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Mochrie, Graeme Blance. "Cytokinin synthesis in duckweeds and epiphytic bacteria." Thesis, University of Cambridge, 2002. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.620541.
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Reinhold, Dawn Marie. "Fate of fluorinated organic pollutants in aquatic plant systems studies with lemnaceae and lemnaceae tissue cultures /." Diss., Atlanta, Ga. : Georgia Institute of Technology, 2007. http://hdl.handle.net/1853/26506.
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Thesis (Ph.D)--Civil and Environmental Engineering, Georgia Institute of Technology, 2008.Committee Chair: Saunders, F. Michael; Committee Member: Huang, Ching-Hua; Committee Member: Hughes, Joseph; Committee Member: Loeffler, Frank; Committee Member: Pullman, Gerald; Committee Member: Spain, Jim. Part of the SMARTech Electronic Thesis and Dissertation Collection.
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Storey, Melissa Cameron. "Preference and performance of the water lily aphid (Rhopalosiphum nymphaeae) among native and invasive duckweeds (Lemnaceae)." Click here to access thesis, 2007. http://www.georgiasouthern.edu/etd/archive/summer2007/melissa_c_storey/Storey_Melissa_C_200705_MS.pdf.
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Thesis (M.S.)--Georgia Southern University, 2007."A thesis submitted to the Graduate Faculty of Georgia Southern University in partial fulfillment of the requirements for the degree Master of Science." In Biology, under the direction of Alan Harvey. ETD. Electronic version approved: July 2007. Includes bibliographical references (p. 59-64) and appendices.
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Whitehead, Alan Joseph. "Experimental culture of duckweed (Lemnaceae) for treatment of domestic sewage." Thesis, University of British Columbia, 1987. http://hdl.handle.net/2429/26665.
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The culture of the floating aquatic plant, duckweed (Lemna minor), as an agent of domestic sewage treatment was studied in a clarification lagoon at Duncan, British Columbia, during the summer of 1986. Duckweed was grown in plastic fabric tanks (3700 L volume, 1.85 m deep, 2.25 m² water surface area) receiving 290 L of sewage per day or 12.8 d hydraulic retention time. Three treatments were tested: cropped duckweed, uncropped duckweed, and no duckweed. Water quality, plant growth and tissue composition were monitored on the basis of weekly sampling.
Removals of VSS, COD, total-N and total-P were greater in the presence than in the absence of duckweed. Unmeasured imports of N and P masked the effect of plant uptake on reducing nutrient concentrations in the tank effluents. Sustainable duckweed yields were possible at both cropping rates, despite a severe infestation of aphids. Dry matter yields of 2.0 g/m².d and 6.4 g/m².d were obtained at the 15%/week and 50%/week cropping rates, respectively. Duckweed contained 6.1 - 6.4% N and 1.1 - 1.4% P (dry wt.). Plant harvest removed 0.14 g N/m².d and 0.03 g P/m².d at the 15%./week and 0.31 g N/m².d and 0.07 g P/m².d at the 50%/week cropping rates. Cropping increased the fraction of total-N and total-P loading that could be removed via plant uptake.
Performance of the experimental treatments is analyzed in the light of concentration data, mass balances, and mass flux estimations. Possible sources of unmeasured N and P imports are discussed, and recommendations for future research are provided. The results suggest that duckweed may hold promise under certain conditions as a means of polishing sewage lagoon effluent.Applied Science, Faculty of
Chemical and Biological Engineering, Department of
Graduate
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Cooley, William Edward. "Comparative studies on the modes of action of SC-0224 and glyphosate." Diss., Virginia Polytechnic Institute and State University, 1985. http://hdl.handle.net/10919/54493.
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The biological actions of the herbicides SC-0224 (trimethylsulfonium carboxymethylaminomethylphosphonate) and glyphosate [N-(phosphonomethyl)glycine] (PMG) were compared. In each study trimethylsulfonium iodide (TMS-I) was included as a treatment because the trimethylsulfonium ion is a constituent of the SC-0224 molecular structure.
In inflated duckweed (Lemna gibba L.), both formulated and technical grade forms of SC-0224 were found to be much more phytotoxic to duckweed than either formulated or technical grade forms of glyphosate. The growth inhibition caused by glyphosate was partially prevented by different combinations of the aromatic amino acids phenylalanine, tyrosine, and tryptophan; whereas, the duckweed growth inhibition caused by SC-0224 could not be reduced by the same amino acid combinations. TMS-I and SC-0224 were found to be equally phytotoxic to duckweed. SC-0224 caused larger increases than glyphosate in the pool levels of amino acids; the increases caused by SC-0224 were similar, however, to those caused by trimethylsulfonium iodide. Expressed on a per gram fresh weight basis none of the chemical treatments caused significant changes in soluble protein or the incorporation of ¹⁴C-leucine into soluble protein. On a per flask basis (allowing for decreased growth in treated flasks), both herbicides and TMS-I caused significant decreases in soluble protein and ¹⁴C-leucine incorporation. SC-0224 and TMS-I caused larger decreases than glyphosate in both cases but the SC-0224 and TMS-I treatments were not significantly different. These data indicate that differences in the phytotoxicity of SC-0224 .and glyphosate may be due to the action of the trimethylsulfonium ion of the SC-0224 structure.
The effects of these herbicides on the conversion of shikimate to anthranilate in a cell-free extract of Klebsiella pneumoniae ATCC 25306 were also compared. SC-0224 and glyphosate equally inhibited the production of anthranilate indicating that SC-0224 has action similar to glyphosate on the shikimate pathway.
The effects of these herbicides on photosynthetic electron transport (the Hill reaction) was determined using isolated thylakoids from Alaska pea (Pisum sativum L.). The action of SC-0224 was compared with the action of glyphosate, TMS-I and diuron [3-(3,4-dichorophenyl)-1,1-dimethylurea]. SC-0224, glyphosate and TMS-I did not inhibit the Hill reaction at concentrations up to 10 mM; whereas, diuron caused an almost total inhibition at 0.10 mM. The results of this study indicate that SC-0224 is not an inhibitor of photosynthetic electron transport.
These studies indicate that both constituents of the SC-0224 structure, TMS and PMG, are phytotoxic and may act independently.Ph. D.
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Velásquez, Yorcelis Carmelina Cruz. "Study on the locally available aquatic macrophytes as fish feed for rural aquaculture purposes in South America." Doctoral thesis, Humboldt-Universität zu Berlin, Landwirtschaftlich-Gärtnerische Fakultät, 2016. http://dx.doi.org/10.18452/17510.
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Zur Sicherung der Fischbestände muss die Aquakultur ihren Beitrag zur Weltfischversorgung weiter steigern. Solange jedoch die Fischfutter Produktion stark von der Gewinnung von Fischmehl abhängig ist, bestehen für die Aquakultur natürliche Begrenzungen und die Gefahr der Überfischung der Fischbestände bleibt erhalten. Wenn das Wachstumspotenzial der Aquakultur ausgeschöpft werden soll, müssen beträchtliche Mengen von Nährstoffeinträgen in Form von vollständigen Aquakultur-Mischfuttermitteln auf einer nachhaltigen Basis verfügbar sein. Aufgrund des gestiegenen Preises von kommerziellem Fischfutter sind Kleinproduzenten nicht in der Lage dieses zu erwerben. Daher ist es notwendig, ihnen alternatives Fischfutter zur Verfügung zu stellen. Wasserpflanzen können eine bedeutende Nahrungsquelle für herbivore- und omnivore Fische sein. Dennoch ist die Nutzung dieser Pflanzen als Zusatz für Fischfutter durch eine Reihe antinutritiver Substanzen, welche das normale Fischwachstum negativ beeinträchtigen, begrenzt. Unterschiedliche Behandlungen der Pflanzen können den Anteil an antinutritiven Substanzen reduzieren. Das Ziel dieser Dissertation war es, das nutritive Potential von Wasserpflanzen zu bestimmen. Die Wirkung der Behandlungen wie Sonnentrocknung oder Fermentierung zu bewerten und den Effekt ihrer Nutzung als Fischfutter auf das Wachstum von kultivierten Fischen zu erfassen. Dazu wurden Rationen mit einem geringen Gehalt an Fischmehl (3%) und bis zu 25% der Wasserpflanzen an die Fischspezies P. brachypomus und O. niloticus verfüttert. Die Ergebnisse der Untersuchung zeigen dass, eine ausschließlich auf aquatischen Makrophyten basierende Fütterung nicht empfehlenswert ist. Indem sie jedoch mit anderen lokal verfügbaren Agrar-Nebenerzeugnissen oder sogar mit kommerziellen Futtermitteln kombiniert werden, könnten die Futterkosten erheblich reduziert werden und bäuerlichen Kleinbetrieben eine Möglichkeit zum Wettbewerb auf den lokalen Märkten eröffnen.It is commonly known that aquaculture needs to increase further its net contribution to the total world fish supplies. However, at present almost all farming operations, based on the use of fish feed, are highly dependent on available fishery resources for the production of fish meal, becoming a reducing activity rather than an activity suppling fishery resources. If the aquaculture growth potential is to be maintained, then considerable quantities of nutrient inputs in the form of aquafeeds will have to be available on a sustainable basis. On a long-term the small producers will be unable to depend on commercial aquafeeds based traditionally on fish meal, due to its increased price. Small-scale farmers need an alternative fish feed wherever possible based on the use of non-food grade locally feed resources, which is available in rural areas, is low-cost and is suitable for the proper growth and maintenance of native fish. Aquatic plants are considered important nutritional sources for herbivorous-omnivorous fish. However, the use of plant-derived materials as fish feed ingredient is limited by the presence of wide variety of antinutrients that affect the normal fish growth negatively; so that plants should be processed to reduce the effects of these compounds. Considering these aspects, this study assessed the nutritional potential of aquatic plants available in rural Colombia treated by sun drying and by fermentation and the effect of their use as fish feed on the growth performance of common cultured tropical fish (Piaractus brachypomus and Oreochromis niloticus) fed low fishmeal diets (3%) and until 25% of aquatic plants. The results of this study showed that a feeding exclusively based on aquatic plants is not recommendable; but to combine them with other locally available by-products of agriculture or even with commercial diets might considerably reduce feeding cost and provide to the small-scale farmers the opportunity to compete in local markets.
