Duckweed Final Report

0 Evaluating the Feasibility and Effectiveness of Duckweed Phytoremediation in Lake Sevan An Interactive Qualifying Project Report submitted to the Faculty of WORCESTER POLYTECHNIC INSTITUTE in partial fulfillment of the requirements for the degree of Bachelor of Science By: Eric Bormann Phillip Durgin Alexander Gladu Date: May 12th, 2021 Report Submitted to: Garabet Kazanjian, AUA Acopian Center for the Environment Alen Amirkhanian, AUA Acopian Center for the Environment Advisors: Aaron Sakulich, Worcester Polytechnic Institute Norayr Ben Ohanian, American University of Armenia This report represents the work of WPI undergraduate students submitted to the faculty as evidence of completion of a degree requirement. WPI routinely publishes these reports on its website without editorial or peer review. For more information about the projects program at WPI, please see http://www.wpi.edu/academics/ugradstudies/project-learning.html 1 Table of Contents Abstract 3 Executive Summary 4 Project Goal and Objectives 4 Results of Geographic and Pollution Data Analysis 5 Results of the Assessment of Local Attitudes 6 Results of the Opportunity Analysis 6 Results of the Pilot Farm Development 7 Recommendations 8 Farm Location Recommendations 8 Duckweed Post-Harvest Application Recommendations 9 Farm Design Recommendations 9 Acknowledgments 10 Authorship 11 List of Figures 12 List of Tables 13 Introduction 14 History and Importance of Lake Sevan 17 Table 1. Species Endemic to Lake Sevan 19 Eutrophication, Metal Pollutants and Duckweed Water Treatment 20 Challenges with Maintaining a Duckweed Farm 24 About the AUA Acopian Center for the Environment 27 Summary 28 Methodology 29 Objective 1. Geographic and Pollution Data Analysis 30 Table 2. NSF Water Quality Index Parameter Weights 31 Objective 2. Assessment of Local Knowledge and Attitudes 34 Objective 3. Opportunity Analysis of Duckweed Farming 36 Objective 4. Design of a Duckweed Pilot Farm 41 Results 44 Objective 1. Geographic and Pollution Data Analysis 45 Table 3. Water Quality and Nutrient Concentration Rankings 45 Table 4: Municipality Population Data Circa 2011 47 Table 5: Hydrology Data Calculated for the Gavaraget, Martuni, and Masrik Rivers 47 Objective 2. Assessment of Local Attitudes 48 2 Objective 3. Opportunity Analysis of Duckweed Farming 55 Table 6. Biomass Estimations for the Months Between March and October 56 Objective 4. Design of a Duckweed Pilot Farm 61 Recommendations 67 Farm Location Recommendation 67 Duckweed Post-Harvest Application Recommendation 67 Farm Design Recommendations 72 Conclusions 74 References 76 Appendix A - International Reports of the Ministry of Nature Protection with Wetland Measurements 84 Appendix B - Guiding Questions for Interviews with Municipality Representatives 85 Appendix C - Algorithm Variable Information 86 Appendix D - Ethanol Production Calculations 87 3 Abstract Recurring events of eutrophication, caused by reduced water levels and increased nutrient concentrations, have damaged the Lake Sevan ecosystem. The American University of Armenia’s Acopian Center for the Environment is seeking to use duckweed as an effective, low-cost, and economically beneficial method of phytoremediation. The team identified locations most in need of water treatment, researched the feasibility of post-harvest applications, and determined local attitudes towards the project. Using this information, a pilot farm was designed for future implementation and evaluation. 4 Executive Summary Facing the collapse of its ecosystem due to pollution, Lake Sevan in Armenia is yet another tragic example of the consequences of human exploitation and degradation of natural resources. Our project, sponsored by the American University of Armenia (AUA) Acopian Center for the Environment, was designed to help establish possible approaches that could limit further nutrient and pollutant inflow into Lake Sevan from its tributaries. By doing so, further progress can be made to maintain and restore the fragile ecosystem surrounding the lake through sustainable and economically beneficial methods. The method of phytoremediation which was examined involved the usage of duckweed, a floating macrophyte, to uptake high concentrations of phosphorus and nitrogen from the mouths of rivers flowing into the southern body of Lake Sevan. Previous research has been conducted into the feasibility of using duckweed as a water treatment system. Alongside being able to remove excess nutrients from wastewater, duckweed can remove heavy metals and has many post-harvest applications, making it an ideal plant for phytoremediation systems. Project Goal and Objectives The goal of this project was to determine the feasibility and impact of implementing a duckweed-based phytoremediation system in the tributaries surrounding Lake Sevan. To accomplish this task, objectives were developed in order to effectively work towards the completion of this goal over the duration of the project. An outline of our objectives is displayed in the figure below. 