Modeling duckweed growth in wastewater treatment systems Livestock Research for Rural Development 17 (6) 2005 Guidelines to authors LRRD News Citation of this paper Modeling duckweed growth in wastewater treatment systems (original) (raw)
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Modeling duckweed growth in wastewater treatment systems
Livestock research for rural development, 2005
Species of the genera Lemnaceae, or duckweeds, are floating aquatic plants that show great promise for both wastewater treatment and livestock feed production. Research conducted in the Southern High Plains of Texas has shown that Lemna obscura grew well in cattle feedlot runoff water and produced leaf tissue with a high protein content. A model or mathematical expression derived from duckweed growth data was used to fit data from experiments conducted in a greenhouse in Lubbock, Texas. The relationship between duckweed growth and the total nitrogen concentration in the mediium follows the Mitscherlich Function and is similar to that of other plants. Empirically derived model equations have successfully predicted the growth response of Lemna obscura.
Role of Internal Nutrient Storage in Duckweed Growth for Swine Wastewater Treatment
Transactions of the ASAE, 2005
The objective of this study was to investigate the relationship of the nutrient content of duckweed biomass to duckweed growth in swine wastewater. Batch tests of Spirodela punctata 7776, the selected strain for highest total protein production, were conducted in an environment-controlled growth chamber at 24°C and 16 h of light per day. A prolonged growth period was observed after the nutrients in the medium were exhausted, indicating that duckweed could use its stored nutrients for growth. Prediction of growth using medium concentration as an independent variable was deemed unsuitable to describe this growth. Throughout the 30-day growing period, nitrogen and phosphorus content in the biomass varied from 59.7 to 19.7 mg N /g biomass and from 14.8 to 6.8 mg P /g biomass (dry weight basis), respectively. The relationship between biomass nitrogen content and specific growth rate of Spirodela punctata 7776 was found to follow Monod-type kinetics with m max of 0.24 g N /g biomass /day and K N of 28.8 mg P /g biomass. Reduced growth rate was observed in the duckweed culture with high duckweed density (mass per unit area). Effects of the duckweed density on growth rate and nutrient uptake are modeled and discussed.
A Review on the Role of Duckweed in Nutrient Reclamation and as a Source of Animal Feed
Asian-Australasian Journal of Animal Sciences, 2003
The family of lemnacae colloquially known as duckweed contains the world's smallest species of flowering plants (macrophytes). Aquatic and free-floating, their most striking qualities are a capacity for explosive reproduction and an almost complete lack of fibrous material. They are widely used for reducing chemical loading in facultative sewage lagoons, but their greatest potential lies in their ability to produce large quantities of protein rich biomass, suitable for feeding to a wide range of animals, including fish, poultry and cattle. Despite these qualities there are numerous impediments to these plants being incorporated into western farming systems. Large genetically determined variations in growth in response to nutrients and climate, apparent anti-nutritional factors, concerns about sequestration of heavy metals and possible transference of pathogens raise questions about the safety and usefulness of these plants. A clear understanding of how to address and overcome these impediments needs to be developed before duckweed is widely accepted for nutrient reclamation and as a source of animal feed. (Asian-Aust.
2021 ASABE Annual International Virtual Meeting, July 12-16, 2021, 2021
Sustainable management of leachate produced from the dumpsite is one of the major concerns in developing countries Aquatic plants such as duckweed have the potential to remove pollutants from wastewater which can also be cost-effective and feasible options for leachate treatment. Therefore, the objective of our present study was to examine the growth and nutrient removal efficiency of duckweed (Lemna minor) on leachate. Three tests were performed each by growing lemna minor on synthetic leachate under controlled conditions and on dumpsite leachate under natural conditions. During each test, duckweed was grown in 300 ml plastic containers with a surface area of 25.8 cm 2. About 60 mg of fresh mass of duckweed was grown on 250 ml leachate at an internal depth of 9.5 cm. Results revealed that, in comparison to synthetic leachate, duckweed removed Chemical Oxygen Demand (COD), nitrogen (N), and phosphorous (P) more efficiently from dumpsite leachate under natural climatic conditions. However, the amounts of N and P absorbed into duckweed body mass were about 16% and 35% respectively more at synthetic leachate under controlled conditions. Maximum growth rate of duckweed (7.03 g m-2 day-1) was also observed for synthetic leachate in comparison to the growth rate of 4.87 g m-2 day-1 at dumpsite leachate. Results of this study provide a useful interpretation of duckweed growth and nutrient removal dynamics from leachate under natural and laboratory conditions.
