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A critical review of pretreatment technologies to enhance anaerobic digestion and energy recovery
(Elsevier Sci Ltd, 2020) Atelge, M. R.; Atabani, A. E.; Banu, J. Rajesh; Krisa, David; Kaya, M.; Eskicioglu, Cigdem; Kumar, Gopalakrishnan
Biogas production from different waste resources still has limitations due to its complex structure and slowly biodegradable nature. To improve methane yield and anaerobic digestion performance, various substrate pretreatment methods have been suggested. This paper reviews the latest trends, progress, and research achievements about pretreatment technologies to improve anaerobic digestion efficiency. The pretreatment techniques are divided into four main groups which are physical, chemical, biological, and combined. The effect of inhibitor formation during the pretreatment process is discussed. The energy performance, economics, and environmental impact of these pretreatment technologies are revealed. This study concludes with future trends and emphasizes the necessity of pretreatment methods.
A double-functional carbon material as a supercapacitor electrode and hydrogen production: Cu-doped tea factory waste catalyst
(Springer, 2021) Ozarslan, S.; Atelge, M. R.; Kivrak, Hilal Demir; Horoz, Sabit; Yavuz, Cenk; Kaya, M.; Unalan, S.
In the present study, our main aim is to show that the first synthesized metal-doped tea factory waste (TFW) catalyst can be used in both hydrogen production and supercapacitor application. In this context, TFW catalyst doped with copper (Cu) (TFW-Cu) was synthesized for methanolysis of NaBH4 and supercapacitor measurement. In the presence of four different parameters (metal type, metal amount, carbonization temperature, and carbonization time), methanolysis experiments of NaBH4 were performed and the catalyst with the maximum hydrogen production rate (HPR) was determined. As a result, it was determined that the 30% Cu-doped TFW (TFW-30%Cu) catalyst had a maximum HPR at a carbonization temperature of 300 degrees C and a carbonization time of 60 min compared to other substances. As a result of the methanolysis experiments performed in the presence of TFW-30%Cu catalyst, the maximum HPR and activation energy were determined as 9475 mL (min.g)(-1) and 13.02 kJ mol(-1), respectively. In supercapacitor application, the capacitance of the electrodes in the presence of TFW-30%Cu was calculated as 7-19.9 F.(g)(-1). Thus, it is expected that the synthesized catalyst will make a promising contribution in both energy storage and energy production areas-especially for distributed generation systems operating in national networks.
A novel Microcystis aeruginosa supported manganese catalyst for hydrogen generation through methanolysis of sodium borohydride
(Pergamon-Elsevier Science Ltd, 2020) Duman, Fatih; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.; Kumar, Gopalakrishnan; Sahin, U.; Unalan, S.
In this study, Microcystis Aeruginosa (MA)- microalgae species was used for the first time as a support material with metal ions loading to fabricate a highly efficient catalyst for the hydrogen generation through methanolysis of sodium borohydride (NaBH4). Microalgae was pre-treated with hydrochloric acid (3 M HCl) for 24 h at 80 degrees C. Subsequently, different metal ions (Mn, Co, and Mo) were loaded to the pre-treated samples. Finally, metal-loaded samples were subjected to burning in oven to fabricate the catalyst. Primarily, manganese metal was selected based on the best metal performance. Afterwards, different metal loading ratios, burning temperatures and burning times were evaluated to synthesize the optimal MA-HCl-Mn catalyst. Results showed the optimal conditions as Mn ratio, burning temperature and time as 50%, 500 degrees C and 45 min, respectively. To characterize the catalyst, FTIR, SEM-EDX, XRD, XPS and TEM analyses were performed. Hydrogen generation via methanolysis was performed at various NaBH4 ratio of 1-7.5% while changing concentrations from 0.05 to 0.25 g catalysts with diverge temperatures of (30, 40, 50 and 60 degrees C). The maximum hydrogen generation rate (HGR) by this novel catalyst was found as 4335.3, 5949.9, 7649.4 and 8758.9 mLmin(-1)gcat(-1), respectively. Furthermore, the activation energy was determined to be 8.46 kJ mol(-1). (C) 2020 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Anaerobic co-digestion of oil-extracted spent coffee grounds with various wastes: Experimental and kinetic modeling studies
