Analysis of coals and biomass pyrolysis using the distributed activation energy model

The thermal decomposition of coals and biomass was studied using thermogravimetric analysis with the distributed activation energy model. The integral method resulted in Datong bituminous coal conversions of 3-73% at activation energies of 100-486 kJ/mol. The corresponding frequency factors were e(19.5)-e(59.0)s(-1). Jindongnan lean coal conversions were 8-52% at activation energies of 100-462 kJ/mol. Their corresponding frequency factors were e(13.0)-e(55.8)s(-1). The conversion of corn-stalk skins were 1-84% at activation energies of 62-169 kJ/mol with frequency factors of e(10.8)-e(26.5)s(-1). Datong bituminous coal, Jindongnan lean coal and corn-stalk skins had approximate Gaussian distribution functions with linear ln k(0) to E relationships.     

Biomass production,total protein,chlorophylls, lipids and fatty acids of freshwater green and blue-green algae under different nitrogen regimes

Two green algae (Chlorella vulgaris and Scenedesmus obliquus) and four blue-green algae (Anacystis nidulans, Microcystis aeruginosa, Oscillatoria rubescens and Spirulina platensis) were grown in 81 batch cultures at different nitrogen levels. In all the algae increasing N levels led to an increase in the biomass (from 8 to 450 mg/l), in protein content (from 8 to 54 %) and in chlorophyll. At low N levels, the green algae contained a high percentage of total lipids (45 % of the biomass). More than 70 % of these were neutral lipids such as triacylglycerols (containing mainly 16:0 and 18:1 fatty acids) and trace amounts of hydrocarbons. At high N levels, the percentage of total lipids dropped to about 20 % of the dry weight. In the latter case the predominant lipids were polar lipids containing polyunsaturated C₁₆ and C₁₈ fatty acids. The blue-green algae, however, did not show any significant changes in their fatty acid and lipid compositions, when the nitrogen concentrations in the nutrient medium were varied. Thus the green but not the blue-green algae can be manipulated in mass cultures to yield a biomass with desired fatty acid and lipid compositions. The data may indicate a hitherto unrecognized distinction between prokaryotic and eukaryotic organisms.     

Regulation of blue-green algal buoyancy and bloom formation by light,inorganic nitrogen,C02, and trophic level interactions

In highly eutrophic ponds, buoyancy of the gas-vacuolate blue-green alga Anabaenopsis Elenkinii (Miller) was regulated by complex interactions between chemical and physical parameters, as well as by biological interactions between various trophic levels. Algal buoyancy and surface bloom formation were enhanced markedly by decreased light intensity, and to a lesser extent by decreased CO₂ availability and increased availability of inorganic nitrogen. In the absence of dense populations of large-bodied Cladocera, early season blooms of diatoms and green algae reduced light availability in the ponds thus creating conditions favorable for increased buoyancy and bloom formation by A. Elenkinii. The appearance of blue-green algal blooms could be prevented by a reduced density of planktivorous fish, which allowed development of dense cladoceran populations. The cladocerans limited the growth of precursory blooms of diatoms and green algae, and given the resulting clear-water conditions, buoyancy of A. Elenkinii was reduced, and blue-green algal blooms never appeared.     

Survival of Rhizobium phaseoli in Coal-Based Legume Inoculants

The long-term survival of Rhizobium phaseoli strains 127K17, 127K26, and 127K35 in legume inoculants prepared with eight different coals (one strain and one coal per inoculant) was studied. The coals used were Pennsylvania anthracite, bituminous coals from Illinois, Pennsylvania, and Utah, lignite from North Dakota and Texas, and subbituminous coals from New Mexico and Wyoming; they ranged in pH from 4.7 to 7.5 All coals, with the exceptions of Illinois bituminous coal and Texas lignite (pH's of 5.0 and 4.7, respectively), supported the growth and survival of all R. phaseoli strains. All coal-based inoculants in which rhizobial viability was maintained had more than 10⁶ rhizobia per g for at least 7 months, and most contained more than 10⁷ rhizobia per g after 12 months. It appears that most coals, regardless of grade or source, may be acceptable carriers for R. phaseoli inoculants.     

