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Bioconversion energy
07 Alternative energy sources (bioconversion energy)
07
ALTERNATIVE SOURCES Bioconversion
ENERGY
energy
that unmodified shives develop low mechanical strength, shorter fibres and large amount of fines. Chemical modification of shives with a prereacted mixture of polyol-anhydride reduces refining energy consump tion, improves strength performance but decreases scattering coefficient. From the results of investigation it is suggested that chemically modified refiner pulp from shives cannot be used for high-grade paper manufacture but it can be used as a low-cost filler for low-end applications in packaging or low-performance decorative papers.
Composting of fish offal and biosoiids in northwestern Patagonia
02/02504
Faz500
A mathematical model for fixed dome type biogas
Raheman, H. Energy, 2002, 27, (I), 25-34. This paper describes the development of a mathematical model for determining the dimensions of a fixed dome type Deenbandhu model biogas plant, the most popular model constructed in India. The developed model could estimate the different dimensions within an absolute variation of 6%. This will help the designers to determine the dimensions of various capacities of a Deenbandhu model biogas plant for different hydraulic retention times to suit the local climatic conditions. 02/02501
Birch wood particle shrinkage during rapid
pyrolysis Davidsson, K. 0. and Pettersson, _I. B. C. Fuel, 2002, 81, (3) 263-270. A study of the shrinkage of cubic (05 mm) birch wood particles during pyrolysis is presented, The particles were rapidly injected into a preheated furnace with a constant temperature in the rang 350-900°C. The size of the particles in longitudinal, tangential and radial directions was measured until no further mass loss occurs. The volume shrinkage was found to be 45-70% and the shrinkage in the different directions 5-25, 25-40 and 15-40% for longitudinal, tangential and radial directions, respectively. Longitudinal shrinkage commenced after about 60% mass loss and is not strongly dependent on heating rate or on cellulose chain scission. A maximum shrinkage was found for tangential and radial directions at 400 and 500-7OO”C, respectively, and above these temperatures the shrinkage decreases. The char yield decreases and the char structure becomes more deranged with increasing temperature. Empirical models of shrinkage as a function of conversion are presented.
02/02502 Characterization of degradation products from alkaline wet oxidation of wheat straw Klinke, H. E. ef nl. &resource Technology, 2002, 82, (1) 15-26. Alkaline wet oxidation pre-treatment (water, sodium carbonate, oxygen, high temperature and pressure) of wheat straw was performed as a 2&’ fractional factorial design with the process parameters: temperature, reaction time, sodium carbonate and oxygen. Alkaline wet oxidation was an efficient pre-treatment of wheat straw that resulted in solid fractions with high cellulose recovery (96%) and high enzymatic convertibility to glucose (67%). Carbonate and temperature were the most important factors for fractionation of wheat straw by wet oxidation. Optimal conditions were 10 min at 195°C with addition of 12 bar oxygen and 6.5gI--’ NarCO_+ At these conditions the hemicellulose fraction from 100 g straw consisted of soluble hemicellulose (16 g). low molecular weight carboxylic acids (11 g), monomeric phenols (0.48 g) and 2-furoic acid (0.01 g). Formic acid and acetic acid constituted the majority of degradation products (8.5 g). The main phenol monomers were 4_hydroxybenzaldehyde, vanillin, syringaldehyde, acetosyringone (4-hydroxy-3,5-dimethoxy-acetophenone), vanillic acid and syringic acid, occurring in 0.04-0.12 g per 100 g straw concentrations. High lignin removal from the solid fraction (62%) did not provide a corresponding increase in the phenol monomer content but was correlated to high carboxyiic acid concentrations. The degradation products in the hemicellulose fractions covaried with the pre-treatment conditions in the principal component analysis according to their chemical structure, e.g. diacids (oxalic and succinic acids), furan aldehydes, phenol aldehydes, phenol ketones and phenol acids. Aromatic aldehyde formation was correlated to severe conditions with high temperatures and low pH. Apart from CO2 and water, carboxylic acids were the main degradation products from hemiceiiulose and lignin.
Chemi-refiner mechanical pulping of flax shives: refining energy and fiber properties
02/02503
Sain, M. et al. Bioresource Technology, 2002, 81, (2), 193-200. Oil-seed flax shive has been promoted as a raw material for low-end paper making because of its overall cost benefit over hardwood and groundwood pulp and increasing demand for low-cost pulp in rigid packaging applications. We have made refiner mechanical pulp from oil-seed shives by using a 300 mm Sprout-Bauer pilot refiner. The factors controlled during refining were: consistency, multi-pass refining, temperature, spacing between the plates and polyol-anhydride reactant concentration. Based on the results in this study it is apparent
Laos, F. et al. Bioresource Technology, 2002, 81, (2), 179-186. Composting of fish processing wastes and biosolids with wood byproducts and yard trimmings was conducted during the summer of 1996 and winter of 1997 in NW Patagonia using: (i) static piles for fish offal and (ii) turning piles for biosolids. Fish offal was mixed with sawdust + wood shavings (FOC) at 3:l ratio by weight and biosolids with wood shavings (BCw) and yard trimmings (BCt) at 1:l ratio by volume. Samples were taken at six dates during the composting period and analysed to determine the factors that predict compost maturity. Composting of biosolids was affected by the type of bulking agent during winter. Thermophilic temperatures 255°C were sustained long enough to satisfy the USEPA requirements for processes to further reduce pathogens (PFRP) in FOC and BCt, and for processes to significantly reduce pathogens (PSRP) in summer BCw, while in winter BCw temperatures were lower than those recommended for effective pathogen reduction. However, coliform faecai content in ail BC treatments was less than 10 most probable number (MPN) g-’ dry sample at the end of the process. The ratio of water soluble carbon (WSC) to total nitrogen (TN) appeared to be a more adequate index to predict compost maturity than the ratio of total organic carbon to nitrogen.
Continuous co-digestion of cattle slurry with fruit and vegetable wastes and chicken manure 02/02505
Callaghan, F. J. er al. Biomass and Bioenergy, 2002, 27, 71-77. Anaerobic digestion is a well established process for treating many types of organic waste, both solid and liquid. As such, the digestion of cattle slurries and of a range of agricultural wastes has been evaluated and has been successful. Previous batch studies have shown that based on volatile solids (VS) reduction, total methane production and methane yield, co-digestions of cattle slurry (CS) with fruit and vegetable wastes (FVW) and with chicken manure (CM) were among the more promising combinations. A continuously stirred tank reactor (18 litres) was used as a mesophilic (35°C) anaerobic reactor to examine the effect of adding the FVW and CM to a system which was digesting CS. The retention time was kept at 21 days and the loading rate maintained in the range 3.19-5.01 kg VS mm3 d-l. Increasing the proportion of FVW from 20% to 50% improved the methane yield from 0.23 to 0.45 m3 CHd kg- ’ VS added, and caused the VS reduction to decrease slightly. Increasing the proportion of chicken manure in the feed caused a steady deterioration in both the criteria for judging digester performance. This appeared to be caused by ammonia inhibition.
Delivery systems of forest arisings for energy production in New Zealand
02/02506
Hall, P. ef al. Biomass and Bioenergy, 2001, 21, (6), 391-399. The large area of planted production forest in New Zealand and the expected increase in area to be harvested in the next 10 years, offer good potential for the woody biomass residue to contribute to New Zealand complying with the goals set by the Kyoto protocol. The main focus is on forest arisings, which are residues produced during the harvesting of logs. The objective of this paper is to identify promising delivery systems (including harvesting, storage, transportation and processing) of forest arisings to an energy plant and the associated costs. Costs largely depended on the delivery system chosen, the site characteristics and the transport distance. The cheapest system identified ranged from NZ%22 to 37 per tonne dry matter (NZ$1.22.0 per GJ) for residues accumulating at the landing and from NZS29 to 42 per tonne dry matter (NZ$l&2.2 per GJ) for residues collected from the cutover. The cheapest option tended to be the simplest system because each time the material was handled, extra costs were added. The simulation model developed to compare different delivery systems proved to be a useful tool. However, it was important that input parameters were estimated accurately, especially product characteristics (moisture content and material density) and machine data, because these were the most sensitive model parameters. The results indicate that the use of forest arisings for the generation of heat and/or electricity could be feasible in New Zealand.
Dynamics of nitrate leaching and 15N turnover in intensively fertilized and irrigated basket wiiiow grown in iysimeters
02102507
Aronsson,
P. G. Biomass and Bioenergy,
2001, 21, (3). 143-154.
Fuel end Energy Abstracts
September 2002
231
07 Alternative energy sources (bioconversion energy) A 13-month experiment was conducted to study the dynamics of nitrate leaching from basket willow (S&x viminalis), and the fate of fertilizerN applied after the growing season. Lysimeters with or without plants were supplied daily with water and liquid fertilizer. Nitrate leaching and transpiration were uantified, as well as leaf-, stem- and root growth and N-uptake. ’9N-labelled fertilizer was applied in autumn after leaf fall for the determination of the fate of fertilizer-N. The Nuptake by the willow plants was high during the summer and was correlated with transpiration. It decreased drastically in autumn in the absence of transpiration, but was still significant, which was also the case in early spring, the following year. A leaf rust infection during autumn led to a nine-times increase in nitrate leaching, whereas transpiration was reduced by 26%. After a fertilizer application for IO days after leaf fall in autumn, an average of 8% of the fertilizer-N was taken up by the plants, and 32% was unaccounted for, of which a large portion was likely to be lost through denitritication. Recalculated on a hectare basis, the whole-season nitrogen budget shows that 191 kg N/ ha was applied as liquid fertilizer during the first season, of which 98 kg N/ha was taken up by plants, 69 kg N/ha was leached, and 24 kg N/ha was unaccounted for (i.e. possibly denitrifled). The amount of nitrogen taken up by plants or- lost from the system (possibly through denitrification) corresponded to 36 kg N/tonnes of dry stem wood produced.
Effect of leachln on the ash behavior of olive residue during fluldired be8 gasification
OQ/O2SQQ
Arvelakis, S. er al. Biomass and Bioenergy, 2002, 22, (I), 55-69. Fluidized bed gasification is considered to be the most advanced method for thermochemical conversion of various biomass fuels, e.g. wood, energy crops, agroresidues, etc., to energy offering economical and environmental benefits. Ash-related problems including sintering, agglomeration, deposition, erosion and corrosion resulting due to the low melting point ash of agroresidues are the main obstacles for economical and viable application of this conversion method for energy exploitation of the specific residues. The effect of leaching (washing) the olive residue in order to improve its ash thermal behaviour under the gasification conditions was studied. Gasification tests were performed in a lab scale fluidized bed gasifier with both leached and non-leached samples and the results concerning the ash thermal behaviour of the used samples were associated with their ash elemental analysis, while the deposits produced during the gasification tests were analysed using SEM-EDX analysis technique. The produced results clearly show that leaching could help significantly in avoiding to a great extent, the operational problems associated with the problematic ash thermal behavior in the case of olive residue. In particular, all gasification tests performed using the non-leached olive residue material as feedstock resulted in a rapid agglomeration of the reactor’s bed material and consequently to the end of the gasification tests. One the contrary, gasification tests performed using the leached olive residue material ended without any agglomeration-deposition problems, while the operation time was in all cases longer compared with the tests with the non-leached olive material. 02/02509 Energy evaluation of forest residues originated from Eucalyptus globulus Labill in Galicia
Ntidez-Regueira, L. er al. Bioresource Technology, 2002, 82, (I), 5-13. The possibility of retrieving the energy contained in forest residues orieinatine from wood exoloitation in Galicia (Soain) is evaluated. This ---a--~a ~~ . study was made on Eucalyptus globulus Labjll occupying a forest surface of 240000 ha. This species plays an important role in the economical development of Galicia, as it is the main forest species for production of pulp. Sampling was made over 1999 in seven different zones, three main stations plus four selected for comparison, situated in Galicia. The residues originating from cutting were sorted into three different groups and their calorific values were measured by static bomb calorimetry. These caloritic values, close to 7200 kJ kg- , make possible the use of this residual biomass as an energy source. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters, elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.
