Coffee Husk Research Articles

Effect of Processed Coffee Husk on Feed Intake, Nutrient Digestibility, Body Weight Changes and Economic Feasibility of Bonga Sheep Fed on Natural Pasture Hay as a Basal Diet.

Ethiopia is one of the world's coffee producers, generating about 192,000 metric tonnes of coffee husks annually as by-products. The material can be used for ruminant diets to improve the nutrient utilisation of animals. However, coffee husk has toxic compounds, which can be minimised through different processing methods. Though the above techniques can minimise the toxicity level of coffee husk and increase the bioavailability of nutrients, there is scanty information on the comparative efficacy of these techniques, especially in ruminant nutrition. The study was conducted to examine the effect of processed coffee husk on feed intake, nutrient digestibility, body weight changes and profitability of Bonga rams based on natural pasture hay. In the experiment, 24 rams were used, and the rams were grouped into six blocks based on initial body weight (mean BW 21.5 ± 1.01kg). The rams were quarantined for 21 days, and each ram was randomly assigned to one of the experimental feed treatments in a randomised complete block design (RCBD). The experimental treatment feeds include 400g conventional concentrate mix (CM) containing Noug seed cake and wheat bran (T1); 200g boiled coffee husk + 200g CM (T2); 200g roasted coffee husk + 200g CM (T3) and 200g raw coffee husk + 200g CM (T4). The CM was made in the ratio of 1:1. The data collected from the 90-day experimental period were: dry matter and nutrient intakes, initial body weight, final body weight and body weight changes. After the growth experiment, a 7-day digestibility trial was followed by collecting faeces using a harness bag. The data were managed using Microsoft (MS) Excel 2010 and analysed using R software (v. 4.3.2). The chemical compositions of the CM had maximum crude protein (22%), followed by boiled coffee husk (14.74%), which was higher than natural pasture hay (6.91%) and raw coffee husk (12.4%). The total dry matter intake (p < 0.05), metabolisable energy, and total nutrient intakes of rams were significantly (p < 0.001) maximised when rams fed on boiled coffee husk (T2) than raw (T4) and roasted (T4) coffee husk, except for NDF and organic matter intakes. The apparent digestibility of nutrients and feed conversion efficiency were maximised for rams assigned to T2. There was maximum daily body weight gain (p < 0.001) when rams were supplemented with boiled coffee husk (T2). Also, body weight changes of rams were significantly (p < 0.001) higher for rams supplementation with boiled coffee husk. Therefore, the boiled coffee husk as an alternative feed resource can be replaced by about half of the commercial CM without adverse effects of anti-nutritional factors and enhance the income of smallholder farmers in the coffee crop-livestock production system.

New approach to agro-industrial solid and liquid waste management: Performance of an EGSB reactor at different hydraulic retention times for methane production

This study investigated the removal of agro-industrial wastes (5 g COD L⁻1 from coffee and 0.5 g COD L⁻1 from brewery wastewater, plus 1 g L⁻1 of coffee pulp and husk) in a continuous Expanded Granular Sludge Bed (EGSB) reactor at 35 °C. The effect of Hydraulic Retention Times (HRTs) of 72h, 48h, and 24h on CH₄ yield was examined using a mixed culture of cattle manure and granular sludge. Methane yields were 201, 124.5, and 113.8 mL CH₄ g⁻1 COD for the 1st, 2nd, and 3rd phases, respectively. Volatile fatty acids, particularly acetic acid, increased at lower HRTs. Sequencing of the 16S rRNA gene on the Illumina HiSeq platform revealed a syntrophic relationship between Syntrophorhabdus, Syntrophobacter, and Pseudomonas with methanogens Methanomassiliicoccus, Methanospirillum, and Methanobacterium, aiding in the removal of phenolic compounds. The study suggests that an HRT of 72h is optimal for maximizing CH₄ production in the EGSB reactor.

