Production of biodiesel from macroalgae by supercritical CO2 extraction and thermochemical liquefaction

We compare two different techniques for the extraction of biodiesel from macroalgae: the thermochemical liquefaction and the extraction using supercritical carbon dioxide (sc-CO₂). The first allows to use wet material, while sc-CO₂ requires dry material and uses moderate temperature and pressure so that it can be useful for the extraction of thermolabile compounds which may decompose at the temperature at which thermal methos are carried out. In both cases the extracted oil was characterized quantitatively and qualitatively. The novelty of the work is that in the literature the use of macroalgae for the production of biodiesel has not so far been described, while they are used mainly as food or other purposes.     

生物质成型燃料质量现状及对锅炉大气污染物排放影响分析

生物质成型燃料在锅炉上得到了广泛的应用.生物质成型燃料的质量对锅炉的环保有较大的影响.本文通过对深圳市工业锅炉使用的780个生物质成型燃料的质量进行检测,并对其对应使用的锅炉进行大气污染物排放的测试,得出生物质成型燃料的质量现状,并对表征其质量的几项主要指标对生物质成型燃料锅炉对应的大气污染物排放的影响进行了分析.     

青山水库的浮游植物与营养类型评价

共鉴定青山水库藻类58属101种，其中有多污水体指示种5种，α－中污水体指示种24种、β－中污水体指示种49种，寡污水体指示种21种。优势种为窄颗粒直链藻（Melosiragranulatavar.angustissima）、颗粒直链藻（M.granulata）和小颤藻（Oscillatoriatenuis）。浮游植物的细胞密度为8.53×107个／L，生物量为16.34mg／L，叶绿素a为16.86mg／m3。根据浮游植物群落结构和水化学分析结果，青山水库已属富营养型水体，并有继续发展的趋势，控制污染，保护水质已刻不容缓。     

Triboelectric charging behavior of wood particles during pellet handling processes

Electrostatic charges accumulated on wood particles through triboelectrification during their transportation and handling processes can cause hazardous electrical discharge which may further trigger dust explosion. In this work, tribo-charging behavior of different kinds of wood particles was investigated by a vibrating plate charging method. It was found that reduction in the work function difference between contact bodies might contribute to the reduction of tribo-charge generation, while the reduction of electrical resistivity of wood pellets could effectively accelerate the charge dissipation. As the particle size decreases, accumulated charges increase significantly. In contrast, higher moisture content of wood particles leads to lower charge accumulation due to an accelerated charge dissipation rate. Tribo-charging behaviors of white pellets, torrefied pellet, steam treated pellets and dark pellets have also been investigated. Compared to the white pellets, they all have shown a reduction on charge accumulation to some extent. However, results suggested that all of them have nearly equivalent tribo-charge density as coal and wheat grains used as references in this study.     

Variation in indoor levels of polycyclic aromatic hydrocarbons from burning various biomass types in the traditional grass-roofed households in Western Kenya

Biomass burning as fuel in the traditional grass-roofed rural households of Western Province of Kenya in open fire places, in poorly ventilated conditions, lead to accumulation of soot under the roofs. This study characterized and quantified the polycyclic aromatic hydrocarbons (PAHs) in accumulated soot in these households and determined the variation in PAHs concentrations with fuel biomass type. Soot samples collected from the households were extracted, cleaned and analysed by gas chromatography. The PAHs were identified using retention times, verified by gas chromatographic mass spectral analysis and quantified from peak area responses using the internal standard method. The PAHs levels significantly varied (P ≤ 0.05) with biomass type in the order: dung ≥ indigenous trees ≥ exotic trees ≥ shrubs and crop residues. Use of dung and wood from indigenous trees as fuel should be discouraged since they are higher emitters (P ≤ 0.05) of carcinogenic PAHs.     

