, with high correlation coefficients, an indication of a very strong relationship between experimental data and model parameters. However, the bi-logistic function model showed a better fit in the simulation of the experimental values, as it was able to capture the curves in the plots, with a higher correlation coefficient R2 (0.9920 - 0.9985) than the modified Gompertz model (0.9797 - 0.9968). This work has shown that the phenomenon of diauxic growth in the anaerobic digestion of complex organic substrates could be captured quantitatively in the kinetic model using bi-logistic function model.

scholarly journals Enhanced Methane Production from Anaerobic Co-Digestion of Wheat Straw Rice Straw and Sugarcane Bagasse: A Kinetic Analysis

2021 ◽  
Vol 11 (13) ◽  
pp. 6069
Author(s):  
Saadia Meraj ◽  
Rabia Liaquat ◽  
Salman Raza Naqvi ◽  
Zeshan Sheikh ◽  
Atoofa Zainab ◽  
...  
Keyword(s):  
Kinetic Parameters ◽  
Wheat Straw ◽  
Rice Straw ◽  
Methane Production ◽  
Kinetic Models ◽  
Gompertz Model ◽  
Logistic Function ◽  
Lignocellulosic Residues ◽  
Function Model ◽  
Modified Gompertz Model

Future energy and environmental issues are the major driving force towards increased global utilization of biomass, especially in developing countries like Pakistan. Lignocellulosic residues are abundant in Pakistan. The present study investigated the best-mixed proportion of mechanically pretreated lignocellulosic residues i.e., wheat straw and rice straw (WSRS), bagasse and wheat straw (BAWS), bagasse, and rice straw (BARS), bagasse, wheat straw, and rice straw (BAWSRS) through anaerobic co-digestion. Anaerobic batch mode bioreactors comprising of lignocellulosic proportions and control bioreactors were run in parallel at mesophilic temperature (35 °C) for the substrate to inoculum (S/I) ratio of 1.5 and 2.5. Maximum and stable biomethane production was observed at the substrate to inoculum (S/I) ratio of 1.5, and the highest biomethane yield 339.0089123 NmLCH4/gVS was achieved by co-digestion of wheat straw and rice straw (WSRS) and lowest 15.74 NmLCH4/gVS from bagasse and rice straw (BARS) at 2.5 substrates to inoculum ratio. Furthermore, anaerobic reactor performance was determined by using bio-kinetic parameters i.e., production rate (Rm), lag phase (λ), and coefficient of determination (R2). The bio-kinetic parameters were evaluated by using kinetic models; first-order kinetics, Logistic function model, Modified Gompertz Model, and Transference function model. Among all kinetic models, the Logistic function model provided the best fit with experimental data followed by Modified Gompertz Model. The study suggests that a decrease in methane production was due to lower hydrolysis rate and higher lignin content of the co-digested substrates, and mechanical pretreatment leads to the breakage of complex lignocellulosic structure. The organic matter degradation evidence will be utilized by the biogas digesters developed in rural areas of Pakistan, where these agricultural residues are ample waste and need a technological solution to manage and produce renewable energy.

scholarly journals Enhancement anaerobic digestion and methane production from kitchen waste by thermal and thermo-chemical pretreatments in batch  leach bed reactor with down flow

2018 ◽  
Vol 64 (No. 3) ◽  
pp. 128-135 ◽  
Author(s):  
Radmard Seyed Abbas ◽  
Alizadeh Hossein Haji Agha ◽  
Seifi Rahman
Keyword(s):  
Anaerobic Digestion ◽  
Microwave Irradiation ◽  
Methane Production ◽  
Biogas Production ◽  
Oxygen Demand ◽  
Lag Phase ◽  
Kitchen Waste ◽  
Gompertz Equation ◽  
Chemical Pretreatments ◽  
Pretreatment Conditions