Empowerment of the Curah Indah Farmers Group in Banyuwangi through the Processing of Cascara Tea as a Functional Beverage Modified from Coffee Husk Waste

Empowerment of the Curah Indah Farmers Group in Banyuwangi through the Processing of Cascara Tea as a Functional Beverage Modified from Coffee Husk Waste

Effects of Time based Different Integrated Organic and Mineral Fertilizer Rate Application on Improved Coffee Cultivar Yield in South Ethiopia

Coffee Production plays a significant role in Ethiopian economy, even though the productivity at farm level is among the lowest as compared to other coffee producing country. Soil degradation is one of the most challenging problems in coffee growing areas of Ethiopia. Declining of soil fertility is a fundamental problem to agricultural growth and a major reason for slow growth of food production. Therefore, this activity was designed to determine optimum application time of integrated organic and inorganic fertilizers under coffee growing areas and to assess the effects of temporal application effects of integrated organic and inorganic fertilizers on coffee yield and yield stability performance of coffee cultivar. The experiment was conducted with RCBD design with four replication and ten treatments settled from integrated organic and inorganic inputs at Awada Agricultural research sub-center starting from 2013-2023 for the last 10 consecutive years. The result demonstrated that, application of 200kgha-1N, 77kgha-1P and 12.5tonha-1 integrated nutrient application at each cropping season resulted statically significant higher yield result as compared to the other nutrient applications. The plot treated with the recommended NP + recommended decomposed coffee husk application per year (200kgha-1N, 77kgha-1P and 12.5ton ha-1) indicated over all yield advantage over the other plots by 22.07% or 345kg/ha of clean coffee yield over the recommended (200kgha-1N, 77kgha-1P) applied alone per year and 33.39% or 522kg/ha of clean coffee yield over the plots treated with recommended decomposed coffee husk (12.5ton ha-1) alone application per each cropping season.

Emission Factors for Biochar Production from Various Biomass Types in Flame Curtain Kilns

Simple and low-cost flame curtain (“Kon-Tiki”) kilns are currently the preferred biochar technology for smallholder farmers in the tropics. While gas and aerosol emissions have been documented for woody feedstocks (twigs and leaves) with varying moisture contents, there is a lack of data on emissions from other types of feedstocks. This study aims to document the gas and aerosol emissions for common non-woody feedstocks and to compare emissions from finely grained, high-lignin feedstock (coffee husk) with those from coarser, low-lignin feedstocks (maize cobs, grass, sesame stems). Throughout each pyrolysis cycle, all carbon-containing gases and NOx were monitored using hand-held sensitive instruments equipped with internal pumps. Carbon balances were used to establish emission factors in grams per kilogram of biochar. The resulting methane emissions were nearly zero (&lt;5.5 g/kg biochar) for the pyrolysis of three dry (~10% moisture) maize cobs, grass, and a 1:1 mixture of grass and woody twigs. For sesame stems, methane was detected in only two distinct spikes during the pyrolysis cycle. Carbon monoxide (CO) and aerosol (Total Suspended Particles, TSP) emissions were recorded at levels similar to earlier data for dry twigs, while nitrogen oxide (NOx) emissions were negligible. In contrast, the pyrolysis of finely grained coffee husks generated significant methane and aerosol emissions, indicating that technologies other than flame curtain kilns are more suitable for finely grained feedstocks. The emission results from this study suggest that certification of biochar made from dry maize, sesame, and grass biomass using low-tech pyrolysis should be encouraged. Meanwhile, more advanced systems with syngas combustion are needed to sufficiently reduce CO, CH4, and aerosol emissions for the pyrolysis of finely grained biomasses such as rice, coffee, and nut husks. The reported data should aid overarching life-cycle analyses of the integration of biochar practice in climate-smart agriculture and facilitate carbon credit certification for tropical smallholders.

