Thermal hazard evaluation for γ-valerolactone production by using formic acid as hydrogen donor

Aiming at the green and sustainable energy substitution and supply, biomass valorization has become a potential strategy to face the energy crisis and increasing demand all over the world from long-term perspectives. Among the bio-based chemicals, γ-valerolactone (GVL) production from hydrogenation of levulinic acid (LA) and its esters has attracted great interests due to its wide applications, such as fuel, solvent, and additives. However, the safety evaluation for this hydrogenation reaction has received few attentions. To fill this gap, thermal hazard evaluation for GVL production from LA hydrogenation by using formic acid (FA) as hydrogen donor was first performed. The process conditions were optimized by using orthogonal experimental method for further calorimetry study. Thermal stability of chemicals and thermal risk of reaction process under adiabatic conditions were investigated by applying differential scanning calorimetry and accelerating rate calorimeter Phi-Tec II, respectively. The results revealed that the chemicals were stable in temperature range from 30 to 250 °C except FA due to its evaporation and decomposition with endothermic behaviors. The reaction process under isothermal and adiabatic conditions demonstrates that the decomposition of FA was rapid and followed by the hydrogenation of LA to GVL. Based on kinetic model under adiabatic conditions and risk matrix, the thermal runaway risk was found to be medium, indicating that certain safety measures should be properly designed and taken for loss prevention. This work could benefit the safety design and thermal risk prevention for GVL production by using FA as hydrogen donor.     

Emission factors, ozone and secondary organic aerosol formation potential of volatile organic compounds emitted from industrial biomass boilers

To evaluate the potential benefits of biomass use for air pollution control, this paper identified and quantified the emissions of major reactive organic compounds anticipated from biomass-fired industrial boilers. Wood pellets(WP) and straw pellets(SP) were burned to determine the volatile organic compound emission profiles for each biomass-boiler combination. More than 100 types of volatile organic compounds(VOCs) were measured from the two biomass boilers. The measured VOC species included alkanes, alkenes and acetylenes, aromatics, halocarbons and carbonyls. A single coal-fired boiler(CB) was also studied to provide a basis for comparison. Biomass boiler 1(BB1) emitted relatively high proportions of alkanes(28.9%–38.1% by mass) and alkenes and acetylenes(23.4%–40.8%),while biomass boiler 2(BB2) emitted relatively high proportions of aromatics(27.9%–29.2%)and oxygenated VOCs(33.0%–44.8%). The total VOC(TVOC) emission factors from BB1(128.59–146.16 mg/kg) were higher than those from BB2(41.26–85.29 mg/kg). The total ozone formation potential(OFP) ranged from 6.26 to 81.75 mg/m~3 with an average of 33.66 mg/m~3 for the two biomass boilers. The total secondary organic aerosol potential(SOAP) ranged from 61.56 to 211.67 mg/m~3 with an average of 142.27 mg/m~3 for the two biomass boilers.The emission factors(EFs) of TVOCs from biomass boilers in this study were similar to those for industrial coal-fired boilers with the same thermal power. These data can supplement existing VOC emission factors for biomass combustion and thus enrich the VOC emission inventory.     

Charcoal production in a UK moorland wildfire – How important is it?

Wildfires are a common feature of peatland environments, but the carbon balance of these wildfires is often not considered and the production of refractory black carbon in these wildfires could be an important addition to carbon accumulation and mitigate losses of biomass during the fire. This study investigates the biomass and carbon losses during a moorland wildfire. Changes in above-ground carbon stocks were calculated using a combination of field data, laboratory measurements and literature values. The results show that approximately 14% of the carbon in the original above-ground biomass remained on the site after the burn. Black carbon production was approximately 6 gC m(-2) which constituted 4.3% of the biomass lost. The survival of biomass and black carbon may help to mitigate the loss of carbon during the fire.     

Agricultural waste as household fuel: Techno-economic assessment of a new rice-husk cookstove for developing countries