(Elsevier Sci Ltd, 2021) Atelge, M. R.; Atabani, A. E.; Abut, Serdar; Kaya, M.; Eskicioglu, Cigdem; Semaan, Georgeio; Lee, Changsoo
The effect of oil extraction from spent coffee grounds as a pre-treatment strategy prior to anaerobic digestion besides assessing the feasibility of defatted spent coffee grounds co-digestion with spent tea waste, glycerin, and macroalgae were examined. Mesophilic BMP tests were performed using defatted spent coffee grounds alongside four co-substrates in the ratio of 25, 50, and 75%, respectively. The highest methane yield was obtained with the mono-digestion of defatted spent coffee grounds with 336 +/- 7 mL CH4/g VS and the yield increased with the increase in the mass ratio of defatted spent coffee grounds during co-digestion. Moreover, defatted spent coffee grounds showed the highest VS and TS removal at 35.5% and 32.1%, respectively and decreased thereafter. Finally, a linear regression model for the interaction effects between substrates was demonstrated and showed that distinctly mixing defatted spent coffee grounds, spent coffee grounds, and spent tea waste outperforms other triple mixed substrates.
Anaerobic digestion of dry palms from five cultivars of Algerian date palm (Phoenix dactylifera L.) namely H?mira, Teggaza, Tinacer, Aghamou and Takarbouchet: A new comparative study
(Pergamon-Elsevier Science Ltd, 2023) Djaafri, Mohammed; Drissi, Aicha; Mehdaoui, Sabrina; Kalloum, Slimane; Atelge, M. R.; Khelafi, Mostefa; Kaidi, Kamel
The lignocellulosic properties of date palm waste (dry palm) differ significantly from one cultivar to another, which affects the anaerobic digestion (AD) process. This study is believed to be amongst the first to evaluate the influence of date palm cultivars on the biomethane yield in order to offer an annual, continuous and cost-effective biogas production model. In this work, 5 cultivars from date palm waste namely; H'mira (H), Teg-gaza (Tg), Tinacer (Ti), Aghamou (Ag) and Takarbouchet (Tk) were evaluated for biogas production. All experi-ments were performed for 45 days with 5 reactors in triplicate under mesophilic conditions (37 degrees C). The highest methane yield of 231.87 ml of CH4/g of Volatile Solid (VS) was obtained with the Ag cultivars with a difference that varied between 37% and 62% depending on the cultivar type. These results indicate that the date palm cultivars massively influence the biomethane yield, it may give an opportunity for researchers to select the most suitable cultivars for methane production and provide opportunities to valorize other cultivars on other bene-ficial uses, such as adsorption, thermal insulation, or charcoal production etc.
Carbon molecular sieve production from defatted spent coffee ground using ZnCl2 and benzene for gas purification
(Elsevier Sci Ltd, 2020) Kaya, M.; Atelge, M. R.; Bekirogullari, M.; Eskicioglu, Cigdem; Atabani, A. E.; Kumar, Gopalakrishnan; Yildiz, Y. S.
The aim of the current study is to manufacture molecular sieve from the defatted spent coffee ground. The defatted spent coffee ground for the specified particle size (100 mu m) was chemically activated with different agents (ZnCl2, H3PO4, KOH) and then carbonized at different temperatures (400-900 degrees C). A thorough characterization of the produced activated carbon was performed and activated carbons with the highest BET surface area were subsequently used to produce carbon molecular sieve. The surface modification was performed with benzene vapor at different temperatures (600-900 degrees C) and different combustion times (30-90 min.). In addition to the BET analysis, SEM, TGA and FT-IR analysis were also undertaken. The results obtained through characterizations showed that the pore diameters of carbon molecular sieve produced from defatted spent coffee ground varied from 2 to 4 angstrom. To conclude, the results suggest that the fabricated carbon molecular sieve can be used for the removal of impurities such as CH4, CO2, NOx and other impurities in natural and biogas considering the porosity of the sieves.
