Developing a Naturally-Derived Nutrient Solution Using

Recirculating Aquaculture EffluentJoe Tetreaulta, Todd Guerdata, Paula Mouserb, Michael Timmonsc

University of New Hampshire, Department of Agriculture, Nutrition, and Food Systems

University of New Hampshire, Department of Civil and Environmental Engineering

Cornell University, Department of Biological and Environmental Engineering

Seafood Production in the United States

• US is the largest importer and consumer of seafood• Ranks 15th globally in production• Untapped Domestic Market

• US generated $362 billion from seafood industry 2016• Over 60% of revenue came from aquaculture

• Aquaculture has grown by more than 5% in the past decade• Commercial fishing dropped 15% since 1990

• Land-based aquaculture most sustainable• Decreased water usage, recycling nutrients• IF we can handle the waste load• Recirculating aquaculture systems fastest growth

FAO.org

Recirculating Aquaculture Systems• Culture water is treated through

solids separation and biofiltration

• Water reuse rates > 95%• Solids removal results in concentrated

waste which requires treatment prior to discharge• Why not [re]use the wastes as a

resource?

Re-Thinking Waste Management to Stimulate US Aquaculture Growth

•Operating costs limiting the growth of domestic RAS

•RAS waste management is internalized unlike animal agriculture• Aquaculture is agriculture• Waste reutilization similar to conventional

agriculture monetizes RAS waste stream

•Developing a nutrient solution is economically and environmentally sustainable • Improve nutrient utilization efficiency, reduces

nutrient mass discharge of waste nutrients from RAS• Enables USDA Organic certification for hydroponic

growers

Terrestrial Agriculture Waste Management

Key macronutrients for plant growth are abundant in the manure of the most commonly farmed livestock

Image retrieved from: umnextenstion.com

Typical RAS Waste Management Approach

Current Approach• Treated to acceptable limits (C, N, P) and

discharged into rivers• EPA sets discharge limits for each water body

• Some facilities discharge to municipal wastewater treatment systems• Costly!

• Solid waste management remains an internalized cost for RAS producers• Increases break-even costs for producers• Results in higher market price for consumers

Why Aren’t RAS Wastes Utilized?• High liquid content is not conducive to land based

agriculture• >95% moisture content• Soil application becomes hydraulically-limiting

• Better suited for aquatic-based agriculture • Hydroponics – soilless, crop production using aqueous

nutrient solutions

• Nutrient profile and availability questions• Are plant macro/micro nutrients present?• Are the nutrients plant-available?• Microbes matter, not soil

RAS Waste Solids: Nutrient ProfilesTilapia Waste Profile

Brown Trout Waste Profile

Nutrient N P K Ca Mg S Fe Mn B Cu Zn Mo Na Al

Solid Mass* 1.57 0.23 0.01 0.50 0.05 283.07 63.62 47.76 128.37 3.71 54.88 0.37 458.37 562.63

Solid Conc (mg/L) 51.34 7.52 0.33 16.35 1.63 0.93 0.21 0.16 0.42 0.01 0.18 0.00 1.50 1.84

Liquid Conc (mg/L) 99.95 1.08 251.73 35.47 17.15 21.96 1.97 0.22 0.00 0.04 0.78 0.08 30.85 1.13

Total Mass (mg/L) 151.28 8.60 252.06 51.82 18.78 22.89 2.18 0.38 0.42 0.05 0.96 0.08 32.35 2.97

% Mass Liquid 66% 13% 100% 68% 91% 96% 90% 58% 0% 77% 81% 99% 95% 38%

Nutrient N P K Ca Mg S Fe Mn B Cu Zn Mo Na Al Solid Mass* 1.22 0.24 0.05 0.45 0.06 366.03 640.67 22.57 126.79 10.58 39.90 1.39 390.35 588.63

Solid Conc (mg/L) 19.03 3.74 0.78 7.02 0.94 0.57 1.00 0.04 0.20 0.02 0.06 0.00 0.61 0.92Liquid Conc (mg/L) 16.11 2.77 14.13 29.69 9.25 12.50 0.01 0.06 0.00 0.00 0.07 0.08 54.00 0.99Total Mass (mg/L) 35.14 6.51 14.91 36.71 10.19 13.07 1.01 0.10 0.20 0.02 0.13 0.08 54.61 1.91

% Mass Liquid 46% 43% 95% 81% 91% 96% 1% 63% 0% 0% 53% 97% 99% 52%

* Solid Mass of N-Mg reported in % of TSS, S-Al reported in mg/kg

Is Microbial Digestion the Answer?

