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With a growing world population and the concentration of citizens in big cities new methods of agriculture are required. Vertical farming attracts more attention in mending these growing problems. To enable a widespread use of low-cost hydroponic systems this study investigates minimal requirements for plants (different herbs and vegetables) in such a hydroponic vertical farming system and the suitability of textiles as sustainable substrates. Therefore, this study aims to investigate plant stress levels, germination rates and water usage in a low-cost hydroponic system with no special lightning in principle comparison with indoor cultivation in soil. The results of the pulse-amplitude-modulation (PAM) measurements as measure of photosynthetic performance indicate that the plants were equally stressed in hydroponic and in soil cultivation. In this respect, the photosynthetic quantum yield in both cultivation systems is on average only slightly lower than the values expected under optimal conditions. It was observed that chive and lovage not only had a significantly higher germination rate in the hydroponic system but also accumulated significantly more fresh as well as dry biomass, while spinach, thyme and marjoram showed higher germination rates in soil cultivation. The water consumption in the setup was considerably higher for the hydroponic system compared to indoor soil cultivation. [ABSTRACT FROM AUTHOR]

The green microalgae Chlorella vulgaris can be used in diverse applications from food to biofuel production. Growing them in suspension leads to challenging harvesting and processing. One possibility to overcome these problems is growing them as biofilms, i.e. adhering on a surface. While previous experiments of several research groups concentrated on flat, rigid surfaces, partly chemically modified, here the possibility to grow them on different textile substrates was investigated which were shown to be suitable as substrates for germination and growth of higher plants. Microalgae were counted after one week, subdivided into adhered and suspended ones, to evaluate the ideal substrate for cultivation and harvesting. The results show clear differences between the different woven and knitted fabrics from diverse materials, indicating that especially an open-pore jute woven fabric increased the overall algae concentration by approx. a factor of 2 and increased the adhesion of C. vulgaris by a factor of 5-10, as compared to most other textile substrates under investigation, followed by two other hairy knitted fabrics. Such textile fabrics can thus be suggested as possible substrates for improved growth and harvesting of this microalga. [ABSTRACT FROM AUTHOR]

Due to their large inner surface, nanofiber mats are often used in tissue engineering and examined with respect to cell adhesion, e.g., for cultivation of fibroblasts. The combination of different polymers with a large contact area, however, could also be used for growth of different plants including green microalgae. Here, the cultivation of the microalga Chlamydomonas reinhardtii on different polymer substrates was examined. We investigated growth on two nanofiber mats consisting of polyamide (PA6) and polyacrylonitrile (PAN) and a polypropylene (PP) microfiber mat as substrates, compared with a pure multi-well plate. It was found that the algae were able to grow on all textile mats without change in morphology, indicating that all polymers were non-toxic to the cells. Thus, these nonwovens might be suitable filters for the separation of microalgae in biotechnological processes. [ABSTRACT FROM AUTHOR]