Co-digestion of vegetable peel with cow dung without external inoculum for biogas production: Experimental and a new modelling test in a batch mode
(Elsevier Sci Ltd, 2021) Lahbab, Abderrahmane; Djaafri, Mohammed; Kalloum, Slimane; Benatiallah, Ali; Atelge, M. R.; Atabani, A. E.
This paper examined both experimental and a new modelling test for biogas production based on Co-Digestion Ratio (CDR) of vegetable peel (VP) with cow dung (CD) without external inoculum. For this, vegetable peel was used as a substrate and cow dung was used as a co-substrate. Reactors in triplicate were prepared. The vegetable peel concentrations were 12, 8, 6 and 4 g VS/l with the same cow dung concentration (4 g of VS/l) which corresponds to a CDR of 3:1, 2:1, 1.5:1 and 1:1. A new mathematical model corresponding to the biotech anaerobic digestion process based only on the (CDR) and (VS) was implemented under Matlab Simulink. The experimental results indicate that the optimal cumulative methane production (CMP) of 2000 ml was generated in the reactor containing a (CDR) of 3:1 which corresponds to a methane yield of 170 ml CH4/ g VS. i.e., an improvement between 23 and 26% comparing to all other CDRs. The experimental results were conformed by the new mathematical model. After applying the invented new idea by converting the constants (Rm, L and Gm) into functions (Rm =f1 (CDR), L=f2(CDR) and Gm = f3 (VS)) and relating them to each other using the Gompertz relation. The new model was able to predict the methane produced using only two inputs: VS and CDR. While in the literature studies, which were used Gompertz relationship for kinetic modelling, the constants must be recalculated each time as a new model, although the substrates used are the same, only the composition is different. Analysis of the variance (ANOVA) between the experimental and modelling results showed that there is no statistically significant difference, with a significance level of 0.05. Finally, the invented new idea can be a key to another different research that uses the same substrate.
Comparative investigation of multi-walled carbon nanotube modified diesel fuel and biogas in dual fuel mode on combustion, performance, and emission characteristics
(Elsevier Sci Ltd, 2022) Atelge, M. R.; Arslan, Esenay; Krisa, David; Al-Samaraae, R. R.; Abut, Serdar; unalan, Sebahattin; Atabani, A. E.
Biogas has been investigated as an alternative biofuel in dual fuel operating mode in a direct injection diesel engine. However, there is not sufficient information about using modified fuels with biogas. This study aimed to investigate the effects of modified diesel fuel and biogas on combustion behavior, performance, and emissions characteristics at 1500 rpm constant speed with 5 different load conditions at an interval of 25%. Diesel was modified with multi-walled carbon nanotubes with 30, 60, and 90 ppm. Diesel fuel and three modified fuels were used as pilot fuel and biogas was introduced through the intake manifold with the flow rate of 500 g/h as the primary fuel. Diesel mode fuels were denominated F1 while dual fuel mode fuels were labeled as F2, and the concentration levels were given subscript such as F2 (@60ppm). The experimental study revealed that modified fuel showed better combustion behaviors, performance, and emissions in comparison to diesel fuel. Further, the same trend was observed in the dual fuel mode. The maximum pressure of F2(@60 ppm) was 1% higher than F2 under dual fuel mode at the full load. Moreover, the coefficient of variation of the indicated mean effective pressure for dual fuel mode was found approximately 9.2, 6.9, 6.2, and 7.2% for F2, F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively at full load. In addition, the energy share of biogas increased by 7.9, 8.7, and 7.1% for F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively in comparison with F2 at full load. The highest decrease of brake specific energy consumption under the dual mode was obtained to be an 8% drop from F2(@60 ppm) compared to F2 at full load. At the same load, the brake thermal efficiency of F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm) were noted to be 30.2, 30.4, and 30.0%, respectively which are higher than F2 (27.9%). The value of replaced diesel with biogas was noted 0.09, 0.23, 0.24, and 0.22 kg/h for F2, F2(@30 ppm), F2(@60 ppm), and F2(@90 ppm), respectively under the full load condition. Lastly, CO and HC emissions were almost the same value with and without modified fuel for dual fuel mode at the full load. Nevertheless, NO emission was slightly increased with modified fuel compared to F2. From these findings, it can be suggested that 60 ppm multi-walled carbon nanotubes additive can be an optimum level for combustion, performance, and emissions under the dual fuel mode.
