Optimization of Vertical Farming – Economic and Environmental sustainability

Vertical farming (VF) is a method of cultivating plants in vertically stacked layers. Usually coupled with VF are soilless cultivation systems that include hydroponics, aquaponics and aeroponics. Hydroponics is the mostly used method where plant roots are in direct contact with nutrient solution, further on called hydroponic solution. VF is a method of controlled environmental agriculture (CEA), and it offers control over all environmental factors. This control allows for stable productivity and high quality of crops. Two main disadvantages of VF system are high energy consumption which leads to high costs and wastewater management when hydroponics is present. To have an optimization of VF system it is necessary to secure economic sustainability as well as environmental sustainability. Economic sustainability includes cultivation of crops for the biomass production and for the production of high added-value molecules (molecular farming). High biomass yield possible to obtain in VF is contributing but it is not sufficient to sustain high costs, initial and operational, thus molecular farming can be used as an supplementary source of income. In this thesis, two examples of molecular farming are shown. First, where N. benthamiana plants are infected with modified Tomato bushy stunt virus for the production of liprin 1. Liprin 1 is 12 amino acids peptide, and it is a peptide candidate for the treatment of Rheumatoid arthritis (RA). The second example is the production of human enzyme α-mannosidase in transgenic tobacco plants, where recombinant α-mannosidase is used for enzyme replacement therapy. One step closer to complete environmental sustainability is valorization of the wastewater coming from hydroponic cultivation of plants. After the plant growth cycle, hydroponic solution is still rich in nutrients and has to be valorized. One of the possibilities for the use of a spent hydroponic solution is to consume it as a medium for the growth of microalgae C. vulgaris, where nutrients left will be transformed into valuable microalgal biomass. Proof of concept for this method of wastewater management is demonstrated in this thesis. After obtaining useful algal biomass, the next logical step was to find appropriate application. It is known that microalgae can improve the growth of plants acting as biofertilizers or biostimulants. Furthermore, the effect of Chlorella vulgaris was tested on basil plants, when applied as foliar spray or directly added in nutrient solution, with positive results. This thesis offers an insight into possibilities and opportunities for the development of innovative process needed for optimization of Vertical farming through the implementation of main circular bioeconomy concepts.