02/02510 pyrolisis
Fertlliser influence on alkali release during straw
Davidsson,, K. 0. ef al. Fuel, 2002, 81, (3) 259-262. Comparattve studies of alkali release from wheat and oat straws cultivated in the laboratory with chloride-rich and sulphate-rich fertilizers are reported. The release of alkali during pyrolysis in the temperature range 25-1060°C is measured using the sensitive surface ionization technique. Straw cultivated with a chloride-rich fertilizer releases two to four times more alkali than straw fertilized with a sulphate-rich fertilizer, and the release takes place at lower temperatures. The temperatures for maximum alkali release are =~800”C for 332
Fuel and Energy Abstracts
September 2002
straw cultivated with a chloride-rich fertilizer, and =870°C for straw supplied with a sulphate-rich fertilizer. The samples were also subject to simple water leaching, and alkali was observed to be easily removed by leaching irrespective of fertilizer. Application of chloride-free fertilizer is concluded to be a simple and efficient way to reduce the alkali release from the fuels, and the method can easily be combined with other methods in order to improve fuel quality.
02/02511 Floristic structure and biomass distribution of a tropical seasonal rain forest in Xishuangbanna, southwest China
Shanmughavel, P. et al. Biomass and Bioenergy, 2001,21, (3), 165-175. The aim of this research was to study the forest community structure, tree species diversity and biomass production of a tropical seasonal rain forest in Xishuangbanna, southwest China. The community structure showed a diversified species composition and supported many species of economic significance. This tropical rain forest is closely related to Malaysian forests. The biomass and its distribution were studied using standard regression analysis and the clear-cut method for shrubs and herbs. The total biomass was 360.9 t/ha and its allocation in different layers was: tree layer 352.5 t/ha, shrub layer 4.7 t/ ha, liana 3.1 t/ha and herb layer 0.5 t/ha. Most of the biomass was concentrated in the trees: stem 241.2 t/ha, root 69.6 t/ha, branch 37.2 t/ ha and leaves 4.3 t/ha: The DBH class allocation of the tree biomass was concentrated in the middle DBH class. The biomass of six DBH classes from 20 to 80 cm was 255.4 t/ha. There are 26 species with biomass over 0.5% of the total biomass of the tree layer; and three species with biomass over 5%, i.e. Pometia lomenlosa, Barringronia macroslachva 15.4%) and Terminalia mvriocaroa (5.2%). Data on stem. branch, leaves and ‘root of the individual tree ‘species were used to develop regression models. D2H was found to be the best estimator of the biomass in this tropical rain forest. However, higher biomass figures have been reported from tropical forests elsewhere, e.g. 415-520 t/ha in the tropical forests of Cambodia, the tropical moist mixed dipterocarp forests, and the tropical moist logged moist evergreen-high, medium, and low yield forests of Sri Lanka. In some forests, lower accumulation of biomass was reported, e.g. LO-295 t/ha in the tropical moist forests of Bangladesh, the tropical moist dense forest of Cambodia, the tropical dry forests of India, the tropical moist forests of Penninsular-Malaysia, the tropical moist mixed dipterocarps forests of Sarawak-Malaysia, the tropical evergreen forests of Myanmar and the tropical moist ever-green logged forests of Sri Lanka.
02/02512 improved cookstoves in rural India: how improved are they? A critique of the perceived benefits from the National Programme on improved Chulhas (NPIC) Kishore, V. V. N. and Ramana, P. V. Energy, 2002, 27, (I), 47-63. The National Programme on Improved Cookstove (NPIC) was started by the Ministry of Non-conventional Energy Sources (MNES), Government of India, in 1985 to achieve the twin objectives of fuelwood conservation and smoke reduction in kitchens. NPIC has overseen the installation of 28 million improved cookstoves, saving nearly 20 million tons of firewood per year. These achievements, though seemingly impressive, are not realistic as they are based on certain assumptions, particularly regarding the life expectancy of stoves. This paper examines the various assumptions made in such calculations and tries to arrive at some realistic numbers regarding fuelwood savings, which can be used to evolve a policy for refining the NPIC further.
02/02513 Lactic acid oroduction from wheat straw hemicellulose hydrolyiate by Lactobaciflus pentosus and Lactobacillus brevis
Garde, A. ef al. Bioresource Technology, 2002, 81, (2), 217-223. Lactic acid production by Lactobaci&s brevis and Lb. pentosus on a hemicellulose hydrolysate (HH) of wet-oxidized wheat straw was evaluated. The potential of 1 l-12 g/l fermentable sugars was released from the HH through either enzymatic or acidic pretreatment. Fermentation of added xylose in untreated HH after wet-oxidation, showed no inhibition on the lactic acid production by either Lb. penrosus or Lb. brevis. Lb. penrosus produced lactate corresponding to 88% of the theoretical maximum yield regardless of the hydrolysis method. whereas Lb. brevis oroduced 51% and 61% of the theoretical maximum yield after enzymatic, or acid treatment of HH, respectively, Individually, neither of the two strains were able to fully utilize the relatively broad spectra of sugars released by the acid and enzyme treatments; however, lactic acid production increased to 95% of the theoretical maximum yield by co-inoculation of both strains. Xylulose was the main sugar released after enzymatic treatment of HH with Celluclast’. Lb. brevis was able to degrade xylobiose, but was unable to assimilate xylulose, whereas Lb. penrosus was able to assimilate xylulose but unable to degrade xylobiose.
07 A~emaf~e energy sources (bioconversbn energy) g$;;$-i:
Lanthanum(lll)-catalyzed degradation of cellulose
Seri, K. er al. Bioresource Technology, 2002, 81, (2), 257-260. Lanthanum(II1) chloride was found to effectively catalyse the degradation of cellulose in water at 250°C. The degradation conversion of celiulose in the presence of a catalytic amount of lanthanum chloride reached 80.3% after 180 s, which corresponded to the turnover number of 83, whereas the reaction did scarcely proceed in the absence of the catalyst. The degradation products were separately quantified as watersoluble (WS), methanol-soluble (MS), methanol-insoluble (MI), and gaseous (G) products. The HPLC and GC analyses revealed that the WS materials are mainly composed of 5-hydroxymethyl-2-furaldehyde (HMF), D-glucose, and levulinic acid, Cellobiose, the disaccharide component of cellulose, was scarcely detected during the reaction. 02102515 Life cycle assessment of biofibres replacing aiass flbres as reinforcement in elastics &&b&e-Nicollier, T. et al. Resow&, Conservation and Recycling, 2001, 33, (4), 267-287.
This article aims to determine the environmental performance of China reed fibre used as a substitute for glass fibre as reinforcement in ptastics and to identify key environmental parameters. A life cycle assessment (LCA) is performed on these two materials for an appIi~tion to plastic ~ans~rt pallets. Transport pallets reinforced with China reed fibre prove to be ecologically advantageous if they have a minimal lifetime of 3 years compared with the S-year lifetime of the conventional pallet. The energy consumption and other environmental impacts are strongly reduced by the use of raw renewable fibres, due to three important factors: (a) the substitution of glass fibre production by the natural fibre production; (b) the indirect reduction in the use of polypropylene linked tu the higher proportion of China reed fibre used and (c) the reduced pallet weight, which reduces fuel consumption during transport. Considering the whole life cycle, the polypropylene production process and the transport cause the strongest environmental impacts during the use phase of the life cycle, Since thermoplastic composites are hardly biodegradable, incineration has to be preferred to discharge on landfills at the end of its useful life cycle. The potential advantages of the renewable fibres will be effective only if a purer fibre extraction is obtained to ensure an optimal material stiffness, a topic for further research. China reed biofibres are finalIy compared with other usages of biomass, biomaterials, in generai, can enable a three to ten times more efficient valorization of biomass than mere heat production or biofuels for transport. 02!02516 Lipid production by Yarrowia lipolytica growing on industrial glycerol in a single-stage continuous culture Papanikolaou, S. and Aggelis, G. Bioresource Technology, 2002,82, (I), 43-49.
Yurrowia lipolyrica LGAM s(7)l presented remarkable growth on industrial glycerol used as soie carbon substrate. Nitrogen-limited flask cultures were accompanied by restricted synthesis of reserve lipid, whilst amounts of citric acid were produced extracellularly. On the contrary, high amounts of reserve lipid (up to 3.5 g/l, 43% w/w of lipids in dry biomass) were produced in highly aerated continuous cultures. Lipid production was favoured at low specific dilution rates whilst fatfree material yield increased over the whole range of D (h-l). The maximum volumetric productivity obtained was 0.12 g lipid/l h. Storage lipid composition did not present remarkable changes in the specific dilution rates tested. Ofeate and linoleate were the dominant cellular fatty acids. 02/02517 Nitrate leaching from lysimeter-grown shortrot&ion willow coppice in relation to N-application, irrigation and soil type Aronsson, P. G. and Bergstrom, L. F. Biomass and Bfoenergy, 2001,21, (3), 153-164.
The use of willow vegetation filters for wastewater treatment is gaining interest in Sweden. A study was conducted in order to determine reasonable rates of wastewater application to such vegetation filters. NOs-N leaching loads and N-uptake by the plants were quantified in relation to nitrogen application rate, irrigation rate, shoot growth, and soil type during 3 years after planting of willow (.Wix viminafis) in I6 1200-Iitre lysimeters filled with clay or sand soil. Nitrogen was applied at rates corresponding to 1IO-244 kgN/ha year combined with irrigation of 3-6 mm/day during 100-110 days each growing season. NOs-N leaching loads were very high the first year after plant establishment (on average 341 kg N/ha from clay and 140 kg N/ha from sand lysimeters). However, NOs-N leaching loads decreased and were low or negligible during the second (43 from clay and 17 kg N/ha from sand lysimeters) and third year (3 kg N/ha from clay and less than 1 kg N/ha from sand lysimeters). Harvest of the plants after the second growing season did not seemingly affect NO,-N leaching loads during the third year. Soil type and N application rate strongly influenced NOs-N leaching loads, whereas irrigation rate had only a slight effect, and thus, dosing of wastewater should be based on N-amounts.
