Aquaponic Systems: Nutrient recycling from fish wastewater by vegetable production
Metadata
- Cite key: graberAquaponicSystemsNutrient2009
- Item type: Journal Article
- Authors: A. Graber, R. Junge
- Affiliation: ZHAW Zurich University of Applied Sciences, Institute for Natural Resource Sciences Gruental, CH-8820 Waedenswil, Switzerland
- Journal: Desalination 246 (2009) 147-156
- Date: 09/2009
- Date added: [not reported]
- DOI: 10.1016/j.desal.2008.03.048
- Funding: Swiss Federal Office for Agriculture (FOAG) — stated in Acknowledgements
- URL: https://doi.org/10.1016/j.desal.2008.03.048
- PDF:
Graber and Junge - 2009 - Aquaponic Systems Nutrient recycling from fish wa.pdf
Opinion
An early, foundational aquaponics paper describing a genuinely novel system (LECA-filled trickling filters doubling as grow beds) with real mass-balance data across three crops over two years. The honesty about limitations is a strength — the authors flag their own >100% phosphorus recycling figure as unreliable, and openly discuss the potassium deficiency in fish-only nutrient sources. The weakness is methodological: aquaponic and hydroponic arms for each crop were run sequentially rather than concurrently (sometimes with meaningfully different durations, e.g. tomato: 43 d control vs 67 d treatment), no replication or statistics are reported, and several data points reference unpublished theses/reports not available for verification. Read as a descriptive proof-of-concept rather than a controlled comparison.
Abstract
This chapter describes the possibility to combine wastewater treatment in recirculating aquaculture systems (RAS) with the production of crop plants biomass. In an aquaponic RAS established in Waedenswil, Zurich, the potential of three crop plants was assessed to recycle nutrients from fish wastewater. A special design of trickling filters was used to provide nitrification of fish wastewater: Light-expanded clay aggregate (LECA) was filled in a layer of 30 cm in vegetable boxes, providing both surface for biofilm growth and cultivation area for crop plants. Aubergine, tomato and cucumber cultures were established in the LECA filter and nutrient removal rates calculated during 42–105 days. The highest nutrient removal rates by fruit harvest were achieved during tomato culture: over a period of >3 months, fruit production removed 0.52, 0.11 and 0.8 g m⁻² d⁻¹ for N, P and K in hydroponic and 0.43, 0.07 and 0.4 g m⁻² d⁻¹ for N, P and K in aquaponic. In aquaponic, 69% of nitrogen removal by the overall system could thus be converted into edible fruits. Plant yield in aquaponic was similar to conventional hydroponic production systems. The experiments showed that nutrient recycling is not a luxury reserved for rural areas with litlle space limitation; instead, the additionally occupied surface generates income by producing marketable goods. By converting nutrients into biomass, treating wastewater could become a profitable business.
Summary
Researchers at ZHAW Waedenswil built a novel aquaponic recirculating system where the biofilter itself — light-expanded clay aggregate (LECA) packed into shallow boxes — doubled as the plant grow bed, aiming to combine wastewater nitrification with vegetable production rather than just denitrifying nitrogen away. Over 2004–2005 they grew aubergine (with tilapia), then tomato and cucumber (with Eurasian perch) in this aquaponic system, each paired with a conventional fertilized hydroponic control on the same LECA-box design, and calculated nitrogen, phosphorus and potassium mass balances from fish feed input through to fruit harvest. Tomato achieved the best performance, converting 69% of the nitrogen removed by the whole system into edible fruit, with aquaponic fruit yields close to hydroponic; cucumber and aubergine recycled less. The main limitation identified was potassium: fish-derived water contained roughly 45 times less potassium than the hydroponic fertilizer, since potassium is not a fish dietary requirement, which measurably reduced aquaponic tomato tissue potassium and fruit quality. The paper is useful as an early demonstration that a trickling-filter/grow-bed hybrid can nitrify effectively while recycling a majority of feed-derived nitrogen into marketable biomass, though the aquaponic and hydroponic arms for each crop were grown in sequential, not concurrent, cycles and no replication or statistical testing was applied to the core nutrient-balance results.