Defatted spent coffee grounds-supported cobalt catalyst as a promising supercapacitor electrode for hydrogen production and energy storage
(Springer, 2023) Karakas, Duygu Elma; Akdemir, Murat; Atelge, M. R.; Kaya, Mustafa; Atabani, A. E.
The effect of several parameters, such as different Co2+ ratios, burning temperatures, and burning times, was examined by using defatted spent coffee grounds (DSCG) as organic waste to obtain the most effective catalyst for producing hydrogen. Under optimum conditions, the most active catalyst/metal ratio was obtained by burning 50% Co (2+) at 400 degrees C for 90 min. To measure the time-dependent amounts of hydrogen, 0.1 g of DSCG-Co catalyst was dissolved in 10 mL of a methanol solution containing 0.25 g sodium borohydride (NaBH4) at 30 degrees C. The maximum hydrogen generation rate obtained from the methanolysis of NaBH4 at 30 and 60 degrees C was found to be 8749 and 17,283 mL min(-1) gcat(-1), respectively, and the activation energy of the catalyst was found to be 23.2 kJ mol(-1). FTIR, ICP-OES, XRD, BET, and SEM-EDX analyses were performed for the characterization of the prepared DSCG-Co-Cat catalyst. Furthermore, a supercapacitor cell was constructed by using this catalyst as an active substance for electricity storage. The specific capacitance of the electrode at the current density of 1 A/g was calculated as 67 F/g for two-electrode systems. The results of electrochemical analysis of the prepared supercapacitor were found to be similar to the ideal supercapacitor curves. The obtained capacitance values are at very good levels in terms of the capacity and cost factors. The results indicated that the multifunctional capacitor-catalyst material produced by Co-doped waste coffee could constitute an important element in a hybrid system that includes capacitor and catalyst systems that can be installed in the future. [GRAPHICS] .
Effect of stirring speeds on biodiesel yield using an innovative oscillatory reactor and conventional STR (A comparative study)
(Elsevier Sci Ltd, 2022) Khelafi, Mostefa; Djaafri, Mohammed; Kalloum, Slimane; Atelge, M. R.; Abut, Serdar; Dahbi, Abdeldjalil; Bekirogullari, Mesut
This paper aims to study the effect of stirring speed on biodiesel yield using an innovative oscillating reactor compared to the conventional stirring tank reactor. The efficiency of the invented reactor was compared with the conventional system, employing two catalysts (a homogeneous catalyst and a heterogeneous bio-catalyst). The obtained results showed that under low agitation speed of 50 rpm, the invented oscillating reactor is more efficient than the conventional system with a biodiesel yield of 93% compared to 90.13% using the heterogeneous catalyst and 93.53% compared to 92.7% using the homogeneous catalyst respectively. As for the higher stirring speeds, the conventional system was found to be slightly more efficient than the oscillating reactor when using the heterogeneous biocatalyst (96.03% against 94.42%) while the contrary was observed when using the homogeneous catalyst (94.43% against 95%). However, this slight increase in the biodiesel yield at higher speeds results in increasing production costs. This indicates that biodiesel production using the innovative oscillating reactor at low speeds is more economically viable. The characteristics of the produced biodiesel using the invented reactor were in agreement with the ASTM D6751 biodiesel standards. Moreover, a two-way ANOVA analysis was conducted to compare between groups that have been split on two independent variables as reactor type and stirring speed. The statistical analysis proved that the invented oscillating reactor performs better when using heterogeneous catalysts at low stirring speed levels. This study suggests that the biodiesel yield of the innovative reactor can be further enhanced by introducing a baffle system which provides a relatively larger contact surface area. Similarly, synthesis of other heterogeneous bio-catalysts derived from the date seed of another date palm cultivar can be tested to further improve the biodiesel yield.
