Essential Nutrient Additions for Algal Bioremediation of Reverse Osmosis Treated Landfill Leachate

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Title:
Essential Nutrient Additions for Algal Bioremediation of Reverse Osmosis Treated Landfill Leachate
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Journal of Undergraduate Research
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English
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Brene, Adrian
Wilkie, Ann
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University of Florida
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Gainesville, Fla.
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Liquid wastes from landfills, termed landfill leachates, must be managed on a daily basis and for many years after a landfill is closed. Reverse osmosis (RO) is an experimental method for landfill leachate treatment. At the Alachua County Southwest Landfill, the process uses a two-stage RO filtration system to reduce ammoniacal nitrogen to groundwater cleanup target levels. Pairing RO with algal bioremediation may eliminate the need for the second RO treatment step. Primary RO treatment removes nutrients essential for algal growth and therefore adding nutrients to primary RO permeate should increase both algal growth rates and bioremediation rates. The alga Scenedesmus sp. was cultured in primary RO treated landfill leachate with elemental additions and compared with a control. A customized nutrient medium containing essential macro and micronutrients was shown to provide increased algal growth and remediation rates. Landfill leachate was tested as a source of micronutrients and shown to provide equivalent growth and remediation as the customized micronutrient solution, suggesting that low concentrations of landfill leachate may be a viable option as a micronutrient supplement to support algal bioremediation of RO treated landfill leachate.

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University of Florida
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sobekcm - UF00091523_00602
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University of Florida | Journal of Undergraduate Research | Volume 15, Issue 3 | Summer 2014 1 Essential Nutrient Additions for Algal Bioremediation of Reverse Osmosis Treated Landfill Leachate Adrian Brene and Dr. Ann C. Wilkie College of Agriculture and Life Sciences University of Florida Liquid wastes from landfills, termed landfill leachates, must be managed on a daily basis and for many years after a landfill is closed. Reverse osmosis (RO) i s an experimental method for landfill leachate treatment. At the Alachua County Southwest Landfill, t he process uses a two stage RO filtration system to reduce ammoniacal nitrogen to groundwater cleanup target levels. Pairing RO with algal bioremediation m ay eliminate the need for the second RO treatment step. Primary RO treatment removes nutrients essential for algal growth and therefore adding nutrients to primary RO permeate should increase both algal growth rates and bioremediation rates The alga Scenedesmus sp. was cultured in primary RO treated landfill leachate with elemental additions and compared with a control. A customized nutrient medium containing essential macro and micronutrients was shown to provide increased algal growth and remediation rates. Landfill leachate was tested as a source of micronutrients and shown to provide equivalent growth and remediation as the customized micro nutrient solution, suggesting that low concentrations of landfill leachate may be a viable option as a micro nutrie nt supplement to support algal bioremediation of RO treated landfill leachate. INTRODUCTION Landfills, the primary means of solid waste disposal, are a current global environmental concern. One of the prim ary concerns with landfills is the production of landfill leachate, a liquid waste generated as water percolates through a landfill. Landfill leachate contains various organic and inorganic compounds dissolved from the accumulated solid waste. Many of the constituents of leachate are toxic or hazardous (Pablos et al ., 2011) and therefore must be managed and remediated prior to discharge. An emerging leachate treatment method is reverse osmosis (RO) filtration. This method involves forcing leachate through a semi permeable membrane at high pressure, allowing water to pass, but retaining much of the suspended and dissolved solids on the membrane (Renou et al. 2008). At the Alachua County Southwest L andfill (ACSWL) in Archer Florida, an experimental RO filtr ation system is currently operating to determine the feasibility of RO in the treatment of landfill leachate ( Edmundson and Wilkie, 2013). After membrane filtration, RO treated landfill leachate passes all necessary treatment parameters except for the conc entration of ammonia nitrogen, which is an order of magnitude higher than groundwater cleanup target levels (FDEP 2005) Therefore, the current design incorporates a two stage RO filtration system. However, even after the second RO treatment the leachat e still does not meet groundwater cleanup target levels. Eliminating the need for the secondstage RO filtration would reduce the operating costs of the RO treatment system. In this study, algae were employed to remediate ammonia nitrogen within the primary RO treated landfill leachate, referred to as primary RO permeate. Algae are known to uptake and synthesize ammonia nitrogen in to cell biomass. Primary RO treatment removes nutrients essential for algal growth Therefore, i n order to remediate permeate at the highest rate, nutrient supplementation is vital to supporting algal growth. An essential nutrient medium can be based on the elementa l composition of macronutrients in Scenedesmus obliquus, as provided by Krauss and Thomas (1954). This study was based on growing the alga in 300L polyethylene lined vats under constant light and temperature in a controlled environmental chamber with a stream of 5% carbon dioxide in air. Growth was measured by means of cell count, dry we ight, and packed cell volume; analyses of cells harvested daily established the range of inorganic composition in algae grown in both complete and micronutrient deficient cultures. In addition to the composition of the major macronutrient constituents of t he alga, the study also indicate d that the reduction in availability of micronutrients is a major limiting factor in the growth of alga in mass culture; supplementary addition of micronutrients permitted resumption of rapid growth ( Krauss and Thomas, 1954) The current study determined the feasibility of an essential nutrient medium in providing higher algal growth and ammonia remediation rates in permeate. OBJECTIVE The objective of this study was to d erive a simple, essential nutrient medium supplement based on the elementa l composition of Scenedesmus obliquus This medium would support higher algal biomass production

