RESUMO
In this study, an anaerobic pneumatic mechanical digester (PMD) was designed for the first time to investigate the impact of pneumatic agitator on increasing the bioethanol production and compared with a mechanical digester (MD). Fermentation was performed during an optimized pretreatment and hydrolysis process by RSM (Response Surface Method). Ultrasound optimized points (the time values, the acid concentration, and the biomass load) were 30 min, 1.95% v/v, and 6%, and hydrolysis was done within 45 min at the acid concentration of 2.04% v/v and temperature of 148.4 °C. The hydrolysis solutions were poured and the fermentation process took place within 20 days in the PMD and MD. The sampling sequence was every 5 days. According to the results, the PMD could produce bioethanol more than the MD by 27.94%. Besides, CO, H2S and O2 were measured through fermentation. In PMD, the amount of H2S and O2 was lower than the MD, but then the production of CO in the PMD was meaningfully higher. Finally, by the application of the PMD, the amount of harmful mixtures produced throughout the process can be controlled. It can be said that with the new method designed in this study, it is possible to take an important step in the biorefinery and use the biomass produced in nature in an economical and environmentally friendly way.
Assuntos
Digestão , Lignina , Biomassa , Lignina/metabolismo , Fermentação , Hidrólise , BiocombustíveisRESUMO
The aim of this study was the discrimination and optimization of irradiation effect under physical and mechanical experiments on garlic. The samples were irradiated with 0, 75, and 150 Gy doses and stored at 4 and 18°C for 5 months. Physical, mechanical, and color properties were measured in the period of storage. Based on the results, all irradiated garlic samples had less quality variation than control samples. Response surface methodology (RSM) optimized dose, storage time, and temperature of the stored garlic which was 75 Gy, 2 months, and 17°C, respectively. In addition, after finding the optimal dose, time, and temperature, the most effective factor as weight loss was obtained and the data were classified by the principal component analysis (PCA) approach. The results showed that the PCA method had a high ability to classify and separate the data obtained from measuring the physicochemical properties of garlic and cover 99% variance of data. Moreover, partial least square (PLS) was applied for predicting weight loss data with R2 0.9999. As well, a mechanical test was investigated for finding the best situation and duration of storage condition. Finally, irradiation prevented the destruction of garlic and saved garlic in the best quality as compared with control or nonirradiated samples. After all this, it can be decided to keep garlic in warehouses and transfer this product with minimum damage.
RESUMO
An anaerobic pneu-mechanical digester (PD) was designed to ferment lignocellulosic compounds. So, wheat and rice straws were pretreated using an ultrasound-acid, and then thermal-acid hydrolysis was conducted. Hydrolysis optimization was performed using the response surface method and the optimal points for time, temperature, and acid concentration were 45 min, 148.4 °C, and 2.04 % v/v, respectively. Cold plasma was then used as detoxification to reduce the amount of inhibitory compounds and acids. This method was capable of reducing the amounts of acetic acid, formic acid and furfural by 73, 83 and 68 % in hydrolyzed biomass, respectively. The biomass was fermented in a PD for 20 days and compared with a conventional digester (CD). The obtained results showed that the PD could increase the efficiency of bioethanol by 37 % in the detoxified state and 22 % in the non-detoxified state after 20 days of fermentation compared to the CD. Moreover, H2S, CO and O2 were measured during fermentation process. In PD, the amount of H2S and O2 was lower than CD, but CO was significantly higher in the PD.