Coal methanogenesis: a review of the need of complex microbial consortia and culture conditions for the effective bioconversion of coal into methane

Microbial biodegradation of coal into low-molecular-weight compounds such as methane has been extensively researched in the last two decades because of the underlying environmental and industrial applications of this technique as compared to the chemical and physical methods of coal conversions. However, the irregular structure of coal and the need for complex microbial consortia under specific culture conditions do not make this biotransformation an ideal process for the development of anaerobic bioreactors. The most abundant species in a methanogenic culture are acetoclastic and hydrogenotrophic methanogens which utilize acetate and H₂+CO₂, respectively. Medium- to low-rank coals such as high-volatile bituminous, sub-bituminous and lignite are more promising in this bioconversion as compared to semi- and meta-anthracite coals. While covering the details of the ideal culture conditions, this review enlightens the need of research setups to explore the complex microbial consortia and culture conditions for maximum methane production through coal methanogenesis.     

DETECTION OF LIMITING OR SURPLUS NITROGEN IN ALGAE AND AQUATIC WEEDS1

The rate of NH₄+-N absorption by algae and aquatic weeds in the dark has been shown to be 4-5 times greater for plants which are N-limited as compared to plants with sufficient available N. Eight species of green algae, 2 blue-green algae, 2 diatoms, and 3 aquatic weeds were used to demonstrate the usefulness of the test in determining if available N was in surplus or limited supply in a particular environment. The test was shown not to differentiate between blue-green algae capable of fixing N (4 species) from media with NO₃-N or without combined nitrogen. The factors influencing the results of NH4⁺-N absorption tests have been investigated. In order to differentiate between plants with sufficient available N and those which are N limited, the rate of NH₄⁺-N absorption (0.1 mg N) over 1-hr incubation in the dark by 10-20 mg of algae or aquatic weed tissues is measured. The relatively simple analysis for NH₄⁺-N in the samples makes it very easy to follow the changing N nutrition of plants in cultures with a limited N supply or in the presence of possible N sources.     

Effect of growth and subsequent decomposition of blue-green algae on the transformation of iron and manganese in submerged soils

N₂-fixing blue-green algae (Cyanobacteria), besides enriching soils with N and organic carbon, may modify a number of chemical and electro-chemical properties of the soils resulting in a change in availability of some micronutrient elements. Keeping this in view, an experiment was conducted to study the effects of growth and subsequent decomposition of blue-green algae on changes in the different forms of Fe and Mn in four soils under submerged condition. A mixed algal culture containing Anabaena, Nostoc, Cylindrospermum, and Tolypothrix was used as inoculum. It was allowed to grow for 2 months, after which the soils were sequentially extracted with (i) M NH₄OAc (pH 7.0), (ii) M K₄P₂O₇, (iii) 0.1 M NH₂OH.HCl (pH 2.0), (iv) 0.2 M (NH₄)₂C₂O₄ (pH 3.0) and (v) 0.1 M ascorbic acid to obtain water-soluble plus exchangeable, organically bound, easily reducible, amorphous oxides-and crystalline oxides-bound forms of Fe and Mn, respectively, both during the growth as well as the subsequent in-situ decomposition of the algal biomass in soils. Iron and Mn in the extracts were estimated by atomic absorption spectrophotometry.The results showed that growth of blue-green algae in submerged rice soils caused a decrease in the NH₄OAc-extractable forms of Fe and Mn with concomitant increases in all the other four determined forms of the elements. Such decreases and/or increases in different forms of Fe and Mn in soils were explained as being due to release of O₂, addition of organic matter and liberation of extracellular organic compounds by the blue-green algae during their growth. The decomposition of algal biomass resulted in an increase in the NH₄OAc-, K₄P₂O₇- and (NH₄)₂C₂O₄-extractable forms of Fe and Mn with a simultaneous decrease in the NH₂OH · HCl- and ascorbic acid-extractable forms. Development of strong reducing conditions and formation of organic acids with chelating properties were suggested as being the cause of the above changes. The implication of these changes in the forms of Fe and Mn for the Fe and Mn nutrition of rice plants were discussed.     

