Enhancement of biohydrogen producing using ultrasonication

Ultrasonication was evaluated as a pretreatment for biological hydrogen production from glucose in batch studies, in comparison with heat-shock pretreatment, acid pretreatment, and base pretreatment. The optimized sonication energy for hydrogen production using anaerobic digester sludge was 79 kJ/gTS. Sonication with temperature control (less than 30 °C) increased volumetric hydrogen production by 120% over the untreated sludge, and by 40% over the heat-shock and acid pretreated sludge, with a marginal (∼10%) increase in hydrogen production rate. Upon comparing the molar hydrogen yield in sonicated sludge with and without temperature control, the deleterious effect of heat on some hydrogen producers as reflected by a 30% decrease in yield to 1.03 mol H₂/mol glucose is evident. Sonication with temperature control affected a 45% increase in molar hydrogen yield to 1.55 mol H₂/mol glucose over heat-shock pretreatment at 70 °C for 30 min and acidification to pH 3.0 for 24 h at 4 °C. Sonication with temperature control produced a biomass yield of 0.13 g VSS/g COD, as compared to 0.24 g VSS/g COD for the untreated sludge. The hydrogen yield increased linearly with the molar acetate to butyrate ratio and decreased linearly with the biomass yield.     

Steady-state and dynamic modeling of biohydrogen production in an integrated biohydrogen reactor clarifier system

Steady-state operational data from the integrated biohydrogen reactor clarifier system (IBRCS) during anaerobic treatment of glucose-based synthetic wastewater at HRT of 8 h and SRT ranging from 26 to 50 h and organic loading rates of 6.5–206 gCOD/L-d were used to calibrate and verify a process model of the system developed using BioWin. The model accurately predicted biomass concentrations in both the bioreactor and the clarifier supernatant with average percentage errors (APEs) of 4.6% and 10%, respectively. Hydrogen production rates and hydrogen yields predicted by the model were in close agreement with the observed experimental results as reflected by an APE of less than 4%, while the hydrogen content was well correlated with an APE of 10%. The successful modeling culminated in the accurate prediction of soluble metabolites, i.e. volatile fatty acids in the reactor with an APE of 14%. The calibrated model confirmed the advantages of decoupling of the solids retention time (SRT) from the hydraulic retention time (HRT) in biohydrogen production, with the average hydrogen yield decreasing from 3.0 mol H₂/mol glucose to 0.8 mol H₂/mol glucose upon elimination of the clarifier. Dynamic modeling showed that the system responds favorably to short-term hydraulic and organic surges, recovering back to the original condition. Furthermore, the dynamic simulation revealed that with a prolonged startup periods of 10 and 30 days, the IBRCS can be operated at an HRT of 4 h and OLR as high as 206 gCOD/L-d without inhibition and/or marked performance deterioration.     

Sequential supercritical water gasification and partial oxidation of hog manure

The catalytic hydrogen production from hog manure using supercritical water gasification and partial oxidation was investigated in a batch reactor at a temperature of 500 °C, and pressure of 28 MPa using several metallic catalysts. Hog manure was characterized by a total and soluble chemical oxygen demand (TCOD, SCOD) of 57,000 and 28,000 mg/L, total and volatile suspended solids (TSS, VSS) of 25,000, 19,000, and ammonia of 2400 mg/L, respectively. The order of H₂ production was the following: Pd/AC > Ru/Al₂O₃ > Ru/AC > AC > NaOH, and the order of COD reduction efficiency was as follows: NaOH > Ru/AC > AC > Ru/Al₂O₃ > Pd/AC. The behavior of the volatile fatty acids (VFAs), ethanol, methanol, ammonia, H₂S, and sulfate was investigated experimentally and discussed. A 35% reduction in the H₂ and CH₄ yields was observed in the sequential gasification partial oxidation (oxidant at an 80% of theoretical requirement) experiments compared to the gasification experiments (catalyst only). Moreover, this reduction in gas yields was coincided with a 45% reduction in the liquid effluent chemical oxygen demand (COD), 60% reduction of the ammonia concentration in the liquid effluent, and 20% reduction in the H₂S concentration in the effluent gas.     