The effects of thermal (autoclave and microwave irradiation (MW)) and thermo-chemical (autoclave and microwave irradiation – assisted NaOH 5N) pretreatments on the chemical oxygen demand (COD) solubilisation, biogas and methane production of anaerobic digestion kitchen waste (KW) were investigated in this study. The modified Gompertz equation was fitted to accurately assess and compare the biogas and methane production from KW under the different pretreatment conditions and to attain representative simulations and predictions. In present study, COD solubilisation was demonstrated as an effective effect of pretreatment. Thermo-chemical pretreatments could improve biogas and methane production yields from KW. A comprehensive evaluation indicated that the thermo-chemical pretreatments (microwave irradiation and autoclave- assisted NaOH 5N, respectively) provided the best conditions to increase biogas and methane production from KW. The most effective enhancement of biogas and methane production (68.37 and 36.92 l, respectively) was observed from MW pretreated KW along with NaOH 5N, with the shortest lag phase of 1.79  day, the max. rate of 2.38 l·day<sup>–1</sup> and ultimate biogas production of 69.8 l as the modified Gompertz equation predicted.

scholarly journals Kinetic Study on Biogas Production from Cabbage (Brassica oleracea) Waste and Its Blend with Animal Manure Using Logistic Function Model

2021 ◽  
pp. 34-43
Author(s):  
Christian C. Opurum
Keyword(s):  
Anaerobic Digestion ◽  
Kinetic Parameters ◽  
Goodness Of Fit ◽  
Biogas Production ◽  
Logistic Function ◽  
Gas Production ◽  
Cow Dung ◽  
Function Model ◽  
Biogas Yield ◽  
Significant Difference

This research paper aimed to evaluate the kinetics of anaerobic digestion (AD) of mixtures of cabbage waste (CW) with (Poultry dropping (PD) and Cow dung (CD). The study was conducted in 10L bio-digesters for 35 days under mesophilic conditions (25 - 35OC). Logistic function equation was used to simulate the experimental data to test for its goodness of fit and kinetic parameters namely: maximum biogas potential (Pb), the maximum biogas production rate (Rm), and the lag phase duration (λ) were estimated in each treatment. Chemical analysis showed that individual substrates possess characteristics that could support microbial activities in biogas production. The biogas yield in terms of added  volatile solids (VS) in decreasing order was as follows: 0.022, 0.018, 0.017, 0.014, 0.014 and 0.013 dm3/g VS for CW/CD 2:1, CW/PD3:1, CW/CD 1:1, CW alone, CW/PD1:1 and  CW/PD 2:1, respectively. A significant difference (P ≤ 0.05) in biogas yield was recorded in CW/CD 2:1 with 7.19 dm3 (53.29% increase). The kinetic parameters (Pb, Rm, and λ) for CW/CD 2:1 was 7.01 dm3, 1.58 dm3.d, and 2.29 days, respectively. This was followed by CW/PD 3:1 (5.84 dm3); with 24.92% increase in gas production and CW/CD 1:1 (5.42 dm3) with 15.53% increase relative to CW alone, 4.69 dm3. The digesters fed with CW/PD 1:1 and CW/PD 2:1 exhibited inhibitory effects on biogas production, with 7.51 and 2.05% decrease in gas yield, respectively. The logistic function model demonstrated a strong relationship between the experimental and model-predicted data. The high correlation coefficient (R2) ranging between 0.978 - 0.993 is evident. The model proved to be a useful tool in predicting anaerobic digestion and biogas production process.

scholarly journals Pretreatment of Lignocellulosic Biomass with 1-Ethyl-3-methylimidazolium Acetate for Its Eventual Valorization by Anaerobic Digestion

Resources ◽  
2021 ◽  
Vol 10 (12) ◽  
pp. 118
Author(s):  
Jose D. Marin-Batista ◽  
Angel F. Mohedano ◽  
Angeles de la Rubia
Keyword(s):  
Ionic Liquid ◽  
Anaerobic Digestion ◽  
Wheat Straw ◽  
Lignocellulosic Biomass ◽  
Methane Production ◽  
Liquid Fraction ◽  
Soluble Sugars ◽  
Crystallinity Index ◽  
Barley Straw ◽  
Cellulose Crystallinity

