Sigurd Schober

Mathematical modeling of poly((R)-3-hydroxyalkanoate) synthesis by Cupriavidus necator DSM 545 on substrates stemming from biodiesel production

Two low structured mathematical models for fed-batch production of polyhydroxybutyrate and poly[hydroxybutyrate-co-hydroxyvalerate] by Cupriavidus necator DSM 545 on renewable substrates (glycerol and fatty acid methyl esters-FAME) combined with glucose and valeric acid, were established. The models were used for development/optimization of feeding strategies of carbon and nitrogen sources concerning PHA content and polymer/copolymer composition. Glycerol/glucose fermentation featured a max. specific growth rate of 0.171 h(-1), a max. specific production rate of 0.038 h(-1) and a PHB content of 64.5%, whereas the FAME/valeric acid fermentation resulted in a max. specific growth rate of 0.046 h(-1), a max. specific production rate of 0.07 h(-1) and 63.6% PHBV content with 4.3% of 3-hydroxyvalerate (3HV) in PHBV. A strong inhibition of glycerol consumption by glucose was confirmed (inhibition constant ki,G=4.28×10(-4) g L(-1)). Applied concentration of FAME (10-12 g L(-1)) positively influenced on PHBV synthesis. HV/PHBV ratio depends on applied VA concentration.

Novel Description of mcl-PHA Biosynthesis by Pseudomonas chlororaphis from Animal-Derived Waste

A novel description of mcl-PHA biosynthesis by Ps. chlororaphis from tallow-based biodiesel as an inexpensive carbon feed stock is presented. Fermentation protocols, kinetic analysis, an efficient product recovery strategy, and product characterization are included. Maximum specific growth rates (μmax.) of 0.08 h(-1), 0.10 h(-1) and 0.13 h(-1), respectively, were achieved in three different fermentation set-ups. Volumetric productivity for mcl-PHA amounted to 0.071 g/L h, 0.094 g/L h and 0.138 g/L h, final intracellular PHA contents calculated from the sum of active biomass and PHA from 22.1 to 29.4 wt.-%, respectively. GC-FID analysis showed that the obtained biopolyester predominantly consists of 3-hydroxyoctanoate and 3-hydroxydecanoate, and, to a minor extent, 3-hydroxydodecanoate, 3-hydroxynonanoate, 3-hydroxyhexanoate, and 3-hydroxyheptanoate monomers. The overall distribution of the monomers remained similar, regardless to working volumes, biodiesel concentrations and pre-treatment of the inoculum.

Novel precursors for production of 3-hydroxyvalerate-containing poly[(R)-hydroxyalkanoate]s

Abstract Polyhydroxyalkanoates (PHAs) with tailored properties are needed to meet consumer demands regarding the use of eco-compatible biobased polymeric materials and relevant plastic items. Inserting 3-hydroxvalerate (3HV) monomeric units in PHA biopolyesters results in poly[(R)-3-hydroxybutyrate-co-(R)-3-hydroxyvalerate] (PHBHV) copolyesters aimed at their conversion into production of biodegradable eco-friendly plastic items. As inexpensive novel precursor substrate structurally related to 3HV, a mixture of odd-numbered carboxylic acids with 9–17 carbon atoms was produced by oxidative ozonolysis of alkenes. This mixture was successfully applied for biomediated PHBHV production by Cupriavidus necator. Applying this mixture as carbon substrate, a molar 3HV fraction exceeding 0.12 was obtained. The isolated copolyesters featured a low degree of crystallinity, narrow molar mass distribution, and low melting temperatures. These properties should make application of the novel 3HV-precursors interesting for large-scale production of easily processable copolyesters.

Biodiesel synthesis by direct transesterification of microalga Botryococcus braunii with continuous methanol reflux

Direct transesterification of Botryococcus braunii with continuous acyl acceptor reflux was evaluated. This method combines in one step lipid extraction and esterification/transesterification. Fatty acid methyl esters (FAME) synthesis by direct conversion of microalgal biomass was carried out using sulfuric acid as catalyst and methanol as acyl acceptor. In this system, once lipids are extracted, they are contacted with the catalyst and methanol reaching 82%wt of FAME yield. To optimize the reaction conditions, a factorial design using surface response methodology was applied. The effects of catalyst concentration and co-solvent concentration were studied. Hexane was used as co-solvent for increasing lipid extraction performance. The incorporation of hexane in the reaction provoked an increase in FAME yield from 82% (pure methanol) to 95% when a 47%v/v of hexane was incorporated in the reaction. However, the selectivity towards non-saponifiable lipids such as sterols was increased, negatively affecting biodiesel quality.

