Increase in efficiency of hydrogen production by optimization of food waste fermentation parameters

The aim of the work was to optimize the ratio of weight of solid (food waste) and liquid (water) phases in order to ensure high efficiency of molecular hydrogen synthesis and degradation of multi-component food waste. Assessment of the efficiency of fermentation process was carried out using colorimetric and potentiometric methods for pH and redox potential measuring, volumetric and chromatographic methods for volume and composition of gas investigation, and mathematical calculations for fermentation parameters determination. The dynamics of hydrogen fermentation of waste in the horizontal reactor using different ratios of solid (food waste) and liquid (water) phases was investigated. The optimization of the ratio of solid and liquid phases was shown to lead to the increase in efficiency of molecular hydrogen synthesis and destruction of waste particles. The ratio of solid and liquid phases 1:3 was determined to be optimal for the effective synthesis of hydrogen as well as for maximum waste decomposition. It provided effective hydrogen fermentation of multi-component food waste and allowed to rationally use material and technical resources. Obtained results are promising for further development of efficient industrial biotechnologies for waste destruction with the simultaneous synthesis of environmentally friendly energy carrier, i.e. molecular hydrogen.

Co-Digestion of Napier Grass with Food Waste and Napier Silage with Food Waste for Methane Production

Enhancement of methane production by co-digestion of Napier grass and Napier silage with food waste was investigated in batch and repeated batch modes. First, the ratios of Napier grass to food waste and Napier silage to food waste were varied at different g-volatile solids (VS) to g-VS at an initial substrate concentration of 5 g-VS/L. The optimum ratios of Napier grass to food waste and Napier silage to food waste were 1:4 and 3:2 (g-VS/g-VS), respectively. This gave maximum methane yields (MY) of 411 and 362 mL-CH4/g-VSadded, respectively. Subsequently, the suitable ratios were used to produce methane at various substrate concentrations. A maximal MY of 403 and 353 mL CH4/g-VS were attained when concentrations of Napier grass co-digested with food waste and Napier silage co-digested with food waste were 15 g-VS/L and 20 g-VS/L, respectively. Under the optimum substrate concentration, the maximum MY from co-digestion of Napier grass with food waste was 1.14 times higher than that of Napier silage with food waste. Thus, co-digestion of Napier grass with food waste was further investigated at various organic loading rates (OLRs) in a 10.25 L horizontal reactor with a working volume of 5 L at an optimal ratio of 1:4 (g-VS/g-VS) and substrate concentration of 15 g VS/L. An OLR of 1.5 g-VS/L∙d gave a maximum methane production rate and MY of 0.5 L CH4/L∙d and 0.33 L-CH4/g-VSadded, respectively. Under the optimum OLR, the predominant methane producers were Methanoregula sp., Methanotorris sp., Methanobacterium sp., Methanogenium sp. and Methanosarcina sp. An energy production of 11.9 kJ/g-VSadded was attained.

Optimization of activation temperature on the preparation of sliced porous activated carbon from date fronds by physical activation

Saudi Arabia is the major date producer in the world. In order to get the maximum production from date tree there is a need to prune the trees on annual basis and is considered as a serious environmental threat. The single step procedure for the synthesis of porous activated carbon (AC) from Saudi date tree fronds using mixture of gases (N2 and CO2) was carried out at different carbonization/activation temperatures staring from 700?C to 1000?C at a ramp rate of 10 degree per minute. Alloy 330 horizontal reactor was used in tube furnace. Flow rate of N2 and CO2 gases were kept at 150 and 50ml/min respectively. Results reveal that at 850oC larger surface area was achieved and can offer higher potential to produce activated carbon of greater adsorption capacity from date fronds waste. The BET surface areas of the activated carbons prepared at 850?C after 30 minutes activation time are 1094 m2/g.

Characterization of Bio-Oil Obtained from Sewage Sludge Pyrolysis Catalyzed by Char

The pyrolysis of sewage sludge (SS) in the presence of sewage sludge pyrolysis char (SSC) as catalyst was conduct in a horizontal reactor at 500°C. Gas chromatography-mass spectroscopy (GC-MS), element analysis, high heating value (HHV) analysis, water content analysis and gel permeation chromatography (GPC) were used to characterize the pyrolysis oil. The declined char yields with increased SSC mix ratio (MR) indicated that SSC could promote the devolatilization reaction. Meanwhile the declined top phase oil (TPO) yield and increased bottom phase oil (BPO) and gas yield showed that crack reaction may happen catalyzed by SSC. According to the result of GC-MS, aliphatics and steroids content drops apparently since MR increased to 50 wt.%, while aromatic compounds and phenols content increased at the same time. Element analysis showed an apparent transportation of hydrogen and oxygen from TPO to BPO. HHV of TPO decreased with MR increased. The result of GPC indicated that increased MR caused continuing decreased average molecular weight of TPO. Consequently, the increased SSC addition could promote the devolatilization and large molecular compounds catalysis crack of sewage sludge.

Response Spectrum 0.9-2.65 μm of In0.82Ga0.18As Detectors by Two-Step Growth Technique

InP/In0.82Ga0.18As/InP heterostructure used for infrared detector were grown on (100) S-doped InP substrates using two-step growth technique by low temperature metal-organic chemical vapor deposition. The growth was performed using TMIn, TMGa, AsH3, and PH3 as growth precursors in a horizontal reactor. The substrates on a graphite susceptor were heated by inductively coupling RF power, their temperatures were detected by a thermocouple, and the reactor pressure was kept at 10000 Pa. The growth structure of detector included In0.82Ga0.18As buffer with the thickness of 100 nm, In0.82Ga0.18As absorption layer with the thickness of 2.8 μm, and the InP cap with the thickness of 0.8 μm. The planar type of p-i-n detector was fabricated by Zn diffusion. The properties of In0.82Ga0.18As detector were studied, the curves of the I-V characteristics, the range of response spectrum, and the detectivity (D*) were obtained.