Capitalizing on a Wasted Potential• Macro/micro nutrients for plant growth are

present

• High liquid content is ideal for direct application in hydroponic systems

• Both RAS and hydroponic industries will benefit from the development of a natural fertilizer

• Need to make the nutrients plant-available!

Microbial Nutrient Solubilization• Utilizes microbes (bacteria) to breakdown

organic matter• Aerobic vs. Anaerobic treatment

• Commonly employed methods already in municipal WWTX and large-scale RAS• Potentially capitalizes on existing infrastructure

• End result is reduced BOD, TOC, and solubilized nutrients• Ideally-suited for existing hydroponic infrastructure• Plant-available!

Preliminary Microbial Digestion Research

• Characterized different microbial digestion methods• Quantified nutrient solubilization

rates

• Lab-scale anaerobic and aerobic digestors constructed• Mesophilic Temperatures• Treated tilapia & brown trout wastes

• Bioreactor progress tracked through TDS, FSS, and EC• Additional operating parameters

included pH, alkalinity, DO, TAN

Preliminary Tilapia Results

15-Apr 20-Apr 25-Apr 30-Apr 5-May 10-May0

1000

2000

3000

4000

5000

6000

Filterable Suspended Solids

Aerobic Mesophilic

Date

mg/

L

15-Apr 20-Apr 25-Apr 30-Apr 5-May 10-May0

200

400

600

800

1000

1200

1400

Total Dissolved Solids

Aerobic Mesophilic

Date

mg/

L

15-Apr 20-Apr 25-Apr 30-Apr 5-May 10-May0

0.20.40.60.8

11.21.41.61.8

Electrical Conductivity

Aerobic Mesophilic

Date

mS

Preliminary Brown Trout Results

18-Apr 23-Apr 28-Apr 3-May 8-May0

500

1000

1500

2000

2500

Filterable Suspended Solids

Aerobic Mesophilic

Date

mg/

L

18-Apr 23-Apr 28-Apr 3-May 8-May0

100

200

300

400

500

600

700

800

Total Dissolved Solids

Aerobic Mesophilic

Date

mg/

L

18-Apr 23-Apr 28-Apr 3-May 8-May0

0.20.40.60.8

11.21.41.61.8

Electrical Conductivity

Aerobic Mesophilic

Date

mS

Before and After

N P K Ca Mg S Fe Mn B Cu Zn Mo Na Al 0.0%

20.0%

40.0%

60.0%

80.0%

100.0%

Tilapia% mineralization as a function of treatment regime

Initial AER ANA-Mes

N P K Ca Mg S Fe Mn B Cu Zn Mo Na Al 0.0%

10.0%20.0%30.0%40.0%50.0%60.0%70.0%80.0%90.0%

100.0%

Rainbow Trout% mineralization as a function of treatment regime

Initial AER ANA-Mes

Takeaways and Future Needs

• Microbial digestion is effective at solubilizing particle bound nutrients in RAS sludge!• More comprehensive analysis of nutrients in untreated RAS Sludge• Development of solution with nutrient concentrations designed for

specific crop growth – N:P:K • Microbial digestion is effective at solubilizing particle bound nutrients

in RAS sludge• Carbon-Nitrogen ratios of waste streams

Carbon/Nitrogen Ratio

• Preliminary ranging studies did not account for imbalance in carbon/nitrogen ratio• Ratios of 5:1 and 20-30:1 are common for municipal WWTX and terrestrial

agricultural waste digestion, respectively• Samples of initial waste and treated effluent are currently being analyzed• It is hypothesized that the C:N ratio will impact the degree of solubilization

• C:N ratio will be accounted for in upcoming research• Preliminary research shows higher C:N rates in trout than tilapia

