Biohydrogen production from biomass and industrial wastes by dark fermentation

Hydrogen is a clean energy carrier which has a great potential to be an alternative fuel. Abundant biomass from various industries could be a source for biohydrogen production where combination of waste treatment and energy production would be an advantage. This article summarizes the dark fermentative biohydrogen production from biomass. Types of potential biomass that could be the source for biohydrogen generation such as food and starch-based wastes, cellulosic materials, dairy wastes, palm oil mill effluent and glycerol are discussed in this article. Moreover, the microorganisms, factors affecting biohydrogen production such as undissociated acid, hydrogen partial pressure and metal ions are also discussed.     

茶多酚对棕榈油抗氧化性的研究

在棕榈油中添加茶多酚,维生素E及茶多酚与柠檬酸的混合物,对油脂的 PV 和 AV 进行测定,结果表明,它们均有抑制棕榈油 PV 和 AV 升高的作用.在相同剂量下,茶多酚的抗氧化能力最优。     

Combustion and emission performances of coconut,palm and soybean methyl esters under reacting spray flame conditions

The spray combustion characteristics of coconut (CME), palm (PME) and soybean (SME) biodiesels/methyl esters were compared with diesel by using an axial swirl flame burner. Atomisation of the liquid fuels was achieved via an airblast-type nozzle with varied atomising air-to-liquid ratios (ALR) of 2–2.5. The fully developed sprays were mixed with strongly swirled air to form combustible mixtures prior to igniting at the burner outlet. Under fuel-lean condition, biodiesel spray flames exhibited bluish flame core without the yellowish sooty flame brush, indicating low sooting tendency as compared to baseline diesel. Increasing the atomising air led to the reduction of flame length but increase in flame intensity. Measurements of post-combustion emissions show that SME produced higher NO as compared to CME and PME due to higher degree of unsaturation, while the most saturated CME showed the lowest NO and CO emissions amongst the biodiesels tested across all equivalence ratios. By preheating the main swirl air to 250 °C, higher emissions of NO, CO and CO₂ were observed for biodiesels. Higher ALR led to reduced NO and CO emissions regardless of the fuel used, making it a viable strategy to resolve the simultaneous NOCO reduction conundrum. This work shows that despite different emission characteristics exhibited by biodiesels produced from different feedstock, they are in principle potential supplemental fuels for practical combustion systems. The pollutants emitted can be mitigated by operating at higher ALR in a twin-fluid based swirl combustor.     

Pilot-scale of biohythane production from palm oil mill effluent by two-stage thermophilic anaerobic fermentation

The pilot-scale of two-stage thermophilic (55 °C) for biohythane production from palm oil mill effluent (POME) was operated at hydraulic retention time (HRT) of 2 days and organic loading rate (OLR) of 27.5 gCOD/L⋅d) for first stage and HRT of 10 days and OLR of 5.5 gCOD/L⋅d for second stage. Biohythane production rate was 1.93 L-gas/L⋅d with biogas containing 11% H₂, 37% CO₂, and 52% CH₄. Recirculation of methane effluent mixed with POME at a ratio of 1:1 can control pH in the first stage at an optimal range of 5.0–6.5. Microbial community in hydrogen stage dominated by Thermoanaerobacterium sp., while methane stage dominated by Methanosarcina sp. The H₂/CH₄ ratio of biohythane was 0.13–0.18 which suitable for vehicle fuel. Biohythane production from POME could be promising cleaner biofuel with flexible and controllable H₂/CH₄ ratio.     

A study into syngas production from catalytic steam reforming of palm oil mill effluent (POME): A new treatment approach

This paper reports on the novel application of catalytic steam reforming process to convert palm oil mill effluent (POME) into syngas over a 20wt%Ni/80wt%Al₂O₃ catalyst. The catalyst possessed high degree of crystallinity and was impurity-free, judging from the obtained XRD pattern. Furthermore, the BET specific surface area of catalyst was low (2.09 m² g⁻¹), consistent with smooth surface captured by the FESEM images. CO₂-desorption and NH₃-desorption profiles showed a presence of both acid and basic sites on the surface of catalyst. In the absence of catalyst, about 7.0% reduction of chemical oxygen demand (COD) was achieved at 6.0 mL h⁻¹ flow rate of POME, reforming temperature of 873 K and 20 mL min⁻¹ of N₂-flow. Significantly, the COD reduction shot up to 93.7% in the presence of catalyst and liquid-hourly-space-velocity (LHSV) of POME of 90 mL h⁻¹ g_cat⁻¹ at 873 K. The corresponding biochemical oxygen demand (BOD) reduction recorded was 93.8%. However, normalized carbon loss indicates that a high LHSV would favour carbon deposition. In addition to high LHSV, the carbon deposition was also influenced by reaction temperature. High reaction temperature has reduced carbon deposition, as well as organics removal. COD reduction was 99.41% and BOD reduction was 99.52% at 1173 K when LHSV was 60 mL h⁻¹ g_cat⁻¹. In the gas phase, four species were consistently detected, viz. H₂, CO₂, CO and CH₄, with H₂ as the major component. The H₂ selectivity increased with both LHSV and reaction temperature.     

