Evaluation of a Swirl Separator in the University of the Virgin Island’s

Aquaponic SystemR. Charlie Shultz , Jason J. Danaher, James E. Rakocy, and Don S. Bailey

University of the Virgin IslandsAgricultural Experiment Station

RR 1 Box 10,000Kingshill, VI 00850

AquaponicsThe combined

culture of fish and plants in a closed, recirculatingsystem

Hydroponic tanks

Rearing tanks

Effluent line

SumpClarifierFilter tanks Return line

Base additionDegassing

UVI Aquaponic System Layout

Total water volume, 110 m3 Land area - 0.05 ha

System Design Four fish rearing tanks, 7.8 m3 each Two cylindro-conical clarifiers, 3.8 m3 each Four filter tanks, 0.7 m3 each One degassing tank, 0.7 m3 Six hydroponic tanks, 11.3 m3 each Total plant growing area, 214 m2 One sump, 0.6 m3 Base addition tank, 0.2 m3 Total water volume, 110 m3 Land area - 0.05 ha

Clarifier CharacteristicsCylindro-conical 45O sloped cone

Water retention = 20 min Waste removed 3 × daily Advantage

Inexpensive operational cost

Easy to clean and rarely clogs

Disadvantage Size

• Temperate climates Installation

• Excavation Loading rate

Installing a Clarifier

Swirl Separator Characteristics

Solids settle via centrifugal force

Advantage: Compact Size Ease of Installation Readily Available

Disadvantage: Unproven in Raft

Aquaponics

Objectives

Compare water quality, tilapia production, and plant production in a UVI aquaponic system using a clarifier or swirl separator

UVI Small Aquaponic System Design

Rearing Tank = 7.8m3 Net Tank = 0.7m3 Hydroponic Area = 14m2Hydroponic Volume = 4.4m3 Sump = 0.6m3 1/6 Hp Centrifugal Pump

Experimental Design Eight week experiment Two treatments with three

replicates Clarifier Swirl Separator

• Flow rate 57 liters/min Tilapia (Oreochromis niloticus)

Stocking rate = 36 fish/m3• Avg wt. = 376 g

Fed 32% protein floating diet• 60 - 140 grams/m2 plant

area/day Water Spinach (Ipomoea aquatica)

2-week old transplants• 3.3 kg w.w. per system

7-8 cuttings per raceway Harvested every 3 weeks Sprayed with BT 2x weekly

Methods: Water Quality Water sampled biweekly

Temperature Oxygen pH Alkalinity Electrical Conductivity (EC) TAN Nitrite – Nitrogen Nitrate – Nitrogen TSS

• Enter Filter• Exit Filter• Exit Net Tank• Discharged Effluent

Water sampled monthly Micro & Macronutrients

• Culture system• Discharged Effluent

Plant tissue analysis Week 8

Filter Placement

Clarifier Swirl Separator

Water Quality ResultsParameter (mg/L) Treatment

Swirl Separator Clarifier

Temperature (oC) 27.4 ± 0.1a 27.5 ± 0.0aOxygen (mg/L) 6.0 ± 0.2a 5.6 ± 0.1apH 7.1 ± 0.1a 7.0 ± 0.1aAlkalinity (mg/L) 82.4 ± 10.4a 83.3 ± 18.0aEC (µS/cm) 0.6 ± 0.1a 0.5 ± 0.1aTAN (mg/L) 0.7 ± 0.1a 0.6 ± 0.1aNitrite – N (mg/L) 0.7 ± 0.1a 0.6 ± 0.1aNitrate - N (mg/L) 9.1 ± 1.4a 10.0 ± 1.8aTSS (mg/L)

In 6.0 ± 4.0a 8.3 ± 3.5aOut 3.3 ± 1.1a 3.5 ± 0.7aNet Tank Exit 2.7 ± 1.5a 3.8 ± 2.6aRetained in Net Tank 2025.0 ± 368.6a 2520.0 ± 540.4aDischarged effluent 10250 ± 3246.2a 18500.0 ± 4346.6a

Tilapia Production ResultsVariable Treatment

Swirl Separator Clarifier

Production (kg/m3) 17.7 ± 1.6a 16.2 ± 1.6a

Average harvest weight (g) 562.4 ± 29.2a 582.6 ± 33.4a

Survival 87.9 ± 11.4a 78.0 ± 10.5a

FCR 3.1 ± 1.3a 4.9 ± 2.2a

Water Spinach Production ResultsParameter Treatment

Swirl Separator ClarifierTotal Weight Harvested (kg) 331.7 ± 21.6a 319.8 ± 14.4aTotal Production (kg/m2) 23.7 ± 1.5a 22.8 ± 1.0aAnnual Production (kg/m2/yr) 160.2 ± 10.1a 154.1 ± 6.8a

Percent Moisture (%) 90.4a 90.5aD.W. Tissue Analysis (%)Nitrogen 6.7a ± 0.9a 6.8a ± 2.2aPhosphorus 0.5a ± 0.01a 0.5a ± 0.02aPotassium 3.3a ± 0.7a 3.6a ± 0.5aCalcium 0.5a ± 0.02a 0.5a ± 0.01aMagnesium 0.1a ± 0.00a 0.1a ± 0.00a

Conclusions

Swirl Separator = Clarifier Fish Production

• Total Production, Average Weight, Survival, FCR Spinach Production

• Grows vigorously in system• Easy to manage and transplant

Reduces need for large greenhouse nursery area • Marketable

UVI Farm Store Price ~ US $4.40/kg

Conclusions Swirl Separator = Clarifier

TSS removal• Entering filter, Exiting filter, Exiting Net Tank

Swirl Separator = 45% reduction; Clarifier = 58% reduction TSS particles < 100 microns in RAS

TSS concentration in Net Tanks

Discussion

Will Need to Size Up Piping

Study Different Flow Rates

Can Net Tanks Handle the Increased Flow

Acknowledgments

Virgin Islands Water Resources Research Institute award #2009VI90B

Evaluation of a Swirl Separator in the University of the Virgin Island’s Aquaponic SystemAquaponicsSlide Number 3System DesignSlide Number 5Clarifier CharacteristicsInstalling a ClarifierSwirl Separator CharacteristicsObjectivesUVI Small Aquaponic System DesignExperimental DesignMethods: Water QualityFilter PlacementWater Quality ResultsTilapia Production ResultsSlide Number 16Water Spinach Production ResultsSlide Number 18Slide Number 19Slide Number 20Slide Number 21ConclusionsConclusionsDiscussionAcknowledgmentsSlide Number 26