Assuming an annual shoot growth of 10 tonnes (dry weight),/ha in a willow vegetation filter, wastewater could be applied at rates corresponding to 160-190 kg N/ha without substantial NOx-N leaching losses. 02102516 Pigs as recyclers for nutrients contained in Bermuda grass harvested from spray fields ;y%grpen, T. A. T. G. er al. Bioresource Technology, 2002, 81, (2), The ability of pigs to use nitrogen and energy in Bermuda grass was evaluated in order to assess whether Bermuda grass harvested from spray fields could be fed to pigs as a means to recycle nitrogen. Digestibility of Bermuda grass incorporated into corn-soybean meal diets was evaluated in heavy ~nishing pigs and gestating sows. Results suggest that Bermuda grass digestibility is negative in animals not adapted to a high-fibre diet. Enzymes improve this digestibility, but even with enzymes, nitrogen digestibility was poor. Pigs fed a diet containing 10% Bermuda grass required a one week adaptation period for maximal digestion; following adaptation, pigs can digest approximately 40% of the energy in Bermuda grass but none of the nitrogen. Feeding Bermuda grass to pigs as a means of recycling nitrogen is thus not recommended. 02102519 Production of carboxyltc acids from hydrolyzed COM meal by immobilized cell fermentation in a fibrous-bed bioreactor Huang, Y. L. et al. Bioresource Technology, 2002, 82, (I), 51-59. Corn meal hydrolysed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via an-aerobic fermentations. In this study, corn mea!, containing 75% (w/w) starch, 20% (w/w) fibres, and 1.5% (w/w) protem, was first hydroiysed using amylases at 60°C. The hydrolysis yiefded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactacoccus lactis and Cfos/ridium ,formicoaceticum was used to produce acetic acid from glucose, Propionibacterium acidipropionici was used for propionic acid fermentation, and Cfosrridium tyrohutyficum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirredtank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37°C and 7.6, respectively, for acetic acid fermentation, 32°C and 6.0, respectively, for propionic acid fermentation, and 37°C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(1 h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(1 h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(1 hf. These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fibre present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized ceil bioreactor systems. It is concluded that the FBB technology is suitabte for producing value-added biochemicats directly from agricultural residues or commodities such as corn meal. 02/02520 Solid state fermentation of broiler litter for production of biocontrol agents Adams, T. T. ef al. Bioresource Technology, 2002, 82, (l), 33-41. Several varieties of heat-sterilized broiler litter with 60% (wet basis, wb) moisture content were substrate in solid-state fermentations to produce biocontrol agents. Litter varieties included litter produced by one flock of broilers from medicated and non-medicated controlled rations, and litter produced by two flocks and four flocks on a single apphcatton of bedding material from medicated commercial sources. Litter preparations were inoculated with monocultures of Brrcilfxs thuringiensis serovar japonensis strain Buibui, a pathogen of Japanese beetle larvae (Popillia japonfca), or Pseudomonas ffuorescens 2-79. B. thuringiensis did not grow in unextracted one-flock litter nor in water extracted litter, but grew in methanol extracted litter to 5 x 10” cell forming units (CFU)/g litter (dry weight, dw) and a spore count of 1 x 10” CFU/g litter (dw). ii. thuringiensis also grew in unprocessed twoflock and four-flock litter, achieving cell counts of 3 x lo9 and 1 x 10” CFU/g litter (dw), respectively, and spore counts of 1 x lo9 CFUjg litter (dw). P. fluorescens grew in medicated one-flock litter with no extraction to a cell density greater than 4 x IO” CFU/g litter (dw). Bioassays in soil containing over 0.5% (db) litter fermented with B, thurtngiensb resulted in over 90% mortality in 21 days for first instars of Japanese beetie when compared to a control treatment using Fuel and Energy Abstracts
September 2002
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07 Alternative energy sources (bioconversion energy) comoost without fermented litter. The investieations demonstrate that bacterial biocontrol agents produced via sob&substrate fermentations using broiler poultry litter have potential in biocontrol applications in the soil environment. 02iO2521 Studies on biomass for production of blobriquette in Chongqing, China Gao. S. et al. Taiki Kankvo Gakkai.shi. 2001. 36. (2). 78-87. Bio-briquette is a sort of’composite fuel consisting’bf 70-85% of coal and 15-30% of biomass by weight, produced by high-pressure - _ briquetting method with compression only in the roll-press technique without any binder. The biomasses working as a binder are various woody wastes and agriculture wastes such as rice straw, rice bran, sorghum stalk, wheat straw and so on. Total yearly output of woody wastes and agriculture wastes in Chongqing of China amounted to approximately 18.0 million tons based on our investigating data. Using 5% of them, yearly output of bio-briquette will be approximately 3.60 million tons and enough as the domestic fuels. So, there were enough biomass materials to produce bio-briquette in Chongqing. Ten types of biomasses including four types of agriculture wastes, one type of woody waste and wild grass, and four types of food manufacturing. Wastes collected in Chongqing were investigated for their combustion characteristics, emissions, binder action and breaking strength of biobriauette Dreoared from each of them. The exoerimental results indi‘cated thatihkre were little emissions of air polluiants from biomass combustion and emission amounts for HCI and SO1 were 35-912 and 52-1764 mg per 1 kg of biomass, respectively. Compared with raw coal, the biomass can reduce the ignition temperature and increase the combustibility of the bio-briquette. The breaking strength of the biobriquette increased with increase of additional amount and lignin contents of biomasses, which were in range of 12.1-33.3%. It is estimated based on our experimental results that the reduction efficiency of HCI, SOz and dust for the bio-briquette ranged 26-61%, 82-87%-and 55-83%: respectively. As a useful countermeasure for control of air pollutants discharged from civilian and small factory coal combustions, the bio-briquette with satisfactory strength could be produced by adding 25% biomasses without any special binder. 02102522 Suitability of steam exploded residual softwood for the production of binderless anels. Effect of the pretreatment severity and lignin adBition Angles, M. N. ef al. Biomass and Bioenergy: 2001, 21, (3), 21 l-224. A steam explosion pre-treatment was apphed at various severities to softwood residual substrate to determine the most suitable pretreatment for the manufacture of binderless panels. The effect of adding acid to the pre-treatment of fibres was also evaluated. The changes in the chemical composition and morphology of the original material were investieated bv fractionation analvses and scanninn electron micrographs.” High severities caused defibrillation of the material allowing to build links to form the panels. Pre-hydrolysis with acid had a great-effect on the structure of the material even at-low acid concentration. The physical and mechanical properties of the panel improved as the severity of the pre-treatment increased up to a point where mechanical properties deteriorated. The composites with highest internal bond had a high cellulose content and a medium lignin content. All these factors suggested that steamed pre-treated residual could be improved by adding a natural binder to produce the panels. A test of producing panels with addition of several kinds of lignin (up to 20%) was performed. With no significant changes in density, water stability (thickness swelling and water absorption) internal bond and mechanical properties wee greatly improved. Results after accelerated ageing test were also enhanced. 02/02523 The effect of kaolin particles on the behavior of nitrifylng activated sludge units Campos, J. L. e/ al. Bioresource Technology, 2002, 81, (2), 225-231. The effects of the addition of powered particles of kaolin to nitrifying activated sludge systems were studied. Kaolin was added to a nitrifying activated sludge reactor, during the operational phase, to observe the effects of this clay on reactor performance. The results were compared to those obtained from a similar unit operated without kaolin. The settling properties of the sludges from both units were similar (sludge volume index (SVI) of 14.5 ml/g VSS; zone settling velocity (ZSV) of 7.5 m/h), but the specific nitrifiing activities of ammonia and nitrite oxidizing processes were enhanced up to 75% and 50%, respectively, when kaolin was added. The mechanism of action of kaolin was not clear. Additional ammonia. nitrite and nitrate adsorotion tests showed that these compounds were not adsorbed by kaolin. ‘?his demonstrated that no beneficial effect was caused by adsorption of either substrates or products. Short-term activity tests also showed that the stimulating effects of kaolin on specific activity were not immediate. The effects of kaolin when nitrifying units were operated under unfavourable conditions were also evaluated: In a second set of experiments, a nitrifying unit was operated with low levels of dissolved oxygen (DO), with and without kaolin. The presence of kaolin exerted practically no 334
Fuel and Energy Abstracts
September 2002
effect on ammonia oxidation but nitrite oxidation slightly diminished. In a third set of experiments, a nitrifying unit was subjected to pH shocks (9,10 and 11) over 3 h with pH then restored to 7.8. A pH shock of 11 caused a decrease of 60% in nitrifying activity for 12 days. When kaolin was added to this unit the efficiency of the system was completely restored in 4 days. Therefore, kaolin might be useful to restore damaged units. 02/02524 The effects of fuel washing techniques on alkali release from blomass Davidsson, K. 0. ef al. Fuel, 2002, 81, (2) 137-142. The influence of different washing techniques on the alkali release during pyrolysis of biomass is studied. After washing and drying, samples of wheat straw, wood waste and cellulose are subjected to a constant heating rate in a Ns atmosphere, and the release rate of alkali compounds from the sample is measured continuously by a surface ionization technique. Alkali is released form the untreated biomass in two temperature Intervals: (1) in connection with the pyrolysis process taking place at 200-5oo”C, and (2) from the material remaining after pyrolysis at temperatures above 600°C. Separate vacuum pyrolysis experiments show that the alkali release is dominated by potassiumcontaining compounds, with minor contributions form sodium-containing compounds. The effect of water washing of the biomass is compared with a more thorough acid leaching technique. In the temperature range 20&5OO‘C, washing with water reduces the alkali emission form wood waste and wheat straw by 5-30%, while acid leaching is more effective and reduces the emission by around 70%. Above 600°C where the vaporization of alkali compounds from untreated wheat straws increases sharply, the washing procedures are sufficient for a reduction in the measured alkali release bv more than 90%. Experiments with pure cellulose (ash content O.Of%) indicate that the washing methods are ineffective in removing alkali bound to the organic structure of the biomass. The results support the conclusion from earlier studies that relatively simple washing techniques can improve the combustion properties of biomass fuels with a high ash content. For fuels with a lower ash content like woody biomass, the concentration of alkali bound to the organic structure limits the effect of the washing techniques. 02/02525 Winterisation of waste cooking oil methyl ester to improve cold temperature fuel properties Gonzdlez Gbmex, M. E. ef al. Fuel, 2002, 81, (I), 33-39. Waste cooking oil methyl ester (WCOME) was winterized at 1, 0, -1 and -2°C following a 4 x 2 factorial design with one replication per cell. The process was carried out by filtration and both the filtrate (solid phase) and the liquid phase were analysed by gas chromatography (GC), differential scanning calorimetry (DSC), and thermoeravimetric analvsis ITGA). Cold filter ulurutinn ooint (CFPP) and calorific values herd measured. Tempe;atiFes”oi 0 and -1’C in conjunction with the quickest cooling rate (O.l”C min-‘) and 15-24 h of cooling gave the most successful results in terms of fuel properties. Improvements in the low temperature properties of the winterized fuel were reflected by a reduction of saturated fatty acid methyl esters (SFAME) in the composition by 1.5-6%, by a decrease in the CFPP values by 2-4C and by a shift of the DSC high temperature melting peak (approx. 5°C) towards lower temperatures in corn arisen to the original fuel. Calorific values of the winterized WC8 ME did not significantly change and boiling temperatures increased (approx. 26%) in comparison to the non-winterized WCOME. 02102526 Yield improvements through modification of piantlng density and harvest frequency ln short rotation coppice Sallx spp. - 1. Yield response in two morphologically dlverse varleties Bullard. M. J. et al. Biomass and Bioenerpv. 2002. 22. (II. 15-25. An experiment comparing the dry matteryield of intensively managed short rotation coppice (SRC) under factorial combinations of two plant varieties (S. vim%ialisiv. Jorunn and S. x dasycludos), five planting densities (10000-111000 plants ha-‘) and two harvesting frequencies is reported. Data are presented from the first biennial and triennial harvest cycles at two sites (East Anglia and Warwickshire, UK) planted in spring 1996 and flailed in autumn 1996. Higher annual yields were attainable by more intensive packing of plants combined with more frequency harvesting. With S. viminaiis cv. Jorunn, yield increased by 34% between the lowest and highest planting densities. Biennial harvesting increased yield compared with triennial harvests. S. viminali,s, on average, yielded 2.7 t ha-’ year-’ more than S. x dasyclados, with peak yields of II.4 t ha-’ year-‘. Significant differences in yield between sites were noted, with an average of 1 t ha-’ year-’ benefit on a mineral soil compared with a peaty loam. There were no statistically significant interactions in the data. Biennial plots reached peak heights of 254-297 cm (S. viminalis) and 239-273 cm (S. x dusycfudos) in 1998. Peak heights of triennial plots (achieved in 1999) were 40 l-5 15 cm ($. viminalis) and 3 16-420 cm (S. x dasyclados). There was a gradual increase in height through the 3 years and a non-
07 Alternative energy sources (geothermal energy) significant trend towards decreased height with increasing planting density at the ends of the growing seasons. Both varieties demonstrated phenotypic plasticity, with individual plant weight and stem number decreasing as a function of increasing density. A range of parameters including stem width reduction, stem mortality and plant mortality were seen to vary. The population of primary stems was found to increase up to the time of canopy closure, on a per plant basis and per unit ground area basis. After this time, competition for light resulted in self-thinning of stems through until final harvest for S. dasyclados but not S. viminalis. Stem numbers per plant, recorded after leaf fall, showed different responses between both harvesting frequency and variety. With S. viminalis, stem numbers remained constant after cut back for up to 2 year, but increased rapidly as a result of a harvest after 2 year. With S. x dasyclados, a similar regrowth of stems was observed after a 2-year harvest. Prior to the harvest, stem numbers per plant decreased steadily for 2 of the 3 year depending on harvest cycle. After 3 year stem populations with S. x dasyclados were also decreasing. The degree to which non-destructive measurements could be used to (a) determine annual increment and (b) be used to predict eventual yield was examined. Cylindrical volume was the only growth measurement that enabled a reasonable tit between crop morphology and final yield to be made. The relationship was found to be a good fit and the fit improved with a longer harvest interval. Regression equations were not significantly different between sample sites but were significantly different between both variety (P < 0.001) and harvest interval (P < 0.05). In summary, it was deduced that modern varieties of S. viminalis such as Jorunn, are more suited to higher planting density and intensive harvesting, due to more erect growth reducing intra-specific competition at high planting densities.