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Mangum, Lauren Heard. "Treatment of Timtek process water by co-composting and aqueous phytoremediation." Master's thesis, Mississippi State : Mississippi State University, 2009. http://library.msstate.edu/etd/show.asp?etd=etd-04022009-101708.
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Falabi, Ablawa Jeanne. "Pathogen removal from wastewater by a duckweed pond." Thesis, The University of Arizona, 1996. http://etd.library.arizona.edu/etd/GetFileServlet?file=file:///data1/pdf/etd/azu_etd_hy0093_sip1_w.pdf&type=application/pdf.
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Emson, D. "The ecology and palaeoecology of diatom-duckweed relationships." Thesis, University College London (University of London), 2015. http://discovery.ucl.ac.uk/1462713/.
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This thesis focuses on the ecology and palaeoecology of diatom-duckweed relationships and utilises a combined experimental, ecological and palaeoecological approach. In particular, the study sought to determine the potential of the epiphytic diatom Lemnicola hungarica to be utilised as a proxy indicator of past dominance of duckweed (Lemna) in small ponds. To this end, contemporary sampling of epiphytic diatom assemblages from a variety of macrophytes (including multiple samples of free-floating plants) were collected from around the world and analysed for diatom epiphytes. In this study, even despite significant environmental gradients, L. hungarica showed a significant association with free-floating plants (including Lemna spp.) as did Sellaphora seminulum. To determine whether this relationship might be used to infer Lemna-dominance in sediment cores, diatom assemblages were analysed in surface sediments from English Lemna and non-Lemna covered ponds and in a core from a pond (Bodham Rail Pit, eastern England) known to have exhibited periods of Lemna-dominance in the past. In both cases, the data suggested that both L. hungarica and S. seminulum were excellent predictors of past Lemna-dominance. Finally, to infer the consequences of Lemna-dominance for the long-term biological structure and ecosystem function of the Bodham Rail Pit, the sedimentary remains of diatoms, plant pigments, and plant and animal macrofossils were enumerated from two sediment cores. These stratigraphic data were compared with the diatom Lemna-indicator metric which indicated three distinct Lemna cycles. Sediment core analyses suggested major compositional, structural and ecological changes brought about by the Lemna cycles, especially in the submerged macrophyte community and in fish-invertebrate relationships. These data reveal that duckweed proliferation, often brought about by eutrophication and terrestrialisation in ponds, can result in dramatic ecological changes due to a strong physical ecosystem engineering effect.
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Zhao, Xin. "Optimization of the production of bioethanol from duckweed (Lemna minor)." Thesis, University of East Anglia, 2014. https://ueaeprints.uea.ac.uk/54302/.
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This project has investigated the production of bioethanol from duckweed (Lemna minor) biomass. The project includes four main sections: firstly, analysis of the chemical characteristics of duckweed, particularly the polysaccharides of the cell wall; secondly, exploration of suitable commercial enzymes for degrading duckweed biomass to fermentable sugars; thirdly, optimisation of pretreatments and enzymatic saccharification; finally, fermentation and optimisation of the ethanol yield. Pond-grown L. minor contained 51.2 % carbohydrate (w/w dry matter) of which 77 % (including glucose, galactose and xylose) is fermentable. A series of enzymatic hydrolyses was used to evaluate the commercial enzymes and optimise conditions for their use in the saccharification of duckweed biomass. Celluclast 1.5L (CE) and Novozyme 188 (BG) were identified as suitable for hydrolysing duckweed cell walls (prepared as alcohol insoluble residues). The additional use of thermophysical pretreatment (steam explosion) results in a dramatic decrease in the amount of enzyme required for quantitative saccharification. A more advanced commercial cellulase cocktail (Cellic® CTec 2; CTec 2) is likely to further reduce the enzyme cost. Methods for the simultaneous saccharification, using CTec 2 and BG, and fermentation of steam exploded duckweed were developed. These resulted in an 80 % ethanol yield at a diluted substrate concentration (1 % w/v). However the ethanol yield decreased dramatically at higher substrate concentrations (to 18 % at 20 % w/v substrate concentration, which is a highly viscous suspension). Further studies involved the development of approaches to address this: (i) increasing the yeast titre in the inoculum or (ii) growing the inoculum on steam-exploded duckweed. These approaches facilitated an ethanol yield of up to 70 % (w/w) at a substrate concentration of 20 % (w/v). Maximising the final ethanol yield is of great importance in reducing the costs of production. The optimized ethanol production process indicates the technical potential for industrial ethanol production from duckweed. Operating costs have also been estimated and are discussed in relation to the potential exploitation of protein as a co-product.
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Nguyen, Vu, Thi Thuy Trang Nguyen, Thi My Chi Vo, and ThanhSon Dao. "Single and binary effects of atrazine, copper and chromium on duckweed." Technische Universität Dresden, 2019. https://tud.qucosa.de/id/qucosa%3A70809.
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Recently, the agricultural, industrial and mining activities have led to increase in contaminant emission. Trace metals or herbicides are among the pollutants to be concerned in the world. In this study we evaluated the effects of the herbicide atrazine (at the concentrations of 5, 50 and500 µg L-1) and its combination with copper (Cu, 50 µg L-1) and chromium (Cr, 50 µg L-1) on duckweed over the period of 10 days in the laboratory conditions. We found that 50 and 500 µg atrazine L-1 severely impacted on the growth or even caused the death of the plants, whereas there was no statistically significant difference in the duckweed growth rate between the 5 µg atrazine L-1 exposure and control. In the combined treatments (50 µg atrazine L-1 with Cu; with Cr or with both Cu and Cr), the plant growth rate of atrazine with either Cu or Cr was strongly reduced. However, the mixture of atrazine with Cu and Cr did not significantly decrease the development and growth rate of duckweed. Besides, atrazine and investigated heavy metals resulted in turning whiteof duckweek leaves that evidence ofthe chlorophyll degradation. Our results showed the negative influences of the herbicide atrazine and metals on development and morphology of duckweed.Gần đây, những hoạt động nông nghiệp, công nghiệp và khai khoáng đã và đang dẫn đến sự gia tăng phát thải các chất gây ô nhiễm. Kim loại nặng hoặc thuốc diệt cỏ là những chất gây ô nhiễm đang được quan tâm trên thế giới. Trong nghiên cứu này, chúng tôi đánh giá ảnh hưởng của thuốc diệt cỏ atrazine (nồng độ 5, 50 và 500 µg/L) và sự kết hợp của chất này với đồng (Cu, 50 µg/L) và crom (Cr, 50 µg/L) lên bèo tấm trong thời gian 10 ngày trongđiều kiện phòng thí nghiệm. Chúng tôi nhận thấy atrazine tại nồng độ 50 và 500 µg/L đã gây nên những ảnh hưởng nghiêm trọng lên sự phát triển hay thậm chí làm cho bèo tấm bị chết, trong khi đó, không ghi nhận được bất kì sự khác biệt có ý nghĩa thống kê về tốc độ tăng trưởng của bèo tấm giữa lô thí nghiệm phơi nhiễm 5 µg atrazine / L và lô đối chứng. Trong những lô phơi nhiễm kết hợp (50 µg atrazine / L với Cu, với Cr hoặc với đồng thời Cu và Cr), tốc độ tăng trưởng của bèo tấm khi phơi nhiễm với atrazine và Cu hoặc Cr bị giảm mạnh, tuy nhiên, việc phơi nhiễm đồng thời atrazine với Cu và Cr đã không làm giảm đáng kể sự phát triển và tốc độ tăng trưởng của bèo tấm. Bên cạnh đó, atrazine và kim loại nặng đã làm cho màu của lá bèo tấm chuyển sang màu trắng, điều này chứng tỏ có sự suy giảm chlorophyll. Kết quả nghiên cứu này đã cho thấy những ảnh hưởng tiêu cựccủa thuốc diệt cỏ atrazine và kim loại lên sự phát triển và hình thái của bèo tấm.
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Kesaano, Maureen. "Sustainable Management of Duckweed Biomass Grown for Nutrient Control in Municipal Wastewaters." DigitalCommons@USU, 2011. https://digitalcommons.usu.edu/etd/879.
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The use of duckweed as a nutrient removal option for municipal wastewaters can only be realized through regular plant harvesting. As a result, the nutrient-rich biomass generated needs to be effectively managed and disposed of. This study looked at three alternative options for biomass management that would make duckweed-based nutrient removal systems sustainable and attractive to small communities like Wellsville City, Utah. The options included: the use of harvested duckweed biomass as an animal feed, anaerobic digestion of duckweed for methane production, and fermentation of biomass for ethanol production.
Duckweed feed quality was determined using feed analysis reports and results from digestibility studies (in vitro fermentation). The performance of the anaerobic digestion process was determined by monitoring pH, VS, TS, NH4-N, VFAs, and alkalinity. The ethanol production yields were obtained from starch content values and ethanol concentrations observed from batch fermentation experiments.
Duckweed was composed of 21 - 38% crude protein, 94 - 96% water, 78.5% organic matter, < 10% starch and an average of 19% starch after accumulation by nutrient starvation. Relative feed values (RFVs) of 230 - 241, crude protein content of 21-38%, and neutral and acid detergent fiber values of 30.2% and 13.7%, respectively, showed duckweed as a potential feed for ruminants comparable to alfalfa and corn silage (RFVs of 100). Digester performance showed an average methane yield of 6.3 and 5.8 ft3/lb VS destroyed with methane composition values of 67.1% and 62.5% for fresh DW fed reactor (R1) and air dried DW fed reactor (R2), respectively. The ethanol production yield observed was less than 100 mg ethanol/g DW for both fresh and oven dried DW samples. The recommended duckweed biomass management option for a small community like Wellsville is anaerobic digestion because it is a source of energy and at the same time the digestate can be used as a low-quality feed.