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ADRIAN BRENE AND ANN C. WILKIE University of Florida | Journal of Undergraduate Research | Volume 15, Issue 3 | Summer 2014 2 and effective reductions in the ammonia nitrogen content of permeate, with algal growth rate positively correlating with remediation rate. METHODS Medium Development Concentrations of nutrient s upplements w ere determined from the potential amount of algal biomass producible from the concentration of ammonia nitrogen in primary RO permeate, based on the elementa l composition of Scenedesmus obliquus provided by Krauss and Thomas (1954). T hus, t he maximum biomass produc tion potential of Scenedesmus in permeate under optim al conditions is 1.8 g/L Nutrients already present in permeate (Table 1) were subtracted from required supplement concent rations The macronutrient supplement wa s based on the aforementioned calculations derived from the elementa l composition of Scenedesmus obliquus (Table 2), and was therefore named the Krauss Thomas M edium (KTM) T he micronutrient supplement was composed of the trace metals and their respective concentrations given by Bolds Basal Medium (BBM) including FeSO4, ZnSO4, MnCl2, Na2MoO4, CuSO4, and Co(NO3)2, but not including any other components from BBM as formulated by Andersen (2005). Algae Cultivation A species of Scenedesmus originally collected and isolated from the ACSWL site was used as the primary test organism in this medium nutrition study. Inoculation densities of 10% (v/v) were used to initiate algal cultures in primary RO permeate, with or without nutrient supplementation. Th e experiment included triplicate cultures of four treatments receiving different nutrient additions: a negative con trol with no nutrient addition, a positive control with 10% Bolds Basal Medium (10% BBM), an experimental treatment with customized macronutrient supplement as well as a micronutrient supplement (KTM+ M icronutrients ), and another experimental treatment with the customized macronutrient supplement and 1% (v/v) leachate (KTM+1% L eachate ) C ulture volumes of 100 mL were placed in 300 mL Erlenmeyer flasks sealed with rubber stoppers to limit ammonia volatilization (Figure 1) All cultures were placed on an orbital shaker at 150 rpm under fluorescent illumination. The average light intensity across the bottom panel was ~100 sensor ( Li Cor LI 1400). Ill u mination was provided on a 12 hour cycle. Total ammoniacal nitrogen (TAN) within the algae cultures was measured approximately every 12 hours using an ionselective electrode ( Orion 95 12) according to standard methods (APHA, 2012 ). Growth was measured as optical density based on absorbance at 680 nm, using a Genesys 10vis spectrophotometer Table 1. Nutrient Concentrations in Primary Reverse Osmosis Permeate Component Concentration ( mg/L ) Ammonia N 120.00 Nitrate 0.35 Phosph orus 0.09 Potassium 41.00 Magnesium 0.43 Iron 0.14 Figure 1. Algae cultures at initiation of experiment, from left to right (in triplicate) : Control, 10% BBM, KTM+ M icronutrients KTM+1% L eachate. Table 2 Elementa l Composition of Scenedesmus and P ermeate Amended for G rowth of Scenedesmus Element % Dry Weight of Algae Biomass (Scenedesmus) ** Concentration in Amend ed Permeate (mg/L) Nitrogen 6.8 120* Phosphorus 1.42 20.51 Sulfur 0.34 4.86 Potassium 1.41 20.39* Magnesium 0.54 7.84 Already p resent in ACSWL permeate ** Krauss and Thomas 1954

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ESSENTIAL NUTRIENT ADDITIONS FOR ALGAL BIOREMEDIATION OF REVERSE OSMOSIS TREATED LANDFILL LEACHATE University of Florida | Journal of Undergraduate Research | Volume 15, Issue 3 | Summer 2014 3 RESULTS Growth of Scenedesmus was highest and very similar in the two KTM custom media experimental treatments KTM+Micronutrients and KTM+1% Leachate (Figure 2 ). Although the micronutrient treatment experienced the highest growth rate in the first 12 hours, the 1% leachate treatment experienced higher growth in the second 12 hours, catching up to the micronutrient treatment and eventually surpassing it slightly in total algal growth. This suggests th at 1% leachate may be a viable option as a micronutrient supplement. Bioremediation results correlated with growth results and were highest in the micronutrient and 1% leachate treatments, with TAN reductions of 73% and 71%, respectively compared to only 29% in the control (Figure 3) The average TAN remediation rate reached 2.53 and 2.88 mgN/L/hour in the KTM+Micronutrients and KTM+1% Leachate treatment s, respectively compared to 1.16 mgN/L/hour for the control (Figure 4) Figure 2. Growth of Scenedesmus in primary reverse osmosis permeate with nutrient supplements ( mean SD n=3) Figure 3. Algal bioremediation of primary reverse osmosis permeate with nutrient supplements ( mean SD n=3) 0.25 0.35 0.45 0.55 0.65 0.75 0.85 0 12 24 36 48 60Absorbance (680nm) Elapsed Time (Hours) Control 10% BBM KTM+Micronutrients KTM+1% Leachate 10 20 30 40 50 60 70 80 90 1000 12 23Total Ammoniacal Nitrogen (mgN/L) Elapsed Time (Hours) Control 10% BBM KTM + Micronutrients KTM+1% Leachate