Yield improvements through modification of planting density and harvest frequency in short rotation coppice Saiix spp. - 2. Resource capture and use in two morphoiogicaiiy diverse varieties
MI02527
Bullard, M. C. et al. Biomass and Bioenergy, 2002, 22, (l), 27-39. In the second paper in this series factorial combinations of two short rotation coppice (SRC) willow varieties (S. viminalis cv. Jorunn and S. x dasyclados) and five planting densities (10000-111000 plants ha-‘) were compared at a site in Cambridgshire, UK. Frequent measurements of above-ground and below-ground biomass accumulation (AGBA and BGBA), canopy radiation interception (0, green leaf area index (GLAI), radiation use efficiency (RUE), and attenuation coefftcient (k) were made in 1997, 1998 and 1999 in order to explain density, variety and harvest interval related yield effects. At full canopy, the highest GLAIs attained, usually by the highest plant density, were in the range 5-6.5. GLAI declined rapidly once this peak had been attained. GLAI decreased following canopy closure (radiation interception > 90%), due to loss of leaves lower down the canopy profile. Despite a more rapid loss of leaf area by the highest planting density, GLAD values were consistently greater at the highest planting density (P z 0.05) and GLAD for S. dasyclados was significantly greater than S. viminalis in each year (P < 0.05). GLAD was related to final dry matter production. Higher planting densities also had earlier dates of canopy closure, which were correlated with increased final yield, k values were in the range -0.2 to -0.51, indicating differences in morphology between the varieties although no consistent trends could be determined. Patterns of AGBA mirrored canopy development. Peak AGBA in the first season was I9 and 14 t ha-’ for S. viminalis and S. x dasyclados, respectively. End of season yield was significantly lower (11.5 and 12.9 t ha-’ for S. viminalis and S. x dasyclados, respectively) due to leaf fall and carbohydrate movement. End of season yields followed a clear, significant trend of increased yield with increasing plant density in the case of S. viminalis. This trend was not apparent with S. x dasyclados after the first season. RUE values were significantly increased (P < 0.05) by planting density and variety, ranging from 1.55 to 2.55 g MJJ’ for 10000 and 111000 plant ha-‘, respectively, in S. viminalis, which had significantly higher RUE values than S. x dasyclados. Plant mortality, after three seasons, was approximately 15% at the highest density but less than 5% at the three lowest densities. The two varieties behaved similarly. Thus, very high plant populations were sustained at the high planting densities. An inverse relationship between individual plant weight and planting density was evident, but there was no linear relationship. Higher plant densities supported larger plants than would have been expected from a linear relationship. As a consequence, yields at high densities were higher than yields at low densities.
Geothermal
energy
02/02528 A 3-D water/rock chemical interaction model for prediction of HDR/HWR geothermal reservoir performance Jing, Z. e/ a/. Georhermics,
2002, 31, (1). l-28.
A three-dimensional (3-D) water/rock chemical interaction model has been developed to examine the effect of water/rock chemical interaction (WRCI) on the long-term performance of hot dry rock and hot wet rock (HDFUHWR) reservoirs. The model, which integrates many field observations and thus generates a fracture network very similar to the natural fracture distribution in the reservoir, can predict the influence of WRCI on the overall fractured reservoir. Factors affecting WRCI and the effect of WRCI on long-term performance of Hijiori deep reservoir (Japan) have been modelled. Simulated results show that fluid chemistry, initial rock temperature, magnitude of flow rate and well spacing have a major effect on WRCI, and for such a multi-well Hijiori geothermal system, WRCI seems to make the flow distribution tend towards uniformity. The model described deals solely with chemical interactions as a function of flow rate and temperature, and takes no account of aperture variation as a result of thermoelastic effects. It is only a partial model, though it could form an important module of a coupled model.
Appraisal of the Tokaanu-Waihi geothermal field an~,~;eiationshrp with the Tongarrro geothermal freid, New 02/02529
Risk, Cl. F. et al. Geofhermics, 2002, 31, (I), 45-68. Tokaanu-Waihi geothermal field is situated near the southern end of the Taupo Volcanic Zone, New Zealand. Neutral chloride thermal waters discharge at Tokaanu and Waihi in the north of the field on flat land between the andesite volcanoes Tihia and Kakaramea and the shore of Lake Taupo, while steam-heated thermal features occur at Hipaua on the northern flanks of Kakaramea. Electrical resistivity surveys have been made over the field using several different measurement techniques. In the north of the field where roads and tracks allow vehicle access, resistivity profiling using Schlumberger arrays with electrode spacings (AB/2) of 500 m and 1000 m show that Tokaanu, Waihi and Hipaua all lie within a continuous region of low apparent resistivity (S-20 Dm) and are thus part of the same geothermal system. Along the eastern edge of the system there is a sharp transition to apparent resistivities greater than 100 Qm in the cold surrounding region. Surveys on Lake Taupo using an equatorial bipole-bipole electrode array towed behind boats (spacing equivalent to AB/2 = 500 m) found that the low resistivity zone extends offshore by about 1 km. The steep, bush-clad, southern part of the field was surveyed with magnetotelluric (MT) resistivity measurements using both naturally occurring signals and the 50 Hz radiation from the power wires as sources. These measurements found low resistivities over the north-eastern slopes and around the summits of Tihia and Kakaramea, indicating thermal activity. However, the measurements were too widely spaced to allow the field boundary to be clearly delineated. Interpretation of the resistivity and other data suggests that the Tokaanu-Waihi thermal waters rise nearly vertically from a source deep beneath the elevated southwestern part of the field to the water table. These waters then flow north to discharge at the surface near Lake Taupo. Neighbouring geothermal systems, which occur at Tongariro about 18 km south of Tokaanu-Waihi, and at Motuoapa about 10 km to the northeast, are separated from the Tokaanu-Waihi field by high resistivity ground. This suggests that the thermal fluids discharging at the three fields do not have a common source, as has been suggested previously.
Experimental results of silica removal from simulated solutions of geothermal brine of Kiziidere field, Turkey 02/02530
Badruk, M. and Matsunaga, I. Geofhermics, 2001, 30, (S), 561-570. The Denizli-Kizildere geothermal power plant in western Anatolia, Turkey, has a capacity of 20 MW. The waste brine from the plant has a flow rate of 1500 ton/h and contains approximately 400 mg/dm3 of silica, which cause scaling. This paper describes experimental work carried out to investigate the optimum conditions of silica removal from Denizli-Kizildere geothermal wastewater by precipitation.
Flashing point compressibiii of geothermal fluids with low COz content and its use7 n estimating reservoir volume
02/02531
Satman, A. and Ugur, Z. Geothermics, 2002, 31, (I), 29-44. In this study, the bubble point pressure effect or, as it is more commonly known, the flashing point effect of CO2 on geothermal fluids is shown, and the compressibility of the geothermal fluids containing low concentrations of dissolved COz at the flashing point is formulated for isoenthalpic phase change. The compressibility, termed the isoenthalpic flashing point compressibility, can be calculated with well-known parameters. New, easy-to-use graphs are presented to estimate the compressibility for such systems. Correction for ionic strength of the geothermal brine is also considered. The practical use of the compressibility is illustrated to estimate the fluid content of a geothermal reservoir. A material balance method incorporating the isoenthalpic flashing point compressibility in geothermal modeling is investigated. The material balance method presented in the paper is of Fuel and Energy Abstracts
September 2002
335
07
ALTERNATIVE SOURCES Bioconversion
ENERGY
energy
that unmodified shives develop low mechanical strength, shorter fibres and large amount of fines. Chemical modification of shives with a prereacted mixture of polyol-anhydride reduces refining energy consump tion, improves strength performance but decreases scattering coefficient. From the results of investigation it is suggested that chemically modified refiner pulp from shives cannot be used for high-grade paper manufacture but it can be used as a low-cost filler for low-end applications in packaging or low-performance decorative papers.
