From Science & Research
From Science & Research Reactor contents transfer From Waste 2 Gold: Making bioplastic products from biomass waste streams Article contributed by Dr Alan Fernyhough, Unit Manager of the Bioplastics Engineering Group, Scion, Rotorua, New Zealand New Zealand is widely regarded as pristine and uncluttered. But the country has waste management challenges just like everywhere else. A large volume of these wastes arise from its prolific agricultural, forestry and horticultural sectors. Innovative research programmes aimed at turning these organic wastes into high-value bioplastic products are being run by Scion, a Crown Research Institute based in Rotorua, at the heart of New Zealand’s green hinterland. At Scion, teams working on wastewater and environmental (bio)technologies have come together with those working on biopolymers, and materials formulation and processing technologies to create a suite of technology options for converting wastes into bioplastic related products. The programmes include turning wastes into bioplastics, or into functional additives for use in bioplastics, or directly into processed bioplastics products. Dr Trevor Stuthridge is the leader of the ‘Waste 2 Gold‘ programme, an overarching framework developed by Scion for turning wastes into valuable products. He explains why this research is of vital interest to a nation focused on minimising waste: “New Zealanders landfill the equivalent of 872 kg of solid waste per year per person – one of the highest per capita rates in the OECD (Organisation for Economic Co-operation and Development). Our primary industries contribute 55% of this total; a major proportion is organic material 28 bioplastics MAGAZINE [07/04] Vol. 2
From Science & Research which can generate methane, a potent greenhouse gas (GHG), and harmful leachates.” In a bid to help minimise GHG emissions, New Zealand has implemented a Waste Management Strategy that aims to see 95% of these industrial organic wastes re-directed from landfills by 2010. Dr Stuthridge believes that New Zealand’s primary sectors can best meet this challenge by actively exploiting the intrinsic worth of their organic wastes. “The only effective way to provide incentives for minimising liquid and solid wastes and redirecting organic material from landfills is to ensure that the resource has an economic value. The ‘Waste 2 Gold‘ initiative is proactively generating sustainable solutions, which will simultaneously help to increase revenues, reduce costs and add value to businesses,” he says. Carbon-rich industrial wastes, such as those from the pulp and paper, food processing, and biorefinery sectors are low cost, high volume feedstocks that are ideal for sustainable production of biopolymers, fine chemicals and biofuels. Microbial biotechnologies and chemical functionalisation technologies are under development by Scion scientists who are exploring ways of utilising these feedstocks. One project involves the use of mixed and/or pure cultures of bacteria that directly fix nitrogen from the atmosphere, allowing them to remediate carbon-rich wastes from these sources, without the need for additional costly chemicals, and convert the carbon into useful products. Dr Stuthridge explains that a novel function of these nitrogen-fixing bacteria is their ability to store excess carbon in the form of polyhydroxyalkanoates (PHAs, >50% of dry cell mass). “We are exploiting this characteristic to produce biopolymers and biopolymer composites from industrial waste streams. Given that feedstock costs can comprise over 60% of manufacturing costs, this type of process is expected to offer substantial economic advantages.” Nitrogen fixation processes produce very low ecological footprints since no supplemental nitrogen needs to be added to achieve microbial growth. This approach can give a 35% saving in operational costs over conventional bioconversion methods. In addition, very low nutrient final wastewater discharges are achieved, amounting to over 90% reductions in nitrogen and phosphorus over conventional methods. Finally, these aerobic nitrogen fixation processes have a lower oxygen demand than normal systems, offering a 25% saving in aeration energy costs. “Of course, in the case of solid wastes, there is a requirement to make them more easily accessible for microbial bioconversion”, explains Dr Stuthridge. “Here, we are integrating proprietary green chemistry-based technologies that break down the solid organic material, such Bacteria with PHA Biodegradable pots bioplastics MAGAZINE [07/04] Vol. 2 29