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Farrell, Jonathan Bay. "Duckweed Uptake of Phosphorus and Five Pharmaceuticals: Microcosm and Wastewater Lagoon Studies." DigitalCommons@USU, 2012. https://digitalcommons.usu.edu/etd/1212.
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Duckweed species L. turionifera and W. borealis grow on Wellsville Municipal Sewage Lagoons in northern Utah and, when harvested, contribute to the removal of phosphorus and pharmaceuticals from wastewater. Microcosm studies showed that duckweed contains an average of 1% phosphorus (dry weight) and removes 113 mg-P/m2day under 200 μmol/m2sec light. Duckweed in laboratory experiments reduced influent phosphorus ranging from 3.88 to 5.2 mg-TP/L to effluent concentrations of 0.88 mg-P/L in 3 days to 0.16 mg-P/L (0.32 mg-TP/L) with continual harvesting and a liquid retention time of 46 days. Duckweed removal of pharmaceuticals was comparable to removal by membrane bio-reactors. Duckweed removed 99% acetaminophen mainly by plant uptake; 98% progesterone primarily by absorption to plant tissue; 90% fluoxetine by adsorption with some biological removal attributed to plants; and sulfamethoxazole removal varied between 25 to 90% depending on polarity. Carbamazepine did not react with duckweed. Typical influent wastewater concentrations of the five pharmaceuticals in this study were not toxic to duckweed with an EC50 value of 614 μg/L per compound. HPLC/MS detection of pharmaceuticals in liquid samples using solid phase extraction at a neutral pH and silanized glassware produced 92-102% recoveries. Analysis of extracted solids produced lower recoveries. Solid extraction efficiencies ranged from 56-70% for samples stored for 24 hours and decreased with increasing storage time. Field growth studies showed higher than expected duckweed growth rates in the spring compared to three models due to turion germination after the ice melts. The growth rates decreased in the fall due to turion formation in preparation for winter. Harvesting duckweed from the Wellsville Municipal Sewage Lagoons should begin after full surface coverage around June 17th and end when temperatures fall below 15 °C around September 15th. Bi-weekly harvests with a starting plant density of 75 g-dry duckweed/m2 for the lagoons operating at 0.547 MGD and 5 mg-TP/L are required to physically remove enough phosphorus in order to meet the city’s 432 kg-P/yr discharge permit. A duckweed phosphorus harvesting system in Wellsville was estimated to produce enough biomass to meet the P-discharge limit until the flow increases above 0.656 MGD around the Year 2017.
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Chaddick, Justin Garrett. "Sustainable tilapia feed derived from urban food waste." Thesis, Georgia Institute of Technology, 2015. http://hdl.handle.net/1853/54468.
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Finding an alternative to fishmeal and fish oil in animal feeds has been a topic of increasing interest due to the pressures being put on the ocean’s fisheries and the increasing world demand for animal protein. An often-overlooked source of nutrients is in the form of food waste. One third of all food produced globally ends up in landfills, wasting a huge amount of nutrients and embodied energy that could otherwise be redirected towards productive use. This study investigated the feasibility of feeding Hermetia illucens, the black soldier fly larvae (BSFL), grown on urban food waste, and Lemna minor, a species of duckweed, to tilapia in a recirculating aquaponic system as a compound feed. The study compared the growth of two groups of 58 tilapia over 44 days; one group was fed commercial pellets and the other a compound feed composed of BSFL and duckweed. The group fed the commercial pellets achieved heavier weight gain than the group fed the experimental feed but both groups resulted in steady weight gain and had similar mortality rates. Feeding the experimental feed composed of BSFL and duckweed to tilapia in an aquaponics system is an effective method of diverting food waste from the landfill and further research should be done to optimize this process.
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Mohammed, Dana. "Accumulation and toxicity of cadmium, lead and thallium in duckweed (Lemna minor L.)." Thesis, University of Plymouth, 2017. http://hdl.handle.net/10026.1/9285.
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Accumulation and toxicity of cadmium, lead and thallium in duckweed (Lemna minor L.) The toxicity and accumulation of lead, cadmium and thallium in the aquatic plant Lemna minor was investigated, using a modification of the Organisation for Economic Co-operation and Development (OECD) standard growth inhibition test. Plants were cultured in modified Swedish Institute Standard (SIS) at pH 6.5±0.5 under 85 µmol m-2 S-1 at 25°C and exposed to a wide range of lead, cadmium, and thallium concentrations from environmentally realistic to very high concentrations (0.001, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1) for seven days. Various physico-biochemical endpoints were measured after seven days of exposure. The concentrations of dissolved lead, cadmium, and thallium remaining in the residual solutions, and accumulation of lead, cadmium and thallium in fronds and roots were assessed using Inductively Couple Plasma – Mass Spectroscopy (ICP-MS). Over the exposure duration, lead, cadmium, and thallium concentrations in solution decreased rapidly and chlorosis was observed in fronds exposed to the three highest lead, cadmium, and thallium concentrations. After seven days of exposure, there were significant decreases in the relative growth rate (RGR), relative frond area (RFA), pigment content (chlorophyll a, b and total carotenoid) and activity of photosystem II (Fv/Fm) at concentrations of 0.1, 1, 10, 100, 1000 and 10 000 µmol L-1Pb, 10, 100, 1000 and 10 000 µmol L-1cd, 0.01,0.1, 1, 10, 100, 1000 and 10 000 µmol L-1TI. However, our results suggested that root elongation based on relative growth rate of L. minor will be an optimal and relevant endpoint in compare to other endpoints. As expected, results demonstrated that root elongation was concluded that root length was most predictive of a dose response model compared to the rest of growth endpoints and physiological and biochemical endpoints when assessing toxicity of lead, cadmium and thallium using L. minor. Toxicity testing for the floating macrophytes should include root elongation measurement which alone will be sufficient to meet sensitivity and variability requirements for toxicity testing. Cellular concentrations of lead, cadmium, and thallium were higher in roots than fronds, whereas more lead, cadmium, and thallium was adsorbed to the extracellular matrix of fronds than roots. The bio - concentration factor (BCF; i.e. lead concentration in plant tissue at day seven relative to residual lead concentration in the growth medium at day seven) indicates that L. minor is a good accumulator of lead, cadmium, and thallium particularly at lower concentration, but the physiological data shows that these metals toxic at concentrations that can be encountered in wastewater treatment facilities. The translocation factor (TF) value was found to be less than 1. Though, lead, cadmium and Thallium was mostly stored in roots, only minor amounts of lead, cadmium and thallium were trans located to fronds.
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Clark, Piers Benedict. "Enhancing the anaerobic digestion of poultry manure through nutrient supplementation via duckweed biomass." Thesis, University of Southampton, 1994. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.239890.
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Vo, Thi-My-Chi, Minh-Phap Dao, and Thanh-Son Dao. "Growth of duckweed upon exposure to aluminum and atrazine in the laboratory conditions." Technische Universität Dresden, 2018. https://tud.qucosa.de/id/qucosa%3A32724.
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The trace metals and pesticides are commonly found in surface water receiving industrial and agricultural effluents. However, the potential negative effects of these compounds on aquatic ecosystems have not been deeply studied. Hence, the aim of this study is to assess the single and combined effects of aluminum (Al) and atrazine on the development and growth rate of duckweed, Lemna minor L. The single exposures were implemented with either Al or atrazine at the concentration of 5, 50 and 500 μg L-1 and a binary exposure was conducted with 50 μg L-1 of Al and 5 μg L-1 of atrazine for two weeks. The results revealed that both Al and atrazine at the concentration of 500 μg L-1 strongly inhibited the development and growth rate of the duckweed. On the contrary, the mixture of Al and atrazine showed antagonistic effects on the plant. To our knowledge, this is the first report on the combined effects of these two contaminants on the duckweed. Therefore, our results could be useful for environmental managers in setting up and adjusting the safe guideline values in Vietnam for Al and atrazine in natural waters in term of ecological health protection.Kim loại nặng và thuốc trừ sâu thường được tìm thấy trong các nguồn nước mặt, nơi tiếp nhận nước thải công nghiệp và nông nghiệp. Tuy nhiên, những ảnh hưởng tiềm tàng mang tính tiêu cực của những hợp chất này đối với hệ sinh thái thủy vực chưa được nghiên cứu đầy đủ. Do đó, mục tiêu của nghiên cứu này nhằm đánh giá những ảnh hưởng riêng lẻ và kết hợp của nhôm (Al) và atrazine lên sự phát triển và tốc độ sinh trưởng của bèo tấm, Lemma minor L. Sự phơi nhiễm riêng lẻ với Al hoặc atrazine được thực hiện ở các nồng độ 5, 50 và 500 μg L-1, trong khi đó, quá trình phơi nhiễm kết hợp được tiến hành với Al tại nồng độ 50 μg L-1 và atrazine tại nồng độ 5 μg L-1 trong hai tuần. Kết quả cho thấy cả Al và atrazine ở nồng độ phơi nhiễm 500 μg L-1 kìm hãm mạnh mẽ sự phát triển và tốc độ sinh trưởng của bèo tấm. Ngược lại, sự kết hợp Al và atrazine dẫn kết tác động triệt tiêu trên bèo tấm. Theo sự hiểu biết của chúng tôi, đây là ghi nhận đầu tiên về những ảnh hưởng kết hợp của hai chất gây ô nhiễm này lên bèo tấm. Vì vậy, những kết quả này có thể hữu ích cho các nhà quản lý môi trường tại Việt Nam trong việc thiết lập và điều chỉnh các giá trị an toàn đối với Al và Atrazie trong môi trường nước tự nhiên về khía cạnh bảo vệ sức khỏe sinh thái.
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Ardiansyah. "Efficacy of duckweed (Lemna minor Linnneus) integrated in barramundi recirculating aquaculture system (RAS)." Thesis, Curtin University, 2018. http://hdl.handle.net/20.500.11937/81910.