Evaluation of hybrid nanoparticles to oxygenated fuel with ethanol and n-butanol on combustion behavior
(Elsevier Sci Ltd, 2023) Atelge, M. R.; Arslan, Esenay; Kahraman, Nafiz; Unalan, Sebahattin
The internal combustion engine type is widely used in diesel engines due to its energy efficiency. However, the use of conventional diesel has negative effects on human health and the environment. In an effort to find a more sustainable fuel option with less harmful emissions, the focus has shifted towards investigating the effects of hybrid nano additives, which are a combination of nonmetallic (graphene nanoplate) and metal oxide (TiO2), on conventional diesel (D) and oxygenated fuels (OF). The engine test was conducted at 4 different loading cases with increments of 25% from 25% to 100% at a constant speed of 1500 rpm. The results showed that the modified fuels had superior combustion behaviors, such as peak in-cylinder pressure, combustion duration, and ignition delay, compared to conventional diesel and oxygenated fuels. The peak pressures in the cylinder of modified diesel (Dm) and modified oxygenated fuel (OFm) under full load increased by 2% and 2.9%, respectively, compared to conventional diesel (D). Additionally, the brake thermal efficiencies (BTEs) of Dm and OFm were found to be 5.5% and 3% higher than D under the same test conditions. In terms of emission analysis, the modified fuels demonstrated superiority over the conventional diesel and oxygenated fuels. During full load conditions, the CO, UHC, and NO emissions of OFm compared to D dropped by 49.1%, 54.2%, and 4%, respectively. The study results indicate that the use of a hybrid fuel additive consisting of nonmetallic (graphene nanoplate) and metal oxide (TiO2) can significantly reduce harmful emissions and improve engine performance.
Experimental study of a blend of Diesel/Ethanol/n-Butanol with hydrogen additive on combustion and emission and exegetic evaluation
(Elsevier Sci Ltd, 2022) Atelge, M. R.
The energy demand and consumption due to population growth, urbanization, and industrialization have been dramatically increasing day by day, therefore, researchers have devoted their efforts to figuring out renewable and clean energy sources because of the reduction of drawbacks of fossil fuel usage. Attention has been drawn to alcohols as a renewable biofuel due to their favorable biological production pathways in the recent decade. Therefore, the study aims to reveal information about ternary blend fuels with H-2 additives. In the present study, a ternary blend fuel, labeled as D + A, containing diesel (80% v/v), ethanol (10% v/v), and n-butanol (10% v/v) was investigated with a direct injection compression ignition engine. The combustion, emission, and exergy analysis were performed at 1750 rpm from 0 to 100% loading conditions with a 25% interval. Furthermore, the effects of H-2 additive with different three flow rates (5, 15, and 25 g/h) on performance of the test engine and emissions were examined under dual-fuel mode. The ternary blend fuel generally increased BSFC and decreased BTE compared to diesel (D). At the full load, BSFC of D + A increased by 7.2% and BTE of D + A decreased by 1.3% with respect to D as base case. However, H-2 addition through the intake manifold improved both BTE and BSFC. BTEs of D + A (@5H2) (5 g/h flow rate), D + A (@15H2), and D + A (@25H2) increased by 9.9, 6.1, and 5.7% improvement compared to D at the full load. Moreover, at the same load condition and base fuel, the highest drop of BSFC was observed to be 4.3% from D + A (@5H2) that is followed by D + A (@15H2), and D + A (@25H2) by 2.2 and 1.7%, respectively. The exergy efficiency was recorded as ~ 1.5% decrement and ~ 10.2% increment for D + A and D + A (@5H2), respectively according to D at the full load. For all tested fuels at the full load, D + A (@5H2) had the highest exergy performance coefficient of 0.61 and the most sustainable fuel mixture was found to be D + A (@5H2) with 1.45 of the sustainability index value. The thermoeconomic and the exergoeconomic parameters showed the same trend. In the emission aspect, D + A showed a better performance than D with respect to CO, HC, and NO emissions. Under dual-fuel mode for all flow rates, CO emission was lower than D while HC and NO were slightly higher.
