The pig is no longer simply a source of food. It has now become an alternative source of energy, as well as a source of products that can be recovered and used in agriculture. It is only now that the traditional Spanish culinary saying “del cerdo se aprovecha todo” (the entire pig is availed of) has truly become a reality.

As is the case with most human activities, livestock and agro-food processing, apart from generating the product that is the object of the activity, also generates by-products and waste.

For example, only between 32% and 80% (depending on the species) of animals slaughtered in abattoirs is suitable for human consumption, with the remaining fraction being used for the production of by-products. Almost 20 million metric tonnes (MMT) of such by-products are generated in Europe alone every year.
Spain, with a total of almost 2 MMT per annum, is third in the list of European countries in terms of volume of animal by-products processed, behind only France and Germany.

Current management of these by-products represents a serious environmental problem, because of the volume and also due to the fact that there is little or no recovery of many of these by-products. This problem is particularly significant in the area of pig carcass management. In this respect, it should be borne in mind that Europe is the world’s second largest producer of pigs, with a census of over 148.3 million head in 2014. Spain is the second largest pig producer in Europe (behind only Germany), with a 2014 census of 26.6 million head.
Statistics for livestock slaughter reveal even higher figures. 251 million pigs were slaughtered in 2014, 43 million of which were from Spain. Based on the previous census, it is estimated that the generation of pig carcass remains in Europe and Spain is 5.4 MMT and 0.9 MMT, respectively. For this reason, finding an efficient alternative for pig carcass management is a priority in Spain and in Europe.

Another problem associated with the pig industry is the generation of enormous quantities of manure. The European Commission estimates total EU pig manure production of 1,400 MMT. France is the largest producer, followed by Germany, the UK, and Spain, in that order.

It is estimated that around 140 MMT of slurry and manure is produced in Spain every year, 50% of which comes from cattle and 40% from pigs. Most of this cannot be used directly as fertiliser because it would result in excessive nitrification of soil. Moreover, many farms operate intensive livestock breeding, without associated crop cultivation, meaning that manure production is a problem.

The quantities of both livestock and agro-food waste outlined above provide an idea of both the volume of the problem and the enormous quantities of potential raw materials. If availed of, these raw materials would open up a wide range of possibilities, in terms of energy, fertilisers, extraction of active ingredients, etc. Of significance is the fact that the agro-food waste available in Spain would enable the generation of 2,600 million m3/annum of biogas, the equivalent of 4.2 % of annual natural gas production.

The VALPORC project proposes a sustainable alternative to pig carcass and slurry management (Figure 1). It addresses the environmental problem associated with current management and seeks to recover these wastes by converting them into biofuels (biogas and biodiesel) and organic fertilisers, with all the corresponding environmental and socioeconomic benefits that this will afford.

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Dra. M. Dolores Hidalgo Barrio
CARTIF Technology Centre – Institute of Advanced Production Technologies
(ITAP) Universidad de Valladolid