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Six experiments were conducted to evaluate nitrogen uptake capacities of duckweed in barramundi recirculating aquaculture systems (RAS). Harvesting duckweed every four days increased the abundance and diversity of both heterotrophic and phosphate-solubilising bacteria, and maximised nitrogen uptake efficiency. A stocking density of less than 18.75 kg m-3 is recommended for culturing barramundi in integrated RAS. The inclusion of fermented duckweeds up to 35% is feasible without adversely affecting growth and physiological parameters of barramundi.
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Gausman, Maria M. "A COMPARISON OF DUCKWEED AND STANDARD ALGAL PHYTOTOXICITY TESTS AS INDICATORS OF AQUATIC TOXICOLOGY." Miami University / OhioLINK, 2006. http://rave.ohiolink.edu/etdc/view?acc_num=miami1153752259.
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Hounkpe, Wendeou Sèna Peace. "Wastewater treatment and resource recovery for poverty alleviation : a combined duckweed and water hyacinth pond system." Thesis, University of Edinburgh, 2016. http://hdl.handle.net/1842/20965.
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Floating macrophyte pond systems, with the ability to produce nutrient enriched plants simultaneously with wastewater treatment, are a sustainable solution to contribute to environmental protection and safe nutrient recovery from domestic wastewater. However, to meet the requirements for reuse with high strength wastewater containing high levels of metal pollution generated in developing countries, an adequate combination of water hyacinth and duckweed ponds is proposed in order to take advantage of the best characteristics of each of these macrophyte ponds. This research focused on the advancing of the understanding of the effectiveness of treatment and resource recovery under the effect of changing operational parameters such as pH, light intensity, influent metal content and fluctuating pollutants loading rate on pond performance and recycling ability in order to fill the noticed gap of knowledge. Experiments conducted in water hyacinth ponds (WHP), under batch and tropical natural weather conditions, revealed that pH between 6.4 and 7.1, full sunlight and seven days hydraulic retention time were optimum for plant biomass production and pollutant removal in WHP. WHP was able to regulate pH when the initial pH values moved outside this interval with a drop in biomass production as a side effect. These ponds showed a first order kinetic for the removal of iron, zinc and copper from aqueous solution and their accumulation in plants biomass with a preferential sequence Fe > Zn > Cu. However the presence of metals in water hyacinth biomass led to the reduction in ponds performances and a risk of re-pollution of the effluent through the release of metals into water. A comparative study carried out over sixty-two weeks in a pilot scale combined water hyacinth and duckweed ponds (DWP) channel and waste stabilization ponds channel working under fluctuating loading rates showed different environmental conditions occurred these ponds. The fluctuating loading rate was also found to have a reduced effect on the combined WHP/DWP channel performance and effluent quality stability with the effluents meeting the entire reuse requirement at high hydraulic flow rate (retention time greater than 20 days). Fish was able to grow in the WHP/DWP channel. Results suggested some guidelines on WHP/DWP system design, operation and maintenance. The overall outcome of this research is a significant contribution to the development of integrated combined WHP/DWP technology for treatment of wastewater and resource recovery on site.
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Hügel, Stefan [Verfasser]. "Duckweed and Azolla as livestock feed for improving resource efficiency and nutritional quality / Stefan Hügel." Hamburg : Universitätsbibliothek der Technischen Universität Hamburg-Harburg, 2020. http://d-nb.info/1220774979/34.
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Phuong, Hoang Thi Nhu [Verfasser]. "Comparative cytology and cytogenomics for representative species of the five duckweed genera / Hoang Thi Nhu Phuong." Halle, 2019. http://d-nb.info/1176519662/34.
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Pena, Luís Miguel Apolónia. "Depuração de efluente suinícola por Lemna minor e valorização energética da biomassa por co-digestão anaeróbia." Master's thesis, ISA/UL, 2014. http://hdl.handle.net/10400.5/8291.
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Mestrado em Engenharia do Ambiente - Instituto Superior de AgronomiaOver the last decades, phytodepuration has been considered an efficient technology to treat agricultural wastewaters. Swine wastewater is rich in nutrients that can be used to grow biomass, producing a treated wastewater that can be used for irrigation and a biomass that may be useful for potential energy production by anaerobic digestion (AD). In this study a comparative polishing treatment assays were developed, at a bench scale, through Lemna minor growth in swine wastewater (4%) with similar concentration at a real scale last lagoon and Lemna minor growth in synthetic medium. The highest observed growth rate obtained in swine wastewater was 28.7 ± 2.3 g m-2 day-1 or 3.1 ± 0.3 gDM m-2 day-1. The highest nitrogen and phosphorus uptake rates in swine wastewater system were 140 mg m-2 day-1 and 3.47 mg m- 2 day-1, respectively. The COD removal efficiency was 60.0 ± 1.0%. Furthermore, an integrated approach was investigated assessing possible valorisation of biomass by anaerobic co-digestion of swine wastewater with Lemna minor. Results showed a clear improvement in gas production rate and methane specific production in 40% and 44%, respectively, when compared to mono-substrate digestion
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Short, Michael Douglas, and m. short@unsw edu au. "Advanced techniques for the upgrading of waste stabilisation pond effluent: rock filtration; duckweed; and attached-growth media." Flinders University. Medicine, 2008. http://catalogue.flinders.edu.au./local/adt/public/adt-SFU20090408.141832.
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Waste Stabilisation Ponds (WSPs) are a relatively simplistic and non-intensive wastewater treatment technology; with various WSP configurations widely employed to treat a range of different wastewaters the world over. Whilst the advantages of WSP treatment are both numerous and well recognized, performance problems relating to the presence of occasionally large and unpredictable quantities of plankton (both algal and zooplankton) biomass in the final pond effluents have posed significant operational problems for WSP operators; with this suspended biomass representing the single biggest drawback associated with the technology. Research conducted during this project was concerned with assessing a selection of so-called advanced in-pond treatment processes for the upgrading or polishing of a final WSP effluent. The particular research emphasis was on the removal of problematic algal and zooplankton biomass from WSP effluent prior to Dissolved Air Flotation/Filtration (DAF/F) treatment and wastewater reuse at the Bolivar Wastewater Treatment Plant (WWTP) north of Adelaide.
The in situ WSP upgrade systems assessed in this thesis were: the native floating plant Duckweed (DW); Rock Filters (RFs); and an artificial Attached-Growth Media (AGM); all of which were assessed for their relative treatment efficacies parallel to a non-interventional Open Pond (OP) system which served as an effective control. These performance comparisons were assessed on a pilot-scale using a custom made pilot treatment plant which was located at the Bolivar WWTP. Performance monitoring was periodically carried out over a 12 month period from July 2005August 2006, with algal and zooplankton populations monitored in addition to the more conventional wastewater quality parameters.
Results from pilot plant investigations demonstrated that of the four pilot upgrade series, the RF and AGM systems displayed the greatest treatment potential in terms of both the magnitude and reliability of suspended solids, algal and zooplankton biomass removals. The DW system was also shown to be at least as effective and in some instances significantly more advanced than the uncovered OP system in terms of its ability to significantly improve the final effluent quality of the Bolivar WSPs. Both the RF and AGM upgrades (and to a lesser degree also the DW system) were found to offer considerable potential for producing a higher quality WSP effluent for more efficient processing by the Bolivar DAF/F plant; although there were various operational advantages and disadvantages as well as varying capital establishment costs associated with each of the candidate technologies. This part of the research represented the first direct performance comparison between two popular pond upgrade technologies (i.e. RFs and DW) and also constituted the first assessment of a novel AGM for the upgrading of tertiary-level WSP effluent. In addition to this, results from ecological performance monitoring also provided the first detailed insights into algal and zooplankton population dynamics within these WSP upgrade environments.
In addition to these pilot-scale WSP upgrade performance investigations, another branch of the research project investigated additional research questions regarding the survival of algal cells within these pond upgrade environments. A series of laboratory experiments attempted to recreate the in situ conditions (in terms of light and oxygen availability) that might exist within the adopted upgrade environments. Using two common WSP algal species, long-term monitoring of the physiological status of phytoplankton cells during prolonged dark-exposure under conditions of reduced oxygen availability was performed in order to assess the likely effects of these particular environmental conditions on their survival potential in situ.
Results from these laboratory-based experiments showed that both algal species were capable of quickly adjusting their cellular metabolism in response to dark incubation. Results also showed that a reduced environmental oxygen concentration (25% of saturation) had no bearing on the ability of either Chlorella or Chlamydomonas species to withstand long-term dark-exposure; with both species retaining what was essentially full biological viability following up to two months of continuous dark-exposure. In an applied context, these results suggested that subjecting algal cells to conditions of simultaneous darkness and reduced oxygen availability would be expected to have no significant adverse effects on algal survivorship within an advanced in-pond upgrade system such as a duckweed-covered WSP, a rock filter or an AGM system.
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Paterson, Jaimie Bruce. "Removing phosphate from wastewater : evaluation of the performance of duckweed (Lemna minor) operating under cool temperate conditions." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/19177/.
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Reserves of rock phosphate are expiring, increasing the pressure on global agriculture already under stress from growing populations and unsustainable water supplies. The UK imports phosphate for agriculture and primary industries, but subsequently returns much of what it has imported after use as wastes to watercourses through diffuse discharges from agricultural runoff and point discharges from wastewater treatment works. It proves costly to control phosphorus to the low discharge concentrations required in order to avoid eutrophication in water courses. Duckweed is a free floating macrophyte that has been shown to remove large quantities of nutrients from wastewater under tropical and sub-tropical conditions, but its potential for wastewater remediation and nutrient recovery in cool temperate countries is largely unknown. This thesis explores that potential, by exposing the duckweed Lemna minor to simulated and real wastewater treatment conditions of a cool temperate climate, while observing the influence of process variables controlling biomass growth and phosphorus uptake from both growth solution and wastewater. Under controlled microcosm experiments, it was found that the most influential variables controlling biomass growth and phosphorus uptake were photoperiod and acclimation to phosphorus respectively. When duckweed was acclimated to low phosphorus concentrations, cellular phosphate reduced, causing subsequent periods of rapid phosphate uptake when the inoculum was resupplied with higher phosphorus concentrations. As a result, phosphate in solution was removed from 15 mg P L-1 to <0.1 mg L-1 in four days while under simulated UK summer and winter conditions. In mesocosm experiments conducted under continual flow conditions with a hydraulic retention time of two days, it was found that two duckweed tanks in series were able to remove phosphate from wastewater at 10 mg P L-1 to concentrations similar to that achieved by large wastewater treatment works in the UK (< 0.2 mg P L-1). Preliminary results using an outdoor pilot-scale system helped to better understand the challenges of operating within more realistic conditions, as the entire process is profoundly affected by changes in wastewater characteristics feeding the system; however, time constraints prevented a full study to assess the magnitude of such impacts on phosphorus uptake and biomass growth.
