## 3 Results and Discussion
### Industrial-Scale (100 m\({}^{3}\))

Table 6: Impact assessment results associated with the industrial-scale process (100 m\({}^{3}\)) per batch and per litre of culture, and the respective allocation for each co-product (mass allocation (MA) and economic allocation (EA)). Figure 6: Relative contribution (in %) per subsystem of the industrial-scale process (100 m\({}^{3}\)) to each impact category: global warming (GW), stratospheric ozone depletion (SOD), terrestrial acidification (TA), freshwater eutrophication (FE), marine eutrophication (ME), terrestrial ecotoxicity (FET), freshwater ecotoxicity (FET), marine ecotoxicity (MET), human carcinogenic toxicity (HCT), human non-carcinogenic toxicity (HNCT), fossil resource scarcity (FRS). impacted by the wastewater discharged during the cleaning process, and in S2, which was impacted using sodium nitrate. However, the energy requirements of large-scale production processes have been assessed in detail previously by [PERSON] et al. [17] and [PERSON] et al. [38], and the culture control equipment (i.e., mixing, aeration, and temperature) depends on the time of year and outside temperature. The assessed values are an average for annual consumption in the Netherlands and Portugal. An alternative to reduce the impact is to reduce emissions from downstream processes, such as the dewatering process. Drying is one of the most crucial steps in determining the efficiency of the downstream process for cyanobacteria, and the most common drying methods used in large-scale production are freezing, spray and convection drying, and the feasibility of these methods depends on the desired end-use application [50]. [PERSON] et al. [51] compared conventional convection (tray-) drying, freeze-drying and spray drying for phycobiliprotein extraction in _Arthospira platensis_, leading to the selection of tray-drying (70 \({}^{\circ}\)C for 8 h) as the optimal method, although freeze-drying resulted in high purity of the final product. Furthermore, [PERSON] et al. [43] proposed freeze-drying for the laboratory scale and spray drying for the pilot scale, as this type of equipment is less time-consuming. Furthermore, to reduce the impact on the upstream process, the cyanobacteria could be cultured under the semi-continuous mode, using a fraction of the final culture as pre-inoculum for the next one. A different strain of _Cyanobium_ sp. has been studied in semi-continuous mode before for up to ten cycles on a laboratory-scale [52]. This could represent a reduction of impact from cleaning the reactor and pre-inoculation (S1), which is only needed once every ten batches. Furthermore, the scale-up processing can lead to a substantial decrease in biomass productivity, and on a large scale, the loss can be up to 50% of the production [49]. Considering the previous discussion, a sensitivity analysis was carried out based on four different scenarios for the industrial-scale process, taking into consideration the identified hotspots of the downstream process life cycle: (I1) reducing the biomass productivity by 50% [49]; (I2) the use of spray-drying of biomass [38]; (I3) the use of tray-drying of biomass [51]; (I4) and the use of a semi-continuous process (reduction of S1 impact) [52]. The results of the sensitivity analysis are shown in Figure 7.  
Figure 7: Sensitivity analysis from the industrial-scale process, considering four alternative scenarios: (I1) reducing biomass production by 50%; (I2) the use of spray-drying of biomass; (I3) the use of tray-drying of biomass; (I4) the use of a semi-continuous process (reduction of S1 impact). Impact categories: global warming (GW), stratospheric ozone depletion (SOD), terrestrial acidification (TA), freshwater eutrophication (FE), marine eutrophication (ME), terrestrial ecotoxicity (TET), freshwater ecotoxicity (FET), marine ecotoxicity (MET), human carcinogenic toxicity (HCT), human non-carcinogenic toxicity (HNCT), and fossil resource scarcity (FRS).