User:Schmtim/sandbox

Spirodela Polyrhiza

Spirodela Polyrhiza Modified wiki-entry Properties Use S. polyrhiza is a perennial aquatic plant usually growing in dense colonies, forming a mat on the water surface. Each plant is a smooth, round, flat disc 0.5 to 1.0 cm wide. Its upper surface is mostly green, sometimes red, while the lower surface is dark red. (Wiki deutsch) It produces several minute roots. It also produces a pouch containing male and female flowers. The top part dies in the fall and the plant often overwinters as a turion. S. polyrhiza, living in ponds and slow-moving water bodies, differs developmentally from terrestrial plants in morphology and physiology. It undergoes mainly vegetative growth in spring and summer, forming new fronds. S. polyrhiza only flowers rarely (Landolt and Kandeler 1987). In autumn and winter it switches into a dormant phase represented by turions in due to nutrition starvation and freezing temperatures. Turions could also be induced by the plant hormone ABA in the lab. Researchers reported that turions were rich in anthocyanin pigmentation and had a density that submerged them in liquid media. Transmission electron microscopy l of turions showed in comparison to fronds shrunken vacuoles, smaller intercellular space, and abundant starch granules surrounded by thylakoid membranes. Turions accumulated more than 60% starch in dry mass after two weeks of ABA treatment (old Wiki aricle, copied) Distribution S. polyrhiza is found worldwide, namely in North America (Gobotany), Asia (Pandey et al), more rarely in Central and South America, but also in Central Europe (Flowgrow ). It grows in tropical and temperate climates (Flowgrow). It is not found in New Zealand and only rarely in Australia. (Buch) Use S. Polyrhiza can be used for bioremediation, removing toxic substances from aquatic environment as well as cleaning eutrophic waters, especially in wastewater treatment plants. Its uses as biofuel and animal feed are also gaining importance. Bioremediation Because of its capability to hyperaccumulate heavy metals and its high uptake of nutrients from the water, S. polyrhiza is used for bioremediation. The main pollutants it can be used to remediate is Arsenic (As) and Mercury (Hg) (Rahman and Hus) and common wastewater Nutrients, like Sulphate (SO42-), Phosphate (PO43-) and Nitrate (NO3-). Arsenic Greater duckweed showed accumulation of arsenic in laboratory tests. Arsenic uptake was found to be negatively correlated with phosphate and positively correlated with iron uptake. This indicates that phosphate and arsenic compete for uptake by S. polyrhiza, while arsenics’ absorption is facilitated by iron oxides, because it shows an affinity to the root surface of S. polyrhiza, where it is taken up. S. polyrhiza is thought to detoxify the Arsenic by reducing As (V) to the less toxic As (III). Difficulties arise with the management of the plants with high As contents. One possible use of the biomass containing As is production of charcoal and gas as a byproduct, which can be used as a fuel. The problems with this approach are low charcoal quality and high investments. Direct burning or burning of the coal is thought to release arsenic into the air, which would pollute the environment. Other options for fuel production would be Hydrolysis and fermentation, which are economically not feasible because the biomass would have to be treated with strong acids and heat, which are too capital intensive. Briquetting is considered one of the best options, where the plants are dried and pressed into pellets of briquets. This also raises the question of whether the arsenic is released back into the environment during the burning process. The production of biogas is also considered, but again, the redistribution of the As has to be avoided (Rahman and Hus)

Mercury S. polyrhiza was found to be an efficient bio accumulator of mercuric chloride (HgCl2) in labor settings. Its plant biomass showed a 1000 times higher concentration than its aquatic environment. This is higher than Lemna gibba and Lemna minor, which were also investigated (Yang et al.).

Urban wastewater treatment S. Polyrhiza has been used for urban wastewater treatment, to remove common pollutants from wastewater. In a laboratory setting, S. Polyrhiza has a maximum of 90% removal efficiency of NO3-, 99.6% of PO43- and 69.8% SO42-. All three nutrients together, the efficiency is 85.6%, which makes it an environmentally and economically viable bioremediatory for wastewater treatment. (Pandey et al.)

Biofuel S. polyrhiza has great potential in bioethanol production due to space-efficient starch production and good growth in animal wastewater (Cui and Cheng 2015). Despite environmental problems associated with production and competition from human and animal feed, corn is the main raw material for bioethanol. S. polyrhiza could produce up to 50% more bioethanol on the same area (Xu et al. 2011). At the same time the production of bioethanol from S. polyrhiza is not in competition with human food. The production of bioethanol from S. polyrhiza is still in the development phase.

Animal feed In small-scale agriculture S. polyrhiza is used as fish or poultry feed (Rusoff et al. 1980). Due to its fast growth and high protein content it is an interesting feedstuff. Due to sanitary problems and the risk of heavy metal accumulation, it is not yet used for feeding in larger animal husbandry systems (van der Spiegel, Noordam, and van der Fels-Klerx 2013). For rainbow trout, poorer growth rates were found when S. polyrhiza was added to the feed (Stadtlander et al. 2019). For tilapia, Oreochromis niloticus L. greater weight gains were found when 30% of the fish meal in the feed was replaced with S. polyrhiza (Fasakin, Balogun, and Fasuru 1999). A review of Sońta, Rekiel, and Batorska (2018) has also shown that duckweed can be used in cattle, pig and poultry diets. There too there are problems of heavy metals and pathogen contamination.

Literature Cui, W., and J. J. Cheng. 2015. “Growing Duckweed for Biofuel Production: A Review.” Plant Biology. Fasakin, E. A., A. M. Balogun, and B. E. Fasuru. 1999. “Use of Duckweed, Spirodela Polyrrhiza L. Schleiden, as a Protein Feedstuff in Practical Diets for Tilapia, Oreochromis Niloticus L.” Aquaculture Research. Landolt, Elias, and Riklef Kandeler. 1987. “Biosystematic investigations in the family of duckweeds (‘Lemnaceae’). Vol. 4 : The family of ‘Lemnaceae’ : a monographic study. Volume 2.” Veröffentlichungen des Geobotanischen Institutes der Eidg. Tech. Hochschule, Stiftung Rübel, in Zürich 95:1. Sońta, Marcin, Anna Rekiel, and Martyna Batorska. 2018. “Use of Duckweed (Lemna L.) in Sustainable Livestock Production and Aquaculture - A Review.” Annals of Animal Science 19(2):257–71. van der Spiegel, M., M. Y. Noordam, and H. J. van der Fels-Klerx. 2013. “Safety of Novel Protein Sources (Insects, Microalgae, Seaweed, Duckweed, and Rapeseed) and Legislative Aspects for Their Application in Food and Feed Production.” Comprehensive Reviews in Food Science and Food Safety 12(6):662–78. Stadtlander, Timo, Svenja Förster, Dennis Rosskothen, and Florian Leiber. 2019. “Slurry-Grown Duckweed (Spirodela Polyrhiza) as a Means to Recycle Nitrogen into Feed for Rainbow Trout Fry.” Journal of Cleaner Production 228:86–93. Xu, Jiele, Weihua Cui, Jay J. Cheng, and Anne M. Stomp. 2011. “Production of High-Starch Duckweed and Its Conversion to Bioethanol.” Biosystems Engineering.