Investigation of a novel Defatted Spent Coffee Ground (DSCG)-supported Ni catalyst for fuel cell and supercapacitor applications
(Elsevier, 2024) Hansu, Tulin Avci; Al-Samaraae, R. R.; Atelge, M. R.; Kaya, Mustafa; Kivrak, Hilal Demir; Bogrekci, Ismail; Yildiz, Yalcin Sevki
With the increase in energy demand, a material that can be used in fuel cell applications has been developed for both energy storage and the use of alternative energy sources to fossil fuels. In this study, a new Defatted Spent Coffee Ground (DSCG)-based electrode material was synthesized for two different application areas. A new electrocatalyst synthesis was carried out by subjecting DSCG to chemical activation and carbonization processes. The glycerol electrooxidation performances of the catalysts synthesized at 10-50 % Ni loading rates were investigated by CV measurements. 30 % Ni-DSCG catalyst exhibited the highest catalytic activity with 3.290 mA/ cm2.As 2 .As a result of the electrochemical measurements, 30 % Ni-DSCG catalyst with the best catalytic performance was used as the supercapacitor electrode material. The electrochemical performances of the produced super- capacitor electrodes were tested at room temperature using galvanostatic charge-discharge (GCD), Cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) techniques, and the capacity and stability of the electrodes were calculated as a result of the findings. In the calculations, the energy and power density of the 30 % Ni-DSCG supercapacitor electrode were calculated as 22.897 Wh kg(- 1) , 841.114 W kg(- 1) , respectively. The supercapacitor electrode capacitance was found to be 50.48 F/g. Its cyclic capacity was found to be 90 %. It showed that the DSCG-based synthesized electrocatalyst could be a good option for energy storage technology as EDLC electrode material and fuel cell applications as anode catalyst due to its good conductivity, superior cyclic stability, environmental friendliness and low cost.
Investigation of a ternary blend of diesel/ethanol/n-butanol with binary nano additives on combustion and emission: A modeling and optimization approach with artificial neural networks
(Elsevier, 2022) Atelge, M. R.
The increase in global energy consumption and concerns about fossil fuels depletion are pushing the demand for renewable and clean energy sources. Alcohols are a promising candidate for internal combustion engines as alternative fuels. This study aims to reveal the effect of a ternary blend, which is denominated D80E10nB10, consisting of diesel (80%), ethanol (10%), and n-butanol (10%) on combustion and emission characteristics. The addition of both metal oxide (TiO2) and nonmetallic nanoparticle (MWCNT) was also investigated with the above-mentioned ternary blend fuels, which are denominated m- . The compression ignition engine was run under dual fuel mode with feeding H-2 in the range of 5 and 15 g/h, which were labeled D80E10nB10H5 and 15. The results revealed that the maximum pressure increased by 3.63 and 3.94% by adding 5 and 15 g/h H-2 respectively into ternary blend fuel under the full load. The highest BTE was obtained from modified diesel fuel which was 23.24% higher than diesel. Furthermore, 60 Artificial Neural Network (ANN) models were built to optimize test conditions. The optimal conditions for ternary blend fuel were found to be 4 g/h H-2 feeding rate while 5.5 g/h H-2 addition with modified ternary blend fuel would be the optimal.