Novel sensitive determination of steryl glycosides in biodiesel by gas chromatography-mass spectroscopy.

A new method was developed for the quantitative analysis of steryl glycosides in biodiesel (fatty acid methyl esters). This method is much more sensitive than existing methods and has minimum limits of quantification of 50 μg/kg, compared to previously published minimum limits of quantification of about 15 mg/kg. The analysis is based on gas chromatography-mass spectroscopy determination of simple pre-treated and silylated samples via single ion monitoring at 204, 217, 247 m/z, which are specific ions for the silylated sugar moiety. Quantification was carried out using cholesteryl β-D-glucopyranoside as internal standard. The modified synthesis and purification of the internal standard is also presented as well as the characterization by NMR and mass spectroscopy. The advantage of the method compared with other approaches is the simplified sample preparation avoiding extra pre-treatment steps coupled with complete derivatization of the sugar hydroxyl groups by using N,O-bis(trimethylsilyl)acetamide with 5% trimethylchlorosilane as derivatization reagent. On the given conditions high recovery rates ≥ 89% can be obtained. Evaluation of lab specific variance and intermediate precision underline the robustness of the method which will be further assessed by Round robin tests.

Hydrotreating of non-food feedstocks over Raney nickel for the production of synthetic diesel fuel

ABSTRACT Non-food feedstocks including castor oil, palm fatty acid distillate and waste tallow were successfully converted into liquid hydrocarbon mixtures. This was achieved by a batch hydrotreating process over commercial Raney nickel as a catalyst within 5 h at a reaction temperature of 360 °C and an initial hydrogen pressure of 90 bar. The obtained liquid products consist of straight chain alkanes in the range from C8 to C20. Low amounts (2.5–4.4%) of higher n-alkanes (up to C28) could be detected. The occurrence of the latter indicates a Fischer-Tropsch like process under the chosen conditions besides the expected decarbonylation/decarboxylation and accompanying cracking reactions. Products obtained from castor oil also comprised an overall amount of 19% of ketones in the range from C8 to C19. All obtained products were tested on important fuel properties according to well-established methods given in EN 590, the European Standard for diesel fuel. Comparison with the obligatory boundary values given within this specification suggests an excellent suitability as blending components for fossil diesel fuel. For a full replacement further upgrading would be necessary.

