Leave nothing to waste in agriculture: Spain’s race to top circular economy

Archive image of a slurry treatment plant in Catalonia. [EFE Archive]

This article is part of our special report Bioeconomy in the CAP’s nine objectives.

This article is also available in Italian, Spanish and Portuguese.

The agrifood sector is aiming to become a leader in the circular economy, in which every kind of waste, from crop to industrial waste, can have an added value and help improve economic, environmental and social sustainability. EURACTIV’s partner EFEAGRO reports.

“From the pig, we can even exploit the way it walks,” a Spanish farmer said, referring to the fact that all of the animal’s body parts are profitable, which is a notion at the heart of the circular economy’s philosophy. The pig industry is one of the most committed industries in the circular economy.

Pig excrement, known as slurry, is one of the livestock’s by-products that is leading in this respect thanks to the fact that, with good treatment and processing, it can be used as manure or as a method for producing biogas.

The livestock cooperative Jisap, established in Lorca, Spain, is an example of this philosophy in action. The cooperative uses slurry as an organic fertiliser which provides water but also micro and macronutrients for crops – provided they are used in right concentrations and rationally.

Sources from this group told EFEAGRO that they have integral management systems both on farms and in treatment plants.

Firstly they separate the solid part from the pig slurry to obtain manure that is then combined with those products that come from calf farms, allowing them to achieve “valuable” manure for farming. And the fluid part is submitted to physical-chemical processes. It will later be passed through biological filters, and they will then extract suitable water to be used as fertiliser.

This water will be applied in soils destined to produce cereals, oils and citrus that are next to those areas, which apply slurry treatments.

This way, they ensure that pig slurry is given a different use, but they also get organic fertilisers that help the soil to recover and reduce greenhouse gas emissions produced by the faeces.

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Researchers from the Catalan Institute of Agrifood Research and Technology (IRTA) are aware of this possibility and are immersed in the European project called “Circular Agronomics”. The Project aims to ensure the recovery and recycling of nutrients throughout the agrifood chain, with the participation of centres for investigation and universities from ten different countries.

In this case, IRTA is in charge of implementing a project to valorise slurry and not only use it as a biofertiliser but as biogas and a generator of clean energy.

IRTA researcher Víctor Riau explained that the slurry will be treated in a factory in Lérida (Cataluña) with anaerobic digestion to obtain methane gas that could be used as energy.

Yet, with cows often being the main focus of attention due to their polluting properties, IRTA has decided to dedicate another project to dairy production of cattle.

They have already started with an investigation that aims to find out amounts of nitrogen and phosphorus are needed to ensure animal feed could lead to decreasing the volume of polluting emissions they release.

They will also study the influence of the different kind of beddings for cows so they can prove whether they influence the animal’s health in any way and whether these affect emissions.

Olive oil sector leads the way

The goals of the circular economy are not alien to Spain’s agricultural sector. There are areas in which such practices have become commonplace, like in the olive oil sector, in which Spain is a global leader.

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For example, in the Andalusian olive cooperative El Tejar, 30-35 % of the “alperujo” that is produced in Spain (2,5 million tonnes per year) is being recycled. Alperujo is a by-product of the process of production of olive oil obtained in the oil mills.

El Tejar president Francisco Serrano told Efeagro that the “alperujo” is submitted to a centrifugation and drying process to obtain “orujillo”, which then goes to power plants so they can use it to produce electric energy through combustion.

With this treatment, they also obtain the ashes that are reused as agricultural fertiliser because it is rich in potassium and microelements.

The cooperative also gives new life to olive stones, used for example as fuel, and to the olive leaves because these contain polyphenols of high pharmaceutical value.

There are similar cases with other products, like in the case of persimmon, whose producer association just signed an agreement with the company Genia Global Energy – promoter of biogas plants – to obtain energy from the 18,000 tonnes of low-quality fruit that, in each campaign, doesn’t reach the market.

The produced biogas will be injected into the distribution network and it is renewable energy that can be stored and used as heat, electricity and fuel.

The industry is another ally, and in the case of the company Cerealto Siro Foods, with its partner Tuero, they have already started a new plant in Venta de Baños (Palencia) destined to produce biogas and organic fertiliser.

This way, they managed to reduce the shipments to landfills or waste treatment centres by 30,000 tonnes per year, which translates into a significant decrease of emissions.

The benefits will not only come because of the possible sale of biogas or fertiliser but also because of the savings in energy consumption, as has been highlighted by the company.

Recycling and zero emissions are the final goals of all these practices, which have changed the way we perceive the agrifood sector.

[Edited by Daniel Eck, Zoran Radosavljevic]

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