Investigation of H2 enrichment of ternary blended fuel modified with graphene nanoplate on cycle-by-cycle variations
(Pergamon-Elsevier Science Ltd, 2024) Atelge, M. R.; Arslan, Esenay; Kahraman, Nafiz; Kaushal, Rajneesh; Unalan, Sebahattin
Despite the global goal of achieving e-mobility in the future, the majority of the transportation sector still heavily relies on fossil fuels. Previous studies in the area have revealed the benefits of hydrogen additives and nanoparticles mixed with blended diesel fuels on engine performance and emissions. However, there is a significant gap in the research when it comes to exploring the combination of non-metallic nanoparticle additives with alcohol and diesel blend fuels under dual-fuel mode with hydrogen. In the study, a fuel blend (BF) comprising 80% diesel, 10% n-butanol, and 10% ethanol, which represents a potential alternative fuel composition for compression ignition engines, was specifically focused on. To further enhance the fuel properties and combustion characteristics, the addition of 50 ppm graphene nanoplatelets (GNP) was introduced as a non-metallic additive. By examining this novel fuel composition and investigating its impact under both single and dual-fuel mode, the dimension of hydrogen addition in the dual-fuel mode is aimed to explore potential synergistic effects. A diesel engine was used under dual fuel mode, with hydrogen fed at a rate of 0.25 g/min. The prepared fuels were tested at 1800 rpm engine speed by applying five different loads. 50 ppm GNP of modified fuels resulted in an increase of peak pressures by 3.1%, 4.2%, and 5.6% for DGNP, BFGNP, and BFGNP15H respectively, compared to D. At full load, the COVIMEP values were approximately 0.3%, 0.2%, 0.4%, 1.3%, and 1.6% for D, DGNP, BF, BFGNP, and BFGNP15H, respectively. In the term of thermal efficiency, BFGNP15H had a 3.9% lower BTE than BFGNP at 25% load, but BFGNP15H showed a 0.4% increase in BTE at full load compared to BFGNP. For emission analysis, BFGNP15H showed a reduction of 42.31%, 15.1%, and 10% in CO emissions compared to D, BF, and BFGNP, respectively, under full load in dual operating condition. However, the NO emissions of BFGNP15H were 7.2% higher than those of D under the same condition.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.
Modeling and simulation of co-digestion performance with artificial neural network for prediction of methane production from tea factory waste with co-substrate of spent tea waste
(Elsevier Sci Ltd, 2021) Ozarslan, Saliha; Abut, Serdar; Atelge, M. R.; Kaya, M.; Unalan, S.
The production of biofuel from waste has become an important topic for waste management and reducing its environmental hazard. Tea factory waste is a strong candidate due to its availability and sourceability. This study aimed to reveal the biochemical methane potential (BMP) of tea factory waste (TFW) and spent tea waste (STW). Additionally, the results revealed that both substrates had high biodegradability due to high VS removal. The BMP tests took 49 days under mesophilic conditions with a batch reactor and the cumulative methane yields were 249 +/- 3, and 261 +/- 8 mL CH4/g VS for TFW and STW, respectively. According to prediction data with the selected ANN model, which was 50 hidden layer sizes, trained with Bayesian Regularization algorithm, the maximum cumulative specific methane yield of the co-digestion was simulated as 468.43 mL CH4/g VS when the ratio of 65 and 35% (w/w by VS) of TFW and STW, respectively. The predicted methane yield for co-substrates was 183% higher than mono substrates. This result revealed that TFW can be a good candidate for biogas production as biofuel for not only its availability and sourceability but also the synergistic effect possible for codigestion.
Production of biodiesel and hydrogen by using a double-function heterogeneous catalyst derived from spent coffee grounds and its thermodynamic analysis
(Pergamon-Elsevier Science Ltd, 2022) Atelge, M. R.
Biodiesel and hydrogen are promising liquid and gas energy source alternatives to satisfy fossil fuel demand. In this study, a heterogeneous catalyst, spent coffee grounds derived activated carbon supported, was synthesized using KOH as an activation agent. The highest iodine number was obtained at 600 ?C carbonization temperature and the synthesized catalyst was subjected to the characterization and evaluated in terms of biodiesel and hydrogen production efficiencies. The optimal transesterification reaction parameters were determined as 3 wt% catalyst loading, 9:1 methanol-to-waste cooking oil molar ratio, 90 ?C reaction temperature, and 120 min re-action time. Under optimal reaction conditions, the biodiesel yield was 91.57%. For hydrogen production, 100% conversion was observed in all cases. Among the experimental conditions, the fastest reaction was obtained with the addition of 0.25 g superior catalyst with 2.5% of NaBH4 concentration at 30 ?C reaction temperature. Moreover, the chosen superior catalyst was successfully reused for five cycles to test the reusability of the catalyst. The catalyst performance was almost the same as of the first cycle after regeneration for both trans-esterification and dehydrogenation reactions. Additionally, the activation energy of the transesterification and methanolysis reactions was calculated as 19.15 and 15.48 kJ/mol, respectively. In the thermodynamic aspect, both reactions were endergonic and unspontaneous. Additionally, it can be concluded that the reactants were converted to the products very well due to the indication of entropy change.