Composting of fish offal and biosoiids in northwestern Patagonia
02/02504
Faz500
A mathematical model for fixed dome type biogas
Raheman, H. Energy, 2002, 27, (I), 25-34. This paper describes the development of a mathematical model for determining the dimensions of a fixed dome type Deenbandhu model biogas plant, the most popular model constructed in India. The developed model could estimate the different dimensions within an absolute variation of 6%. This will help the designers to determine the dimensions of various capacities of a Deenbandhu model biogas plant for different hydraulic retention times to suit the local climatic conditions. 02/02501
Birch wood particle shrinkage during rapid
pyrolysis Davidsson, K. 0. and Pettersson, _I. B. C. Fuel, 2002, 81, (3) 263-270. A study of the shrinkage of cubic (05 mm) birch wood particles during pyrolysis is presented, The particles were rapidly injected into a preheated furnace with a constant temperature in the rang 350-900°C. The size of the particles in longitudinal, tangential and radial directions was measured until no further mass loss occurs. The volume shrinkage was found to be 45-70% and the shrinkage in the different directions 5-25, 25-40 and 15-40% for longitudinal, tangential and radial directions, respectively. Longitudinal shrinkage commenced after about 60% mass loss and is not strongly dependent on heating rate or on cellulose chain scission. A maximum shrinkage was found for tangential and radial directions at 400 and 500-7OO”C, respectively, and above these temperatures the shrinkage decreases. The char yield decreases and the char structure becomes more deranged with increasing temperature. Empirical models of shrinkage as a function of conversion are presented.
02/02502 Characterization of degradation products from alkaline wet oxidation of wheat straw Klinke, H. E. ef nl. &resource Technology, 2002, 82, (1) 15-26. Alkaline wet oxidation pre-treatment (water, sodium carbonate, oxygen, high temperature and pressure) of wheat straw was performed as a 2&’ fractional factorial design with the process parameters: temperature, reaction time, sodium carbonate and oxygen. Alkaline wet oxidation was an efficient pre-treatment of wheat straw that resulted in solid fractions with high cellulose recovery (96%) and high enzymatic convertibility to glucose (67%). Carbonate and temperature were the most important factors for fractionation of wheat straw by wet oxidation. Optimal conditions were 10 min at 195°C with addition of 12 bar oxygen and 6.5gI--’ NarCO_+ At these conditions the hemicellulose fraction from 100 g straw consisted of soluble hemicellulose (16 g). low molecular weight carboxylic acids (11 g), monomeric phenols (0.48 g) and 2-furoic acid (0.01 g). Formic acid and acetic acid constituted the majority of degradation products (8.5 g). The main phenol monomers were 4_hydroxybenzaldehyde, vanillin, syringaldehyde, acetosyringone (4-hydroxy-3,5-dimethoxy-acetophenone), vanillic acid and syringic acid, occurring in 0.04-0.12 g per 100 g straw concentrations. High lignin removal from the solid fraction (62%) did not provide a corresponding increase in the phenol monomer content but was correlated to high carboxyiic acid concentrations. The degradation products in the hemicellulose fractions covaried with the pre-treatment conditions in the principal component analysis according to their chemical structure, e.g. diacids (oxalic and succinic acids), furan aldehydes, phenol aldehydes, phenol ketones and phenol acids. Aromatic aldehyde formation was correlated to severe conditions with high temperatures and low pH. Apart from CO2 and water, carboxylic acids were the main degradation products from hemiceiiulose and lignin.
Chemi-refiner mechanical pulping of flax shives: refining energy and fiber properties
02/02503
Sain, M. et al. Bioresource Technology, 2002, 81, (2), 193-200. Oil-seed flax shive has been promoted as a raw material for low-end paper making because of its overall cost benefit over hardwood and groundwood pulp and increasing demand for low-cost pulp in rigid packaging applications. We have made refiner mechanical pulp from oil-seed shives by using a 300 mm Sprout-Bauer pilot refiner. The factors controlled during refining were: consistency, multi-pass refining, temperature, spacing between the plates and polyol-anhydride reactant concentration. Based on the results in this study it is apparent
Laos, F. et al. Bioresource Technology, 2002, 81, (2), 179-186. Composting of fish processing wastes and biosolids with wood byproducts and yard trimmings was conducted during the summer of 1996 and winter of 1997 in NW Patagonia using: (i) static piles for fish offal and (ii) turning piles for biosolids. Fish offal was mixed with sawdust + wood shavings (FOC) at 3:l ratio by weight and biosolids with wood shavings (BCw) and yard trimmings (BCt) at 1:l ratio by volume. Samples were taken at six dates during the composting period and analysed to determine the factors that predict compost maturity. Composting of biosolids was affected by the type of bulking agent during winter. Thermophilic temperatures 255°C were sustained long enough to satisfy the USEPA requirements for processes to further reduce pathogens (PFRP) in FOC and BCt, and for processes to significantly reduce pathogens (PSRP) in summer BCw, while in winter BCw temperatures were lower than those recommended for effective pathogen reduction. However, coliform faecai content in ail BC treatments was less than 10 most probable number (MPN) g-’ dry sample at the end of the process. The ratio of water soluble carbon (WSC) to total nitrogen (TN) appeared to be a more adequate index to predict compost maturity than the ratio of total organic carbon to nitrogen.
Continuous co-digestion of cattle slurry with fruit and vegetable wastes and chicken manure 02/02505
Callaghan, F. J. er al. Biomass and Bioenergy, 2002, 27, 71-77. Anaerobic digestion is a well established process for treating many types of organic waste, both solid and liquid. As such, the digestion of cattle slurries and of a range of agricultural wastes has been evaluated and has been successful. Previous batch studies have shown that based on volatile solids (VS) reduction, total methane production and methane yield, co-digestions of cattle slurry (CS) with fruit and vegetable wastes (FVW) and with chicken manure (CM) were among the more promising combinations. A continuously stirred tank reactor (18 litres) was used as a mesophilic (35°C) anaerobic reactor to examine the effect of adding the FVW and CM to a system which was digesting CS. The retention time was kept at 21 days and the loading rate maintained in the range 3.19-5.01 kg VS mm3 d-l. Increasing the proportion of FVW from 20% to 50% improved the methane yield from 0.23 to 0.45 m3 CHd kg- ’ VS added, and caused the VS reduction to decrease slightly. Increasing the proportion of chicken manure in the feed caused a steady deterioration in both the criteria for judging digester performance. This appeared to be caused by ammonia inhibition.
Delivery systems of forest arisings for energy production in New Zealand
02/02506
Hall, P. ef al. Biomass and Bioenergy, 2001, 21, (6), 391-399. The large area of planted production forest in New Zealand and the expected increase in area to be harvested in the next 10 years, offer good potential for the woody biomass residue to contribute to New Zealand complying with the goals set by the Kyoto protocol. The main focus is on forest arisings, which are residues produced during the harvesting of logs. The objective of this paper is to identify promising delivery systems (including harvesting, storage, transportation and processing) of forest arisings to an energy plant and the associated costs. Costs largely depended on the delivery system chosen, the site characteristics and the transport distance. The cheapest system identified ranged from NZ%22 to 37 per tonne dry matter (NZ$1.22.0 per GJ) for residues accumulating at the landing and from NZS29 to 42 per tonne dry matter (NZ$l&2.2 per GJ) for residues collected from the cutover. The cheapest option tended to be the simplest system because each time the material was handled, extra costs were added. The simulation model developed to compare different delivery systems proved to be a useful tool. However, it was important that input parameters were estimated accurately, especially product characteristics (moisture content and material density) and machine data, because these were the most sensitive model parameters. The results indicate that the use of forest arisings for the generation of heat and/or electricity could be feasible in New Zealand.
Dynamics of nitrate leaching and 15N turnover in intensively fertilized and irrigated basket wiiiow grown in iysimeters
02102507
Aronsson,
P. G. Biomass and Bioenergy,
2001, 21, (3). 143-154.
Fuel end Energy Abstracts
September 2002
231
07 Alternative energy sources (bioconversion energy) A 13-month experiment was conducted to study the dynamics of nitrate leaching from basket willow (S&x viminalis), and the fate of fertilizerN applied after the growing season. Lysimeters with or without plants were supplied daily with water and liquid fertilizer. Nitrate leaching and transpiration were uantified, as well as leaf-, stem- and root growth and N-uptake. ’9N-labelled fertilizer was applied in autumn after leaf fall for the determination of the fate of fertilizer-N. The Nuptake by the willow plants was high during the summer and was correlated with transpiration. It decreased drastically in autumn in the absence of transpiration, but was still significant, which was also the case in early spring, the following year. A leaf rust infection during autumn led to a nine-times increase in nitrate leaching, whereas transpiration was reduced by 26%. After a fertilizer application for IO days after leaf fall in autumn, an average of 8% of the fertilizer-N was taken up by the plants, and 32% was unaccounted for, of which a large portion was likely to be lost through denitritication. Recalculated on a hectare basis, the whole-season nitrogen budget shows that 191 kg N/ ha was applied as liquid fertilizer during the first season, of which 98 kg N/ha was taken up by plants, 69 kg N/ha was leached, and 24 kg N/ha was unaccounted for (i.e. possibly denitrifled). The amount of nitrogen taken up by plants or- lost from the system (possibly through denitrification) corresponded to 36 kg N/tonnes of dry stem wood produced.
Effect of leachln on the ash behavior of olive residue during fluldired be8 gasification
OQ/O2SQQ
Arvelakis, S. er al. Biomass and Bioenergy, 2002, 22, (I), 55-69. Fluidized bed gasification is considered to be the most advanced method for thermochemical conversion of various biomass fuels, e.g. wood, energy crops, agroresidues, etc., to energy offering economical and environmental benefits. Ash-related problems including sintering, agglomeration, deposition, erosion and corrosion resulting due to the low melting point ash of agroresidues are the main obstacles for economical and viable application of this conversion method for energy exploitation of the specific residues. The effect of leaching (washing) the olive residue in order to improve its ash thermal behaviour under the gasification conditions was studied. Gasification tests were performed in a lab scale fluidized bed gasifier with both leached and non-leached samples and the results concerning the ash thermal behaviour of the used samples were associated with their ash elemental analysis, while the deposits produced during the gasification tests were analysed using SEM-EDX analysis technique. The produced results clearly show that leaching could help significantly in avoiding to a great extent, the operational problems associated with the problematic ash thermal behavior in the case of olive residue. In particular, all gasification tests performed using the non-leached olive residue material as feedstock resulted in a rapid agglomeration of the reactor’s bed material and consequently to the end of the gasification tests. One the contrary, gasification tests performed using the leached olive residue material ended without any agglomeration-deposition problems, while the operation time was in all cases longer compared with the tests with the non-leached olive material. 02/02509 Energy evaluation of forest residues originated from Eucalyptus globulus Labill in Galicia
Ntidez-Regueira, L. er al. Bioresource Technology, 2002, 82, (I), 5-13. The possibility of retrieving the energy contained in forest residues orieinatine from wood exoloitation in Galicia (Soain) is evaluated. This ---a--~a ~~ . study was made on Eucalyptus globulus Labjll occupying a forest surface of 240000 ha. This species plays an important role in the economical development of Galicia, as it is the main forest species for production of pulp. Sampling was made over 1999 in seven different zones, three main stations plus four selected for comparison, situated in Galicia. The residues originating from cutting were sorted into three different groups and their calorific values were measured by static bomb calorimetry. These caloritic values, close to 7200 kJ kg- , make possible the use of this residual biomass as an energy source. Calorific values were measured by static bomb calorimeter in an oxygen atmosphere. Flammability was determined using a standard epiradiator. Simultaneously, some other parameters, elementary chemical composition, heavy metal contents, moisture, density, ash percentage after combustion in the bomb, and main bioclimatic characteristics, were also determined.