Next Steps

Solid RAS Waste Solubilization Under Aerobic and Anaerobic Conditions

• Increased volume and collection time for solids collection• Lab scaled, triplicated experiment

• Characterize degree of solubilization by aerobic and anaerobic bioreactors

• Weekly samples for C concentration• Will conduct experiment again with C

additions if waste is limited

Anaerobic Bioreactor

Aerobic Bioreactor

Materials and Methods

• Nutrient analysis will be conducted on initial waste and final effluent

• Operating and Monitoring parameters will be measured every 48 hours• Parameters: ORP, FSS, TDS, DO,

pH, and temperature• Experiment “completion” will be

based on week-long stabilization of ORP, FSS, TDS

Operating Parameter Acceptable RangeDO (ANA, AER) < 1.0mg/L, > 2.0mg/LpH (ANA, AER) 6.5-7.5

Monitoring Parameter

ORPFSSTDS

Operating DataTANEC

AlkalinityTKN*TN*

TOC*

* Indicates parameters to be measured only in initial waste and final effluent

Future Goals• The development of a sludge mineralization unit process into existing

waste treatment designs• Ideally suited for decoupled systems• Combined ANA and AER approach• Adds value to both hydroponic and aquaculture industries

ANAEROBIC AEROBIC CLARIFIERFERTILZER SOLUTION

TO WASTE

RECYCLE STREAM

SOLID WASTE

Integrated Aquaculture Applications

Coupled Decoupled

• Decoupling allows for greater control over both fish and plants• Fish do not have to tolerate greenhouse conditions• System pH can be more closely optimized• Fish to plant ratio balancing is not required

• RAS waste from a decoupled system would be solubilized and used in hydroponics• Solution could be optimized to meet specific crop needs through additional supplementation

Questions?

AppendixTilapia Feed

Solids N (%) P (%) K (%) Ca (%) Mg (%) S (mg/L)

Fe (mg/L)

Mn (mg/L)

B (mg/L)

Cu (mg/L)

Zn (mg/L)

Mo (mg/L)

Na (mg/L)

Al (mg/L)

6.44 0.97 0.96 1.17 0.14 1024 208.56 91.77 5.9 46.48 89.64 4.13 2051 0

Trout Feed

Solids N (%) P (%) K (%) Ca (%) Mg (%) S (mg/L)

Fe (mg/L)

Mn (mg/L)

B (mg/L)

Cu (mg/L)

Zn (mg/L)

Mo (mg/L)

Na (mg/L)

Al (mg/L)

