초록
Nowadays there is a growing demand for natural products from microalgae with applications in the food industry (additives, pigments, vitamins and colorants) as well as in the pharmaceutical, nutraceutical and cosmetic sectors. A life cycle assessment (LCA) of the production of bioactive compounds with applications in the pharmaceutical and food/feed sectors (PUFAs, α-tocopherol, chlorophyll, β-carotenoid and polyphenols) from the microalgae Tetraselmis suecica was carried out in this study. Following a biorefinery perspective of the production system, the anaerobic digestion of the algal residual paste obtained after the extraction step was also included. Accordingly, the life cycle was divided in five main stages: i) sterilization, ii) inoculation and culturing, iii) harvesting, iv) extraction and v) anaerobic digestion. The inoculation and culturing stage was identified as the stage with major contribution to the environmental impact, ranging from 73% to 97% depending on the impact category. The nitrogen source (sodium nitrate) required for algae growth was a very relevant issue. As a consequence, alternative nitrogen sources (inorganic and organic fertilizers) were proposed and assessed here, finding notable improvements depending on the source. The valorization of the algal residual paste used as nutrients source (N, P and K) was also an interesting alternative. Regarding the photobioreactor configuration, the combination of a PBR and an open raceway was proposed here in order to demonstrate the potential reductions in terms of electricity consumption.