Anaerobic Digestion, Codigestion of Food Waste, and Chicken Dung: Correlation of Kinetic Parameters with Digester Performance and On-Farm Electrical Energy Generation Potential

Valorization of agro-food waste through anaerobic digestion (AD) is gaining prominence as alternative method of waste minimization and renewable energy production. The aim of this study was to identify the key parameters for digester performance subjected to kinetic study and semicontinuous operation. Biochemical methane potential (BMP) tests were conducted in two different operating conditions: without mixing (WM) and continuous mixing (CM). Three different substrates, including food waste (FW), chicken dung (CD), and codigestion of FW and CD (FWCD) were used. Further kinetic evaluation was performed to identify mixing’s effect on kinetic parameters and correlation of the kinetic parameters with digester performance (volatile solid removal (VS%) and specific methane production (SMP)). The four models applied were: modified Gompertz, logistic, first-order, and Monod. It was found that the CM mode revealed higher values of Rm and k as compared to the WM mode, and the trend was consistently observed in the modified Gompertz model. Nonetheless, the logistic model demonstrated good correlation of kinetic parameters with VS% and SMP. In the continuous systems, the optimum OLR was recorded at 4, 5, and 7 g VS/L/d for FW, CD, and FWCD respectively. Therefore, it was deduced that codigestion significantly improved digester performance. Electrical energy generation at the laboratory scale was 0.002, 0.003, and 0.006 kWh for the FW, CD, and FWCD substrates, respectively. Thus, projected electrical energy generation at the on-farm scale was 372 kWh, 382 kWh, and 518 kWh per day, respectively. Hence, the output could be used as a precursor for large-scale digester-system optimization.

Effect of Engineered Biomaterials and Magnetite on Wastewater Treatment: Biogas and Kinetic Evaluation

In this study, the principle of sustaining circular economy is presented as a way of recovering valuable resources from wastewater and utilizing its energy potential via anaerobic digestion (AD) of municipality wastewater. Biostimulation of the AD process was investigated to improve its treatability efficiency, biogas production, and kinetic stability. Addressing this together with agricultural waste such as eggshells (CE), banana peel (PB), and calcined banana peels (BI) were employed and compared to magnetite (Fe3O4) as biostimulation additives via 1 L biochemical methane potential tests. With a working volume of 0.8 L (charge with inoculum to substrate ratio of 3:5 v/v) and 1.5 g of the additives, each bioreactor was operated at a mesophilic temperature of 40 °C for 30 days while being compared to a control bioreactor. Scanning electron microscopy and energy dispersive X-ray (SEM/EDX) analysis was used to reveal the absorbent’s morphology at high magnification of 10 kx and surface pore size of 20.8 µm. The results showed over 70% biodegradation efficiency in removing the organic contaminants (chemical oxygen demand, color, and turbidity) as well as enhancing the biogas production. Among the setups, the bioreactor with Fe3O4 additives was found to be the most efficient, with an average daily biogas production of 40 mL/day and a cumulative yield of 1117 mL/day. The kinetic dynamics were evaluated with the cumulative biogas produced by each bioreactor via the first order modified Gompertz and Chen and Hashimoto kinetic models. The modified Gompertz model was found to be the most reliable, with good predictability.

Kinetic evaluation of methylene blue decolorization by CuO as a Fenton-like catalyst

The presence of dyes in wastewater is one of the main problems in wastewater treatment. Wastewater containing dyes can damage the ecosystem because it can block sunlight into the water and is often accompanied by toxic materials. This paper proposes an alternative method to decolorize dyes in water using CuO as a Fenton-like catalyst, especially for wastewater contaminated by methylene blue dye. The Fenton method is an advanced oxidation process method with a radical group of H2O2 acting as the primary decolorizing agent. By measuring the concentration using a UV-Vis spectrophotometer, we found that the proposed decolorization method effectively degraded the color of methylene blue. To understand the decolorization mechanism, we investigated the reaction kinetics of the decolorization process. We found that compared to the pseudo-first-order and second-order reaction kinetics models, the BMG model had higher accuracy and conformed to the color concentration degradation curve.

A study of Thermal Decomposition and Kinetic Evaluation of Boron blended Flash Powder Composition

Herein, the thermal characteristics of flash powders of different combinations of Potassium Nitrate, Sulphur, Aluminium and Boron are reported. From the literature, it is identified that Boron implements lack of sensitiveness to flash powder mixture, which promotes the safety during the manufacturing process. But the thermal behaviour of the Boron blended compositions remain a mystery. Hence, various combinations of flash powder compositions are prepared by keeping the % of KNO3 and % of S as constant, and gradually 23% of Aluminium is reduced (23% to 0) by increasing the quantity of Boron (0 to 23%) in 19 trials, and are subjected to TGA/DSC analysis individually. The TGA and the DSC analysis reveals that the 65.65% replacement of Aluminium with Boron mixture shows predominant characteristics which is suitable for fireworks. Also, the reaction kinetics and the critical ignition temperature are calculated for the optimum composition. The performance of the fireworks product is checked with varying quantity to meet out the optimum quality.