LCA-based carbon footprint analysis of anaerobic digestion of coffee husk waste

While studies have shown that anaerobic digestion (AD) with energy generation of agricultural residues have many benefits, it is still unclear the extent to which this technology can reduce greenhouse gas (GHG) emissions, particularly in the context of coffee husk wastes. To address this knowledge gap, this work explored three scenarios of coffee husks as an energy source: 0) business-as-usual (landfilling); 1) AD with energy generation; 2) same as the previous one, adding a hydrothermal hydrolysis pre-treatment step. The study adopted a Life Cycle Assessment (LCA) methodology to estimate the environmental impacts of this technology in terms of GHG emissions. The results indicate that the main benefit of using AD is to avoid the impacts of landfilling, as the carbon footprint for the landfilling scenario was more than 13 times higher than the others. The emissions from digestate management were the main source of the overall emissions, accounting for 34 %. However, its use to replace chemical fertilizers affected the environmental performance positively. The inclusion of the pre-treatment was a key factor in making the bioenergy from coffee husks less carbon-intensive than natural gas and oil, although common renewable sources such as wind and hydropower tend to have lower GHG emissions. Sensitivity analyses indicate that this type of bioenergy can mitigate GHG emissions from energy generation in coffee-producing countries with fossil-based energy mixes. Overall, this work fills a knowledge gap by providing empirical evidence to the potential benefits of using coffee husks in the world's transition to a low-carbon economy.

Evaluation of a phenolic-tolerant Wickerhamomyces anomalus strain for efficient ethanol production based on omics analysis

Lignocellulosic biomass is a highly economically viable substrate for ethanol fermentation, but the presence of phenolic compounds (PCs) in lignocellulosic hydrolysates severely hinders the growth of ethanologenic strains. This study aims to investigate the ethanol fermentation capabilities and PC tolerance of the newly isolated Wickerhamomyces anomalus CAP5. The strain demonstrated remarkable ethanol production, achieving 87.1 g/L with a yield of 0.47 g/g, exceeding 90 % of the theoretical maximum. To elucidate the mechanisms responsible for this high ethanol yield, comprehensive genome and transcriptome analyses were performed. These analyses identified key metabolic pathways, including acetate reabsorption and an incomplete glycerol synthesis pathway, as crucial factors contributing to the strain's superior performance. Moreover, W. anomalus CAP5 demonstrated notable resistance to PCs, particularly phenolic acids. In fermenting with coffee husk hydrolysate (CHH), which is rich in PCs, W. anomalus CAP5 achieved noteworthy ethanol production of 60.5 g/L, marking a record for ethanol production from CHH. Hence, W. anomalus CAP5 emerges as a promising strain for effective ethanol production from lignocellulosic hydrolysates enriched with PCs.

Post-Extractivism and Bioeconomy: An Experimental Analysis of Combustion and Pyrolysis Processes as Alternatives to Add Value to Agro-Residues (Coffee Husks) Generated in Farmer Cooperatives of the Ecuadorian Amazon

A post-extractivist development model for communities in the Amazon that is not based on non-renewable resource extraction demands the study and demonstration, in the field, of alternative economic activities that add value to currently generated residual biomass. Following the principles of bioeconomy, this study presents an experimental analysis of a retort burner and a pilot-scale auger-type pyrolysis reactor used to convert coffee husks generated in a collection and post-harvesting center of a farmer’s cooperative into thermal energy and biochar, respectively. This study shows that coffee husks, whether used as feedstock for combustion or pyrolysis processes, can supply the thermal energy required by the post-harvesting processes. The combustion or pyrolysis of coffee husks avoids its accumulation and decomposition while replacing fossil fuels used in post-harvesting operations, reducing costs and making farmers independent of fossil fuel subsidies. Unlike combustion (11,029.4 mg/Nm3), the CO concentration in the flue gas during the pyrolysis process was 458.3 mg/Nm3, which is below the eco-design standard of 500 mg/Nm3. According to the European Biochar Certificate, carbon content (67.4 wt%) and H/Corg, O/Corg (0.6 and 0.1, respectively) are within the typical values of biochars used for soil amendment and carbon sequestration. Nonetheless, the concentration of polycyclic aromatic hydrocarbons must be assessed to fully regard this material as biochar. Finally, further studies are required to assess the ability of cooperatives to generate and trade carbon credits linked with the application of biochar in their cropping systems.