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Chaiprapat, Sumate. "Modeling Nutrient Uptake Process and Growth Kinetics of Duckweed Spirodela punctata 7776 for Nutrient Recovery from Swine Wastewater." NCSU, 2002. http://www.lib.ncsu.edu/theses/available/etd-08132002-090507/.
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Use of plants for swine waste management involves the removal of nutrients from the swine wastewater by the plants and the utilization of the plant biomass for other useful purposes such as feed supplement and soil amendment. Duckweed has gained much interest for this purpose in the past decades because of its high growth rate and high protein content. The goal of this research was to study the characteristics of duckweed growth and nutrient uptake from swine wastewater in order to improve the efficiency of duckweed nutrient recovery. In the first part of this research, nutrient distribution and transport in a quiescent duckweed-covered pond containing swine lagoon liquid were investigated and described mathematically. A superior duckweed strain for total protein production in swine wastewater Spirodela punctata 7776 was used as a subject of the study. Diffusive transport of ammonium was shown to be a limiting process in nitrogen removal by duckweed plants in static ponds. In addition, a pH profile developed along the depth of the pond, creating an additional barrier to ammonia volatilization from the pond covered with a duckweed mat. In the second part of the research, growth and nutrient uptake characteristics of Spirodela punctata 7776 in artificial swine medium were examined in sterile batch cultures. Growth of Spirodela punctata 7776 corresponded to the amount of nitrogen storage in its biomass rather than the nutrient concentration in the growth medium. The relationship followed Monod-like kinetics with a maximum specific growth rate of 0.2381 g/g/d. Reduction in the specific growth rate of Spirodela punctata 7776 was observed in the culture with higher crop density, which signified the adverse effects of surface crowding. A mathematical expression to represent the effects of crop density (mass per unit area) on specific growth rate was developed, which can be used in optimization of crop density management in duckweed nutrient recovery systems.
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Reid, Wayne Stanley Jr. "Exploring Duckweed (Lemna gibba) as a Protein Supplement for Ruminants Using the Boer Goat (Capra hircus) as a Model." NCSU, 2004. http://www.lib.ncsu.edu/theses/available/etd-05242004-103543/.
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Duckweed is the common name used to refer to members of the aquatic plant family Lemnaceae. Duckweed commonly grows on stagnant, nutrient enriched waters throughout tropical and temperate zones. Growth conditions include water temperatures of 6 ? 33oC and a wide pH range. Under ideal conditions, duckweed can double its biomass every sixteen hours to four days. Its nutrient uptake capability helps to account for a CP of 15 ? 40% and high growth rate. Scientists have studied duckweed?s feed attributes for fish, poultry, swine, and ruminants. A duckweed feeding trial was carried out at North Carolina State University Metabolism Educational Unit with 19 goat wethers fed four different diets. The objective of the trial was to characterize the composition of wastewater grown duckweed and evaluate its use as a protein supplement for ruminants. Our hypothesis was that duckweed is a suitable protein source for goats and will behave in a similar fashion to soybean meal. The diets included a negative control, positive control (all of the supplemental protein from soybean meal), 1/3 duckweed, and 2/3 duckweed (1/3 and 2/3 of the supplemental protein came from duckweed, respectively). The goats were fed equal amounts of hay and supplement at 4% of body weight (as fed). Duckweed exhibited a similar compositional profile to soybean meal except for being lower in CP and higher in minerals. Amino acid and protein fraction profiles were also comparable between duckweed and soybean meal. There was no significant difference among treatments for DMI, ADF, and NDF digestibility. Nitrogen intake, N digested (g/d), and N retained (% of digested) showed no significant differences among the supplemental protein diets. Nitrogen retained as a percent of intake and N retained (g/d) tended to be slightly lower in the diets containing duckweed. Serum urea nitrogen levels also showed no significant differences for the protein diets except for a linear response (P = 0.09). The P balance showed no significant difference for P intake but both linear and quadratic responses for P retained (g/d), and P digested (g/d) as well as a linear response for P retained (% of digested). Similarities of the rumen pH, NH4 and VFA data among the diets show that duckweed does not abnormally affect rumen function and is comparable to soybean meal in dietary function. Duckweed appears to be a viable source of protein and phosphorus (at lower dietary levels) supplementation for ruminants and is nearly comparable to soybean meal in its utilization.
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Affonseca, Mario Eduardo Pardini [UNESP]. "Avaliação da viabilidade e aplicabilidade de macrófitas aquáticas para polimento de efluentes de estações de tratamento de esgoto doméstico – estudo em escala real." Universidade Estadual Paulista (UNESP), 2016. http://hdl.handle.net/11449/143767.
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Vários estudos já foram realizados no Brasil, a grande maioria em escala de bancada, para avaliação da eficiência de remoção de nutrientes através do uso de macrófitas, atestando a sua viabilidade técnica. Os sistemas de tratamento de esgoto doméstico por lagoas não removem fósforo e nem a amônia, o que tem gerado uma série de problemas para atendimento às exigências legais brasileiras para a qualidade de corpos d’água que recebem esses efluentes. Além disso, o excesso de nutrientes ocasiona problemas ambientais que podem inviabilizar outros usos para esses recursos naturais. A ampla disseminação da tecnologia de tratamento por lagoas de estabilização se deu pelo baixo custo de implantação e operação, e pelos bons resultados para a remoção de parâmetros até o nível secundário. Portanto, o país possui um passivo ambiental significativo, o qual requer melhorias para que se ajuste à realidade que se busca alcançar com as restrições pelos órgãos ambientais e pelo arcabouço legal atualmente existente. Neste trabalho foram realizadas duas baterias de testes em escala real na Lagoa da Estação de Tratamento de Recreio, no Município de Charqueada, SP. Os testes foram feitos em dois períodos sazonais completamente distintos, e demonstraram que as variáveis ambientais como radiação solar, ventos e chuvas exercem influencia direta na capacidade de desenvolvimento e remoção de nitrogênio e fósforo para o grupo de macrófitas Lemnaceae, que se encontrava naturalmente instalado nesse sistema. Apesar disso, os resultados obtidos foram muito promissores, chegando a remoções médias de 75% para ambos os parâmetros, sendo os melhores resultados pontuais obtidos para a amônia. Outras constatações evidenciam a necessidade de aprofundamento quanto a melhor forma e periodicidade de manejo, considerando que não pode ser realizada retirada única com o risco de diminuir a capacidade de competitividade dessa macrófita com as algas, que também geraram impacto negativo nas remoções. Após essas constatações, foi realizado um estudo de viabilidade econômica, onde a alternativa de remoção de fósforo total por macrófitas considerou a mão-de-obra, periodicidade e destinação, com o diferencial de que a Companhia de Saneamento Básico do Estado de São Paulo adquiriu em 2013 um equipamento de baixo custo que permite compostar a massa retirada com o lodo do esgoto e dar uma destinação agrícola ao material final. O Valor Presente Líquido (VPL) foi positivo quando comparado à alternativa de implantar um sistema anexo à lagoa instalada, apenas para polimento; e comparado à implantação de um sistema compacto com remoção físico-química. Ambos os estudos foram analisados apenas para sistemas para remoção de fósforo total (PT), e não considerou a remoção de amônia.
Several studies have been conducted in Brazil, the vast majority in bench scale to evaluate the nutrient removal efficiency through the use of macrophytes, attesting to their technical feasibility. Domestic wastewater treatment systems for ponds do not remove phosphorus neither ammonia, which has generated a number of problems to meet the Brazilian legal requirements for the quality of water bodies receiving these effluents. Furthermore, the excess of nutrients causes environmental problems that may prevent other uses for these resources. The wide spread treatment technology by stabilization ponds was due to the low cost of deployment and operation, and the good results for the removal of parameters to the secondary level. Therefore, the country has a significant environmental liability, which requires improvements to fit the reality that seeks to achieve with the restrictions by environmental agencies and the currently existing legal framework. In this work were two full-scale test batteries in the Lagoon Recreational Treatment Plant in the Municipality of Recreio, SP. The tests were done in two completely different seasonal periods, and demonstrated that environmental variables such as solar radiation, wind and rain have a direct influence on the development capacity and nutrient removal for macrophyte group Lemnaceae which found itself naturally installed on this system . Nevertheless, the results were very promising, reaching mean removal of 75% for both parameters, with the best results obtained for specific ammonia. Other findings highlight the need for further development as the best way and management basis, considering that can not be performed only withdrawal at the risk of reducing the competitiveness capacity of water lettuce with algae, which also generated a negative impact on removals. Following these findings, a study was conducted of economic viability, where the alternative removal by macrophytes considered the hand labor, timing and allocation, with the difference that the Basic Sanitation Company of the State of São Paulo acquired in 2013 one low cost equipment that allows the compost mass withdrawal with sewage sludge and to an agricultural destination to the final material. The NPV was positive when compared to the alternative of deploying an attachment system the installed pond, only for polishing; and compared to the deployment of a compact system with physico-chemical removal. Both studies were analyzed only for systems for removal of PT and did not consider the removal of ammonia.
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Zanetoni, Filho José Antônio. "Cultivo de Landoltia punctata na remoção de desreguladores endócrinos e no polimento de esgoto sanitário em lagoa com recirculação /." Ilha Solteira, 2019. http://hdl.handle.net/11449/182218.