氮、磷对热带浅水湖泊惠州西湖蓝藻的控制

湖泊富营养化常导致蓝藻生物量的增加,水质恶化.于2011年2月至12月对热带浅水湖泊惠州西湖六个湖区的蓝藻群落结构进行研究,以了解其时空变化特征及主要影响因素.结果表明,以沉水植物为优势的元妙观湖区与南南湖蓝藻无明显的优势种;平湖蓝藻优势种为银灰平裂藻(Merismopedia glauca)和湖丝藻(Limnothrix sp.),南丰湖、北丰湖和北南湖的主要优势种均为银灰平裂藻(Merismopedia glauca).平湖、南丰湖、北丰湖和北南湖蓝藻丰度及生物量存在显著的季节变化.相关分析显示惠州西湖夏季蓝藻生物量受氮、磷盐控制.冬季温度的影响,蓝藻生物量与氮、磷的相关性不显著.     

Comparative study of pyrolysis of algal biomass from natural lake blooms with lignocellulosic biomass

Pyrolysis experiments were performed with algal and lignocellulosic feedstocks under similar reactor conditions for comparison of product (bio-oil, gas and bio-char) yields and composition. In spite of major differences in component bio-polymers, feedstock properties relevant to thermo-chemical conversions, such as overall C, H and O-content, C/O and H/C molar ratio as well as calorific values, were found to be similar for algae and lignocellulosic material. Bio-oil yields from algae and some lignocellulosic materials were similar; however, algal bio-oils were compositionally different and contained several N-compounds (most likely from protein degradation). Algal bio-char also had a significantly higher N-content. Overall, our results suggest that it is feasible to convert algal cultures deficient in lipids, such as nuisance algae obtained from natural blooms, into liquid fuels by thermochemical methods. As such, pyrolysis technologies being developed for lignocellulosic biomass may be directly applicable to algal feedstocks as well.     

Rapid physiological assays for nutrient demand by the plankton. I. Nitrogen

Three assays for nitrogen demand were compared on samples ofnatural plankton and on green and blue-green algal species inculture. The most reliable guide was selective luxury uptakeof nitrogen by the plankton after enrichment with a 10-to-1(wt/wt) mixture of inorganic N and P. Ammonium transport capacity,measured either directly (cultures) or by V_max for uptake ofthe NH₄⁺ analogue methylammonium (lakewaters), was generallyhigh in lakewaters with low dissolved inorganic N-to-P ratiosand in N-deficient cultures of green algae. By contrast, transportcapacity was much reduced in both natural and cultured populationsof heterocystous blue-green algae growing under conditions oflow combined inorganic nitrogen. Ammonium enhancement assays(heterotrophic CO₂, fixation after NH₄⁺ enrichment) were conductedat monthly intervals on eutrophic Lake Rotorua. There was astrong, negative correlation between this indicator of N deficiencyand dissolved inorganic N-to-P ratios below a threshold of 6:1.Ammonium enhancement was not, however, a reliable indicatorof combined inorganic N-demand by populations of heterocystousblue-green algae. All three assays provided strong evidenceof a persistent shortage of nitrogen relative to phosphorusfor algal production in Lake Rotorua.     

Productivity and nutrient uptake of water hyacinth,Eichhornia crassipes I. Effect of nitrogen source

