## 1 Introduction  
Cyanobacteria are the only known prokaryotic organisms capable of oxygenic photosynthesis, making them a unique class of organisms. Many ecosystems rely on cyanobacteria for carbon dioxide fixation and oxygen release, making these organisms key primary producers in the trophic chain [1]. As producers of secondary metabolites, such as mycosporine-like amino acids, alkaloids, amides, fatty acids and peptides, cyanobacteria are a valuable source of natural products [2]. Because they are photosynthetic organisms, cyanobacteria synthesise a variety of pigments (chlorophylls, carotenoids and phycobilipproteins). Due to their colour and bioactive characteristics, these pigments are well known for their commercial application in food, feed, nutraceuticals, cosmetics, and pharmaceuticals [3, 4]. Considering the content in pigments, they have become the components with the highest market growth potential for microalgae producing companies [5]. On the other hand, the biotechnological potential of cyanobacteria has not yet been fully exploited. It is estimated that there are more than 100,000 species [6], but only a few thousand strainsare preserved in culture collections and only a minority have been produced on a large scale [7]. To ensure pigment production by cyanobacteria on an industrial scale, the current gap in technical scale-up to produce higher biomass yields at reduced production costs must be overcome [8; 9]. This problem is intensified by the fact that most research is carried out on a small scale, with technologically complex equipment where scale-up is a challenging step. Consequently, industrial-scale processes based on cyanobacteria still present limitations in biological, engineering, and economic terms [8; 9]. The present study focused on the marine cyanobacterium _Cyanobium_ sp. LEGE 06113 isolated in northern Portugal. It is unicellular with a small size (approx. 1 \(\upmu\)m), it does not form biofilms, and is easily harvestable by centrifugation. Its potential was first proposed as a producer of some bioactive compounds, such as hierridin B and C, with antitumor and antimalarial activities [10; 11; 12], however, the content of such compounds is extremely low, which reduces its interest in favour of the synthetic route [13]. On the other hand, the production and extraction processes of pigments with antioxidant and anti-inflammatory properties have been investigated [14; 15; 16]. Specifically, the process was optimised by focusing on two bioactive pigment extracts from the same biomass, one targeting carotenoids and the other phycobiliproteins. Both pigment extracts can be used in the cosmetic industry, especially considering the short range of species approved for food or nutraceuticalals in Europe. However, all studies with this cyanobacterium have been conducted on a small scale (maximum 20 L). To assess the potential development of a large-scale production process, it is necessary to apply process modelling and software-based tools to estimate the main process flows and thus carry out a preliminary techno-economic assessment. In the framework of cyanobacteria-based production processes, [PERSON] et al. [17] evaluated direct ethanol production using a genetically modified _Synechocystis_ sp. in a 100 m\({}^{3}\) reactor. Other studies on pigments techno-economics can be found for microalgae, including astaxanthin from _Haematococcus pluvialis_[18], \(\beta\)-carotene from _Dunaliella salina_[19], and a carotenoid-rich extract from _Chlorella vulgaris_[20]. Biorefineries routes based on a techno-economics analysis were also reported for pigment production, such as the one proposed for _D. salina_ and _H. pluvialis_ by [PERSON] et al. [21], and comprehensively reviewed by [PERSON] et al. [22] and by [PERSON] et al. [23].