In many rural contexts of the developing world, agricultural residues and the organic fraction of waste are often burned in open-air to clear the lands or just to dispose them. This is a common practice which generates uncontrolled emissions, while wasting a potential energy resource. This is the case of rice husk in the Logone Valley (Chad/Cameroon). In such a context household energy supply is a further critical issue. Modern liquid fuel use is limited and traditional solid fuels (mainly wood) are used for daily cooking in rudimentary devices like 3-stone fires, resulting in low efficiency fuel use, huge health impacts, increasing exploitation stress for the local natural resources. Rice husk may be an alternative fuel to wood for household energy supply. In order to recover such a biomass, the authors are testing a proper stove with an original design. Its lay-out (featuring a metal-net basket to contain the fuel and a chimney to force a natural air draft) allows a mix of combustion/gasification of the biomass occurring in a completely burning fire, appropriate for cooking tasks. According to results obtained with rigorous test protocols (Water Boiling Test), different lay-outs have been designed to improve the performance of the stove. Technical and economic issues have been addressed in the development of such a model; building materials have been chosen in order to guarantee a cost as low as possible, using locally available items. The feasibility of the introduction of the stove in the studied context was assessed through an economic model that keeps into account not only the technology and fuel costs, but also the energy performance. According to the model, the threshold for the trade-off of the stove is the use of rice husk to cover 10–15% of the household energy needs both with traditional fireplaces or with improved efficiency cookstoves. The use of the technology proposed in combination with improved woodstove would provide householders with an appropriate and convenient cooking technology portfolio, increasing the opportunities of choice of the preferred energy system for the user and allowing significant savings for the family budget (up to 50% of the total annual cooking energy expenditure). The proposed model may be used also as a tool for the evaluation of the affordability or for the comparison of different cooking technologies also in other similar contexts, given their specific techno-economic parameter values.     

Effect of grazing on plant attributes and hydrological properties in the sloping lands of the East African highlands

Extending livestock grazing to the steep slopes has led to unstable grazing systems in the East African Highlands, and new solutions and approaches are needed to ameliorate the current situation. This work was aimed at studying the effect of livestock grazing on plant attributes and hydrological properties. The study was conducted from 1996 to 2000 at the International Livestock Research Institute at Debre Ziet Research Station. Two sites were selected: one at 0–4% slope, and the other at 4–8% slope. The treatments were: (1) no grazing (control); (2) light grazing, 0.6 animal unit months per hectare (aum/ha); (3) moderate grazing, 1.8 aum/ha; (4) heavy grazing, 3.0 aum/ha; (5) very heavy grazing, 4.2 aum/ha; (6) initially plowed and continuously very heavily grazed, 4.2 aum/ha. The result showed that species richness, infiltration rate, bare ground, and soil loss significantly varied with grazing pressure. Species richness was higher in grazed plots compared to nongrazed plots. Biomass yield improved on heavily grazed plots as cow dung accumulated over years. Cynodon dactylon plant species persisted with livestock grazing pressure in both sites. Infiltration rate improved and soil erosion declined in all treatments after the first year.     

Recovery of biomass cellulose from waste sewage sludge

In our previous work, the primary sludge from wastewater treatment plants was shown to contain a considerable amount of cellulose (about 20%, based on suspended solids) owing to the discharge of toilet paper. For the purpose of using the cellulose as a biomass resource, this study examined a simple method for its recovery. When fibrous cellulose was suspended in 0.3% sulfuric acid and autoclaved at 130°C for 60 min, 85%–88% of the initial solids remained without dissolving. Under these conditions, an activated sludge sample not containing cellulose was strongly hydrolyzed and only 7% of the initial solids remained. The prescribed amounts of cellulose added to the activated sludge sample were quantitatively recovered by the autoclaving treatment. In the treatment of primary sludge containing >20% cellulose, residual solids with relatively high levels of cellulose (>69%) could be obtained. The results indicate that the method proposed here could recover cellulose practically from waste sewage sludge for biomass utilization. Received: July 17, 2000 / Accepted: July 4, 2001     

Particle-bound polycyclic aromatic hydrocarbons in typical urban of Yunnan-Guizhou Plateau: Characterization,sources and risk assessment

• The sampling was conducted in city on the Yunnan-Guizhou Plateau for one year. • The groups of PAHs revealed their different environmental fates and migration paths. • Seasonal biomass burning could affect the concentration by long-distance transport. • Industrial sources and traffic emissions were the main contributor of PAHs. • Living in industrial areas or winter had higher health risk by exposure PAHs in PM_2.5. Monthly particle-phase ambient samples collected at six sampling locations in Yuxi, a high-altitude city on the edge of Southeast Asia, were measured for particle-associated PAHs. As trace substances, polycyclic aromatic hydrocarbons (PAHs) are susceptible to the influences of meteorological conditions, emissions, and gas-particulate partitioning and it is challenging job to precise quantify the source and define the transmission path. The daily concentrations of total PM_2.5-bound PAHs ranged from 0.65 to 80.76 ng/m³, with an annual mean of 11.94 ng/m³. Here, we found that the concentration of PM_2.5-bound PAHs in winter was significantly higher than that in summer, which was mainly due to source and meteorology influence. The increase of fossil combustion and biomass burning in cold season became the main contributors of PAHs, while precipitation and low temperature exacerbated this difference. According to the concentration variation trend of PM_2.5-bound PAHs and their relationship with meteorological conditions, a new grouping of PAHs is applied, which suggested that PAHs have different environmental fates and migration paths. A combination of source analysis and trajectory model supported local sources from combustion of fossil fuel and vehicle exhaust contributed to the major portion on PAHs in particle, but on the Indochina Peninsula the large number of pollutants emitted by biomass burning during the fire season would affect the composition of PAHs through long-range transporting. Risk assessment in spatial and temporal variability suggested that citizens living in industrial areas were higher health risk caused by exposure the PM_2.5-bound PAHs than that in other regions, and the risk in winter was three times than in summer.     

