Rodolfo Bona

Sustainable Polymer Production

Abstract Sustainable biotechnological production of polyhydroxyalkanoates from renewable resources is an alternative to chemical polyster production from mineral oils. The polymers produced are biodegradable, and due to their characteristics can be used for the production of packaging materials. Many different prokaryotic microorganisms are known to accumulate polyhydroxyalkanoates intercellularly under growth limiting conditions; some of them are able to produce copolyesters from precursors added to the production medium. Production normally is done in a fed-batch process, but PHA production kinetics suggest that continuous production in a chemostat might be favorable. After biomass separation the polyester is extracted from the biomass and refined.

Biotechnological production of poly(3-hydroxybutyrate) with Wautersia eutropha by application of green grass juice and silage juice as additional complex substrates

Alternative inexpensive complex nitrogen- and phosphate sources from agriculture, green grass juice (GGJ) and silage juice (SJ), were added to cultivation medium in order to investigate their impact on growth of the well-known polyhydroxyalkanoate (PHA) accumulating strain Wautersia eutropha. The influence of these additives was directly compared with cultivations on defined minimal mineral medium (M) as well as on the same medium supplemented with more expensive complex additives: corn steep liquor (CSL) and casamino acids (CA). It turned out that the supplementation with most complex additives results in shortening of lag-phases of bacterial growth and in higher end-concentrations of residual biomass compared with M-medium. Finally, higher volumetric productivities for poly(3-hydroxybutyrate) (3-PHB) were achieved. The effect of the inexpensive additive SJ on volumetric productivity was similar to the result for the expensive CA (0.653 vs. 0.619 g L−1 h−1). The same was found for the biomass concentration (7.00 vs. 7.44 g L−1 respectively). Together with an economic appraisal presented in this study, the results suggest it is possible to make the sustainable process of microbial PHA-production more economically feasible. A survey of the thermal characteristics and molecular mass properties of the isolated polymers completes this work.

Sustainable Embedding of the Bioplastic Poly-(3-Hydroxybutyrate) into the Sugarcane Industry: Principles of a Future-Oriented Technology in Brazil

To make the biodegradable polymer poly-(3-hydroxybutyrate) (PHB) economically competitive with common end-of-pipe plastic materials from petrochemistry, the production costs have to be reduced considerably. The embedding of the industrial PHB production into a sugar and ethanol factory starting from the raw material sugarcane makes it possible to achieve a production price per kilogram PHB that is 4–5 times lower than known for prior PHB production processes. This cost reduction is enabled by an extensive utilisation of by-products of the sugarcane plant, especially of bagasse. In the presented process, this typical waste product is burned for generation of the steam and electrical energy required for the process. Furthermore, the availability of the substrate sucrose in high quantities leads to the gained price advantage. Together with the application of ethanol as an alternative fuel, CO2 emissions from the production plant return to the sugarcane fields via photosynthetic fixation, resulting in a carbon balance of nearly zero. The utilisation of medium chain length alcohols, by-products of the ethanol production integrated in this plant, substitutes the classic PHB extraction method using chlorinated agents. In this way, the major drawbacks regarding profitability and environmental embedding of PHB production are solved within a future-oriented, integrated process.

Solid Waste Management and Plastic Recycling in Austria and Europe

Abstract During the last decade plastic waste has become a major problem within the industrialized countries. Many new waste management associations have been founded, and new technologies for sorting, reutilization, and/or energy recovery from sorted or mixed plastic recycling fractions have developed. The main developments will be demonstrated based on the examples of plastic waste treatment in Austria and Germany, and an outlook for the development in Europe will be given.

Production of Poly-3-hydroxybutyrate-co-3-hydroxy-valerate with Alcaligenes latus DSM 1124 on Various Carbon Sources

Polyhydroxyalkanoates are thermoplastic polyesters which are produced as storage compounds by a vast number of bacterial strains under growth limiting conditions. These polymers can be produced in different qualities with a wide range of physical properties, either as homo-polymer (Poly-3-hydroxybutyrate) or, with different co-substrates, as copolymers (e.g. Poly-3-hydroxybutyrate-co-3-hydroxyvalerate, Poly-3-hydroxybutyrateco-4-hydroxybutyrate). They are completely biodegradable and therefore an interesting alternative to the mineral-oil derived plastics as packaging materials. Nevertheless up to now PHAs have not been able to compete with the conventional plastics because their price is still much too high. One possible way to reduce the production costs is to use cheaper carbon sources like agricultural waste materials. The strain Alcaligenes latus DSM 1124 is able to accumulate high amounts of PHAs and therefore very interesting for a future production. The growth and the accumulation of PHAs on various carbon sources like glucose, glycerol and Na-valerate have been investigated in a labscale fermenter. PHA contents and kinetic data like the specific growth rate and yield coefficients were determined.

Synthesis of Biopolymers

A number of polymers can be produced via fermentation, using special consortia of microorganisms to convert renewable raw materials (surplus or waste products from agriculture or foresting) into useful products within sustainable processes. The main groups are either extracellular polysaccharides produced by many eukaryotic or prokaryotic microorganisms, or polyhydroxyalkanoates stored intracellularly as reserve products for carbon and energy in a variety of bacteria. In order to lower production costs for these biopolymers, continuous processes have to be designed for the future.

The Production of Poly-3-hydroxybutyrate-co-3-hydroxyvalerate with Pseudomonas cepacia ATCC 17759 on Various Carbon Sources

Polyhydroxyalkanoates (PHAs) are biodegradable polyesters which can substitute conventional thermoplastics from non-renewable fossil resources. They are accumulated by a vast number of microorganisms as an intracellular storage product. The material properties of PHB (Polyhydroxybutyrate), the most commonly found PHA, can be improved by adding precursors as for instance 3-Hydroxyvalerate or 4-Hydroxybutyrate during the polymer accumulation phase to the medium generating Poly-3-hydroxybutyrate-co-3-hydroxyvalerate and Poly-3-hydroxybutyrate-co-4-hydroxyvalerate respectively. The main obstacle for a wide use of Polyhydroxyalkanoates as thermoplastics is the high production costs, which can be lowered significantly by using cheap carbon sources, since the cost of the carbon source contributes almost 50 % to the production costs. Cheap carbon sources are waste materials from agricultural and food industry. Whey accumulates in high amounts in cheese-production and therefore causes high waste management costs. Since strain Pseudomonas cepacia ATCC 17759 is capable of both producing PHA and utilizing whey composites lactose and its monomers glucose and galactose as carbon sources the whey could be used for this purpose. Growth kinetics and storage behavior of P. cepacia on various carbon sources and valerate as precursor have been investigated.