This study assessed the breakdown of lignocellulosic biomass (LB) with the ionic liquid (IL) 1-ethyl-3-methylimidazolium acetate ([Emim][Ac]) as a pretreatment to increase the methane yield. The pretreatment was conducted for wheat straw (WS), barley straw (BS), and grape stem (GS) at 120 °C for 120 min, using several LB to [Emim][Ac] ratios (1:1, 1:3, and 1:5 w/w). Pretreatment significantly disrupted the lignocellulose matrix of each biomass into soluble sugars. GS showed the highest sugar yield, which was followed by WS, while BS was slightly hydrolyzed (175.3 ± 2.3, 158.2 ± 5.2, and 51.1 ± 3.1 mg glucose g–1 biomass, respectively). Likewise, the pretreatment significantly reduced the cellulose crystallinity index (CrI) of the resulting solid fractions of GS and WS by 15% and 9%, respectively, but slightly affected the CrI of BS (5%). Thus, BMP tests were only carried out for raw and hydrothermally and [Emim][Ac] (1:5) pretreated GS and WS. The untreated GS and WS showed similar methane yields to those achieved for the solid fraction obtained after pretreatment with an LB to [Emim][Ac] ratio of 1:5 (219 ± 10 and 368 ± 1 mL CH4 g–1 VS, respectively). The methane production of the solid plus liquid fraction obtained after IL pretreatment increased by 1.61- and 1.34-fold compared to the raw GS and WS, respectively.

scholarly journals Addition of Different Biochars as Catalysts during the Mesophilic Anaerobic Digestion of Mixed Wastewater Sludge

Catalysts ◽  
2021 ◽  
Vol 11 (9) ◽  
pp. 1094
Author(s):  
Marco Chiappero ◽  
Francesca Cillerai ◽  
Franco Berruti ◽  
Ondřej Mašek ◽  
Silvia Fiore
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Biogas Production ◽  
Chemical Properties ◽  
Principal Component ◽  
Gompertz Model ◽  
Wastewater Sludge ◽  
Total Carbon ◽  
Lag Phase ◽  
Working Volume

Biochar (BC) recently gained attention as an additive for anaerobic digestion (AD). This work aims at a critical analysis of the effect of six BCs, with different physical and chemical properties, on the AD of mixed wastewater sludge at 37 °C, comparing their influence on methane production and AD kinetics. AD batch tests were performed at the laboratory scale operating 48 reactors (0.25 L working volume) for 28 days with the addition of 10 g L−1 of BC. Most reactors supplemented with BCs exhibited higher (up to 22%) methane yields than the control reactors (0.15 Nm3 kgVS−1). The modified Gompertz model provided maximum methane production rate values, and in all reactors the lag-phase was equal to zero days, indicating a good adaptation of the inoculum to the substrate. The potential correlations between BCs’ properties and AD performance were assessed using principal component analysis (PCA). The PCA results showed a reasonable correlation between methane production and the BCs’ O–C and H–C molar ratios, and volatile matter, and between biogas production and BCs’ pore volume, specific surface area, and fixed and total carbon. In conclusion, the physic-chemical properties of BC (specifically, hydrophobicity and morphology) showed a key role in improving the AD of mixed wastewater sludge.

Effect of sodium salt on anaerobic digestion of kitchen waste

2016 ◽  
Vol 73 (8) ◽  
pp. 1865-1871 ◽  
Author(s):  
Naveed Anwar ◽  
Wen Wang ◽  
Jie Zhang ◽  
Yeqing Li ◽  
Chang Chen ◽  
...  
Keyword(s):  
Anaerobic Digestion ◽  
Sodium Salt ◽  
Salt Concentration ◽  
Methane Production ◽  
Volatile Fatty Acids ◽  
Production Performance ◽  
Methane Yield ◽  
Production Model ◽  
Lag Phase ◽  
Kitchen Waste

