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A new eco-friendly process is reported, the implementation of which at the EU level could reduce ammonia and greenhouse gas emissions from fermented biowaste by over 1 Gt yr −1 . The present work reports the case study of municipal biowaste (MBW). The process is based on the use of soluble bio-organic substances (SBOs) as auxiliaries in the anaerobic fermentation of MBW to produce biogas and digestate with reduced ammonia content. The SBO-assisted process enables a virtuous biowaste cycle, where MBW is sequentially fermented under anoxic conditions, the digestate is composted, and the compost generated is hydrolyzed, yielding SBO, which is recycled to the anaerobic fermentation reactor at 0.2% concentration. The results show that depending on the MBW source, fermentation inoculum, and SBO concentration in the fermentation slurry, about 40% reduction of ammonium in the digestate is achieved, whereas the control fermentation without SBO exhibits up to 11% ammonia increase. The microbial community and biogas production are not significantly affected by SBO addition. The data are consistent with biological and chemical processes occurring in SBO-assisted fermentation. These comprise ammonia production by protein hydrolysis catalyzed by proteolytic bacteria and ammonia oxidation to N 2 catalyzed by SBOs. The results confirm the benefit provided by the use of SBOs to reduce the environmental impact of biowaste. These encourage the implementation of SBO-assisted fermentation in the real operational environment.

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A natural resin retrieved from Pistacia terebinthus tree was evaluated as an immobilization carrier of Saccharomyces cerevisiae AXAZ-1 cells targeting successive fermentation batches of sugar synthetic mediums. Fermentation times below 54 h were recorded at temperatures 28–14 °C. In total, 147 compounds were detected using gas chromatography-mass spectrometry (GC-MS) analysis, including alcohols, esters, ketones, aldehydes, acids, and terpenes. Principal component analysis indicated that the state of cells (free/immobilized) and the fermentation temperature primarily affected terpenes’ composition. Importantly, no spoilage of the fermented beverages was noted during 90 days of storage at room temperature, most likely due to the high content of extracted terpenoids and phenols (up to 579.01 mg L−1 and 171.8 mg gallic acid equivalent L−1, respectively). Likewise, the developed novel biocatalyst (yeast cells immobilized within Pistacia terebinthus resin) was suitable for the production of low alcohol beverages with an enhanced aromatic profile. The obtained results revealed that the proposed bioprocess shows great commercialization potential in the new fast-growing low-alcohol beverages sector.

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