Water hyacinth,Eichhornia crassipes, growth and nutrient uptake rates, as influenced by different N sources and N transformations, were measured using microcosm aquaculture systems. Net productivity was highest in the system receiving equal amounts of NH₄ ⁺ and NO₃ ^- (at 10 mg N 1^-1 each) and decreased in the order of NO₃ ^-, NH₄ ⁺, urea (added at 20 mg N 1^-1 each), and methane digestor effluent (at 6 mg N 1^-1). During the first 7-wk study (average ambient air temperature was 26–28°C), biomass yields were in the range of 19–53 g dry wt m^-2 day^-1, while between the 8th and 12th wk (average ambient air temperature was 16–22°C), biomass yields were in the range of 10–33 g dry wt m^-2 day^-1. In the systems with either NH₄ ⁺ or NO₃ ^-, or both added in equal proportions, about 14–20% of the total yield was contributed by roots, whereas in the system with urea and digestor effluent, roots contributed about 23 and 44% of the total yield, respectively. Nitrogen and P uptake per unit area followed trends similar to biomass yields. Nitrogen uptake rates were in the range of 533–2, 161 mg N m^-2 day^-1 for the systems receiving NH₄ ⁺, NO₃ ^-, and urea, while uptake rates were in the range of 124–602 mg N m^-2 day^-1 for the system receiving methane digestor effluent. Phosphorus uptake rates were found to be in the range of 59–542 mg P m^-2 day^-1. Under the most favorable conditions, maximum recorded biomass yield was 53 g dry wt m^-2 day^-1, with N and P removal rate of 2,161 mg N m^-2 day^-1 and 542 mg P m^-2 day^-1, indicating the potential of water hyacinth to produce large amounts of biomass which can be potentially used as a feedstock to produce methane.     

Influence of Water Hyacinth Cover on the Physico-chemical Characteristics of Water and Phytoplankton Composition in a Reservoir near Jaipur (India)

Water hyacinth (Eichhornia crassipes (Mart.) Solms.) invaded a eutrophic reservoir receiving domestic sewage near Jaipur (India) during 1975 and gradually developed a complete thick cover over the whole water body during Sept.–Oct. 1978. The physico-chemical characteristics of the water and the phytoplankton composition were studied during Sept. 1977–Sept. 1979 by fortnightly sampling. The changes observed during the second year of study are ascribed to the water hyacinth cover. The important changes were: lowering of water temperature, pH, dissolved oxygen content and nitrate nitrogen, and increase in total alkalinity, free carbon dioxide, chemical oxygen demand, ammonia nitrogen, sulphides, calcium, magnesium and phosphate phosphorus. The changes in the phytoplankton were both qualitative and quantitative. The green algae, particularly the species of Ankistrodesmus, Chlorella, Crucigenia and Selenastrum, increased considerably and replaced the blue-green algae, of which Oscillatoria and Microcystis disappeared totally. The densities of several other taxa changed significantly.     

Formation of biomass,total protein,chlorophylls, lipids and fatty acids in green and blue-green algae during one growth phase.

Batch cultures (8–32 l.) of Chlorella vulgaris and Scenedesmus obliquus and of Anacystis nidulans and Microcystis aeruginosa were grown in media containing 0.001 % KNO₃ and at several stages in growth sampled for biomass, total protein, chlorophylls, lipids and fatty acids. With increasing time and decreasing nitrogen concentrations, the biomass of all of the algae increased, whereas the total protein and chlorophyll content dropped. Green and blue-green algae, however, behaved differently in their lipid metabolism. In the green algae the total lipid and fatty acid content as well as the composition of these compounds changed considerably during one growth phase and was dependent on the nitrogen concentration in the media at any given day of growth. More specifically, during the initial stages of growth the green algae produced larger amounts of polar lipids and polyunsaturated C₁₆ and C₁₈ fatty acids. Towards the end of growth, however, these patterns changed in that the main lipids of the green algae were neutral with mainly saturated fatty acids (mostly 18:1 and 16:0). Such changes did not occur in the blue-green algae. These differences between prokaryotic and eukaryotic algae can possibly be explained by the ‘endosymbiont theory’.     

TG–FTIR study on co-pyrolysis of municipal solid waste with biomass

Co-pyrolysis of cotton stalk, a representative agricultural biomass in China, mixed with municipal solid waste (MSW) with high ash content and low calorific value was carried out using a thermogravimetric analyzer (TGA) coupled with a Fourier transform infrared (FTIR) spectrometer in Ar atmosphere. Pyrolysis characteristic and pollutant emission performance from MSW and stalk blends at different mass proportions were studied. The results show that as the mass proportion of stalk added increases, the total weight loss of the blend during pyrolysis increases. The addition of stalk has substantial effects on the N-selectivity to HCN, NH₃ and HNCO. In the presence of stalk, lower concentrations of HCl are detected.     