The effect of different sodium salt concentration on anaerobic digestion of kitchen waste was investigated. The methane production performance, the corresponding methane production model and sodium salt inhibition model were studied, and the degradation efficiency was analyzed. With the increase of sodium salt concentration, the methane yield and the maximal methane production rate decreased along with the increase of lag phase time. The highest methane yield of 594 mL/g-VSadded (VS: volatile solids) was found with no sodium salt addition while the lowest was obtained with addition of 16 g/L NaCl. The declines of the methane yield were negligible when the sodium salt concentration was below 8 g/L, which corresponded to &lt;10% inhibiting efficiency. In contrast, a sharp decrease of methane yield was observed with addition of &gt;8 g/L NaCl (causing 17–80% inhibition). Five kinds of regression models were developed to describe the sodium salt inhibition efficiency, and the cubic regression model of y = 0.508 + 2.401x − 0.369x2 + 0.033x3 showed the best fitting. The volatile fatty acids/ethanol gradually accumulated along with the increase of the sodium salt concentration, and the volatile solid removal efficiency represented a gradual decline accordingly. It is recommended that the sodium salt concentration in the anaerobic digesters should be controlled below 8 g/L in order to avoid intense methane inhibition.

Experimental and Modelling Approach of Biogas Production by Anaerobic Digestion of Agricultural Resources

2017 ◽  
Vol 68 (6) ◽  
pp. 1294-1297 ◽  
Author(s):  
Gabriela Alina Dumitrel ◽  
Adrian Eugen Cioabla ◽  
Ioana Ionel ◽  
Lucia Ana Varga
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Biogas Production ◽  
Batch Reactor ◽  
Pilot Scale ◽  
Lag Phase ◽  
Biogas Yield ◽  
Agricultural Resources ◽  
Methane Production Rate ◽  
Modelling Approach

Anaerobic digestion processes of agricultural resources, as single substrates (wheat bran and barley) or as combination of substrates (75 % corn&25% corn cob � named MIX1 and 40 % corn & 40 % wheat&20 % sunflower husks � named MIX2), were performed, at a mesophilic temperature in a batch reactor, at pilot scale. The results proved that the higher quantity of biogas yield was achieved for barley, followed by MIX1, and finally MIX2. The same order was obtained when the total methane production was evaluated. The performances of digesters were mathematically evaluated by using the modified Gompertz equation. The kinetic parameters, such as the methane production potential (MP), the maximum methane production rate (Rm) and the extent of lag phase (l) were calculated, for each experimental case. The values of the performance indicators confirmed that all the models fitted well with the experimental data.

Evaluation of thermal steam-explosion key operation factors to optimize biogas production from biological sludge

2015 ◽  
Vol 72 (6) ◽  
pp. 937-945 ◽  
Author(s):  
S. I. Pérez-Elvira ◽  
I. Sapkaite ◽  
F. Fdz-Polanco
Keyword(s):  
Anaerobic Digestion ◽  
Methane Production ◽  
Steam Explosion ◽  
Treatment Time ◽  
Biogas Production ◽  
Negative Influence ◽  
Point Of View ◽  
Lag Phase ◽  
Biological Sludge ◽  
The One

Thermal steam-explosion is the most extended hydrolysis pretreatment to enhance anaerobic digestion of sludge. Thermal hydrolysis key parameters are temperature (T) and time (t), and the generally accepted values reported from full-scale information are: 150–230 °C and 20–60 min. This study assesses the influence of different temperature–time–flash combinations (110–180 °C, 5–60 min, 1–3 re-flashing) on the anaerobic degradation of secondary sludge through biochemical methane potential (BMP) tests. All the conditions tested presented higher methane production compared to the untreated sludge, and both solubilization (after the hydrolysis) and degradation (by anaerobic digestion) increased linearly when increasing the severity (T–t) of the pretreatment, reaching 40% solubilization and degradation of the particulate matter at 180° C–60 min. However, for the 180 °C temperature, the treatment time impacted negatively on the lag phase. No influence of re-flashing the pretreated matter was observed. In conclusion, thermal steam-explosion at short operation times (5 min) and moderate temperatures (145 °C) seems to be very attractive from a degradation point of view thus presenting a methane production enhancement similar to the one obtained at 180°C and without negative influence of the lag phase.

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