6.86 1.22 1 1.67 0.14 989.37 140.74 55.28 2.81 14.37 106.24 2.2 3001 0

References399 F.3d 486 (2nd Cir. 2005), 03-4470, Waterkeeper Alliance, Inc. v. U.S. E.P.A. (2004). Retrieved April 10, 2019, from vLex website: https://case-law.vlex.com/vid/399-f-3d-486-594928846Adesemoye, A. O., & Kloepper, J. W. (2007). Plant-microbes interactions in enhanced fertilizer-use efficiency.Conroy, J., & Couturier, M. (2010). Dissolution of minerals during hydrolysis of fish waste solids. Aquaculture, 298(3), 220–225. https://doi.org/10.1016/j.aquaculture.2009.11.013Delaide, B., Goddek, S., Keesman, K. J., & Jijakli, M. H. M. (2018). Une méthodologie pour quantifier les performances de digestion aérobie et anaérobie des boues, pour le recyclage des nutriments en aquaponie. Biotechnologie, Agronomie, Société et Environnement, 22(2), 106-112–112.Dolejs, P., El Tayar, G., Vejmelkova, D., Pacenka, M., Polaskova, M., & Bartacek, J. (2018). Psychrophilic anaerobic treatment of sewage: Biomethane potential, kinetics and importance of inoculum selection. http://dx.doi.org/10.1016/j.jclepro.2018.07.134FAO (Ed.). (2018). Meeting the sustainable development goals. Rome.Feng, L., Jia, R., Zeng, Z., Yang, G., & Xu, X. (2018). Simultaneous nitrification–denitrification and microbial community profile in an oxygen-limiting intermittent aeration SBBR with biodegradable carriers. Biodegradation, 29(5), 473–486. https://doi.org/10.1007/s10532-018-9845-xGander, M., Jefferson, B., & Judd, S. (2000). Aerobic MBRs for domestic wastewater treatment: a review with cost considerations. Separation and Purification Technology, 18(2), 119–130.Ge, H., Jensen, P., & Batstone, D. (2011). Relative kinetics of anaerobic digestion under thermophilic and mesophilic conditions. Retrieved March 18, 2019, from https://www.researchgate.net/publication/51811480_Relative_kinetics_of_anaerobic_digestion_under_thermophilic_and_mesophilic_conditionsGreenfeld, A., Becker, N., McIlwain, J., Fotedar, R., & Bornman, J. F. (2018). Economically viable aquaponics? Identifying the gap between potential and current uncertainties. Reviews in Aquaculture. https://doi.org/10.1111/raq.12269Guerdat, T. C., Losordo, T. M., DeLong, D. P., & Jones, R. D. (2013). An evaluation of solid waste capture from recirculating aquaculture systems using a geotextile bag system with a flocculant-aid. Aquacultural Engineering, 54, 1–8. https://doi.org/10.1016/j.aquaeng.2012.10.001J. Cripps, S., & Bergheim, A. (2000). Solids management and removal for intensive land-based aquaculture production systems. Aquacultural Engineering - AQUACULT ENG, 22, 33–56. https://doi.org/10.1016/S0144-8609(00)00031-5Jain, S., Jain, S., Wolf, I. T., Lee, J., & Wah Tong, Y. (2015). A comprehensive review on operating parameters and different pretreatment methodologies for anaerobic digestion of municipal solid waste - ScienceDirect. Retrieved from https://www-sciencedirect-com.libproxy.unh.edu/science/article/pii/S1364032115007388Kobayashi, M., Msangi, S., Batka, M., Vannuccini, S., Dey, M. M., & Anderson, J. L. (2015). Fish to 2030: The Role and Opportunity for Aquaculture. Aquaculture Economics & Management, 19(3), 282–300. https://doi.org/10.1080/13657305.2015.994240Lennard, W. (2015). AQUAPONICS: A Nutrient Dynamic Process and the Relationship to Fish Feeds. Retrieved April 22, 2019, from https://www.was.org/articles/Aquaponics-Nutrient-Dynamic-Process-Relationship-to-Fish-Feeds.aspx#.XL2yXOhKhPYMoffitt, C. M., & Cajas-Cano, L. (2014). Blue Growth: The 2014 FAO State of World Fisheries and Aquaculture. Fisheries, 39(11), 552–553. https://doi.org/10.1080/03632415.2014.966265Morgenroth, E., Kommedal, R., & Harremoës, P. (2002). Processes and modeling of hydrolysis of particulate organic matter in aerobic wastewater treatment–a review. Water Science and Technology : A Journal of the International Association on Water Pollution Research, 45(6), 25–40. https://doi.org/10.2166/wst.2002.0091Rotaru, A.-E., Shrestha, P., Liu, F., Shrestha, M., Shrestha, D., Embree, M., … R. Lovley, D. (2014). A new model for electron flow during anaerobic digestion: direct interspecies electron transfer to Methanosaeta for the reduction of carbon dioxide to methane (Vol. 7). https://doi.org/10.1039/C3EE42189ASharrer, M., Rishel, K., Taylor, A., Vinci, B., & Summerfelt, S. (2010). The cost and effectiveness of solids thickening technologies for treating backwash and recovering nutrients from intensive aquaculture systems. Bioresource Technology, 101, 6630–6641. https://doi.org/10.1016/j.biortech.2010.03.101Timmons, M. B., Guerdat, T., & Vinci, B. J. (2018). Recirculating Aquaculture 4th Edition (4th edition). Ithaca Publishing Company LLC.van Rijn, J. (1996). The potential for integrated biological treatment systems in recirculating fish culture—A review. Aquaculture, 139(3–4), 181–201. https://doi.org/10.1016/0044-8486(95)01151-X