Animal Agricultural Journal, 2013
The research was about investigating the performance of Lemna minor from Lemna spp. of Lemnaceae family when grown for 14 days under 3 different manure types and concentration levels. The beef cattle manure, chicken manure and dairy cattle manure were mixed with 30 liters tap water in a triplicate media concentration of 0g/l, 5g/l and 10 g/l. In addition to the manures 1 kg top soil was added in all experimental units and 20 g of Lemna minor was planted as the initial plant weight. The manure type and manure concentration level were arranged in a 3x3 factorial completely randomized design arrangement and mean comparisons was done with Duncan Multiple Range Test. The results in ANOVA showed that there was significant interaction (F=6.31, p=.0023) as well as significant main effects (F=21.51, p=.0001; F=52.78, p=.001) for FY. For the GR the manure type x concentration level interaction was significant (F=6.30, p=.0024) and type of manure and level of concentration main effects were also significant (F=21.45, p=.0001; F=52.63, p=.0001). Significant interaction was also noticed for CPC (F=28, p=.0001) and significant main effects of manure and concentration (F=72.64, p=.0001; F=29.12, p=.0001). The average pH of the manure solutions before planting and after harvesting was 6.07 and 6.48 respectively. Prior to preparing the mediums duplicate samples of various manure as well as top soil were tested for Kjeldahl Nitrogen on dry matter basis.
Water Research, 2000
AbstractÐThe use of duckweed in domestic wastewater treatment is receiving growing attention over the last few years. Duckweed-based ponds in combination with anaerobic pre-treatment may be a feasible option for organic matter and nutrient removal. The main form of nitrogen in anaerobic euent is ammonium. This is the preferred nitrogen source of duckweed but at certain levels it may become inhibitory to the plant. Renewal fed batch experiments at laboratory scale were performed to assess the eect of total ammonia NH 3 NH 4 nitrogen and pH on the growth rate of the duckweed Spirodela polyrrhiza. The experiments were performed at dierent total ammonia nitrogen concentrations, dierent pH ranges and in three dierent growth media. The inhibition of duckweed growth by ammonium was found to be due to a combined eect of ammonium ions NH 4 and ammonia (NH 3 ), the importance of each one depending on the pH. 7
Duckweed from a Biorefinery System: Nutrient Recovery Efficiency and Forage Value
Energies
This paper presents the results of an interdisciplinary study aimed at assessing the possibility of using duckweed to purify and recover nutrients from the effluent remaining after struvite precipitation and ammonia stripping from a liquid fraction of anaerobic digestate in a biorefinery located at a Dutch dairy cattle production farm. The nutritional value of duckweed obtained in a biorefinery was assessed as well. Duckweed (Lemna minuta) was cultured on a growth medium with various concentrations of effluent from a biorefinery (EFL) and digested slurry (DS) not subjected to the nutrient recovery process. The study’s results showed that duckweed culture on the media with high contents of DS or EFL was impossible because they both inhibited its growth. After 15 days of culture, the highest duckweed yield was obtained from the ponds with DS or EFL contents in the medium reaching 0.39% (37.8 g fresh matter (FM) and 16.8 g FM per 8500 mL of the growth medium, respectively). The recover...
Polish Journal of Ecology
The Monod model describes the relationship between growth rate and ambient nutrient concentration, the Droop model focuses on internal nutrient resources as the driving factor. Both were applied mainly to explain phytoplankton dynamics in lakes or in experimental cultures. Our test plants were two species of duckweeds-Lemna minor L. and Spirodela polyrhiza (L.) Schleiden sampled from 18 natural stands situated in 6 different water bodies. Plants were grown outdoor in original lake water or in mineral media of varying N and P concentrations (0-21 mg N-NO 3 L-1 and 0-1853 μg P-PO 4 L-1 for L.minor and 0-4.2 mg N-NO 3 L-1 and 0-371 μg P-PO 4 L-1 for S. polyrhiza). Moreover, we analysed concentrations of mineral forms of N and P in lake water and tissue nutrient concentrations in plants. Tissue N of both plants was significantly correlated with ambient inorganic nitrogen sources, no such relationship was observed for tissue P. The growth rate of both plants measured under experimental outdoor conditions was better explained by tissue N and P variability (the Droop model) than by the external nutrient availability (the Monod model). The latter also failed to fit the growth rate of both plants in artificial mineral media with a decreasing gradient of N and P concentrations. The plants grew at the expense of internal N and P resources which remarkably declined during 9-day long experiments. Calculated minimum tissue contents (11.19 1.11 mg N g-1 and 0.97 0.07 mg P g-1 in L. minor and 6.10 1.85 mg N and 1.25 0.37 mg P g-1 in S. polyrhiza) show that the latter species would be a superior competitor under N limiting conditions and the former-under P limitation. We confront obtained results with literature data on N uptake kinetics and postulate that the luxury consumption of nutrients and plant growth dependent mainly on internal N and P resources might be an adaptation of duckweeds to varying habitat conditions typical of astatic water bodies.