Sifat Kimia dan Sensori Teh Celup Cascara Stevia dengan Metode Pengeringan Kulit Kopi dan Persentase Gula Stevia (Stevia rebaudiana Bertoni) yang Berbeda

Cascara is a dry tea made from coffee husk waste. Cascara is prepared in the shape of dip packets to make it easier for customers, and stevia (Stevia rebaudiana Bertoni) is added since consumers like sweet drinks and to promote consumer preference. The purpose of this study is to investigate the influence of the coffee skin drying process and cascara and stevia ratio on the physicochemical and sensory qualities of cascara tea bags. This research used a factorial completely randomized design where the first factor is the drying method, and the second is the percentage of added stevia. The research data obtained is then analyzed using Analysis of Variance (ANOVA) and followed with Duncan's Multiple Range Test (DMRT) if there are differences between treatments. The drying technique treatment variance influenced pH, total dissolved solids, and color hedonic. The research revealed that the pH of cascara dried in the oven was higher than that of sun drying, while the total soluble solids of sun drying were higher than that of oven drying. The pH and total soluble solids increased as the proportion of stevia added increased. The hedonic test mean result for fragrance was 3.49 (neutral), color was 3.47 (neutral), and taste was 3.13 (neutral). The cascara scent description test had a mean value of 2.74 (neutral), a cascara color description of 2.74 (light), a sweet taste description of 2.81 (neutral), a sour taste description of 2.24 (weak), a bitter taste description of 1.81 (weak), and an astringent taste description of 2.24 (weak). The total phenols value in sun drying with a 20% stevia addition yielded 139 mg GAE/mL

Chemical activation of biochar derived from coffee husk for the adsorption of phytohormones from waste coconut water

Abstract The potential of NaOH-activated biochar derived from waste coffee husks via pyrolysis for the extraction of phytohormones from waste coconut water was investigated. The raw coffee husk biochar (CHB) and coffee husk activated biochar (CHAB) were characterized and compared in terms of morphology, particle size distribution, elemental composition, surface functional groups, bulk density, phytohormone adsorption efficiency and equilibrium adsorption capacity. The phytohormone adsorption efficiency of the CHB and CHAB produced were 62.36% and 91.33%, respectively. Future work includes flask adsorption experiments and using the phytohormone content extracted from the coconut water for tissue culture studies. Collectively, results from this study present an alternative use of coconut and coffee wastes, and ultimately contribute to the waste management processes of the coconut and coffee industries.

The Effect of Anaerobic Composting Method of Coffee Waste on The Growth of Robusta Coffee Seedlings (Coffea canephora L.)

Coffee is one of the plantation commodities that has significant economic value. A factor that needs to be considered in coffee plant cultivation is good planting media composition. This study aims to determine the effect of planting media composition on the growth of robusta coffee seedlings. This study used a Completely Randomized Design with treatments M0= Soil: 100%, M1= Soil: 50% + Coffee Husk Compost: 25% + Rice Husk: 25%, M2= Soil: 25% + Coffee Husk Compost: 50% + Rice Husk: 25%, M3= Soil: 25% + Coffee Husk Compost: 25% + Rice Husk: 50%. The analyses conducted were compost analysis and initial and post-incubation soil analysis. Observation data were analyzed using the F test followed by DNMRT at the 5% level. The research results show that the provision of coffee husk compost and rice husks affects the chemical properties of the soil and the growth of coffee seedlings. The planting media composition of Soil: 25% + Coffee Husk Compost: 50% + Rice Husk: 25% proved to increase the pH of the planting media from 5.5 to 6.6, increase in total N-value from 0.2% to 0.5%, available P from 18.6 ppm to 38.5 ppm and the soil CEC from 7.6 me/100g to 36.6 me/100g. This planting media composition also makes it possible to enhance the growth of robusta coffee seedlings in plant height, stem diameter, number of leaves, leaf width, and root volume. Thus, this planting media composition is a suitable medium for the growth of robusta coffee seedlings.

Removal of eriochrome black T from aqueous solution using coffee husk as bioadsorbent

The eriochrome black T dye belongs to the azo dye class and is often used as an indicator in complexometric titrations and as a fiber dye in industrial processes. It constitutes a direct threat to human health and the environment due to its toxic and carcinogenic nature. Separating this dye from wastewater is essential before its release into water bodies. In this work, the adsorption capacity of eriochrome black T in aqueous solution conferred on the chemically modified or unmodified coffee husk fibers was evaluated. Adsorption experiments were performed in triplicate and batch. The results obtained were adjusted and presented as adsorption isotherms using the Langmuir-Freundlich model. The mass value of adsorbed dye was 483.9 mg ± 17.35 mg and 547.2 mg ± 22.98 mg of eriochrome black T per gram of unmodified and chemically modified coffee husk, respectively, indicating great potential of coffee husk as an adsorbent for the removal of anionic azo dyes in aqueous solution.

