## 1 Introduction
Currently, existing harvesting methods include mechanical, chemical, biological, and electrical techniques [8]. Harvesting by flocculation or flotation is more economical and suitable for biomass production where high quality is not required for its use. Meanwhile if a higher quality is required in the biomass, the use of centrifugation is recommended, since no chemicals are added for its collection. On the other hand, this technology has a high energy consumption which increases operating costs [29]. It has been reported that carrying out the harvest in two stages increases the efficiency in the collection of biomass [31]. Additionally, the costs associated with the production process and energy consumption are reduced. The first stage consists of enriching the culture medium through flocculation, flotation, gravity sedimentation, electro-flocculation, or ultrasound, and as a second stage, centrifugation or filtration is carried out and with this, the concentration is increased [31; 32]. The costs associated with harvesting the biomass are considerable. It has been reported that the cost of this stage is around 20-30% of the total cost in the production of biodiesel from microalgae [33]. However, these costs depend on the technologies used. At the same time, the selection of technologies depends in most cases on the final destination that the microalgal biomass will have if it will be used for the production of biofuels, obtaining pigments, natural sweeteners, phytochemicals, among others. The harvest stage concentrates the microalgae biomass up to 15-25%, having a large amount of moisture, which would cause an accelerated decomposition of the biomass if it had to be stored for later processing [8]. To avoid its decomposition and so that it can be stored, the biomass must be dried. Drying achieves to concentrate biomass up to 85% to 95% in dry solids [34; 35]. Several drying techniques exist such as solar drying, spray, convection, and freeze-drying; however, the use of these techniques also depends on the final use of the biomass and some of them still have limitations to be used on a large scale. A large amount of research has been carried out related to proposal and evaluation of processes to produce microalgae biomass. Some are proposals on a laboratory scale and do not carry out a techno-economic evaluation. Others do have objective of technically and economically evaluating a particular processing scenario, but only include specific technologies [17; 36; 37; 38]. This has generated different process routes, under different conditions, which complicates their comparison. Few investigations consider comparison of several technologies for their evaluation in same study and that generate different process scenarios. [PERSON] et al. [39] carried out a techno-economic evaluation of two cases of biomass production, where they consider two systems for dewatering. The first case was a conventional clarifier-centrifuge dewatering system, while the second case investigated a single stage dewatering approach, using the wet-end of a paper machine (Fourdrinier former). They determine that the minimum selling cost of the moisture biomass obtained is AU $354.28/ton for the conventional production case and for the second case their minimum selling cost is AU $59.68/ton. Both cases considered the feeding of biomass grown in the open raceway pond, however, they did not consider the cultivation stage in their economic evaluation, but only the technologies for harvesting the biomass. [PERSON] et al. [40] conducted a patent review of technologies applicable to the harvesting of microalgae biomass, based on technological, economic and environmental criteria. The research focused mainly on the technological feasibility of various separation processes. In this research, 13 primary collection methods and eight secondary collection methods were reviewed, focusing on technological, economic and environmental criteria.