02/02510 pyrolisis
Fertlliser influence on alkali release during straw
Davidsson,, K. 0. ef al. Fuel, 2002, 81, (3) 259-262. Comparattve studies of alkali release from wheat and oat straws cultivated in the laboratory with chloride-rich and sulphate-rich fertilizers are reported. The release of alkali during pyrolysis in the temperature range 25-1060°C is measured using the sensitive surface ionization technique. Straw cultivated with a chloride-rich fertilizer releases two to four times more alkali than straw fertilized with a sulphate-rich fertilizer, and the release takes place at lower temperatures. The temperatures for maximum alkali release are =~800”C for 332
Fuel and Energy Abstracts
September 2002
straw cultivated with a chloride-rich fertilizer, and =870°C for straw supplied with a sulphate-rich fertilizer. The samples were also subject to simple water leaching, and alkali was observed to be easily removed by leaching irrespective of fertilizer. Application of chloride-free fertilizer is concluded to be a simple and efficient way to reduce the alkali release from the fuels, and the method can easily be combined with other methods in order to improve fuel quality.
02/02511 Floristic structure and biomass distribution of a tropical seasonal rain forest in Xishuangbanna, southwest China
Shanmughavel, P. et al. Biomass and Bioenergy, 2001,21, (3), 165-175. The aim of this research was to study the forest community structure, tree species diversity and biomass production of a tropical seasonal rain forest in Xishuangbanna, southwest China. The community structure showed a diversified species composition and supported many species of economic significance. This tropical rain forest is closely related to Malaysian forests. The biomass and its distribution were studied using standard regression analysis and the clear-cut method for shrubs and herbs. The total biomass was 360.9 t/ha and its allocation in different layers was: tree layer 352.5 t/ha, shrub layer 4.7 t/ ha, liana 3.1 t/ha and herb layer 0.5 t/ha. Most of the biomass was concentrated in the trees: stem 241.2 t/ha, root 69.6 t/ha, branch 37.2 t/ ha and leaves 4.3 t/ha: The DBH class allocation of the tree biomass was concentrated in the middle DBH class. The biomass of six DBH classes from 20 to 80 cm was 255.4 t/ha. There are 26 species with biomass over 0.5% of the total biomass of the tree layer; and three species with biomass over 5%, i.e. Pometia lomenlosa, Barringronia macroslachva 15.4%) and Terminalia mvriocaroa (5.2%). Data on stem. branch, leaves and ‘root of the individual tree ‘species were used to develop regression models. D2H was found to be the best estimator of the biomass in this tropical rain forest. However, higher biomass figures have been reported from tropical forests elsewhere, e.g. 415-520 t/ha in the tropical forests of Cambodia, the tropical moist mixed dipterocarp forests, and the tropical moist logged moist evergreen-high, medium, and low yield forests of Sri Lanka. In some forests, lower accumulation of biomass was reported, e.g. LO-295 t/ha in the tropical moist forests of Bangladesh, the tropical moist dense forest of Cambodia, the tropical dry forests of India, the tropical moist forests of Penninsular-Malaysia, the tropical moist mixed dipterocarps forests of Sarawak-Malaysia, the tropical evergreen forests of Myanmar and the tropical moist ever-green logged forests of Sri Lanka.
02/02512 improved cookstoves in rural India: how improved are they? A critique of the perceived benefits from the National Programme on improved Chulhas (NPIC) Kishore, V. V. N. and Ramana, P. V. Energy, 2002, 27, (I), 47-63. The National Programme on Improved Cookstove (NPIC) was started by the Ministry of Non-conventional Energy Sources (MNES), Government of India, in 1985 to achieve the twin objectives of fuelwood conservation and smoke reduction in kitchens. NPIC has overseen the installation of 28 million improved cookstoves, saving nearly 20 million tons of firewood per year. These achievements, though seemingly impressive, are not realistic as they are based on certain assumptions, particularly regarding the life expectancy of stoves. This paper examines the various assumptions made in such calculations and tries to arrive at some realistic numbers regarding fuelwood savings, which can be used to evolve a policy for refining the NPIC further.
02/02513 Lactic acid oroduction from wheat straw hemicellulose hydrolyiate by Lactobaciflus pentosus and Lactobacillus brevis
Garde, A. ef al. Bioresource Technology, 2002, 81, (2), 217-223. Lactic acid production by Lactobaci&s brevis and Lb. pentosus on a hemicellulose hydrolysate (HH) of wet-oxidized wheat straw was evaluated. The potential of 1 l-12 g/l fermentable sugars was released from the HH through either enzymatic or acidic pretreatment. Fermentation of added xylose in untreated HH after wet-oxidation, showed no inhibition on the lactic acid production by either Lb. penrosus or Lb. brevis. Lb. penrosus produced lactate corresponding to 88% of the theoretical maximum yield regardless of the hydrolysis method. whereas Lb. brevis oroduced 51% and 61% of the theoretical maximum yield after enzymatic, or acid treatment of HH, respectively, Individually, neither of the two strains were able to fully utilize the relatively broad spectra of sugars released by the acid and enzyme treatments; however, lactic acid production increased to 95% of the theoretical maximum yield by co-inoculation of both strains. Xylulose was the main sugar released after enzymatic treatment of HH with Celluclast’. Lb. brevis was able to degrade xylobiose, but was unable to assimilate xylulose, whereas Lb. penrosus was able to assimilate xylulose but unable to degrade xylobiose.
07 A~emaf~e energy sources (bioconversbn energy) g$;;$-i:
Lanthanum(lll)-catalyzed degradation of cellulose
Seri, K. er al. Bioresource Technology, 2002, 81, (2), 257-260. Lanthanum(II1) chloride was found to effectively catalyse the degradation of cellulose in water at 250°C. The degradation conversion of celiulose in the presence of a catalytic amount of lanthanum chloride reached 80.3% after 180 s, which corresponded to the turnover number of 83, whereas the reaction did scarcely proceed in the absence of the catalyst. The degradation products were separately quantified as watersoluble (WS), methanol-soluble (MS), methanol-insoluble (MI), and gaseous (G) products. The HPLC and GC analyses revealed that the WS materials are mainly composed of 5-hydroxymethyl-2-furaldehyde (HMF), D-glucose, and levulinic acid, Cellobiose, the disaccharide component of cellulose, was scarcely detected during the reaction. 02102515 Life cycle assessment of biofibres replacing aiass flbres as reinforcement in elastics &&b&e-Nicollier, T. et al. Resow&, Conservation and Recycling, 2001, 33, (4), 267-287.
This article aims to determine the environmental performance of China reed fibre used as a substitute for glass fibre as reinforcement in ptastics and to identify key environmental parameters. A life cycle assessment (LCA) is performed on these two materials for an appIi~tion to plastic ~ans~rt pallets. Transport pallets reinforced with China reed fibre prove to be ecologically advantageous if they have a minimal lifetime of 3 years compared with the S-year lifetime of the conventional pallet. The energy consumption and other environmental impacts are strongly reduced by the use of raw renewable fibres, due to three important factors: (a) the substitution of glass fibre production by the natural fibre production; (b) the indirect reduction in the use of polypropylene linked tu the higher proportion of China reed fibre used and (c) the reduced pallet weight, which reduces fuel consumption during transport. Considering the whole life cycle, the polypropylene production process and the transport cause the strongest environmental impacts during the use phase of the life cycle, Since thermoplastic composites are hardly biodegradable, incineration has to be preferred to discharge on landfills at the end of its useful life cycle. The potential advantages of the renewable fibres will be effective only if a purer fibre extraction is obtained to ensure an optimal material stiffness, a topic for further research. China reed biofibres are finalIy compared with other usages of biomass, biomaterials, in generai, can enable a three to ten times more efficient valorization of biomass than mere heat production or biofuels for transport. 02!02516 Lipid production by Yarrowia lipolytica growing on industrial glycerol in a single-stage continuous culture Papanikolaou, S. and Aggelis, G. Bioresource Technology, 2002,82, (I), 43-49.
Yurrowia lipolyrica LGAM s(7)l presented remarkable growth on industrial glycerol used as soie carbon substrate. Nitrogen-limited flask cultures were accompanied by restricted synthesis of reserve lipid, whilst amounts of citric acid were produced extracellularly. On the contrary, high amounts of reserve lipid (up to 3.5 g/l, 43% w/w of lipids in dry biomass) were produced in highly aerated continuous cultures. Lipid production was favoured at low specific dilution rates whilst fatfree material yield increased over the whole range of D (h-l). The maximum volumetric productivity obtained was 0.12 g lipid/l h. Storage lipid composition did not present remarkable changes in the specific dilution rates tested. Ofeate and linoleate were the dominant cellular fatty acids. 02/02517 Nitrate leaching from lysimeter-grown shortrot&ion willow coppice in relation to N-application, irrigation and soil type Aronsson, P. G. and Bergstrom, L. F. Biomass and Bfoenergy, 2001,21, (3), 153-164.
The use of willow vegetation filters for wastewater treatment is gaining interest in Sweden. A study was conducted in order to determine reasonable rates of wastewater application to such vegetation filters. NOs-N leaching loads and N-uptake by the plants were quantified in relation to nitrogen application rate, irrigation rate, shoot growth, and soil type during 3 years after planting of willow (.Wix viminafis) in I6 1200-Iitre lysimeters filled with clay or sand soil. Nitrogen was applied at rates corresponding to 1IO-244 kgN/ha year combined with irrigation of 3-6 mm/day during 100-110 days each growing season. NOs-N leaching loads were very high the first year after plant establishment (on average 341 kg N/ha from clay and 140 kg N/ha from sand lysimeters). However, NOs-N leaching loads decreased and were low or negligible during the second (43 from clay and 17 kg N/ha from sand lysimeters) and third year (3 kg N/ha from clay and less than 1 kg N/ha from sand lysimeters). Harvest of the plants after the second growing season did not seemingly affect NO,-N leaching loads during the third year. Soil type and N application rate strongly influenced NOs-N leaching loads, whereas irrigation rate had only a slight effect, and thus, dosing of wastewater should be based on N-amounts.