5 1. Objective 1 sought to analyze previously collected water quality data in order to determine rivers able to support duckweed growth with the highest contributions to the eutrophication process. 2. Objective 2 focused on the collaboration with the municipalities surrounding the locations which were best suited for implementation. Interviews were conducted to determine the attitudes towards duckweed farm implementation, as well as to reveal logistical challenges and local concerns. 3. Objective 3 estimated the economic impact duckweed farming would create through its various post-harvest applications in order to incentivize continued collaboration with local municipalities. 4. Objective 4 looked to design a pilot farm with the goal of future implementation. This would allow the Acopian Center to corroborate our research and initial estimations with pilot testing. Results of Geographic and Pollution Data Analysis The work we conducted for our first objective used nutrient concentration and water quality data previously collected for a report conducted under the European Union Water Initiative Plus (EUWI+). Rivers were ranked based upon their phosphate and nitrate concentrations, their ability to support optimal duckweed growth, and their National Sanitation Foundation Water Quality Index score. Through the analysis of the initial three rankings, it was determined that the mouths of the Gavaraget, Masrik, and Martuni rivers were locations most in need of water treatment while still able to harbor and optimize duckweed biomass yield. After ranking the ten rivers and selecting the Gavaraget, Masrik, and Martuni as rivers of interest, Google Maps was used to make a list of various towns and villages situated around the rivers. Eighteen towns were selected for conducting potential interviews. It was also determined through the analysis of hydrology data that the Gavaraget river has the largest contribution of nitrogen and phosphorus, 179,662 kg (396,087 lbs) and 29,619 kg (65,299 lbs) respectively, flowing into Lake Sevan. 6 Results of the Assessment of Local Attitudes To better understand local attitudes towards the implementation of a duckweed phytoremediation system and estimate the support and infrastructure available for farm implementation, representatives from the previously identified municipalities surrounding Gavaraget, Masrik, and Martuni were interviewed. The general consensus was that although most of the communities supported the goal of the project, they felt that there was further testing that needed to take place before their municipalities would be willing to support project efforts. Further information regarding the effectiveness of post-harvest applications and the resources needed for farm development and implementation will need to be provided. Results of the Opportunity Analysis To determine the potential economic benefit of duckweed harvesting, an algorithm was developed to estimate the biomass yield from duckweed farming. This model used a variety of parameters that affect duckweed growth as inputs, including water temperature, photoperiod, pH, and nutrient concentration, in order to apply the procedure in a variety of environments. It was estimated that a total of 1,093 kg/m² (223.864 lbs/ft²) of dry duckweed biomass could be harvested from the Gavaraget River. For the Martuni and Masrik rivers, this biomass value was estimated to be 755 kg/m² (154.636 lbs/ft²) and 774 kg/m² (158.528 lbs/ft²) respectively. After estimating biomass production, research shifted towards duckweed applications. Studies have shown that animals fed with duckweed supplementing comercial feed have a significant increase in size, likely a result of dried duckweed having a high protein content and a low fiber content. While this research has shown that duckweed has several benefits when used as feed for fish and other animals, the amount of duckweed used as feed and when the duckweed is fed to the animals varies depending on the animal. Looking first at poultry, various studies note that chicks have stunted growth when fed duckweed, but older birds were seen to have higher growth rates than their counterparts fed with commercial feed. Despite several studies noting negative effects when fish are fed too much duckweed, the amount of 7 duckweed able to be fed to fish without seeing negative impacts varies study to study and seems to be dependent in part on the species of fish in the studies. Research has also shown duckweed to be a promising standalone fertilizer

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