Biomass最新文献

Anaerobic treatment of cheese whey using a 17·5 litre upflow anaerobic sludge blanket reactor was investigated in the laboratory over a range of influent concentration from 4·5 to 38·1 g COD litre⁻¹ at a constant hydraulic retention time of 5 days. The results indicated that two sludge distribution regions, a sludge bed and a sludge blanket, as well as two distinct reaction phases, acidogenic and methanogenic, were formed. However, as the substrate loading was increased, the acidogenic region extended into the methanogenic region in the upper portion of the reactor until the whole region was acidogenic, leading to the failure of the reactor.

The anaerobic treatment of baker's yeast wastewater was studied using an anaerobic biological contact reactor (AnRBC) and a fixed-film reactor. The AnRBC had an active biomass developed within the reactor before this study commenced; however, the fixed-film reactor was started without attached biomass in a support structure. The gas production rates obtained for the AnRBC were between 0·55 and 0·61 litre methane per litre reactor per day. However, a gas production rate of only 0·46 litre methane per litre reactor per day was achieved after a four-month operating period for the fixed-film reactor. Higher chemical oxygen demand reduction was also found in the AnRBC. The results indicated that the presence of high sulfate concentration in baker's yeast wastewater affected teh start-up process. The reactor with fully developed active biomass was less susceptible to sulfate inhibition and showed improved anaerobic digestion. Results indicate that the reactor should be innoculated by feeding nutrient-balanced substrate before it was subjected to the digestion of baker's yeast wastewater. The fixed-film reactor was also fed with the substrate contianing sodium molybdate, an inhibitor of sulfate-reducing bacteria. The results indicated that both methanogenic and sulfate-reducing bacteria were inhibited.

This paper discusses the results of a technoeconomic assessment of direct biomass liquefaction processes converting wood to gasoline and diesel fuels. The study was carried out by the Working Group of the International Energy Agency Direct Biomass Liquefaction Activity, in which Canada, Finland, Sweden, and the US participated. The processes chosen for detailed analysis were Atmospheric Flash Pyrolysis (AFP) and Liquefaction In Pressurized Solvent (LIPS). The assessment covered three steps for each process from feed to final product:

• 1.

  1. primary liquefaction to a crude oil product,

• 2.

  2. catalytic hydrotreating to upgrade the crude product to a deoxygenated product oil,

• 3.

  3. refining the deoxygenated product to gasoline and diesel fuel.

Present technology cases and potential future technology cases were evaluated. A consistent analytical basis was used throughout to allow comparison of the processes. This assessment shows that AFP is more economical than LIPS both for the production of boiler fuel oil as the primary liquefaction product and for the production of gasoline and diesel fuel products. The potential for future cost reduction through research and development is also clearly demonstrated.

The analysis of water-soluble cellodextrins using liquid chromatography is readily achieved with a variety of packings. Direct injection of enzyme incubation mixtures allows quantitation of 10 mM cellodextrins in hydrolysis mixtures, resulting in a method which is useful for kinetic studies. Reported here are operating procedures for a 4% cross-linked, styrene-divinyl benzene cation exchanger (Aminex 50W-X4 (Bio Rad Lab., Griffin, CA, USA), 20–30 μm particle size) in the Ca⁺⁺ form, packed in a column of dimensions 6 mm i.d. × 60 cm long. Using this column, resolution of the cellodextrins, celloheptaose through cellobiose and glucose was possible with 91 mM H₂SO₄ as the eluent. Requirements of the separation system included use of a pulsation free syringe pump to minimize baseline fluctuations, the use of Ca⁺⁺ as the counterion to give a column operational life of 500–1000 injections, and injection of sample volumes of up to 25 μL. cellodextrins were quantified at sub-microgram (nmole) levels using a differential refractometer as the detector. Examples of this technique for analysis of the acid hydrolysis of cellodextrins and enzymatic hydrolysis of cellodextrins and carboxymethylcellulose are described.

The International Energy Agency (IEA) has recognized the importance of the proper use of current technologies in researching the concept of biomass as a renewable energy source. An early program included one project that dealt entirely with the mechanization of harvesting trees grown under short-rotation intensive culture (SRIC) forestry. The Bioenergy Agreement that ended 31 December 1988 expanded this involvement with mechanization by creating a separate Activity called ‘Production Technology’. This Activity investigated the current state of technology for establishing, managing and harvesting SRIC forests or plantations. Five countries participated: Canada, Denmark, Sweden, the UK, and the US. Several workshops were held, and a final joint project evolved. As the final effort, a ‘Sourcebook’ of Production Technology will be made available. A summary of the main findings is provided here. This document will be published by the IEA and updated in future years as needed.

The endeavors of the 1986–88 International Energy Agency activity on ‘Voluntary Standards’ are discussed and summarized. The goal of the work is to facilitate the intercomparison of research and technology results from different laboratories and countries. Three major activities are underway: (1) the carrying out of selected interlaboratory comparisons in biochemical and thermochemical conversion and in feedstock analysis; (2) the establishment of standard reference materials from both woody and herbaceous species; and (3) the assembly of a ‘Sourcebook of Methods of Analysis for Biomass for Fuels and Chemicals’. Progress on these three elements is summarized and contacts given for those wishing to participate in this activity.

The effect of some lignin degradation products, which can be present in wood hydrolysates, on biomass production by Candida sp. was studied. Suspected inhibitors were used as supplements in growth media for C. utilis and C. albicans containing pure glucose as a carbon energy source. The metabolism of inhibitors by C. utilis and C. albicans is approximately the same and is extremely sensitive to the structure and concentration of the phenolic additive. ID₅₀ and ID₁₀₀ values for a 50% or a 100% growth inhibition for 20 lignin monomer model compounds during Candida sp. cultivation were established. Comparison of ID values has shown that the least toxic compounds for C. utilis and C. albicans biomass growth and yield are vanillyl alcohol, conipheryl alcohol and syringic acid. The most toxic compounds are salicylic acid, cinnamic acid, benzoic acid and o-vanillin.

Seven countries participated in the 3-year programme (1986–1988) of the Willow Breeding Activity, Task 2 of the International Energy Agency's Bioenergy Agreement. The objectives of the activity were to facilitate the development of superior, high yielding willow clones for energy plantations by (a) exchange of genetic stock, (b) exchange of information on breeding studies, and (c) joint actions. The results of this cooperative activity are discussed accordingly. Significant achievements are in (a) enrichment of the genetic stock, especially of North American willow species; (b) evaluation and stimulation of genetic studies and breeding programmes; and (c) joint actions on disease surveys, clonal identification problems, joint testing methods and willow feedstock qualities for energy conversion. The development of high yielding stock (30 odt/ha per year or more) seems to be within reach.

A relatively large number of storing and drying studies of wood fuels have been carried out within the countries participating in the International Energy Agency (IEA) Bioenergy Programme. The main purpose of the studies has been to contribute to the knowledge of the processes taking place during storing and drying, and to formulated guidelines for practical storage of wood fuels. This report gives an overview of research carried out over the last few years within the countries participating in the IEA Bioenergy cooperation.