They develop a new solar-powered slurry concentration solution reduce the cost of transport to areas lacking fertilizer.

The project, which has a significant potential for areas vulnerable to nitrates, has companies SOUTH Renewables Yes CIM Aigua and with researchers from Eurecat-CTM.

Researchers at the technology center Eurecat-CTM (member of Tecnio) participated in the development of a new solution that allows the concentration of slurry in an accelerated way to reduce transport costs, it can therefore be sent more economically to areas where there is a lack of fertilizer and thus help reduce the use of chemicals.

The project, which is called SOLARPUR and is led by the companies SUD Renovables and CIM Aigua, has significant potential for areas with a high concentration of nitrates in groundwater in Catalonia and also envisages its application to other areas of Spain and Europe suffering from the same problem.

The technology is based on a optimized intensive evaporation system that allows to obtain less volume of slurry in a more efficient way than solar evaporation, by using an automated ventilation control that measures environmental variables such as temperature, humidity or solar radiation.

With this analysis of the sensors, it is possible to determine the ideal ventilation time to maximize evaporation and that it is faster, compared to an open swimming pool system where it evaporates under the action of solar radiation.

To avoid greenhouse gas emissions derived from the process, mainly ammonia and volatile organic compounds, the slurry has been acidified on the one hand, which fixes the ammoniacal nitrogen and prevents its volatilization and, on the other hand part, it has been installed an air filtration system to ensure a minimum of emissions.

In total, SOLARPUR involved the construction of a pilot plant with a covered basin equipped with a advanced control which allowed to intensify the natural evaporation, the capture of solar thermal radiation and complete control of environmental conditions, as well as the contribution of excess electricity from a photovoltaic installation for self-consumption. This control system made it possible, at a minimum, to double the rate of natural solar evaporation.

It is calculated that this new process will reduce the volume of slurry, so that the transport costs will be reduced to less than 6 € / m3 produced. This will also facilitate use of the residue as a natural fertilizer in nutrient-deficient areas and it will control greenhouse gas emissions associated with storage in slurry ponds.

For the development of the project, the researchers installed a pilot plant in a pig farm in the affected areas, based on the evaporation of the aqueous content of the slurry previously treated with a solid / liquid separation system. In this sense, the system made it possible to reduce by evaporation more than 70% of the liquid content, thus concentrating the nutrients.

The project, which ended at the end of July 2018, benefited from the support of Agroxarxa and the Department of Agriculture, Livestock, Fisheries and Food of the Generalitat of Catalonia, and is part of the Nuclis industrial research and experimental development call. 2015.

Currently, after several studies, it has been concluded that the solution to slurry problems involves the management and use of the technologies best suited to each reality, depending on the balance of nutrients, the transport problem that is due . Resolution and others the requirements to be respected, in particular the prices of the treatments and the energy necessary for the applied processes.