Boosting rural business with innovative manure-based products EU-funded researchers have developed an efficient method of converting livestock manure into safe and stable organic materials, reducing the environmental impact of fertilisers, achieving resource efficiencies and creating new rural business opportunities. Climate Change and Environment © BIOECOSIM Farming in the 21st century is often a balancing act between meeting the ever-increasing demand for cheap and plentiful food, while ensuring that arable land remains fertile and productive. Livestock manure for example is a valuable agricultural resource – providing nitrogen, phosphorous and organic matter to fertilise crops – but overuse can cause significant damage. Negative side effects include surface and groundwater contamination, the emission of greenhouse gases, and long term nutrient imbalances and an accumulation of heavy metals in the soil. This reduces productivity in the long term, in addition to damaging the environment. Around 1 800 million tonnes of manure are produced in Europe every year. Sustainable rural benefits The EU-funded BIOECOSIM project sought to address this ongoing conflict by developing an energy-efficient pilot plant capable of converting livestock manure into safe and stable materials. A key benefit of the new technology is that it has been designed to treat manure directly at its place of origin, which means that farmers – especially those with high livestock densities and a surplus of nutrients in the soil – could adopt the technology to create a new revenue stream. ‘The prototype plant can process 50 kg of raw manure an hour into fertilisers and organic soil improvers, which can then be mixed to match the nutritional requirements of any crop,’ explains project coordinator Dr Jennifer Bilbao from Fraunhofer IGB in Germany. ‘Water can also be reclaimed from the manure and used for irrigation. These products will make crop farmers less dependent on synthetic, non-renewable and imported fertilisers to maintain or enhance their yields, and create new business opportunities for small agricultural entrepreneurs.’ A sustainable and fertile solution Bilbao and her team tested the pilot processing plant on pig manure, which has a high water content of 90 %. It also contains valuable components such as plant nutrients – mainly nitrogen and phosphorus – and indigestible feed solids such as plant fibres. To begin with, the manure is pre-treated so that the phosphorus dissolves completely. This is then separated by coarse filtration into a solid and a liquid phase. The solid phase is then dried using a process developed at Fraunhofer IGB; this works with superheated steam in a closed system and is highly energy efficient. ‘Microorganisms are completely destroyed in this process,’ explains Bilbao. ‘Optionally, the dried organic components can be converted to organic biochar at over 300°C by a pyrolysis process – in an atmosphere of superheated steam, as in the drying step.’ After removing the solid fraction, researchers were able to create a mineral phosphate fertiliser mixture from the remaining liquid. Finally, they also recovered ammonia from the liquid using gas permeable membranes. Lab-scale units capable of integrating all these processes were built to efficiently produce the biochar, gas, phosphorus and ammonia fertilisers and reclaimed water. ‘Our extensive investigations and field studies have shown that the mineral fertilisers and organic soil conditioners made from livestock manure can be used directly in agriculture as readily available fertilisers and soil improver,’ says Bilbao. ‘The mass of the dewatered and processed products makes up only about 4 % of the original volume of livestock manure. The next step is to further develop and transfer these technologies into a marketable plant for serial production.’ Keywords BIOECOSIM, livestock manure, resource efficiency, fertilisers, rural business opportunities, phosphorus, nitrogen, nutrients