Assuming an annual shoot growth of 10 tonnes (dry weight),/ha in a willow vegetation filter, wastewater could be applied at rates corresponding to 160-190 kg N/ha without substantial NOx-N leaching losses. 02102516 Pigs as recyclers for nutrients contained in Bermuda grass harvested from spray fields ;y%grpen, T. A. T. G. er al. Bioresource Technology, 2002, 81, (2), The ability of pigs to use nitrogen and energy in Bermuda grass was evaluated in order to assess whether Bermuda grass harvested from spray fields could be fed to pigs as a means to recycle nitrogen. Digestibility of Bermuda grass incorporated into corn-soybean meal diets was evaluated in heavy ~nishing pigs and gestating sows. Results suggest that Bermuda grass digestibility is negative in animals not adapted to a high-fibre diet. Enzymes improve this digestibility, but even with enzymes, nitrogen digestibility was poor. Pigs fed a diet containing 10% Bermuda grass required a one week adaptation period for maximal digestion; following adaptation, pigs can digest approximately 40% of the energy in Bermuda grass but none of the nitrogen. Feeding Bermuda grass to pigs as a means of recycling nitrogen is thus not recommended. 02102519 Production of carboxyltc acids from hydrolyzed COM meal by immobilized cell fermentation in a fibrous-bed bioreactor Huang, Y. L. et al. Bioresource Technology, 2002, 82, (I), 51-59. Corn meal hydrolysed with amylases was used as the carbon source for producing acetic, propionic, and butyric acids via an-aerobic fermentations. In this study, corn mea!, containing 75% (w/w) starch, 20% (w/w) fibres, and 1.5% (w/w) protem, was first hydroiysed using amylases at 60°C. The hydrolysis yiefded approximately 100% recovery of starch converted to glucose and 17.9% recovery of protein. The resulting corn meal hydrolyzate was then used, after sterilization, for fermentation studies. A co-culture of Lactacoccus lactis and Cfos/ridium ,formicoaceticum was used to produce acetic acid from glucose, Propionibacterium acidipropionici was used for propionic acid fermentation, and Cfosrridium tyrohutyficum was used for butyric acid production. These cells were immobilized on a spirally wound fibrous matrix packed in a fibrous-bed bioreactor (FBB) developed for multi-phase biological reactions or fermentation. The bioreactor was connected to a stirredtank fermentor that provided pH and temperature controls via medium circulation. The fermentation system was operated at the recycle batch mode. Temperature and pH were controlled at 37°C and 7.6, respectively, for acetic acid fermentation, 32°C and 6.0, respectively, for propionic acid fermentation, and 37°C and 6.0, respectively, for butyric acid production. The fermentation demonstrated a yield of approximately 100% and a volumetric productivity of approximately 1 g/(1 h) for acetic acid production. The propionic acid fermentation achieved an approximately 60% yield and a productivity of 2.12 g/(1 h), whereas the butyric acid fermentation obtained an approximately 50% yield and a productivity of 6.78 g/(1 hf. These results were comparable to, or better than those fermentations using chemically defined media containing glucose as the substrate, suggesting that these carboxylic acids can be efficiently produced from direct fermentation of corn meal hydrolyzate. The corn fibre present as suspended solids in the corn meal hydrolyzate did not cause operating problem to the immobilized cell bioreactor as is usually encountered by conventional immobilized ceil bioreactor systems. It is concluded that the FBB technology is suitabte for producing value-added biochemicats directly from agricultural residues or commodities such as corn meal. 02/02520 Solid state fermentation of broiler litter for production of biocontrol agents Adams, T. T. ef al. Bioresource Technology, 2002, 82, (l), 33-41. Several varieties of heat-sterilized broiler litter with 60% (wet basis, wb) moisture content were substrate in solid-state fermentations to produce biocontrol agents. Litter varieties included litter produced by one flock of broilers from medicated and non-medicated controlled rations, and litter produced by two flocks and four flocks on a single apphcatton of bedding material from medicated commercial sources. Litter preparations were inoculated with monocultures of Brrcilfxs thuringiensis serovar japonensis strain Buibui, a pathogen of Japanese beetle larvae (Popillia japonfca), or Pseudomonas ffuorescens 2-79. B. thuringiensis did not grow in unextracted one-flock litter nor in water extracted litter, but grew in methanol extracted litter to 5 x 10” cell forming units (CFU)/g litter (dry weight, dw) and a spore count of 1 x 10” CFU/g litter (dw). ii. thuringiensis also grew in unprocessed twoflock and four-flock litter, achieving cell counts of 3 x lo9 and 1 x 10” CFU/g litter (dw), respectively, and spore counts of 1 x lo9 CFUjg litter (dw). P. fluorescens grew in medicated one-flock litter with no extraction to a cell density greater than 4 x IO” CFU/g litter (dw). Bioassays in soil containing over 0.5% (db) litter fermented with B, thurtngiensb resulted in over 90% mortality in 21 days for first instars of Japanese beetie when compared to a control treatment using Fuel and Energy Abstracts
September 2002
333
07 Alternative energy sources (bioconversion energy) comoost without fermented litter. The investieations demonstrate that bacterial biocontrol agents produced via sob&substrate fermentations using broiler poultry litter have potential in biocontrol applications in the soil environment. 02iO2521 Studies on biomass for production of blobriquette in Chongqing, China Gao. S. et al. Taiki Kankvo Gakkai.shi. 2001. 36. (2). 78-87. Bio-briquette is a sort of’composite fuel consisting’bf 70-85% of coal and 15-30% of biomass by weight, produced by high-pressure - _ briquetting method with compression only in the roll-press technique without any binder. The biomasses working as a binder are various woody wastes and agriculture wastes such as rice straw, rice bran, sorghum stalk, wheat straw and so on. Total yearly output of woody wastes and agriculture wastes in Chongqing of China amounted to approximately 18.0 million tons based on our investigating data. Using 5% of them, yearly output of bio-briquette will be approximately 3.60 million tons and enough as the domestic fuels. So, there were enough biomass materials to produce bio-briquette in Chongqing. Ten types of biomasses including four types of agriculture wastes, one type of woody waste and wild grass, and four types of food manufacturing. Wastes collected in Chongqing were investigated for their combustion characteristics, emissions, binder action and breaking strength of biobriauette Dreoared from each of them. The exoerimental results indi‘cated thatihkre were little emissions of air polluiants from biomass combustion and emission amounts for HCI and SO1 were 35-912 and 52-1764 mg per 1 kg of biomass, respectively. Compared with raw coal, the biomass can reduce the ignition temperature and increase the combustibility of the bio-briquette. The breaking strength of the biobriquette increased with increase of additional amount and lignin contents of biomasses, which were in range of 12.1-33.3%. It is estimated based on our experimental results that the reduction efficiency of HCI, SOz and dust for the bio-briquette ranged 26-61%, 82-87%-and 55-83%: respectively. As a useful countermeasure for control of air pollutants discharged from civilian and small factory coal combustions, the bio-briquette with satisfactory strength could be produced by adding 25% biomasses without any special binder. 02102522 Suitability of steam exploded residual softwood for the production of binderless anels. Effect of the pretreatment severity and lignin adBition Angles, M. N. ef al. Biomass and Bioenergy: 2001, 21, (3), 21 l-224. A steam explosion pre-treatment was apphed at various severities to softwood residual substrate to determine the most suitable pretreatment for the manufacture of binderless panels. The effect of adding acid to the pre-treatment of fibres was also evaluated. The changes in the chemical composition and morphology of the original material were investieated bv fractionation analvses and scanninn electron micrographs.” High severities caused defibrillation of the material allowing to build links to form the panels. Pre-hydrolysis with acid had a great-effect on the structure of the material even at-low acid concentration. The physical and mechanical properties of the panel improved as the severity of the pre-treatment increased up to a point where mechanical properties deteriorated. The composites with highest internal bond had a high cellulose content and a medium lignin content. All these factors suggested that steamed pre-treated residual could be improved by adding a natural binder to produce the panels. A test of producing panels with addition of several kinds of lignin (up to 20%) was performed. With no significant changes in density, water stability (thickness swelling and water absorption) internal bond and mechanical properties wee greatly improved. Results after accelerated ageing test were also enhanced. 02/02523 The effect of kaolin particles on the behavior of nitrifylng activated sludge units Campos, J. L. e/ al. Bioresource Technology, 2002, 81, (2), 225-231. The effects of the addition of powered particles of kaolin to nitrifying activated sludge systems were studied. Kaolin was added to a nitrifying activated sludge reactor, during the operational phase, to observe the effects of this clay on reactor performance. The results were compared to those obtained from a similar unit operated without kaolin. The settling properties of the sludges from both units were similar (sludge volume index (SVI) of 14.5 ml/g VSS; zone settling velocity (ZSV) of 7.5 m/h), but the specific nitrifiing activities of ammonia and nitrite oxidizing processes were enhanced up to 75% and 50%, respectively, when kaolin was added. The mechanism of action of kaolin was not clear. Additional ammonia. nitrite and nitrate adsorotion tests showed that these compounds were not adsorbed by kaolin. ‘?his demonstrated that no beneficial effect was caused by adsorption of either substrates or products. Short-term activity tests also showed that the stimulating effects of kaolin on specific activity were not immediate. The effects of kaolin when nitrifying units were operated under unfavourable conditions were also evaluated: In a second set of experiments, a nitrifying unit was operated with low levels of dissolved oxygen (DO), with and without kaolin. The presence of kaolin exerted practically no 334
Fuel and Energy Abstracts
September 2002
effect on ammonia oxidation but nitrite oxidation slightly diminished. In a third set of experiments, a nitrifying unit was subjected to pH shocks (9,10 and 11) over 3 h with pH then restored to 7.8. A pH shock of 11 caused a decrease of 60% in nitrifying activity for 12 days. When kaolin was added to this unit the efficiency of the system was completely restored in 4 days. Therefore, kaolin might be useful to restore damaged units. 02/02524 The effects of fuel washing techniques on alkali release from blomass Davidsson, K. 0. ef al. Fuel, 2002, 81, (2) 137-142. The influence of different washing techniques on the alkali release during pyrolysis of biomass is studied. After washing and drying, samples of wheat straw, wood waste and cellulose are subjected to a constant heating rate in a Ns atmosphere, and the release rate of alkali compounds from the sample is measured continuously by a surface ionization technique. Alkali is released form the untreated biomass in two temperature Intervals: (1) in connection with the pyrolysis process taking place at 200-5oo”C, and (2) from the material remaining after pyrolysis at temperatures above 600°C. Separate vacuum pyrolysis experiments show that the alkali release is dominated by potassiumcontaining compounds, with minor contributions form sodium-containing compounds. The effect of water washing of the biomass is compared with a more thorough acid leaching technique. In the temperature range 20&5OO‘C, washing with water reduces the alkali emission form wood waste and wheat straw by 5-30%, while acid leaching is more effective and reduces the emission by around 70%. Above 600°C where the vaporization of alkali compounds from untreated wheat straws increases sharply, the washing procedures are sufficient for a reduction in the measured alkali release bv more than 90%. Experiments with pure cellulose (ash content O.Of%) indicate that the washing methods are ineffective in removing alkali bound to the organic structure of the biomass. The results support the conclusion from earlier studies that relatively simple washing techniques can improve the combustion properties of biomass fuels with a high ash content. For fuels with a lower ash content like woody biomass, the concentration of alkali bound to the organic structure limits the effect of the washing techniques. 