The increase in world population has intensified the demand for energy, materials, and food. In particular, the growing demand for animal protein has significantly raised pork production worldwide and specifically in Spain. The EU annually raises approximately 150 million pigs and is the world´s leading exporter of pork products. This fact contributes to a significant environmental impact in several categories such as loss of terrestrial biodiversity, global warming, soil acidification and air pollution (ammonia and greenhouse gases emissions), and water pollution (both N and P). In this context, BIOPIGMA project aims to integrate technological know-how with microbiological characterisation to develop an integrated pig manure treatment/valorisation train. BIOPIGMA aims to produce safe bioproducts, including reclaimed water, microbial proteins, and biopolymers, using biological processes under a holistic approach based on environmental and economic outcomes, also minimising the contribution of the proposed biofactory to the spread of antibiotic resistant genes (ARGs). The coordinated project brings together the experience and capabilities of two teams: (1) the Environmental Biotechnology Group at the Universidade de Santiago de Compostela, with a demonstrated expertise on the development and optimisation of biological treatment and valorisation of wastes (like pig manure); (2) the Environmental Microbiology Group at the University of Granada, whit proven skills in molecular ecology of microbial communities in biological processes and life cycle assessment (LCA).

The project proposes a biofactory that integrates different innovative management strategies for the liquid (LPMF) and solid (SPMF) fractions of pig manure. The LPMF valorisation train will focus on the use of purple phototrophic bacteria (PPB) to obtain protein-rich biomass and reclaimed water. Additionally, the study of a pretreatment with aerobic granular sludge (AGS) for the removal of organic matter and nitrogen removal is proposed to overcome challenges in the PPB process associated with light intensity and high surface area requirements. As for SPMF valorisation train, the processes focus on the recovery of different chemical platforms, like volatile fatty acids (VFA) obtained by a biological hydrolysis/acidification system. The VFA mixture will then be valorised in two possible ways: to produce polyhydroxyalkanoates (PHAs), which are biopolymers that can replace conventional fossil-based plastics, and to obtain protein-rich biomass with the PPB process. After VFA production, the solid is further valorised by chemical hydrolysis to obtain furfural and enzymatic hydrolysis to produce sugars from the hemicellulose content. The synergy of the different processes will be evaluated, such as the integration of the off-gas streams from AGS systems as source of CO2 and N2 for PPB metabolism. Microbiological analysis of the different cultures involved will be carried out to identify the operational parameters that achieve the best performance of the different units. In addition, the analysis of the ARGs in the different bioreactors and bioproducts will help to understand the applicability of the proposed solution. Finally, a comprehensive techno-economic analysis and LCA will be conducted to assess the environmental footprint and competitive advantages of this original integral approach against already implemented technologies.