Seasonal water quality of shallow and eutrophic Lake Pamvotis, Greece: implications for restoration

Lake Pamvotis is a moderately sized (22 km²) shallow (z _avg=4 m) lake with a polymictic stratification regime located in northwest Greece. The lake has undergone cultural eutrophication over the past 40 years and is currently eutrophic (annual averages of FRP=0.07 mg P l^-1, TP=0.11 mg P l^-1, NH₄ ⁺=0.25 mg N l^-1, NO₃ ^–=0.56 mg N l^-1). FRP and NH₄ ⁺ levels are correlated to external loading from streams during the winter and spring, and to internal loading during multi-day periods of summer stratification. Algal blooms occurred in summer (July–August green algae, August–September blue-green algae), autumn (October blue-green algae and diatoms), and winter (February diatoms), but not in the spring (March–June). The phytoplankton underwent brief periods of N- and P-limitation, though persistent low transparency (secchi depth of 60–80 cm) also suggests periods of light limitation. Rotifers counts were highest from mid-summer to early autumn whereas copepods were high in the spring and cladocerans were low in the summer. Removal of industrial and sewage point sources a decade ago resulted in a decrease in FRP. A phosphorus mass balance identified further reductions in external loading from the predominately agricultural catchment will decrease FRP levels further. The commercial fishery and lake hatchery also provides opportunities to control algal biomass through biomanipulation measures.     

海水中藻菌共培养体系对碳氮磷的吸收转化

海洋环境中,细菌和微藻之间的物质交换是生源要素在自然界中迁移转化的重要方式。为进一步了解生源要素的生物地球化学循环,在实验室模拟条件下,研究了共培养体系中营养盐和有机物在细菌和微藻之间的转换。通过纯培养中肋骨条藻(Skeletonema costatum)、东海原甲藻(Prorocentrum donghaiense)、天然海水中的细菌以及藻菌混合培养,分析了营养盐和有机物随藻菌生物量的变化情况,并计算了溶解有机碳(DOC)和溶解有机氮(DON)的浓度比值[(DOC/DON)a]。结果发现,在共培养体系中,细菌对中肋骨条藻的生长有抑制作用,对东海原甲藻影响不明显;中肋骨条藻有利于细菌生长,东海原甲藻抑制细菌生长,这种不同可能与微藻的粒径有关。海洋细菌在2种藻的指数生长均期均会促进微藻吸收氨氮(NH_4-N),但在生长末期NH_4-N以释放为主。硝氮(NO_3-N)的浓度与藻的生长呈负相关,但在衰亡期NO_3-N略有增加,表明NO_3-N再生所需时间较长。细菌对硝氮的吸收量较少,但对其再生有贡献。细菌和中肋骨条藻对磷酸盐(PO_4-P)的吸收存在竞争,但与东海原甲藻的竞争关系不明显。不同培养体系中DOC浓度变化不同,在藻菌共培养体系中增加较快,纯藻培养体系中增加缓慢,在纯菌培养体系中缓慢减少。通过对DOC与DON浓度比值的分析,发现用判断颗粒有机碳(POC)来源的方法可以分析DOC的来源。     

Biomass and photosynthetic productivity of water hyacinth (Eichhornia crassipes) as affected by nutrient supply and mirid (Eccritotarus catarinensis) biocontrol

The biological control of water hyacinth is affected by water nitrogen and phosphorus content and this was investigated experimentally at five levels of nutrient supply by measuring plant photosynthetic and growth responses, and mirid reproduction and herbivory of nutrient treated plants. Low nitrogen (2–0.2 mg L⁻¹) and phosphorus (0.2–0.01 mg L⁻¹) supply decreased hyacinth photosynthesis, growth and biomass accumulation relative to plants supplied 200 mg L⁻¹ N and 20 mg L⁻¹ P. This effect depended more on nitrogen supply than phosphorus supply. Chlorophyll fluorescence showed that the photosynthetic light reactions of low nutrient plants were affected and leaves had decreased chlorophyll content, density of functional photosystems II and dissipated a greater proportion of absorbed energy as heat. Gas exchange parameters showed reduced carboxylation efficiency, rates of RuBP regeneration and light saturated photosynthetic rates, but not quantum yields. Effects on photosynthesis translated into lower plant dry biomass. Mirid herbivory exacerbated the effects of low nutrients noted for chlorophyll fluorescence, gas exchange parameters and biomass accumulation, however, these effects were not always significant and there was no obvious correlation between the level of nutrients supplied and the effect of mirid herbivory. Low nutrient supply did, however, affect mirid performance reducing the number of adult insects, nymphs and herbivory intensity suggesting that in the long-term mirid populations would be significantly affected by water nutrient status.     