Authentication of indigenous Brazilian specialty canephora coffees using smartphone image analysis

The prevention of coffee fraud through the use of digital and intelligence-based technologies is an analytical challenge because depending on the adulterant, visual inspection is unreliable in roasted and ground coffee due to the similarity in color and texture of the materials used. In this work, a 3D-printed apparatus for smartphone image acquisiton is proposed. The digital images are used to authenticate the geographical origin of indigenous canephora coffees produced at Amazon region, Brazil, against canephora coffees from Espírito Santo, Brazil, and to capture the adulteration of indigenous samples. The results evidenced that the technology is favorable to identify the geographical origin and adulteration with multiple substances using smartphone technology. Pure coffees were adulterated with arabica coffee, spent coffee ground, low-quality Canephora coffee, coffee husks, açaí, corn, and soybean in increasing proportions of 10, 20, 30, 40, 50, 60, and 70 %. These adulterants were roasted and grounded similarly to Canephora coffees to mimetize a highly-sophisticated fraud. The images were converted into Red-Green-Blue (RGB) fingerprinting and used as analytical response to construct Data-Driven Soft Independent Modeling of Class Analogy (DD-SIMCA) models. A total of 95 % of all target and non-target samples in the test set were correctely identified, aiding producers and consumers in ensuring accurate labeling and supporting traditional communities economically and culturally. Smartphone-based method demonstrated potential to innovate the coffee safety control representing a new analytical tecnology.

Comprehensive thermal properties, kinetic, and thermodynamic analyses of biomass wastes pyrolysis via TGA and Coats-Redfern methodologies

This study comprehensively analyzes the thermal decomposition characteristics as well as the kinetic and thermodynamic parameters of five biomass wastes, including coffee husk, groundnut shell, macadamia nutshell, rice husk, and tea waste, using Thermogravimetric Analysis (TGA) and the Coats-Redfern method. The TGA experiments were conducted on a PerkinElmer STA 6000 instrument under an inert N2 atmosphere with a heating rate of 20 °C/min, spanning a temperature range from 25 °C to 950 °C. The results identified three distinct pyrolysis stages: drying, devolatilization, and char formation, with macadamia nutshell demonstrating the highest thermal reactivity and efficient devolatilization characteristics, reflected by its lowest initial devolatilization temperature (175 °C) and highest peak temperature (380 °C). Kinetic analysis revealed that coffee husk had the highest overall activation energy (Ea) of 60.59 kJ/mol, indicating complex thermal degradation behavior. The thermodynamic evaluation showed that coffee husk also exhibited the highest enthalpy change (ΔH=55.46 kJ/mol) but the lowest Gibbs free energy change (ΔG=148.34 kJ/mol), suggesting high energy requirements for decomposition but relatively more spontaneous reactions compared to other biomass types. Macadamia nutshell demonstrated high ΔG (163.24 kJ/mol) and moderate ΔH (32.44 kJ/mol), reflecting greater resistance to spontaneous decomposition. The comprehensive pyrolysis index (CPI) and devolatilization index (Ddev) confirmed macadamia nutshell as the most reactive biomass, while rice husk exhibited the lowest reactivity. The findings highlight the importance of multi-step kinetic analysis for accurately understanding pyrolysis processes, providing critical insights for optimizing biomass conversion for energy production. Future research should explore co-pyrolysis with varied biomass mixtures and advanced kinetic modeling to enhance energy yields.