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Orientador: Liliane Lazzari AlbertinResumo: A situação de escassez de recursos financeiros destinados ao tratamento e coleta de esgotos municipais, no Brasil, torna essencial a busca por tecnologias de tratamento que priorizem baixos custos de instalação e operação. Além da negligência que existe no tratamento de esgotos, os métodos utilizados, muitas vezes, não são capazes de remover os micropoluentes que estão presentes nos esgotos domésticos. Os micropoluentes podem ser desde fármacos, que são expelidos na urina ou descartados de maneira inadequada, a hormônios naturais ou sintéticos. Esse trabalho consistiu em realizar um processo de polimento do esgoto sanitário da cidade de Ilha Solteira – SP. O sistema de polimento é constituído por dois tanques, onde foi cultivada a macrófita Landoltia punctata. Foi também avaliado e feito a recirculação do efluente, no tratamento de esgoto. Neste sistema de polimento, foram avaliadas as eficiências de tratamento para os parâmetros de DBO, DQO, NT, NO3-, PT e ST. As maiores eficiências de remoção para DBO, DQO, NT, NO3-, PT e ST foram de 66,35%, 59,08%, 26,76%, 28,38%, 6,85% e 40,08%. Outro aspecto avaliado foi a taxa de crescimento da macrófita cultivada em esgoto sanitário. As maiores taxas de crescimento relativo foram de 3,84 e 3,17 g.m-2.d-1 MS. Considerando a presença de desreguladores endócrinos (DEs) no efluente da Estação de Tratamento de Esgoto (ETE) de Ilha Solteira, foi analisado a absorção dos estrógenos 17α-etinilestradiol (EE2) e o estriol (E3) pela macrófita, av... (Resumo completo, clicar acesso eletrônico abaixo)
Abstract: The scarcity of financial resources for the treatment and collection of municipal wastewater in Brazil makes search for treatment technologies essential with low installation and operation costs. In addition, the methods used are often not able to remove the micropollutants that are present in domestic sewage. Micropollutants can range from drugs that are expelled in the urine or inappropriately discarded to natural or synthetic hormones. This work consisted of a process to polishing the sanitary sewage of the city of Ilha Solteira - SP. The treatment system consists of two tanks, where the macrophyte Landoltia punctata was grown. In one of the tanks, a recirculation system was performed. In this polishing system, the treatment efficiencies for the BOD, COD, TN, NO3-, TP and ST parameters were evaluated. The highest removal efficiencies for BOD, COD, TN, NO3-, TP and ST were 66,35%, 59,08%, 26,76%, 28,38%, 6,85% and 40,08%. Another aspect evaluated was the growth rate of the macrophyte. The highest relative growth rates were 3.84 and 3.17 g.m-2.d-1 MS. Considering the presence of endocrine disrupters (DEs) in the effluent from the Sewage Treatment Plant (ETE) in Ilha Solteira - SP, 17α-ethinyl estradiol (EE2) and estriol (E3) were analyzed on the plant to evaluate possible risks on the reuse of the biomass. The maximum achieved efficiencies for removal of E3 and EE2 were 83.63% and 83.50%, respectively. The recirculation tank was more effective at removing E3, while the non-r... (Complete abstract click electronic access below)
Mestre
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Smith, Ryan Andrew. "Harvesting duckweed by skimming." 2003. http://www.lib.ncsu.edu/theses/available/etd-01272003-121357/unrestricted/etd.pdf.
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Jun-Shiang, Hu, and 胡閏翔. "Floating duckweed - public spaces wooden furniture by hu jun shiang." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/n9wgf8.
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碩士國立新竹教育大學
藝術教育與創作碩士班
103
Abstract Public Art in Taiwan has been getting more and more attention. May it be not as pervasively comprehended and accepted as in other mainstream art countries, we do have our own Taiwan style of art patterns. This discourse on creation is based on the personal observation of the author via the search for public art patterns throughout Taiwan, from which elements were extracted for crating this article "Floating Duckweed - Public Spaces Wooden Furniture". The motive of this artwork creation originated from the exploration of the author's childhood experience of moving, and from which inspirations were extracted to develop three series of creative artwork, themed on public furniture. The purpose of this creative artwork is to let the artistic patterns of public furniture interact with the public, so as to the achieve the objective of "art intimacy with the public". Also, setting out from the author's personal experiences, a venue that allows people's mutual interaction and getting to know one another is created. To fulfill the idea, the author has searched in public spaces for artistic creations embodied in furniture patterns, and explored the creation models of these artists. Seeing these art works personally has widely expanded the author's view on arts. This creative artwork comes with three series: "gathering", "touring", and "leaning", all of which are presented and manifested with tables and chairs in the public furniture forms. Using the image of duckweed, the author tries to symbolize the exterior features of public furniture, with an intention to create a venue that allows the public to take leisure activities and gatherings within. And hopefully, the public's interaction with the creative artwork can ultimately exude the connotation of creation that the author tries to manifest.
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Romão, João Pedro Rosado Tirapicos. "Assessment of the sensitivity of two freshwater macrophytes to the herbicide Roundup." Master's thesis, 2019. http://hdl.handle.net/10773/27475.
Full textAbstract:
Freshwater ecosystems are home to a multitude of species that live in the aquatic environment and are an integral part of the natural communities. Among these, freshwater macrophytes are particularly important, as their functions extend beyond those commonly provided by other freshwater primary producers, creating a variety of microhabitats for other species and being an important part of the ecosystem’s structure as well. The contamination of freshwater systems by herbicides has been recognized for several decades, and is linked with the increasing trends in the use of these pesticides. Glyphosate is the most widely applied herbicide in the world, with its popularity being attributed to the development of the Roundup formulation by Monsanto, which increases the toxicity of the active ingredient to the plants by promoting its penetration into the tissues. In the present dissertation, we assessed the effects of glyphosate and its commercial formulation Roundup to the two water macrophytes, Lemna minor and Lemna gibba. To better understand the impacts these chemicals have on overall plant health, we evaluated the sensitivity of four growth-endpoints (weight, frond number, frond area, and root length), as well as the assessment of sugar profiles as biochemical endpoints, to address the knowledge gap related to non-target biochemical effects of glyphosate in plants. Results evidenced Roundup to be more toxic to both macrophytes than the active ingredient alone, as well as a higher sensitivity of L. minor compared to L. gibba. The lowest EC10 value (0.75 mg a.i. l-1) was obtained for Yield in weight of L. minor exposed to Roundup. Furthermore, root length experienced an abrupt decrease from the concentration of 1 to 3 mg a.i. l-1 in both macrophytes exposed to Roundup, and is argued to be a good bioindicator of pollution by this compound. The concentrations of the different sugars remained unaltered across the evaluated concentrations for both macrophytes, except for the sugar profiles of L. minor, which displayed a significant increase in their content of xylose, galactose, and glucose at the concentration of 5 mg a.i. l-1 of Roundup, relative to the controlOs ecossistemas de água doce alojam múltiplas espécies que habitam no ambiente aquático e formam uma parte integral das comunidades naturais. Entre estes, as macrófitas de água doce são particularmente importantes, uma vez que as suas funções vão para além daquelas comummente prestadas por outros produtores primários de água doce, criando uma variedade de microhabitats para outras espécies e sendo também uma parte importante da estrutura dos ecossistemas. A contaminação de sistemas de água doce por herbicidas tem sido reconhecida há várias décadas e é atribuída à crescente tendência no uso destes pesticidas. O glifosato é o herbicida mais aplicado à escala mundial, devendo a sua popularidade ao desenvolvimento da formulação Roundup pela Monsanto, a qual aumenta a toxicidade do ingrediente ativo para as plantas ao promover a sua penetração nos tecidos. Na presente dissertação, avaliámos os efeitos do glifosato e da sua formulação comercial Roundup a duas macrófitas aquáticas, Lemna minor e Lemna gibba. Para compreender melhor os impactos que estes químicos têm na saúde global das plantas, avaliámos a sensibilidade de quatro parâmetros de crescimento (peso, número de frondes, área das frondes e comprimento da raiz), bem como a avaliação de perfis de açúcares como parâmetros bioquímicos, de forma a colmatar a lacuna de conhecimento relacionada com efeitos bioquímicos não-alvo em plantas. Os resultados revelaram que o Roundup é mais tóxico que o ingrediente ativo para ambas as macrófitas, bem como uma sensibilidade mais elevada de L. minor comparativamente a L. gibba. O valor de EC10 mais baixo (0.75 mg i.a. l-1) foi obtido para o Rendimento de peso em L. minor expostas a Roundup. Adicionalmente, o comprimento da raiz experienciou um decréscimo abrupto da concentração 1 para 3 mg i.a. l-1 em ambas as macrófitas expostas a Roundup, colocando-se a hipótese de este ser um bom bioindicador de poluição por este composto. As concentrações dos diferentes açúcares permaneceram inalteradas para todas as concentrações avaliadas em amabs as macrófitas, com a exceção para os perfis de açúcares de L. minor, os quais apresentaram um aumento significativo no seu conteúdo em xilose, galactose e glucose para a concentração de 5 mg i.a. l-1 de Roundup, relativamente ao controlo
Mestrado em Toxicologia e Ecotoxicologia
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Chou, Wei-Hsueh, and 周煒學. "Consideration for the development of tilapia (Oreochromis spp.)-duckweed (Landoltia punctata) aquaponic system: The use of duckweed as food source for various tilapia sizes and water treatment." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/qkydhn.
