ALGAL GRANULE BIOREACTORS FOR NITROGEN AND PHOSPHORUS REMOVAL

• Sponsoring Institution: National Institute of Food and Agriculture
• Project Status: COMPLETE
• Funding Source: HATCH
• Reporting Frequency: Annual
• Accession No.: 1009980
• Project Start Date: Oct 1, 2016
• Project End Date: Sep 30, 2021
• Program Code: [(N/A)]- (N/A)

Recipient Organization
UNIV OF MINNESOTA
(N/A)
ST PAUL,MN 55108

Performing Department
Soil, Water, and Climate

Non Technical Summary
Nitrogen (N) and phosphorus (P) leaching from agricultural fields can cause eutrophication in rivers and lakes. To mitigate this problem, in this project, novel algae granule bioreactors will be developed and applied. Algae grow fast in response to N and P in water, and accumulate these nutrients in their biomass. Therefore, we can reduce N and P concentrations in agricultural runoff water by collecting and removing algal biomass from the water. In addition, denitrifying bacteria may grow using carbon source provided from algae and reduce nitrate to dinitrogen gas. Once we develop N- and P-removing algal granule bioreactors, we will apply these reactors to treat actual agricultural runoff water to examine the feasibility of this approach.

Animal Health Component

0%

Research Effort Categories

Basic

50%

Applied

0%

Developmental

50%

Classification

Knowledge Area (KA)	Subject of Investigation (SOI)	Field of Science (FOS)	Percent
102	0210	1060	50%
402	0210	2020	50%

Knowledge Area
102 - Soil, Plant, Water, Nutrient Relationships; 402 - Engineering Systems and Equipment;

Subject Of Investigation
0210 - Water resources;

Field Of Science
2020 - Engineering; 1060 - Biology (whole systems);

Keywords

water quality

nutrient removal

bioreactor

Goals / Objectives
The overall goal of this research is to improve water quality by reducing N and P concentrations in agricultural runoff water. To achieve this goal, we set the specific objectives as to:1. Develop N- and P-removing algae granules in laboratory-scale bioreactors2. Apply these reactors to treat actual agricultural runoff water and examine the feasibility of this approach

Project Methods
Activity 1: Develop laboratory-scale N- and P-removing algal granule bioreactors Three laboratory-scale bioreactors will be designed and operated to develop the most efficient N- and P-removing algal granules. Lake sediment will be used as a source of algae and microbes. Synthetic agricultural runoff water with known amounts of N and P will be used in Activity 1 for the stable operation of the reactors. Size and density of the granules, as well as N and P removal rates will be measured to evaluate the overall efficiency of the reactors. The reactor operation conditions will be optimized to maximize the granule size and N and P removal efficiencies. Our target N removal efficiency is >90%. The microbial community in the granules will be identified by using next generation sequencing technology.Activity 2: Apply algal granule bioreactors to clean agricultural runoff water Once we develop algal granule bioreactors for N and P removal, we will feed actual agricultural runoff water to the reactors. We will collect several agricultural runoff water samples with various N and P concentrations from different locations across the state. Stable operation of the reactors will be evaluated by the granule size and the N and P removal efficiency. If necessary, reactor operation conditions will be optimized.

Progress 10/01/16 to 09/30/21

Outputs
Target Audience:Minnesota Corn Growers Association Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student was involved in this project during the project period (2016-2021). How have the results been disseminated to communities of interest?We received funding from the MN Corn Growers Association to further support this research. We communicated with them and submitted a report, which is available online to the public (http://www.mncorn.org/research-item/novel-algae-bioreactornutrient- removal-subsurface-drainage-water/). What do you plan to do during the next reporting period to accomplish the goals? Nothing Reported

Impacts
What was accomplished under these goals? We operated a laboratory-scale algal granule bioreactor and tried to improve the N and P removal efficiencies. We obtained algal granules in the reactor setting, but the N and P removal efficiencies were not very high.

Publications

Progress 10/01/19 to 09/30/20

Outputs
Target Audience:Scientific community Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student wasinvolved in this project. How have the results been disseminated to communities of interest? Nothing Reported What do you plan to do during the next reporting period to accomplish the goals?Summarize the data obtained so far.