Start-up study of biohydrogen production from palm oil mill effluent in a lab-scale up-flow anaerobic sludge blanket fixed-film reactor

A start-up study of lab-scale up-flow anaerobic sludge blanket fixed-film reactor (UASFF) was conducted to produce biohydrogen from palm oil mill effluent (POME). The reactor was fed with POME at different hydraulic retention time (HRT) and organic loading rate (OLR) to obtain the optimum fermentation time for maximum hydrogen yield (HY). The results showed the HY, volumetric hydrogen production rate (VHPR), and COD removal of 0.5–1.1 L H₂/g COD_consumed, 1.98–4.1 L H₂ L^?1 day^?1, and 33.4–38.5%, respectively. The characteristic study on POME particles was analyzed by particle size distribution (PSD), Scanning electron microscopy (SEM), and Energy-dispersive X-ray spectroscopy (EDX). The microbial Shannon and Simpson diversity indices and Principal Component Analysis assessed the alpha and beta diversity, respectively. The results indicated the change of bacterial community diversity over the operation, in which Clostridium sensu stricto 1 and Lactobacillus species were contributed to hydrogen fermentation.     

Chemical ecology of the palm weevilRhynchophorus palmarum (L.) (Coleoptera: Curculionidae): Attraction to host plants and to a male-produced aggregation pheromone

Attraction to host plants by adultRhynchophorus palmarum (L.) palm weevils was studied in the field and in the laboratory. Chemical analysis revealed the presence of ethanol and ethyl-acetate in stems of coco palms and in pineapple fruits and of pentane, hexanal, and isopentanol in coco stems. In the olfactometer, the first two compounds and isoamyl-acetate were attractive to the insects and the last three compounds, although not attractive by themselves, increased attractiveness when mixed with the first two compounds. Mixtures of these compounds, in proportions similar to the one occurring in attractive plant tissue, were as attractive as natural coconut tissue. In the field, the chemical compounds, either presented alone or as a mixture, did not attract the weevil. Males produce an aggregation pheromone when smelling ethyl-acetate. Rhynchophorol, 2(E)-6-methyl-2-hepten-4-ol, the known active component of the aggregation pheromone, attracts weevils in the olfactometer and in the field only if plant tissue, ethyl-acetate, or the above-mentioned odor mix are present. We propose that a complex mix of ethanol, ethyl-acetate, pentane, hexanal, isolamyl-acetate, and/or isopentanol serve as a short-range orientation cue to fresh wounds on the plant and that additional host odors, attracting weevils from a distance, have still to be discovered. Rhynchophorol can be considered to be a Synergist, having an anemotactic action at a distance. We recommend the use of retention traps baited with rhynchophorol, ethyl-acetate, and sugar cane as an alternative control method for the pest.     

Study of the response of the area of the palm to impact: Relationship between the physical characteristic of the palm impact and the subject perception of the severity of the palm impact

Even though using the hand as a hammer causes injury, the practice continues, and may be increasing, in industry and in jobs that require intensive manual labor. This was an exploratory study aimed at measuring the relationships between the forces of strikes, the relative angles of strikes, and/or the number of strikes (up to 3) with the perception of severity of strikes when using the base of the palm of the hand. Eight subjects struck a metal force plate with the base of the palm of the hand at three levels of force, three levels of angle with respect to the surface of a force plate, and with three different numbers of times in a trial. Subjects were then asked to give a psychophysical rating after each trial. The subjective perception of the severity of each impact and force-time curves were recorded. From each force-time curve, peak force, maximum acceleration of force application, and the area of the force curve from initiation to peak were determined. Sixteen ANOVA models were analyzed.     

Contribution of plant-based sauces to the vitamin A intake of young children in Benin

A food consumption survey on 420 children was conducted in four areas in Benin to identify the local vitamin A (VA)-rich foods most frequently eaten and assess their contribution to the coverage of VA requirements of young children. Mangoes, eggs, red palm oil, various leafy vegetable (LV) sauces and palm nut juice sauce appeared to be the main VA-rich foods consumed. The recipes of the most promising sauces were characterised. Sauces with red palm oil/palm nut juice showed high carotenoid contents ranging from 0.9 ± 0.3 to 4.0 ± 0.8 mg Retinol Activity Equivalent/100 g dry matter (DM). Lipid contents were also high (from 39.6 to 66.8 g/100 g DM). When consumed, and taking into account the mean quantity eaten per meal, LV sauces containing red palm oil or palm nut juice contributed to the meeting of more than 70% of the recommended VA intake of young children.     

Antioxidative Properties of <Emphasis Type="Italic">Curcuma longa</Emphasis> Leaf Extract in Accelerated Oxidation and Deep Frying Studies

The antioxidative properties of Curcuma longa (turmeric) leaf extract were evaluated in refined, bleached and deodorized (RBD) palm olein using accelerated oxidation and deep frying studies at 180 °C for up to 40 h. The extract was capable of retarding oil oxidation and deterioration significantly (P < 0.05) at 0.2% concentration, better than 0.02% BHT for the Oxidative Stability Index (OSI) in an accelerated oxidation study and also the peroxide value in deep frying studies. In sensory evaluation, the French fries were acceptable and were not significantly different (P < 0.05) from one another for color, oiliness and crispiness throughout the 40-h frying study. Curcuma longa leaf extract, which had a polyphenol content of 116.3 ± 0.2 mg/g, possessed heat-stable antioxidant properties and may be a good natural alternative to existing synthetic antioxidants in the food industry.