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碩士國立臺灣海洋大學
水產養殖學系
105
Abstract The aim of this study was to investigate the effect of feeding of commercial feeds and fresh duckweed on the growth of the fish, growth of the duckweed and its impact in water quality. The experiment is divided into two parts;(1) the duckweed to replace commercial feed, its effect on growth of Red tilapia and in water quality (2) different size of Red tilapia- duckweed fish symbiotic effect in duckweed growth and in water quality. For experiment 1, the purpose of the study was to evaluate the use of duckweed as a replacement of the commercial feed on the fish growth and its effect in water quality. The experiment has three treatments with 3 replicates. Group A for 7 days feeding with commercial feed (no duckweed cage culture), group B and C, both fed with 6 days commercial feed and 1-day fresh duckweed. The difference between the two was for group B no duckweed cage culture inside the tank while group C has. Feed and fresh duckweed (CP: 35.00%; moisture: 92.5%) were fed at 3% of the body weight of the fish. Treatments were fed with the same protein content of 35.83%. Duckweeds was collected once a week (1/2 of the production area). The initial weight of fish was 4.9 ± 0.91 g and cultured for 12 weeks. The results showed that, there were significant differences in food conversion rates between the three groups, which were 2.25, 6.47 and 6.35, respectively. No significant difference was found in total final weight (TFW), total weight gain (TWG), survival rate (SR), feed conversion rate (FCR) and protein efficiency ratio (PER). The results showed that a day of feeding fresh duckweed will not cause growth differences. In terms of water quality, significant differences were found in total ammonia nitrogen (TAN), nitrite (NO2-N), nitrate (NO3-N) and phosphate (PO4-3). It indicates that, the existence of duckweed in the system can effectively reduce the nutrients in the water. For experiment 2, the purpose was to evaluate the effect of different sizes of Red tilapia with the same biomass on the growth of duckweed and in water parameters. Treatments were consisted of two fish sizes: small (8 fish, average body weight: 5.61±2.38g) and medium-sized fish (4 fish, average body weight: 11.20 ±1.17g) with 3 replicates. The experiment was performed with 5 days feeding of commercial feed, 1-day feeding of fresh duckweed and 1-day without feeding and carried out for 8 weeks. The duckweed was collected once a week (1/2 area) and production was recorded. The results showed that, the small-sized fish group had the better growth performance in terms of TFW, TWG and SGR. Medium-sized fish group had the poor FCR and lowest PER. No difference was found in SR. For duckweed growth, small-sized fish had the highest duckweed production. No significant differences were also found among the water parameters, indicating that the nutrients produced by fish are still in the range of absorption capacity of duckweeds. In conclusion, the feeding of commercial feed with duckweeds will not affect the growth performance of the fish. For the duckweed production, small-sized fish was recommended and the best choice.
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Shiau, Yo-Jin, and 蕭友晉. "Photographic Counting of Duckweed and Fish Population by the Mixture-Gaussian Theory." Thesis, 2006. http://ndltd.ncl.edu.tw/handle/67927383908431048109.
Full textAbstract:
碩士國立臺灣大學
生物環境系統工程學研究所
94
This paper discusses the organism-counting ability of the Mixture-Gaussian theory on photograph analysis and video analysis. The test samples of the photograph experiment were the duckweeds in Xin-Hai-Qiao Constructed Wetlands in Taipei County. The actual leaf-covering quantities of duckweeds on five photos were 336, 412, 1010, 1528 and 1928. Without overlapping of leaves, the counting accuracy rates were 95.7%, 76.8%, 68.2%, 82.1 % and 90%, respectively. The major cause of counting errors was water reflection. The video experiment was done in the laboratory and in the field. In the laboratory, three fish sizes were mixed with three kinds of water turbidity in order to find out the counting variables. As a result, when fishes were smaller, the counting accuracy tended to be inaccurate, from 79.7% to 78.4% and 64.2%. Furthermore, the counting accuracy also decreased when water turbidity increased. In fact, the water turbidity was 2.9 NTU, 10 NTU and 15 NTU, and the counting accuracy was 78.4%, 60.4% and 45.5%. In the field, the underwater video camera was placed into Jin-Gua-Liao River in Taipei County to videotape fishes at the riverbed. After the videotape was brought back to the laboratory, it was analysed by the Mixture-Gaussian theory. The counting result of fish-flux was 4.26fish/minm3. As a matter of fact, fish-overlapping and fish-shadows of close swimming at the riverbed truly affected the counting accuracy. The study shows that it is possible to consider the Mixture-Gaussian theory as an evaluation method of organism-counting in the field of ecological engineering.
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Tsai, Pen-Chun, and 蔡本均. "Toxic effects of common herbicides on duckweed (Lemna aequinoctialis Welwitsch) in Taiwan." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/4rb8w9.
Full textAbstract:
碩士國立中興大學
生命科學院碩士在職專班
106
This study is a toxicity experiment conducted on Lemna aequinoctialis, a native aquatic vascular plant, using 17 commonly used herbicides in Taiwan to assess the risks they present to non-target aquatic plants in the aquatic environment. These herbicides include Haloxyfop, Quizalofop, Alachlor, Butachlor, Metolachlor, Ametryn, Atrazine, Simazine, 2,4-D, Fluroxypyr, Pyrazosulfuron-ethyl, Glufosinate, Glyphosate, Bentazone, Liuron, Diuron and Pendimethalin. The ecological and toxicological data of the environmental impact of herbicides used in flooded farm fields are lacking in Taiwan. Currently, algae are the most commonly used biological indicators for assessing eco-toxicity. However, they cannot represent at all the impact on aquatic vascular plants due to differences in exposure time and species-specific sensitivity. In addition, Lemna aequinoctialis is small and simple in structure with only leaves and roots, and it grows rapidly, doubling in quantity in about 2-3 days. Its ease in cultivation and sensitivity to toxicity makes it suitable for assessing the ecological risks of contaminants in the environment. This experiment assesses the toxicity of herbicides based on how much they suppress the growth of Lemna aequinoctialis (exposure time of 4 days and 7 days). The findings show that Pyrazosulfuron-ethyl presents the highest toxicity to the species with Ametryn coming in second. Fluroxypyr, Haloxyfop and Quizalofop have low toxicity, and 2,4-D and Glyphosate have mild toxicity; these herbicides are considered safe to aquatic organisms at the recommended dosage. All the other herbicides have severe or moderate toxicity based on the estimated environmental concentration (EEC), presenting potential hazard to aquatic organisms even at the recommended dosage. Referencing the Risk Quotient (RQ) of the US Environmental Protection Agency (EPA) to calculate the concentration of each herbicide at the recommended dosage, we find Glyphosate to be the only one with RQ＜1. All the others have very high RQ values on aquatic invertebrates. This finding is consistent with the toxicity level of the herbicides on Lemna aequinoctialis.
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Lin, Yen-yu, and 林彥妤. "The Physiological Adaptation Following Exposure of Common Duckweed (Lemna minor) to Diethyl Phthalate (DEP)." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/24332948374596297155.
Full textAbstract:
碩士國立臺南大學
生物科技學系碩士班
101
The toxicity and effects of diethyl phthalate (DEP) on the growth of duckweed (Lemna minor)were studied. Biochemical analyses and physiological methods were combined to investigate oxidative stress, adverse effects and their mechanisms in duckweeds grown in 0–100 μM of diethyl phthalate (DEP) after cultivation for 12 days and grown in 100 μM of diethyl phthalate (DEP) after cultivation for 0,1,6 and 12 days. The results showed that the effect of DEP on plant growth and photosynthetic pigment contents. The inverted U-shaped curves were exhibited in relative frond number (RFN), fresh weight/dry weight (FW/DW) ratio revealing damaging effect in plant growth. The results showed that J-shape concentration response curves were displayed in ascorbate peroxidase (APX) and gualacol peroxidase (POD) activities, indicating reduced oxidative stress and toxic effect. The inverted U-shaped curves were also found in malondialdehyde (MDA) and H2O2 contents with the increasing concentration of DEP, indicative of enhanced oxidative stress. The results suggest that DEP is toxic to the duckweed by inducing oxidative stress and antioxidative enzymes may play important roles in the defense strategy against DEP toxicity.
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CHUANG, CHIEH, and 莊捷. "Effects of Diethyl Phthalate on the Efficiency of Photosystem II in Greater Duckweed (Spirodela polyrhiza L.)." Thesis, 2016. http://ndltd.ncl.edu.tw/handle/95429691533971945816.
Full textAbstract:
碩士國立臺南大學
生物科技學系碩士班
104
Plasticizes (PAEs) bear numeral functions, such as adjusting the hardness and luster of product, cost reduction...etc, allowing them to be widely used in industries, for instances, plastic additives. However, this prevailing substance has great impact on our environments. Absorption by plants and animals can lead to tissue lesions after accumulation within individuals. Diethyl phthalate (DEP), a member of PAEs, is commonly used in solvents, nursing supplies, ink, and other items. Though having lower toxicity compared to other plasticizers, DEP can still pose safety concerns due to discharging into rivers and lakes after over-usage. In this study, we choose Spirodela polyrhiza L. Schleid. as our sample. By using JIP-test, we analyzed the effect caused by DEP on the donor side, the receptor side and reaction center of photosystem II (PSII) based on fast chlorophyll fluorescence induction dynamics analysis. The result indicates that DEP will affect the electron transfer efficiency of oxygen-evolving complex (OEC) downstream receptors. Reaction center activity was not good during primary light reaction at J site, suggesting that the redox efficiency was decreased between QA and QB. On the other hand, the rise of O site of Spirodela polyrhiza in fluorescent curve under DEP treatment implies that the light absorption complexes of PSII (LHCII) may be damaged, resulting in the rise of basic fluorescent value. Meanwhile, dissipated energy in PSII increased drastically, thus decreasing the energy transferred by electron transport chain. In summary, the photosynthesis efficiency of Spirodela polyrhiza decreases significantly under DEP treatments.
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Lyerly, Courtney Neil. "Swine wastewater treatment in an integrated system of anaerobig digestion and duckweed nutrient removal pilot study /." 2004. http://www.lib.ncsu.edu/theses/available/etd-01092005-001638/unrestricted/etd.pdf.
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Short, Michael Douglas. "Advanced techniques for the upgrading of waste stabilisation pond effluent rock filtration; duckweed; and attached-growth media /." 2008. http://catalogue.flinders.edu.au/local/adt/public/adt-SFU20090408.141832/index.html.
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Bouda, Sana, and 鮑達山. "Primary-level Use of Duckweed and its Meal, Rice Bran, and Blood Meal as Feedstuff for Tilapia Culture." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/24047070514391131801.