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ADRIAN BRENE AND ANN C. WILKIE University of Florida | Journal of Undergraduate Research | Volume 15, Issue 3 | Summer 2014 4 Figure 4 Nitrogen r emediation rates of Scenedesmus in primary reverse osmosis permeate with nutrient supplements ( mean SD n=3) DISCUSSION The customized KTM was determined to be an effective macro nutrient medium for Scenedesmus growth in primary RO permeate under the conditions tested. The results indicate that KTM with added micronutrients provides higher growth and remediation rates than no nutritional supplement, as well as 10% BBM. Also, landfill leachate can supply the necessary micronutrients at a rate of 1% (v/v) in primary RO permeate. These results show that this customized nutritional supplement can be used for future studies in growing algae in permeate, as well as for future experiments in large scale remediation. Using an effective bioreactor design in unison with this nutrient medium may prove to be an economic or even profitable way of remediating permeate, practically eliminating the need for second stage RO filtration. This approach may be implemented at landfills which employ RO filtration, or in similar situation s which may require secondary treatment of highly hazardous wastewaters, especially those with higher ammonia concentrations. Interestingly, the culture receiving 1% landfill leachate had a slightly higher rate of remedi ation, perhaps due to the addition of trace metals or other growth factors not included in the customized micronutrient solution. Advantages of adding landfill leachate as a source of nutrients are the readily available quantity at the landfill site and th e low cost of adding this to the algae culture. Additionally, using leachate contributes to the management and volume reduction of the landfill leachate. FUTURE STUDIES The development and testing of the customized KTM allows the simplified medium to be used in future experimental work. Further optimization can improve resource efficiency by testing nutrient uptake ( e.g. residual phosphorus in solution) and reducing the amount of nutrients added. Using the predetermined concentrations found here or in fu ture experiments, more sustainable macronutrient sources with known nutrient concentrations may then be provided or assessed in terms of bioavailability and growth/remediation. ACKNOWLEDGEMENT S This research was conducted as part of the BioEnergy and Sustainability School (BESS), a summer internship program for undergraduates sponsor ed by the Florida Agricultural Experiment Station, UF IFAS Funding was provided by a grant from the Waste Management Division, Alachua County Public Works Department, Gainesville, Florida. REFERENCES Andersen, R. A. (2005). Alga l c ulturing t echniques Boston, MA: Elsevier Academic Press. APHA (20 12). Standard m ethods for the examination of water and wastewater (22nd ed. ). Washington, D.C. : American Public Health Association American Water Works Association, and Water Environment Federation. Edmundson, S. J. and Wilkie, A. C. (2013). Landfill leachate a water and nutrient resource for algae -based biofuels. Environmental Technology 34 1849 -1857. http://dx.doi.org/10.1080/09593330.2013.826256 FDEP (2005). Technical R eport : Development of Cleanup Target Levels ( CTLs ) for Chapter 62777, F.A.C. Tallahassee, FL: Division of Waste Management, Florida Department of Environmental Protection. http://www .dep.state.fl.us/waste/quick_topics/publications/wc/Final GuidanceDocumentsFlowCharts_April2005/TechnicalReport2Final Feb2005(Final3-28 -05).pdf Krauss, R. W. and Thomas W. H. (1954) The g rowth and i norganic n utrition of Scenedesmus obliquus in m ass c ulture Plant Physiology 29, 205 214. doi :10.1104/pp.29.3.205 Pab los, M. V., Martini, F., Fernndez, C., Babn, M. M., Herraez, I., Miranda, J., Mart nez, J., Carbonell, G., San -Segundo, L., Garc a Hortigela, P., and Tarazona, J. V. (2011). Correlation between physicochemical and ecotoxicological approaches to estimate landfill leachates toxicity. Waste Management 31, 18411847. doi:10 .1016/j.wasman.2011.03.022 Renou, S., Givaudan, J. G., Poulain, S., Dirassouyan, F., and Moulin, P. (2008). Landfill leachate treatment: Review and opportunity. Journal o f Hazardous Materials 150 468 493. doi:10.1016/j.jhazmat.2007.09.077 0 0.5 1 1.5 2 2.5 3 3.5 Remediation Rate (mg N/L/hour) Nutrient Treatment