13. Sustainable Wastewater Utilization for Combined Energy Production and Plastic Pollution Mitigation via Biohydrogen and Polyhydroxyalkanoates

In this chapter, an integrated approach to the combined treatment and exploitation of wastewater is presented, focusing on the concurrent production of biohydrogen (BioH2) and polyhydroxyalkanoates (PHAs) through microbiological processes. The principles and microbiology of BioH₂ production via dark fermentation are examined in detail, with particular emphasis on the key reactions responsible for generating volatile fatty acids (VFAs), which play a crucial role in controlling the efficiency of BioH₂ production and serve as essential precursors for PHA biosynthesis. The fundamentals of PHA biosynthesis by both pure and mixed microbial cultures are further explored, along with a discussion of the current advancements and limitations in industrial PHA production. Special attention is given to the advantages of utilizing acidogenic effluents as substrates for PHA production, addressing the current state of research, identifying existing challenges, and exploring the opportunities offered by this integrated strategy. The presented approach aligns with EU objectives for a circular economy, sustainable energy, and eco-friendly plastic production, providing a promising pathway for waste valorization and environmental protection.