Impacts
What was accomplished under these goals? 1. N cycling in phototrophic granules in cold environment was clarified. These granules were originally found in aglacier ecosystem, but the same concept can be used to develop phototrophic granules for N removal in agricultural runoff water. The results were published as a journal publication (Segawa et al., 2020). The paper was selected as the journal'sEditor's Choice paper. Cryoconite granules are naturally occurring microbial structures on glacier surfaces worldwide. They play a key role in carbon and nitrogen cycling in glacier ecosystems and can accelerate the melting of snow and ice. However, detailed mechanism of nitrogen cycling in cryoconite granules remains unclear. Here, we demonstrate that redox stratification affects the spatial distribution of N cycling processes in cryoconite granules. Based on microsensor measurements for O2, NH4+, NO2- and NO3-, we identified the presence of fine-scale redox stratification within cryoconite granules. Cyanobacteria at the surface layer of the granules created oxic conditions, whereas the inner core of the granules was anoxic. Metatranscriptomic analyses indicated the active occurrences of nitrification in the inner core, whereas denitrification actively occurred both in the inner core and the surface layer of the granules. Cyanobacteria in the inner core of the granules were inactive, and likely dead and being degraded, providing carbon and nitrogen to support nitrifiers and denitrifiers. Quantities of nitrification genes/transcripts were greater in large cryoconite granules than small ones, most likely because nitrogen substrates were more abundantly present in the inner core of large granules due to distinct redox stratification. Our results suggest that the development of a granular structure of cryoconite granules can largely affect carbon and nitrogen cycling on glaciers. 2. We tried to develop a laboratory-scale algal granule bioreactor with synthetic agricultural runoff water, but the N removal rate was not very high. We will use the knowledge obtained by other environments (e.g., Segawa et al., 2020) to improve the N removal in thereactor.

Publications

• Type: Journal Articles Status: Published Year Published: 2020 Citation: Segawa, T., Takeuchi, N., Mori, H., Rathnayake, R.M.L.D., Li, Z., Akiyoshi, A., Satoh, H., Ishii, S. 2020. Redox stratification within cryoconite granules influences the nitrogen cycle on glaciers. FEMS Microbiology Ecology 96, fiaa199.

Progress 10/01/18 to 09/30/19

Outputs
Target Audience: Nothing Reported Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student wasinvolved in this project. How have the results been disseminated to communities of interest?We received funding from the MN Corn Growers Association to further support this research. We communicated with them and submitted a report, which is available online to the public (http://www.mncorn.org/research-item/novel-algae-bioreactornutrient- removal-subsurface-drainage-water/). What do you plan to do during the next reporting period to accomplish the goals?Summarize the data obtained so far.

Impacts
What was accomplished under these goals? The ammonium, nitrate, nitrite, and carbon concentrations were monitored in a laboratory-scale algal granule bioreactor. We tried to improve the N removal efficiencies by optimizing the reactor operating conditions.

Publications

Progress 10/01/17 to 09/30/18

Outputs
Target Audience:Minnesota Corn Growers Association Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One graduate student got involved in this project. How have the results been disseminated to communities of interest?We received funding from the MN Corn Growers Association to further support this research. We communicated with them and submitted a report, which is available online to the public (http://www.mncorn.org/research-item/novel-algae-bioreactor-nutrient-removal-subsurface-drainage-water/). What do you plan to do during the next reporting period to accomplish the goals?Summarize the data obtained so far.

Impacts
What was accomplished under these goals? The ammonium, nitrate, nitrite, and carbon concentrations were monitored in a laboratory-scale algal granule bioreactor. We tried to improve the N removal efficiencies by optimizing the reactor operating conditions.

Publications

Progress 10/01/16 to 09/30/17

Outputs
Target Audience:Minnesota Corn Growers Association, scientific community, state agency personnel Changes/Problems: Nothing Reported What opportunities for training and professional development has the project provided?One postdoc and one graduate and one undergraduate student got involved in this project. How have the results been disseminated to communities of interest?Outreach activities have not been performed. We communicated with MN Corn Growers Association and received funding from them to support this research. What do you plan to do during the next reporting period to accomplish the goals?Continue maintaining the bioreactors and optimize the nutrient removal rates.

Impacts
What was accomplished under these goals? Laboratory-scale bioreactors were designed and developed. We are currently operating these reactors to enhance N and P removals.

Publications