Production of biodiesel from animal fat using supercritical ethanol

Dust generation is related to the durability of products, in other words the wear rate of particles subject to forces. During transport, storage and handling the wood pellets are undergoing different forces within different pieces of equipment. For example impact forces when particles fall down or impact geometries and compressive forces when in storage. The objective of this paper is to assess the representativeness of the so-called tumbling can test in relation to handling conditions in the supply chain for wood pellets. Therefore forces acting on particles in the tumbling can on the one side and during loading and discharging of a flat bottom silo on the other side were compared by Discrete Element Model simulations. It can be concluded that in the presented cases the tumbling can underestimates the handling conditions of the material in reality.F (pinus pinaster pruning), agricultural (grapevine tree pruning) and industry (dealcoholized marc of grape) wastes can be considered as the main biomass sources for energy from the inland regions of Spain, the first being a typical waste from forest maintenance and timber harvesting and the others being typical wastes from unirrigated agriculture and distillery industry, respectively. Pruning of pine is made every five years (on average) with a production of around 5 tonnes per hectare, and pruning of grave pine is made yearly with a production of 0.83 tons per hectare. The production of marc of grape is around 0.14 kg/kg grape (on average). European and Spanish energy policies are encouraging the use of biomass for energy purposes, with three targets: economic and social development of the countryside, elimination of wastes and reduction of CO2 emissions. However, such policies have not been successful yet in Spain owing to uncertainties in the guarantee of provision of raw material, to fluctuations of the raw material prize and to administrative difficulties, leading to the discouragement of investors. In this frame, biomass gasification constitutes an attractive option, and an alternative to the combustion of biomass. The producer gas from gasification can be directly used in internal combustion engines for mechanical or electrical energy production. One of the main advantages of gasification is the possibility to install small, low-cost and efficient gasifierengine couples, which allows the biomass to be used close to source, and thus, the elimination of much of the storage and transportation costs. Additionally, the combination of short-run forestry and agricultural wastes for supplying power plants provides higher operation flexibility and minimizes the effect of seasonal supply variations. However, the gasifier design must be optimised as a function of the physical and thermo chemical parameters of the biomass, while the engine design must be optimised as a function of the producer gas composition. As a consequence, only where these compositions are substantially similar, the original biomass wastes can be used in a flexible supply system. The producer gas compositions obtained from the gasification of the above mentioned wastes in a circulating flow gasifier have been compared in order to determine whether these wastes can be used in combination or interchangeably in gasification systems. Experimental tests were carried out not only considering different fuels but also several operating conditions (equivalence biomass/air ratio, gasification temperature and type of gasifying agent (air, air/steam mixtures). J Fundam Renewable Energy Appl, 5:5 http://dx.doi.org/10.4172/2090-4541.S1.003D years 2014/2015, an area of 9000 acres was planted with cane sugar in Brazil, which corresponds to 659 million tons of cane and that will produce 38 million tons of sugar and 28 billion liters of ethanol. Bioethanol is a renewable fuel and its consumption in Brazil is by blends of ethanol and gasoline (22%) or as single fuel for flex fuel vehicles. The increase in demand for this biofuel and to avoid the expansion area planted with sugarcane, which has been growing 3% per year, the cellulosic ethanol (2G ethanol) production is a promising alternative. The sugar and ethanol industry in 2014 generated about 155 million tons of straw and bagasse potentially capable of generating up sugar to produce 442 billion liters/year of ethanol. In October 2014, the first commercial-scale ethanol-2G plant (GranBio) has initiate with production capacity of 82 million liters of ethanol per year (21.6 million US gallons) in Alagoas, northeastern Brazil. The biodiesel or alkyl-esters produced by transesterification reactions between triglycerides and alcohol, is the second alternative biofuel in Brazil but the current production capacity meets only 170 million liters/year, which correspond to 17% of the demand, considering the mix B2. The raw materials used for biodiesel production has been the oils of palm, babassu, soybean and sunflower. Brazil currently has 89 biodiesel production plants spread across the country. Many of them use transesterification by methyl route. However, due to high production of ethanol in the country, the ethylic route has been proposed, associated with new catalysis methods such as enzyme and solid.Biodiesel is currently produced from a catalytic transesterification reaction of various types of edible and non-edible oil with methanol. The use of waste animal tallow instead of edible oils opens a route to recycle this waste. This material has the advantage of lower costs but the problem of high content of free fatty acids, becoming necessary a pre-esterification reaction that increases the cost of the catalytic process. The production of biodiesel using supercritical alcohols is appropriate for materials with high acidity and water content, therefore the use of this process with animal fat is a promising alternative. Ethanol has been used because it can be produced from biomass via fermentation resulting in a complete renewable biodiesel, instead of methanol that derives from fossil feedstocks. Two different processes have been studied: first, the direct transesterification of animal fat using supercritical ethanol and second a two-step process where the first step is a hydrolysis of the animal fat and the second step is the esterification of the resulting fatty acids. The temperature, the molar ratio ethanol:fat and the time have been modified in the different reactions to study the effect in the final conversion and the degradation of the unsaturated fatty acid esters, main inconvenient of these high temperature and pressure processes.S sorghum is one of the promising energy crops that can provide both sugar juice and bagasse to conversion for bioethanol. Ethanol from the extracted sweet sorghum juice can be easily produced by fermentation process. But the lignocellulosic biomass such as sweet sorghum bagasse has many barriers for ethanol production. For commercial production of bioethanol, effective pretreatments of lignocellulosic materials need to be developed for the reduction of processing costs. In this study, continuous pretreatment system with single screw reactor was applied for the effective hydrolysis of sweet sorghum bagasse. Conditions of hydrolysis were different concentrations of sodium hydroxide (0.2~1.0 M) at 140°C, 1.2 kg/min of biomass loading rate and 7.2L/h of aqueous sodium hydroxide. In case of 0.4 M sodium hydroxide for pretreatment of sweet sorghum bagasse, solid phase was recovered, 49.9% from dry matter sweet sorghum bagasse and its compositions were 59.2% of cellulose, 31.7% of hemicellulose, 6.9% of lignin and 0.9% of ash. Saccharifications of pretreated bagasse were performed with different concentrations of enzyme (between 5 and 15 FPU/g-cellulose from Novozymes) in 72 h, 150 rpm at 50°C. The optimum enzyme loading was 10 FPU/g-cellulose and at this optimum condition the maximum yield of glucose conversion was 88.0% after 72 h. It was produced 25.1 g/L ethanol from pretreated sweet sorghum bagasse (60 g/L glucan) and maximum ethanol yield was 91% by Saccharomyces cerevisiae CHY1011.