Impact of Grazing on Plant Species Richness, Plant Biomass, Plant Attribute, and Soil Physical and Hydrological Properties of Vertisol in East African Highlands

Understanding the problems of grazing land in vertisol areas and seeking long-lasting solutions is the central point where mixed crop livestock is the second stay for the majority of the population. In order to understand this, the current study was conducted at two sites, one with 0–4% slope and the other with 4–8% slope at Ginchi watershed, 80 km west of Addis Ababa, Ethiopia. The specific objectives of the study were to quantify changes in plant species richness, biomass, plant cover, and soil physical and hydrological properties. The grazing regimes were: moderate grazing (regulated), heavy grazing (free grazing), and no grazing (closed to any grazing), which was considered the control treatment. The results showed that the biomass yield in nongrazed plots was higher than in the grazed plots. However, the biomass yield in grazed plots improved over the years. Species richness and percentage of dominant species attributes were better in medium grazed plots than the other treatments. Soil compaction was higher in very heavily grazed plots than in nongrazed and medium-grazed plots. In contrast to that, the soil water content and infiltration rate were better in nongrazed plots than in grazed plots. Soil loss in grazed plots decreased with the increase of biomass yields and as the soil was more compacted by livestock trampling during the wet season. Finally since the medium stocking rate is better in species richness and plant attributes, and lies between nongrazed and heavily grazed plots in the rest of the measured parameters, it could be the appropriate stocking rate to practice by the smallholder farmer.     

Evaluation of procedures to estimate biomass on surface coal mine lands reclaimed under the Surface Mining Control and Reclamation Act of 1977

Current surface mine regulations as ascribed under the Surface Mining Control and Reclamation Act of 1977 require that mine lands be returned to the approximate original contours (AOC) with an area coverage of at least 70% and to biological productivity equal to or greater than that which existed prior to mining. Six different procedures were evaluated on nine mine sites in northwestern Pennsylvania as to their suitability to estimate aboveground biomass on mines reclaimed as hayland and pastures. Biomass estimates determined by different procedures were compared to those obtained by random clip plots and with landowner estimates of the annual yield from each site. Biomass estimates determined from a disk meter and landowner interviews varied approximately ±10% from those obtained from random clip plots compared to a variation of ±8%–37% for the other procedures. The number of samples required to obtain reliable estimates within ±10% of the mean at 95% confidence intervals varied among the different sampling procedures according to the variance in biomass on the site. Although all procedures may be used either singly or in combination to estimate above ground biomass on reclaimed mine lands, the combination of the disk meter, profile board, and vegetation height is recommended because of their ease of measurement compared to the other procedures.     

Plant response to utility right of way construction in the Mojave Desert

Disturbance of flora from utility construction tends to generate new plant growth. This growth changes productivity, diversity, and stability. Although the enhancement of vegetation may balance out the biomass destroyed by the original disturbance, it often adversely affects the quality of the vegetation. Percentage composition of the dominant long-lived perennials combined with quantitative measures are used to assess longterm effects of utility corridor construction. Differential effects of enhancement of vegetation are found along road edges, enhancement under wires of powerlines, and over trenches dug for pipelines. Areas under powerline pylons seem to receive the greatest damage and also show the most variable recovery of vegetation. Significant recovery rates are noticeable where the time span between year of construction has allowed for considerable regrowth of the older corridor. Recovery rates depend on soil type, landform, and other physical features of the disturbed sites. Drastic disturbance in one area or transect site may impede vegetation recovery, whereas slight disturbance might enhance vegetation in another, tending to offset the effect of the drastic disturbance. Disturbed areas and control areas may appear to have similar vegetation covers, biomasses, and densities, but these similarities often vanish when one examines qualitative aspects, such as proportion of long-lived species and presence of characteristic dominants.