Full textAbstract:
碩士國立臺灣海洋大學
水產養殖學系
93
In developing countries not having aquaculture industry, it is very necessary to develop relevant fish diets based on locally available and low cost foodstuffs. Five experiments were conducted indoor to determine best ways to produce duckweed, and its use with rice bran and blood meal to efficiently feed juvenile tilapia at farm level. Experiment 1- Productivity of Lemna perpusilla and Spirodela polyrrhiza was comparatively tested in various environments. Duckweed productivity in spring was higher than that in winter. L. perpusilla had higher productivity than S. polyrrhiza. Sediment was a steady nutrient provider and consequently favored duckweed productivity. One-time fertilization did not have effects on nitrogen nutrient in water nor duckweed productivity. Besides productive species, optimal growing season, contribution of nutrients from sediment, and routine harvesting should be also taken into account in duckweed culture. Experiment 2- We studied feeding preference of 3 sizes of juvenile tilapia for L. perpusilla and S. polyrrhiza. Fish preferred L. perpusilla. Duckweed fronds width appeared as a factor affecting such preference. Experiment 3- We assessed the effect of fish stocking density on ingestion of duckweed at 2 temperatures. At 24oC, ingestion rate increased with stocking density but not in the case at 27oC. Specific and various behaviors that affected feeding of fish were observed at 1 and 2 fish/bucket. Experiment 4- The efficiency of fresh L. perpusilla, pure L. perpusilla pellet and L. perpusilla mixed with rice bran pellet was determined. Pelletization of L. perpusilla reduced dietary performance as compared to fresh material, while 25% rice bran incorporation increased pellet dietary performance. Methionine supplement through rice bran inclusion could explain such improvement. Experiment 5- The optimal percent of blood meal in rice bran pellet in terms of palatability, and food utilization, between 5, 12, 20, 27, 33, 40% was determined. Blood meal inclusion negatively affected feed intake rate; 7.9% blood meal level was found as maximum giving highest feed intake rate. Among the diet types tested, one with 12% blood meal gave the best fish growth and food utilization.
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Коршняков, Едуард Валентинович. "Чутливість індикаторних організмів до забруднення води нафтопродуктами." Магістерська робота, 2020. https://dspace.znu.edu.ua/jspui/handle/12345/4173.
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Коршняков Е. В. Чутливість індикаторних організмів до забруднення води нафтопродуктами : кваліфікаційна робота магістра спеціальності 101 "Екологія" / наук. керівник К. О. Домбровський. Запоріжжя : ЗНУ, 2020. 59 с.UA : В роботі 59 сторінка, 7 таблиць, , було використано 53 літературних джерел, із них 21 іноземною мовою. Об’єктом дослідження водне середовище забруднене нафтопродуктами Предметом дослідження є реакція організмів на вміст у середовищі існування нафтопродуктів. Методами дослідження було біотестування з адопомогою макрофіту та зообентосу наявності у водному середовищі нафтопродуктів Метою кваліфікаційної роботи було з’ясувати можливість використання при біотестуванні забруднення води ряску малу та ракушкового ракоподібного Cypridosis vidua. Теоретично та експериментально визначеноВсі апробовані показники фітотесту із використання Lemna minor та Cypridopsis vidua може бути використано для розроблення експрес-методики щодо визначення токсичності води забрудненої мастильно-охолоджуючою рідиною. Найбільш індикативними показниками для визначення присутності у водному середовищі відпрацьованої мастильно-охолоджуючої рідини для Lemna minor є ростові параметри надводної частини, а саме кількість листців у рослини. Зафіксовано пригнічення росту всіх досліджуваних показників при біотестуванні розчинів досліджених нафтопродуктів. Біотестування водного середовища на присутність мастильно-охолоджуючої рідини за допомогою Cypridopsis vidua є більш ефективним, ніж за допомогою Lemna minor через надто чутливу реакцію ракоподібних на вміст нафтопродуктів у середовищі існуванні. Метод біотестування водного середовища за допомогою Cypridopsis vidua є більш доцільними для використання за умови незначної токсичності, й порівняльним аналізом з іншими тест-об’єктами.
EN : In page 59, 7 tables, 53 literature sources were used, 21 of them in a foreign language. The object of study is the aquatic environment contaminated with petroleum products The subject of the study is the reaction of organisms to the content in the habitat of petroleum products. The research methods were biotesting with the help of macrophyte and zoobenthos presence of petroleum products in the aquatic environment The purpose of the qualification work was to find out the possibility of using duckweed and shellfish Cypridosis vidua in biotesting of water pollution. Theoretically and experimentally determined All tested phytotest parameters using Lemna minor and Cypridopsis vidua can be used to develop a rapid methodology for determining the toxicity of water contaminated with lubricating and cooling fluid. The most indicative indicators for determining the presence in the aquatic environment of spent coolant for Lemna minor are the growth parameters of the surface part, namely the number of leaves in plants. Inhibition of growth of all investigated indicators at biotesting of solutions of the investigated oil products is fixed. Biotesting of the aquatic environment for the presence of lubricating coolant with Cypridopsis vidua is more effective than with Lemna minor due to the overly sensitive response of crustaceans to the content of petroleum products in the environment. The method of biotesting the aquatic environment with Cypridopsis vidua is more appropriate for use with low toxicity, and comparative analysis with other test objects.
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Huebert, David B. "The effect of biological and chemical factors on the uptake and toxicity of cadmium in the duckweed Lemna trisulca L." 1992. http://hdl.handle.net/1993/18534.
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Jie, Luo, and 羅捷. "The Effects of Light Regime and Nutrient on the Growth of Duckweed (Lemna minor) and their Application on the Aquaponic Culture with Red Tilapia (Oreochromis niloticus)." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/b92fk3.
Full textAbstract:
碩士國立臺灣海洋大學
水產養殖學系
105
Duckweed is an aquatic plant that can play the best role in an aquaponics system for its being very productive and capable of cleaning the water in which the aquatic animal inhabits. Here we used Lemna minor, one of the most studied duckweed species. In Experiment 1 (Chapter 2), we successfully employed image analysis system to get covering area of duckweed and estimate duckweed fresh dry weight through weight-area correlation analysis. Considering the convenience and popularity of smart phone, we would prefer it for image taking to digital camera. Equipped with this effective tool to estimate duckweed biomass, we were then able to find out the factors affecting duckweed growth in the following experiments, such as light source and photoperiod (Experiment 2 – Chapter 3) and light intensity and nitrogen nutrient (Experiment 3 – Chapter 4). Both LED white and fluorescent T5 achieved better duckweed growth and nutrient stripping than LED blue, but no difference in between of the former two. LED white was the preferred light source for its higher energy saving than fluorescent T5. Photoperiod had no effects on duckweed growth. However, 16L:8D was chosen for its higher nutrient stripping than 12L:12D but similar performance as 24L:0D. Light intensity at 50, 110 and 220 PPFD (mol m-2s-1) exhibited no effects on duckweed growth and nutrient stripping. Concomitantly, light intensity at 50 mol m-2s-1 should be used if the facility environment met, such as light tube specification and accommodation space. The highest nitrogen nutrient level, 40 mg L-1 total nitrogen (TN) was recommended since it resulted in higher duckweed growth than the other two lower levels, 20 and 10 mg L-1 TN. While the optimal light regime and nutrient level for duckweed’s growth and nutrient stripping became available, we were readily to conduct aquaponics study with duckweed (Experiment 4 – Chapter 5). Red tilapia (Oreochromis niloticus) were chosen because it is easily observe nitrogen metabolism and affect nitrogen nutrient cycle in the system. Disregarding the difference in animal or plant density at present study, duckweed can effectively improve water quality in tilapia aquaponics system as compared to tilapia alone aquaculture system.
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Phunsin-Kantha and 甘富信. "The Effects of Light Regime and Nutrient on the Growth of Duckweed (Spirodela polyrhiza) and their Application on the Aquaponic Culture with Red Tilapia (Oreochromis niloticus) or Crayfish (Procambarus clarkii)." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/832mgd.
Full textAbstract:
碩士國立臺灣海洋大學
水產養殖學系
105
Duckweed is an aquatic plant that can play the best role in an aquaponics system for its being very productive and capable of cleaning the water in which the aquatic animal inhabits. Here we used Spirodela polyrhiza, one of the most studied duckweed species. In Experiment 1 (Chapter 2), we successfully employed image analysis system to get covering area of duckweed and estimate duckweed fresh dry weight through weight-area correlation analysis. Considering the convenience and popularity of smart phone, we would prefer it for image taking than digital camera. Equipped with this effective tool to estimate duckweed biomass, we were then able to find out the factors affecting duckweed growth in the following experiments, such as light source and photoperiod (Experiment 2 – Chapter 3) and light intensity and nitrogen nutrient (Experiment 3 – Chapter 4). Both LED white and fluorescent T5 achieved better duckweed growth and nutrient stripping than LED blue, but no difference in between of the former two. LED white was the preferred light source for its higher energy saving than fluorescent T5. Photoperiod had no effects on duckweed growth. However, 16L:8D was chosen for its higher nutrient stripping than 12L:12D but similar performance as 24L:0D. Light intensity at 55, 110 and 220 PPFD (mol m-2s-1) exhibited no effects on duckweed growth and nutrient stripping. Concomitantly, light intensity at 55 mol m-2s-1 should be used if the facility environment met, such as light tube specification and accommodation space. The highest nitrogen nutrient level, 40 mg L-1 total nitrogen (TN) was recommended since it resulted in higher duckweed growth than the other two lower levels, 20 and 10 mg L-1 TN. While the optimal light regime and nutrient level for duckweed’s growth and nutrient stripping became available, we were readily to conduct aquaponics study with duckweed (Experiment 4 – Chapter 5). Red tilapia (Oreochromis niloticus) and red swamp crayfish (Procambarus clarkii) were chosen as the animals since finfish and crustacean, respectively, may exhibit different nitrogen metabolism and affect nitrogen nutrient cycle in the system. Although total ammonia nitrogen and total nitrogen concentration in crayfish aquaponics system were higher than those in tilapia system, the duckweed growth remained similar. Disregarding the difference in animal or plant density at present study, duckweed can effectively improve water quality in either tilapia or crayfish aquaponics system as compared to tilapia or crayfish alone aquaculture system.