Méthode expérimentale de détermination de l'énergie de rupture des bétons ordinaires

The aim of this paper is to determine the failure energy of ordinary concretes. This energy is considered as an intrinsic characteristic of the cracked material. RILEM recommendations related to three-point bending tests on notched beams have been studied and applied. This experimental model needs appropriate equipment working in controlled displacement mode. The controlled force test is generally unsteady. The result is that tensile curves (σ-w) are hardly achieved until the end of the test. In numerical modelling of the failure, it is precisely the descending branch of the curve (σ-w) which characterises the crack material because the stress reduces, whereas the crack opening increases (strain-softening). The tests carried out are failure tensile tests in mode I. The results obtained are ultimate loads of failure related to three-point bending notched specimens. A prediction method of failure energy based on intensity factor design of critical stress has been used. The latter is the result of experimental models interpolation in the field of failure mechanics. The results obtained are satisfactory and will allow the researchers who wish to simulate the crack by finite element modelling to use these results. For this purpose, experimental curves (σ-w) could be approximated by using linear, two-linear or exponential straight line providing that this failure energy remains steady.     

Viability of ultrasonication of food waste for hydrogen production

Batch anaerobic studies were conducted to study the effect of ultrasonication as a pre-treatment method for pulp waste prior to anaerobic hydrogen production. Pre-treatment was conducted by sonicating a 100 mL of pulp waste at different sonication times varying from 0.5 min to 30 min. The ultimate hydrogen production increased with increasing sonication time. The highest ultimate hydrogen production was achieved at a sonication time of 30 min and reflected an 88% increase over the unsonicated food waste, of 80 mL/g VS_added. The highest final VFAs concentration after fermentation (corresponding to 70% increase over the unsonicated food waste) was also achieved at a sonication time of 30 min. There were no significant differences between the acetate-to-butyrate ratios (HAc/HBu) for the all sonication times. The maximum hydrogen production rate at sonication time of 30 min was about 145% higher than that the unsonicated food waste.     

A novel solution of deep learning for sleep apnea detection: enhancement of SC and elimination of GVICS

Multimedia Tools and Applications - Convolutional neural network (CNN) classification has not achieved a medically-satisfied level of accuracy in sleep apnea detection due to the negative effect of...     

Offline Error Detection in MEDA-Based Digital Microfluidic Biochips Using Oscillation-Based Testing Methodology

Digital microfluidics is an emerging class of lab-on-a-chip system. Reliability is a critical performance parameter as these biochips are employed in various safety-critical biomedical applications. With the introduction of highly scalable, reconfigurable and field programmable Micro-Electrode-Dot-Array (MEDA) architecture, the limitation of conventional DMFBs in varying the droplet size/volume in fine grain manner has been resolved. However, the MEDA-based biochips must be adequately tested upon fabrication to guarantee the correctness of bioassays. In this work, an offline testing approach based on Oscillation-Based Testing (OBT) methodology is presented for MEDA-based digital microfluidic biochips. Various simulations were performed for droplet-electrode short fault model involving single and multiple micro-electrodes. Furthermore, the loss of droplet volume due to the presence of defect was analyzed using COMSOL Multiphysics. The simulation results based on PSpice and COMSOL show that the proposed approach is effective for detecting defects in MEDA-based biochips.     

Bio-hydrogen production from thin stillage using conventional and acclimatized anaerobic digester sludge

To assess the viability of biohydrogen production from thin stillage, a comparative evaluation of anaerobic digester sludge (ADS) and acclimatized anaerobic digester sludge (AADS) for biohydrogen production over a wide range of S⁰/X⁰ ratio (0.5-8 gCOD/gVSS) was performed. A maximum hydrogen yield of 19.5 L H₂/L thin stillage was achieved for the AADS while tests with ADS achieved a maximum yield of only 7.5 L H₂/L thin stillage. The optimum range of S⁰/X⁰ ratio for hydrogen production was found to be 1 to 2 gCOD/gVSS using conventional ADS and 3 to 6 gCOD/gVSS using AADS. The biomass specific hydrogen production rate for the AADS was 3.5 times higher than rate for the ADS throughout the range of S⁰/X⁰ ratio examined in this study. The DGGE profiles of the 16S rDNA gene fragments confirmed the superior performance of the AADS over the ADS, showing that the widely known hydrogen producers Clostridium acetobutyricum, Klebsiella pneumonia, Clostridium butyricum and Clostridium pasteurianum were the predominant species.     

Correction to: Deposition of bismuth sulfide and aluminum doped bismuth sulfide thin films for photovoltaic applications

Journal of Materials Science: Materials in Electronics -