Effects of Hydroxylamine on Photosystem II: II. Photoreversal of the NH(2)OH Destruction of O(2) Evolution

The inactivation of O₂-evolving centers by NH₂OH extraction was shown to be reversible. This reversal required light and manganese. This light-induced restoration of active O₂-evolving centers was analyzed using three green algae and the blue-green alga, Anacystis nidulans. The following results were obtained: [List: see text]     

Algal nitrogen fixation on the lava field of Heimaey,Iceland

Summary Nitrogen fixation (C₂H₂ reduction) by blue-green algae occurring on the juvenile lava field of Heimaey, Iceland was examined both in the laboratory (potential at 20° C and 39° C) and in the field, three and a half years after the volcanic eruption.Already at this early stage of colonization representatives of unicellular and filamentous heterocystous and non-heterocystous blue-green algae were commonly observed. The predominating algae were Nostoc sp. (20° C) and Schizothrix sp. — Microcoleus chthonoplastes, (39° C), the former often in association with the protonemata-rhizoids of moss plants.The potential for nitrogen fixation was recorded at an average rate of 109.2 (20° C) and 138.1 (39° C) ng N g^-1 h^-1 in soil collected from localities randomly distributed over the lava field.Tests for nitrogen fixation performed in situ revealed significant fixation activities in all the eleven localities subject to examination. The activities ranged from 2.8 to 63.4 (mean 21.5) ng N g^-1 h^-1 and 1.9 to 17.7 (mean 7.9) ng N cm^-2 h^-1.All the nitrogen fixation data noted imply that blue-green algae contribute a substantial part of the nitrogen input to the lava. Further, it was found that material incubated under micro-aerophilic conditions exhibited considerably enhanced nitrogenase activity.The role of nitrogen-fixing blue-green algae in general and Nostoc muscorum in particular in being suitable as pioneering organisms preparing the bare lava for ingress of other plants is also discussed.     

Investigations into the pyrolytic behaviour of coal/biomass blends using thermogravimetric analysis

Investigations into the pyrolytic behaviour during co-pyrolysis of coal, biomass materials and coal/biomass blends prepared at different ratios (10:90, 20:80, 30:70 and 50:50) have been conducted using a thermogravimetric analysis (TGA) apparatus. The coal sample selected was Collie sub-bituminous coal from Western Australia, while wood waste (WW) and wheat straw (WS) were used as biomass samples. Three thermal events were identified during the pyrolysis. The first two were dominated by the biomass pyrolysis, while the third was linked to the coal pyrolysis, which occurred at much higher temperatures. No interactions were seen between the coal and biomass during co-pyrolysis. The pyrolytic characteristics of the blends followed those of the parent fuels in an additive manner. Among the tested blends, 20:80 blends showed the lowest activation energies of 90.9 and 78.7 kJmol(-1) for coal/WW and coal/WS blends respectively. The optimum blend ratio for pyrolysis of coal/WS was 50:50 with a high degradation rate in all the thermal events and a higher mass loss over the course of the co-pyrolysis compared to coal/WW blends examined. The reaction orders in these experiments were in the range of 0.21-1.60, thus having a significant effect on the overall reaction rate. Besides the pyrolysis of coal alone, the 50:50 coal/biomass blends had the highest reaction rate, ranging 1x10(9)-2x10(9) min(-1). The experimental results may provide useful data for power generation industries for the development of co-firing options with biomass.