Biomass combustion and indoor air pollution: the bright and dark sides of small is beautiful

About half the world's households cook and/or heat daily with biomass fuels. At small scale, biomass combustion releases significant amounts of particulates, carbon monoxide, and hydrocarbons, the latter with significant concentrations of polycyclic aromatic hydrocarbons. Preliminary measurements in kitchens of developing-country villages have established airborne concentrations of these healthdamaging pollutants that are orders of magnitude above urban levels or relevant standards. Particle size measurements and dose calculations lead to significant concerns about potential health hazards. The few epidemiological studies are consistent with such effects although more work is clearly needed. These findings may have significant implications for the planning of rural energy development in a number of countries. In particular, they may relate directly to the question of the optimum balance between centralized and decentralized systems.     

Fast start-up anammox process using Acyl-homoserine lactones (AHLs) containing supernatant

N-dodecanoyl homoserine lactone (C₁₂-HSL) was detected in the supernatant of an anammox granular sludge reactor (AGSR). C₁₂-HSL could enhance the specific anammox activity of anammox biomass. Adding C₁₂-HSL-containing AGSR supernatant into the continuously stirred tank reactors reduced the start-up time of the anammox process from 80 to 66 days. Moreover, the nitrogen loading rate was also enhanced to 1.6 times that of the control reactor. AHLs could increase the secretion of extracellular polymeric substances and anammox obtained better enrichment with the addition of AHLs-containing AGSR supernatant. Denaturing gradient gel electrophoresis analysis further revealed that AHLs played a role in mediating microbial community parameters. In conclusion, adding AHL-containing supernatant could be an effective and economical way to accelerate the start-up of anammox.     

Spatial impacts of climate factors on regional agricultural and forestry biomass resources in north-eastern province of China

The dynamics of agricultural and forestry biomass are highly sensitive to climate change, particularly in high latitude regions. Heilongjiang Province was selected as research area in North-east China. We explored the trend of regional climate warming and distribution feature of biomass resources, and then analyzed on the spatial relationship between climate factors and biomass resources. Net primary productivity (NPP) is one of the key indicators of vegetation productivity, and was simulated as base data to calculate the distribution of agricultural and forestry biomass. The results show that temperatures rose by up to 0.37°C/10a from 1961 to 2013. Spatially, the variation of agricultural biomass per unit area changed from -1.93 to 5.85 t·km^–2·a^–1 during 2000–2013. More than 85% of farmland areas showed a positive relationship between agricultural biomass and precipitation. The results suggest that precipitation exerts an overwhelming climate influence on agricultural biomass. The mean density of forestry biomass varied from 10 to 30 t·km^–2. Temperature had a significant negative effect on forestry biomass in Lesser Khingan and northern Changbai Mountain, because increased temperature leads to decreased Rubisco activity and increased respiration in these areas. Precipitation had a significant positive relationship with forestry biomass in south-western Changbai Mountain, because this area had a warmer climate and stress from insufficient precipitation may induce xylem cavitation. Understanding the effects of climate factors on regional biomass resources is of great significance in improving environmental management and promoting sustainable development of further biomass resource use.

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Observation and simulation of net primary productivity in Qilian Mountain, western China

We modeled net primary productivity (NPP) at high spatial resolution using an advanced spaceborne thermal emission and reflection radiometer (ASTER) image of a Qilian Mountain study area using the boreal ecosystem productivity simulator (BEPS). Two key driving variables of the model, leaf area index (LAI) and land cover type, were derived from ASTER and moderate resolution imaging spectroradiometer (MODIS) data. Other spatially explicit inputs included daily meteorological data (radiation, precipitation, temperature, humidity), available soil water holding capacity (AWC), and forest biomass. NPP was estimated for coniferous forests and other land cover types in the study area. The result showed that NPP of coniferous forests in the study area was about 4.4 tCha(-1)y(-1). The correlation coefficient between the modeled NPP and ground measurements was 0.84, with a mean relative error of about 13.9%.