Assessment of Cow Dung Pellets as a Renewable Solid Fuel in Direct Combustion Technologies

Valorization of Textile Sludge and Cattle Manure Wastes into Fuel Pellets and the Assessment of Their Combustion Characteristics

The textile wastewater sludge (TWS) treatment and disposal are environmentally challenging due to toxic organics and metals. At the same time, cattle manure (CM), with better combustion performance, i.e., calorific value and uniform burning capability, is still underutilized in many parts of the world. This study evaluated and assessed the TWS and CM blending compatibility to convert them into fuel pellets for the direct combustion option and to stabilize toxic contaminants in TWS. After initial drying, grinding, and particle size control of the raw TWS and CM, both were blended at different ratios. The blended and nonblended TWS and CM samples were converted into pellets and analyzed for proximate and ultimate analyses, namely, moisture content, fixed carbon, CHNO, gross calorific value (GCV), bulk density, ash content, and metals, to evaluate the efficacy for energy applications. Out of three blended ratios, i.e., 75:25 (W/W%; CM/TWS), 50:50, and 25:75, the 75:25 blended pellet composition was found appropriate for fuel application. For the 75:25 blend, the obtained GCV was 12.77 MJ/kg, elemental carbon was 27.5%, volatiles were 41.7%, and residue ash was 42.8% of the total weight. Moreover, the blending ratios of 75:25 and 50:50 revealed that elemental and metal (Fe, Cu, Zn, Ni, Cr, Na, Mg, Mn) concentrations in TWS were stabilized to below threshold limits in the obtained residue ash for safe handling. The explored methods of TWS and CM waste processing, blending, and pelletization proposed a new technique for their sustainable waste valorization into energy sources.

Effect of organic loading on anaerobic digestion of cow dung: Methane production and kinetic study

Organic loading influences the effectiveness of producing biogas through anaerobic digestion. This study set out to investigate the effect of organic loading on the anaerobic mesophilic digestion of cow dung, the parameters involved in the digestion process and to evaluate the kinetics. Anaerobic digestion of cow dung at different organic loading (gVS/L) of 14 gVS/L, 18gVS/L, 22 gVS/L, 26 gVS/L and 30 gVS/L were investigated. Increasing the organic loading increased the methane yield of the cow dung. The highest cumulative methane yield was observed at 30 gVS/L with 63.42 mL CH₄/gVS while the highest biogas yield was reported at 192.53 mL/gVS with the highest methane content of 89%. In addition, the modified Gompertz model equation with an R² of 0.9980 demonstrated strong consistency and a good fit between predicted and experimental data. The high number of substrates added to the systems when increasing the organic loading increased the λ and slow down the nutrient transport and hydrolysis. This study provides current information on the effects of organic loading on the anaerobic digestion of cow dung in batch mode, including experimental conditions and operational parameters.

Assessment of Local Domestic Solid Fuel Sources: A Kenyan Case Study in Kisii, Bomet and Narok Counties

Proximate analyses and decomposition profiles of solid fuels commonly used in Kenya were studied to determine their relative suitability for use as a clean and efficient source of energy in households. The moisture, volatile matter, ash, and fixed carbon content of firewood, charcoal, and briquette samples were investigated, as well as their decomposition profiles under various temperature regimes. Except for the ash content of the briquette sample, which deviated slightly likely due to the presence of binders, all the values were within acceptable limits according to International Energy Agency and World Health Organization. Decomposition profiles revealed that mass change during combustion tends to occur primarily between 350 and 500 °C once the majority of the volatiles had been released. Briquette samples proved to be the most dependable and suitable household fuel due to their longer combustion time and lower volatile matter content, implying lower emissions.

Development and performance analysis of top lit updraft: natural draft gasifier stoves with various feed stocks

The performance of an Ethiopian-designed and built-in gasifier stove was studied and evaluated. The water boiling test (WBT) findings are reported. This test was conducted in a controlled setting utilizing eucalyptus, bamboo, and sawdust-cow dung briquettes as test feedstocks, in accordance with WBT's 4.2.3 standard process and test manuals. Based on moisture content, the net calorific values of eucalyptus, bamboo, and sawdust-cow dung briquettes were calculated and determined to be 15.77 MJ/kg, 14.70 MJ/kg, and 15.35 MJ/kg, respectively. The efficiency of this stove was calculated utilizing those three feedstocks. As a result, the gasifier stove's efficiency having eucalyptus, sawdust-cow dung briquette, and bamboo as feedstock were 32.30 ± 0.3%, 31.5 ± 0.5%, and 26.25 ± 0.25%, respectively. This proportion did not include the ultimate charcoal production, but when this yield was employed as an energy input for additional charcoal burners, it increased to 53 ± 2%. The relationship between gasifier stove charcoal production and total efficiency is negatively related, with a linear equation of Y = - 0.7956X+ 22.766 and an R-squared value of 0.92. When compared to local stoves and foreign gasifier stoves, whose efficiency is in the range of 10 %–39% this efficiency rating was exceptional due to the fact that space between the internal and external cylinder help the secondary air to preheat before combustion and also the interior hallow cylinder help the primary air to move evenly in the vertical circular pattern for proper gasification, it will also help the gases that are produced during gasification process to move to the top part for combustion, indicating that this study can be fostered for prospective use.

Properties of Animal-Origin Ash—A Valuable Material for Circular Economy

In the presented paper, two types of animal-origin biomass, cow dung and chicken litter, are characterized in terms of combustion-related problems and ash properties. It was found that these parameters strongly depend on the farming style. Whether it is cow dung or chicken litter, free-range raw materials are characterized by higher ash contents than industrial farming ones. Free-range samples contain chlorine at lower levels, while industrial farming samples are chlorine rich. Free-range samples are characterized by the predominant content of silica in the ash: 75.60% in cow dung and 57.11% in chicken litter, while industrial farming samples contain more calcium. Samples were classified by 11 “slagging indices” based on the ash and fuel composition to evaluate their tendencies for slagging, fouling, ash deposition and bed agglomeration. Furthermore, an assessment was made against the current EU law regulations, whether the ashes can be component materials for fertilizers. The phosphorus concentration in the investigated ashes corresponds to 4.09–23.73 wt% P2O5 and is significantly higher in industrial chicken litter samples. The concentrations of Hg, Cu, As, Ni, Cd and Pb in all samples are below the limits of the UE regulations. However, concentrations of Cr in all samples and Zn in industrial chicken litter exceed these standards.