02/02525 Winterisation of waste cooking oil methyl ester to improve cold temperature fuel properties Gonzdlez Gbmex, M. E. ef al. Fuel, 2002, 81, (I), 33-39. Waste cooking oil methyl ester (WCOME) was winterized at 1, 0, -1 and -2°C following a 4 x 2 factorial design with one replication per cell. The process was carried out by filtration and both the filtrate (solid phase) and the liquid phase were analysed by gas chromatography (GC), differential scanning calorimetry (DSC), and thermoeravimetric analvsis ITGA). Cold filter ulurutinn ooint (CFPP) and calorific values herd measured. Tempe;atiFes”oi 0 and -1’C in conjunction with the quickest cooling rate (O.l”C min-‘) and 15-24 h of cooling gave the most successful results in terms of fuel properties. Improvements in the low temperature properties of the winterized fuel were reflected by a reduction of saturated fatty acid methyl esters (SFAME) in the composition by 1.5-6%, by a decrease in the CFPP values by 2-4C and by a shift of the DSC high temperature melting peak (approx. 5°C) towards lower temperatures in corn arisen to the original fuel. Calorific values of the winterized WC8 ME did not significantly change and boiling temperatures increased (approx. 26%) in comparison to the non-winterized WCOME. 02102526 Yield improvements through modification of piantlng density and harvest frequency ln short rotation coppice Sallx spp. - 1. Yield response in two morphologically dlverse varleties Bullard. M. J. et al. Biomass and Bioenerpv. 2002. 22. (II. 15-25. An experiment comparing the dry matteryield of intensively managed short rotation coppice (SRC) under factorial combinations of two plant varieties (S. vim%ialisiv. Jorunn and S. x dasycludos), five planting densities (10000-111000 plants ha-‘) and two harvesting frequencies is reported. Data are presented from the first biennial and triennial harvest cycles at two sites (East Anglia and Warwickshire, UK) planted in spring 1996 and flailed in autumn 1996. Higher annual yields were attainable by more intensive packing of plants combined with more frequency harvesting. With S. viminaiis cv. Jorunn, yield increased by 34% between the lowest and highest planting densities. Biennial harvesting increased yield compared with triennial harvests. S. viminali,s, on average, yielded 2.7 t ha-’ year-’ more than S. x dasyclados, with peak yields of II.4 t ha-’ year-‘. Significant differences in yield between sites were noted, with an average of 1 t ha-’ year-’ benefit on a mineral soil compared with a peaty loam. There were no statistically significant interactions in the data. Biennial plots reached peak heights of 254-297 cm (S. viminalis) and 239-273 cm (S. x dusycfudos) in 1998. Peak heights of triennial plots (achieved in 1999) were 40 l-5 15 cm ($. viminalis) and 3 16-420 cm (S. x dasyclados). There was a gradual increase in height through the 3 years and a non-
07 Alternative energy sources (geothermal energy) significant trend towards decreased height with increasing planting density at the ends of the growing seasons. Both varieties demonstrated phenotypic plasticity, with individual plant weight and stem number decreasing as a function of increasing density. A range of parameters including stem width reduction, stem mortality and plant mortality were seen to vary. The population of primary stems was found to increase up to the time of canopy closure, on a per plant basis and per unit ground area basis. After this time, competition for light resulted in self-thinning of stems through until final harvest for S. dasyclados but not S. viminalis. Stem numbers per plant, recorded after leaf fall, showed different responses between both harvesting frequency and variety. With S. viminalis, stem numbers remained constant after cut back for up to 2 year, but increased rapidly as a result of a harvest after 2 year. With S. x dasyclados, a similar regrowth of stems was observed after a 2-year harvest. Prior to the harvest, stem numbers per plant decreased steadily for 2 of the 3 year depending on harvest cycle. After 3 year stem populations with S. x dasyclados were also decreasing. The degree to which non-destructive measurements could be used to (a) determine annual increment and (b) be used to predict eventual yield was examined. Cylindrical volume was the only growth measurement that enabled a reasonable tit between crop morphology and final yield to be made. The relationship was found to be a good fit and the fit improved with a longer harvest interval. Regression equations were not significantly different between sample sites but were significantly different between both variety (P < 0.001) and harvest interval (P < 0.05). In summary, it was deduced that modern varieties of S. viminalis such as Jorunn, are more suited to higher planting density and intensive harvesting, due to more erect growth reducing intra-specific competition at high planting densities.
Yield improvements through modification of planting density and harvest frequency in short rotation coppice Saiix spp. - 2. Resource capture and use in two morphoiogicaiiy diverse varieties
MI02527
Bullard, M. C. et al. Biomass and Bioenergy, 2002, 22, (l), 27-39. In the second paper in this series factorial combinations of two short rotation coppice (SRC) willow varieties (S. viminalis cv. Jorunn and S. x dasyclados) and five planting densities (10000-111000 plants ha-‘) were compared at a site in Cambridgshire, UK. Frequent measurements of above-ground and below-ground biomass accumulation (AGBA and BGBA), canopy radiation interception (0, green leaf area index (GLAI), radiation use efficiency (RUE), and attenuation coefftcient (k) were made in 1997, 1998 and 1999 in order to explain density, variety and harvest interval related yield effects. At full canopy, the highest GLAIs attained, usually by the highest plant density, were in the range 5-6.5. GLAI declined rapidly once this peak had been attained. GLAI decreased following canopy closure (radiation interception > 90%), due to loss of leaves lower down the canopy profile. Despite a more rapid loss of leaf area by the highest planting density, GLAD values were consistently greater at the highest planting density (P z 0.05) and GLAD for S. dasyclados was significantly greater than S. viminalis in each year (P < 0.05). GLAD was related to final dry matter production. Higher planting densities also had earlier dates of canopy closure, which were correlated with increased final yield, k values were in the range -0.2 to -0.51, indicating differences in morphology between the varieties although no consistent trends could be determined. Patterns of AGBA mirrored canopy development. Peak AGBA in the first season was I9 and 14 t ha-’ for S. viminalis and S. x dasyclados, respectively. End of season yield was significantly lower (11.5 and 12.9 t ha-’ for S. viminalis and S. x dasyclados, respectively) due to leaf fall and carbohydrate movement. End of season yields followed a clear, significant trend of increased yield with increasing plant density in the case of S. viminalis. This trend was not apparent with S. x dasyclados after the first season. RUE values were significantly increased (P < 0.05) by planting density and variety, ranging from 1.55 to 2.55 g MJJ’ for 10000 and 111000 plant ha-‘, respectively, in S. viminalis, which had significantly higher RUE values than S. x dasyclados. Plant mortality, after three seasons, was approximately 15% at the highest density but less than 5% at the three lowest densities. The two varieties behaved similarly. Thus, very high plant populations were sustained at the high planting densities. An inverse relationship between individual plant weight and planting density was evident, but there was no linear relationship. Higher plant densities supported larger plants than would have been expected from a linear relationship. As a consequence, yields at high densities were higher than yields at low densities.
Geothermal
energy
02/02528 A 3-D water/rock chemical interaction model for prediction of HDR/HWR geothermal reservoir performance Jing, Z. e/ a/. Georhermics,
2002, 31, (1). l-28.
A three-dimensional (3-D) water/rock chemical interaction model has been developed to examine the effect of water/rock chemical interaction (WRCI) on the long-term performance of hot dry rock and hot wet rock (HDFUHWR) reservoirs. The model, which integrates many field observations and thus generates a fracture network very similar to the natural fracture distribution in the reservoir, can predict the influence of WRCI on the overall fractured reservoir. Factors affecting WRCI and the effect of WRCI on long-term performance of Hijiori deep reservoir (Japan) have been modelled. Simulated results show that fluid chemistry, initial rock temperature, magnitude of flow rate and well spacing have a major effect on WRCI, and for such a multi-well Hijiori geothermal system, WRCI seems to make the flow distribution tend towards uniformity. The model described deals solely with chemical interactions as a function of flow rate and temperature, and takes no account of aperture variation as a result of thermoelastic effects. It is only a partial model, though it could form an important module of a coupled model.
Appraisal of the Tokaanu-Waihi geothermal field an~,~;eiationshrp with the Tongarrro geothermal freid, New 02/02529
Risk, Cl. F. et al. Geofhermics, 2002, 31, (I), 45-68. Tokaanu-Waihi geothermal field is situated near the southern end of the Taupo Volcanic Zone, New Zealand. Neutral chloride thermal waters discharge at Tokaanu and Waihi in the north of the field on flat land between the andesite volcanoes Tihia and Kakaramea and the shore of Lake Taupo, while steam-heated thermal features occur at Hipaua on the northern flanks of Kakaramea. Electrical resistivity surveys have been made over the field using several different measurement techniques. In the north of the field where roads and tracks allow vehicle access, resistivity profiling using Schlumberger arrays with electrode spacings (AB/2) of 500 m and 1000 m show that Tokaanu, Waihi and Hipaua all lie within a continuous region of low apparent resistivity (S-20 Dm) and are thus part of the same geothermal system. Along the eastern edge of the system there is a sharp transition to apparent resistivities greater than 100 Qm in the cold surrounding region. Surveys on Lake Taupo using an equatorial bipole-bipole electrode array towed behind boats (spacing equivalent to AB/2 = 500 m) found that the low resistivity zone extends offshore by about 1 km. The steep, bush-clad, southern part of the field was surveyed with magnetotelluric (MT) resistivity measurements using both naturally occurring signals and the 50 Hz radiation from the power wires as sources. These measurements found low resistivities over the north-eastern slopes and around the summits of Tihia and Kakaramea, indicating thermal activity. However, the measurements were too widely spaced to allow the field boundary to be clearly delineated. Interpretation of the resistivity and other data suggests that the Tokaanu-Waihi thermal waters rise nearly vertically from a source deep beneath the elevated southwestern part of the field to the water table. These waters then flow north to discharge at the surface near Lake Taupo. Neighbouring geothermal systems, which occur at Tongariro about 18 km south of Tokaanu-Waihi, and at Motuoapa about 10 km to the northeast, are separated from the Tokaanu-Waihi field by high resistivity ground. This suggests that the thermal fluids discharging at the three fields do not have a common source, as has been suggested previously.
Experimental results of silica removal from simulated solutions of geothermal brine of Kiziidere field, Turkey 02/02530
Badruk, M. and Matsunaga, I. Geofhermics, 2001, 30, (S), 561-570. The Denizli-Kizildere geothermal power plant in western Anatolia, Turkey, has a capacity of 20 MW. The waste brine from the plant has a flow rate of 1500 ton/h and contains approximately 400 mg/dm3 of silica, which cause scaling. This paper describes experimental work carried out to investigate the optimum conditions of silica removal from Denizli-Kizildere geothermal wastewater by precipitation.
Flashing point compressibiii of geothermal fluids with low COz content and its use7 n estimating reservoir volume
02/02531
Satman, A. and Ugur, Z. Geothermics, 2002, 31, (I), 29-44. In this study, the bubble point pressure effect or, as it is more commonly known, the flashing point effect of CO2 on geothermal fluids is shown, and the compressibility of the geothermal fluids containing low concentrations of dissolved COz at the flashing point is formulated for isoenthalpic phase change. The compressibility, termed the isoenthalpic flashing point compressibility, can be calculated with well-known parameters. New, easy-to-use graphs are presented to estimate the compressibility for such systems. Correction for ionic strength of the geothermal brine is also considered. The practical use of the compressibility is illustrated to estimate the fluid content of a geothermal reservoir. A material balance method incorporating the isoenthalpic flashing point compressibility in geothermal modeling is investigated. The material balance method presented in the paper is of Fuel and Energy Abstracts
September 2002
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