Activated carbon from agricultural industry waste for use as an adsorbent of sulfamethazine: Fascinating and environmentally friendly process

Lignocellulosic wastes have garnered interest in activated carbon (AC) production owing to their abundance and cost-effectiveness. This research utilized coffee husk as a precursor for AC. The methodology involves impregnating the waste with varying proportions of phosphoric acid (H3PO4), 1:1 and 1:3 (masswaste:massH3PO4), and activation in a microwave oven, with different power and activation times. The N2 adsorption/desorption results demonstrated high surface areas (SBET) for the ACs. The optimized AC (C1:3-1000-10) was obtained using a time of 10 min, high impregnation ratio, and power, resulting in an SBET of 1200 m2 g−1. Fourier-transform infrared spectroscopy (FTIR) and X-ray photoelectron spectroscopy (XPS) spectra confirmed the presence of functional groups, such as hydroxyl and ester, on the AC surface. Adsorption tests with sulfamethazine (SMZ) showed a 225 mg g−1 remotion capacity, highlighting the waste potential for sustainable and economical AC production. This underscores the importance of optimizing activation parameters to enhance performance and application versatility in AC production from lignocellulosic sources.

Defect tuning and its effect on conductivity, dielectric properties of combustion derived nano CeO2: A fuel dependent approach

Oxalyldihydrazide (ODH) and coffee extracted fuel (CEF) were used to synthesize Ceria (CeO2) nanoparticles by solution combustion synthesis route. The cubic fluorite structure, crystalline nature, crystallite size and particle size of ceria nanoparticles were confirmed using the powder X-ray diffraction (PXRD) and High-Resolution Transmission Electron Microscope patterns respectively. Field Emission Scanning Electron Microscope (FESEM) images were used to understand the Surface morphology of the synthesized samples. Based on XRD results the volume of coffee husk extract for the optimum phase formation is found to be 40 mL. The fluorite structure of the samples and the presence of oxygen vacancies in the samples were confirmed from the Raman spectral analysis. ESR (Electron Spin Resonance) studies confirmed formation of relatively more intrinsic defects in CEF-ceria nanoparticles compared to ODH-ceria nanoparticles. The semiconducting nature of the synthesized samples was confirmed by analysing UV–visible absorbance spectra. The functional group confirmation was obtained by analysing Fourier Transform Infrared (FTIR) spectra of both the samples. AC conductivity and dielectric relaxation studies of the samples in pellet form were carried out over a wide frequency (20Hz–10 MHz) and temperature (200–640 °C) range using a precision impedance analyser. A higher value of dielectric constant was observed for CEF-ceria nanoparticles.

The effect of coffee husks used as pellet bedding material on the intestinal barrier, immune-related gene expression and microbiota composition in the broiler chicken caecum

Abstract Introduction Using coffee husks as waste material for bedding contributes to sustainable development. A sustainable choice of bedding has also, however, to be a safe choice for poultry. The study analysed immune-related gene expression in the intestinal mucosa and indicator bacteria in caecal content collected from broiler chickens bedded on material with coffee husk addition. Material and Methods One-day-old Ross 308 chickens were divided into four groups of 10 birds each in five replicates: C, the control group kept on wheat straw bedding; CH10, a group kept on bedding of 10% coffee husks and 90% wheat straw; CH25, a group kept on bedding of 25% husks and 75% straw; and CH50, a group kept on bedding of 50% husks and 50% straw. After 42 days, the birds were slaughtered, the caecal mucosae were removed for RNA isolation and the caecal content was collected for bacterial DNA isolation. The expression of genes involved in intestinal immune response and host organism defence and the relative abundance of indicator bacteria were analysed. Results Upregulation of the expression of genes related to the immune response and intestinal tightness was correlated with an increase in the percentage of coffee husks in the pellet. Coffee husk pellets at 50% bedding content caused a significant numerical increase in Bifidobacterium and a statistically significant increase in Lactobacillus. A significant reduction in E. coli bacteria was also demonstrated in this group. Coffee husk pellets at all content percentages resulted in a statistically significant diminution of the level of Streptococcus bacteria. Conclusion The addition of coffee husks to poultry litter effects beneficial changes in the expression of genes related to intestinal health and the caecal bacterial profile.