Semi-continuous mesophilic anaerobic digestion of date palm (Phoenix dactelifyra L.) leaflets of the H'mira cultivar from the Adrar region of Southern Algeria using an alkaline pre-treatment
(Elsevier, 2024) Salem, Fethya; Djaafri, Mohammed; Kaidi, Kamel; Atelge, M. R.; Khelafi, Mostefa; Tahri, Ahmed; Soumia, Balla
This research paper aim to investigate the enhancement potential of mesophilic Anaerobic Digestion (AD) of Algerian date palm (Phoenix dactylifera L.) leaflets from H'mira cultivars using an alkaline pretreatment approach. The experiment was conducted for the first time in semi-continuous digesters. NaOH was applied at various percentages (6 %, 12 % and 18 %) to chemically pretreat the substrate for 5 days at 37 degrees C. The chemical pretreatment results were interpreted for the first time with in-depth FTIR spectroscopic analyses. The Hydraulic Retention Time (HRT) was fixed at 15 days, and the Organic Loading Rate (OLR) at 2 g MO/L/day. The results showed that the methane (CH4) production values were stabilized with a clear distinction at averages of 211.85, 177.26, 143.36 and 123.07 ml of CH4/day, i.e. a CH4 yield of 105.92, 88.63, 71.68 and 61.53 ml of CH4/gVS/day for the reactors containing substrates pre-treated with 12 %, 6 %, 18 % NaOH and the substrate without pretreatment respectively. Compared to the substrate without pre-treatment, the CH4 production rates were improved 1.72, 1.44 and 1.16 times for the reactors containing 12 %, 6 % and 18 % NaOH respectively. These findings were perfectly in accordance with FTIR spectroscopy results. These findings demonstrate that the semicontinuous AD process can be an attractive energy recovery solution from such waste compared to batch digesters, (on one day, it produce 77-105 % of the CH4 produced during 21-55 days in batch digesters), as well as the importance of adequate pre-treatment prior to the AD. FTIR Spectroscopic analysis technology can also be widely used to analyze pre-treatment data for lignocellulosic biomass, as it gives very encouraging results.
Spent coffee grounds anaerobic digestion: Investigating substrate to inoculum ratio and dilute acid thermal pretreatment
(Elsevier Sci Ltd, 2023) Semaan, Georgeio; Atelge, M. R.; Cayetano, Roent Dune; Kumar, Gopalakrishnan; Kommedal, Roald
Spent coffee grounds have the potential of being used in further bioprocesses to produce materials and fuels. In Norway, the relative abundance and ease of collection of this waste substrate make it a candidate for investi-gation. For this study, the substrate-to-inoculum ratio as well as a combined dilute acid-thermal pretreatment were assessed by a series of biochemical methane potential assays using spent coffee grounds as a substrate. Reactors with substrate-to-inoculum ratio 2 demonstrated a relatively low hydrolysis rate constant (kh) and comparatively high volatile fatty acids/alkalinity concentrations rendering them inapt to produce bio-CH4. Pretreatment was conducted over varying contact times (15-45 min), dilute acid concentrations (1.5-2.5 %, v/ v), and liquid-to-solid ratios (10-20 %, v/w) and evaluated using response surface methodology. To determine bio-CH4 yield, pretreatment time and the interaction between acid concentration and liquid-to-solid ratio are considered significant variables, suggesting a shared importance. Chemical oxygen demandremoval is primarily contingent upon changes in liquid-to-solid ratio. Finally, Fourier-transform infrared spectroscopy of the dis-carded solid phase showed that the major functional groups are still widely present in the coffee grounds even after pretreatment was applied. A better understanding of the biodegradability profile of spent coffee grounds as a function of substrate-to-inoculum ratio is achieved.

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