Biomethane Recovery From Anaerobic Co-Digestion of Sewage Sludge and Waste Coffee

ABSTRACTIn this study, anaerobic co-digestion of waste coffee and sewage sludge was used for the production of biogas in a batch scale digester at mesophilic condition (~37 &deg;C). Three experimental conditions were prepared including; sewage sludge (sample 1) which had 2% of solid waste, sewage sludge with waste coffee before oil extraction (sample 2), and sewage sludge with waste coffee after oil extraction (sample 3). 5 grams of waste coffee (before and after oil extraction) were mixed with 100 ml of sewage sludge, the experiments were monitored for 45 days. The results showed that sewage sludge gave the lowest methane yield (0.003 m3/kg VS initial) while the highest was obtained from sample 2 (0.02 m3/kg VS initial) compared to (0.007 m3/kg VS initial) of sample 3. As a conclusion, co-digestion of waste coffee as potential co-substrate is an effective method to enhance biogas yield from sewage sludge. Therefore, more research shall be directed towards the recycling of waste coffee into biogas.Keywords: Biogas, Recycling, Co-digestion, Coffee waste, Sewage sludge.</p

Evaluation of hybrid nanoparticles to oxygenated fuel with ethanol and n- butanol on combustion behavior

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

Investigation of H2 enrichment of ternary blended fuel modified with graphene nanoplate on cycle-by-cycle variations

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

Spent coffee grounds anaerobic digestion: Investigating substrate to inoculum ratio and dilute acid thermal pretreatment

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 investigation. 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 discarded 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.publishedVersio

A novel Microcystis aeruginosa supported manganese catalyst for hydrogen generation through methanolysis of sodium borohydride

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

A state-of-the-art review on spent coffee ground (SCG) pyrolysis for future biorefinery

Coffee is a globally consumed beverage that produces a substantial amount of valuable organic waste known as spent coffee grounds (SCG). Although SCG is a non-edible biomass, research initiatives focused on valorizing/utilizing its organic content, protecting the environment, and reducing the high oxygen demand required for its natural degradation. The integration with biorefinery in general and with pyrolysis process in specific is considerered the most successful solid waste management strategy of SCG that produce energy and high-value products. This paper aims at providing a quantitative analysis and discussion of research work done over the last 20 years on SCG as a feedstock in the circular bioeconomy (CBE). Management stratigies of SCG have been thoroughly reviewed and pyrolysis process has been explored as a novel technology in CBE. Results revealed that explored articles belong to Chemical, physical., biological and environmental science branches, with Energy & Fuels as the most reporting themes. Published works correlate SCG to renewable energy, biofuel, and bio-oil, with pyrolysis as a potential valorization approach. Literature review showed that only one study focused on the pyrolysis of defatted spent coffee grounds (DSCG). The insightful conclusions of this paper could assist in proposing several paths to more economically valorization of SCG through biorefinery, where extracted oil can be converted to biofuels or value-added goods. It was highlighted the importance of focusing on the coupling of SCG with CBE as solid waste managment strategy.Deanship of Scientific Research, King Faisal UniversityScopu

Biogas Production from Organic Waste: Recent Progress and Perspectives

Anaerobic digestion (AD) from organic waste has gained worldwide attention in reducing greenhouse gas emissions, lowering fossil fuel combustion, and facilitating a sustainable renewable energy supply. Biogas mainly consists of methane (CH4) (50–75%), carbon dioxide (CO2) (25–50%), hydrogen sulphides (H2S), hydrogen (H2), ammonia (NH3) (1–2%) and traces of other gases such as oxygen (O2) and nitrogen (N2). Methane can replace fossil fuels in various applications such as heat and power generation and the transportation sector. The degradation of organic waste through an AD process o?ers many advantages, such as the decrease of pathogens and prevention of odour release. The digestate from anaerobic fermentation is a valuable fertilizer, however, the amount of organic materials currently available for biogas production is still limited. New substrates, as well as more e?ective conversion technologies, are needed to grow this industry globally. This paper reviewed the latest trends and progress in biogas production technologies including potential feedstock. Recycling of waste has recently become an important topic and has been explored in this paper.The Unit of Scientifc Research Project Coordination (Bilimsel Araştırma Projeleri Koordinatörlüğü, BAP) of Erciyes Univerity, Kayseri, Turkey for the fnancial support under the University Project: FOA-2018-8183 (Priority Research Project) (Öncelikli Araştırma Proje). This work was also supported in part by grants from the Korea Ministry of Environment, as a “Global Top Project” (Project No.: 2016002210003)

Comparative investigation of multi-walled carbon nanotube modified diesel fuel and biogas in dual fuel mode on combustion, performance, and emission characteristics

© 2021Biogas 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