Development and performance investigation of coffee husk-derived carbon-based nanofluid for solar thermal applications

Managing agricultural waste effectively is a serious concern, particularly in agrarian economies, where poor disposal practices cause environmental and public health problems. This paper discusses the synthesis of a carbon-based nanofluid from coffee husk char for solar thermal applications, utilising pyrolysis as an effective method for valorising agro-residue. The synthesis used the left-over solid residue during coffee husk pyrolysis after gaseous product extraction. The feasibility of the synthesized fluid for solar thermal application is studied by physical, chemical and optical characterisations. The synthesized fluid had a thermal conductivity of 0.87 W/mK and a pH of 10.26. The fluid was stable with a zeta potential value of −59.4 mV. The mean size of particles in the synthesized fluid was 6.24 nm. The optical characteristics of the synthesized fluid were studied from UV–Vis absorption spectroscopy. The solar-weighted absorption fraction of carbon-based nanofluid was 62.6 %, and that of deionised water was 12.3 %. When investigated with a solar simulator (at irradiance values of 700, 800, 900, 1000 and 1100 W/m2), the maximum improvement in photothermal conversion efficiency was 14.35 % at 1100 W/m2. At all irradiance levels, the sensible heat gain and the photothermal conversion efficiency were found to be greater than those of deionised water.

Study on using waste biomass as carbon reducing agent in industrial silicon smelting

In this study, seven types of biomass (coffee husk, macadamia husk, peanut husk, rice husk, rice straw, tobacco straw, and cotton straw) were carbonized at temperatures ranging from 300 °C to 1000 °C. This study explored the potential of these biomass samples as carbon reducing agents for industrial silicon and compared them with charcoal in terms of their proximate analysis, electrical resistivity, and apparent activation energy of the reaction. The results indicated that as the pyrolysis temperature increased, the oxygen content and aliphatic functional groups in biochar gradually decreased, as did the volatiles content, while the proportions of fixed carbon and ash increased. The resistivity decreased upon the removal of volatiles and an increase in the degree of graphitization. At 600 °C, the fixed carbon content of all biochar exceeded 65%, and the fixed carbon content of macadamia husk biochar reached 91.32%, which was higher than that of charcoal (81.44%), the maximum specific surface area was 335.706 m2/g, which was much higher than that of charcoal (5.705 m2/g). Thermogravimetric analysis and kinetic analysis indicated that coffee husk had better reactivity than charcoal. The gasification reactivity of coffee husk was R = 3.1949%/min °C, which was higher than that of charcoal (0.7930 %/min °C). The apparent activation energy during the coking reaction stage was 51.86 kJ/mol, which was lower than that of charcoal (98.9 kJ/mol). Overall, biochar had a suitable fixed carbon and electrical resistivity at 600 °C and can be used as a carbon reducing agent for industrial silicon, among them, macadamia husk with high fixed carbon and coffee husk with high reactivity have greater application potential.

Growth improvement of immature quinine by applying coffee husk compost and biofertilizer

The growth of immature Cinchona ledgeriana can be optimized by applying fertilizers to fill the nutritional needs of plants. Nutrients can be provided through the help of microorganisms derived from organic fertilizers and biofertilizers. This study aims to evaluate the effect of applying coffee husk compost and biofertilizer consortium on the growth of immature quinine plants. This research was conducted from November 2023 – January 2024 at Gambung Tea and Cinchona Research Center, Pasir Jambu District, Bandung Regency, West Java. The research used a randomized block design with four replications and six treatments, namely control (Urea 17 g.plant-1 + SP36 8 g.plant-1 + KCl 4 g.plant-1); solid coffee husk compost 3 kg.plant-1; liquid coffee husk compost 80 mL.L-1; biofertilizer 10 mL.L-1; solid coffee husk compost 3 kg.plants-1 + biofertilizer 10 mL.L-1; and liquid coffee husk compost 80 mL.L-1 + biofertilizer 10 mL.L-1. The results showed applying organic fertilizer from coffee husk waste and biofertilizer improved the growth of immature quinine plants. Combination of liquid organic fertilizer from coffee husk waste 80 mL.L-1 water + biofertilizer 10 mL.L-1 water produced a high increase in leaf area. Combination of solid organic fertilizer from coffee husk waste 3 kg. plants-1 + biofertilizer 10 mL.L-1 water showed the highest plant height increment. It implied the success of quinine improvement growth at the immature phase by applying coffee husk waste and biofertilizers.