Experiment data
- Location: Waedenswil, Zurich, Switzerland (ZHAW research greenhouse)
- Design: Aquaponic (LECA trickling-filter grow beds, RAS with tilapia then perch) vs conventional hydroponic (same LECA-box design, mineral fertilizer, EC ~2.5 mS/cm) for each of 3 crops in turn; tomato additionally had a non-quantified soil-culture control. Arms run sequentially per crop, not concurrently. No stated randomisation or replicate treatment units.
- Replicates / n: [not reported] — single interconnected system per treatment per crop; not independently replicated (see Extraction notes)
- Duration: 42–105 days per crop cycle (Table 2)
- Organisms: Tilapia (Oreochromis niloticus) (aubergine, 2004) / Eurasian perch (Perca fluviatilis) (tomato & cucumber, 2005); Aubergine, Tomato, Cucumber
- Statistics: None reported for the core nutrient-balance/yield results — mass-balance calculation only. A small unrelated taste-preference survey (n=19) reports raw percentages, no test.
- Feed Conversion Rate (FCR): [not reported]
- Nitrate (NO3) (water): 1.9–42 mg/L (tilapia trial) / 12.1–95 mg/L (perch trials, pooled tomato+cucumber) — range only, no mean (Table 1)
- Fruit nitrogen recycling: 69% (tomato, aquaponic) — the paper’s headline finding
Water quality and nitrification
This paper: Table 1 gives only ranges (no trial mean±SD) of water quality across the trial period, split by fish species: tilapia (aubergine, N=8–12 samples) and perch (tomato+cucumber pooled, N=7–13 samples). NH4-N stayed under the 1.0 mg/L tolerance limit in both; NO2-N exceeded the 0.2 mg/L limit during tilapia culture (“sometimes above 0.2 mg N l⁻¹”, p.152) but not during perch culture, attributed to the perch trials’ feeding load being “almost halved” (p.152). Overall trickling-filter nitrification capacity was calculated at 0.26 kg fish feed m⁻³ LECA d⁻¹ (secondary figure, cites Gnauck 2005 unpublished thesis, ref [26]). Dissolved oxygen during the tilapia/aubergine trial (2.6–4.8 mg/L) ran below the stated >6 mg/L tolerance limit throughout monitoring.
Compared with:
- todo Vymazal 2007 — constructed wetlands treating municipal wastewater achieve 250–630 g N m⁻² a⁻¹ and 45–75 g P m⁻² a⁻¹ removal, with 32–40% of TN and 22–27% of TP recyclable via aboveground vegetation harvest (secondary comparison figures, p.155).
- todo Headley, Herity & Davison 2005; Garcia et al. 2004 — shallower constructed-wetland beds (0.27 m) reportedly outperform deeper beds (0.5 m) for COD/BOD5/ammonia/phosphorus removal, cited to support the paper’s own surface-to-volume argument (p.155-156, secondary).
Nutrient removal and recycling (NPK mass balance)
This paper: Table 2 mass-balance data (full figures preserved in Experimental Remarks of each trials.csv row, since no dedicated column exists for area/time-normalized nutrient-flux rates): tomato achieved the highest fruit-harvest nutrient removal and recycling (69% N recycled to fruit in aquaponic; >100% P recycling calculated but explicitly flagged by the authors as unreliable due to confounding soil-irrigation water loss). Aubergine and cucumber recycled substantially less nitrogen (9% and 17% respectively, aquaponic). Potassium was the clear limiting nutrient in aquaponic: fish water contained ~45x less K than the hydroponic fertilizer (vs ~3x less N, ~10x less P), reflected directly in tomato fruit tissue K (22.0 g/kg DM aquaponic vs 40.8 g/kg DM hydroponic).
Compared with: [not reported — the paper does not benchmark its own NPK recycling percentages against other aquaponic studies, only against constructed-wetland literature, see above]
System design
This paper: A “planted trickling filter” — LECA (light-expanded clay aggregate), 30 cm deep, in green PVC boxes (0.4×0.6×0.4 m) — served simultaneously as nitrifying biofilter and plant grow bed. Aquaponic: 74 boxes / 2 rows / 3.0 m³ LECA, fed from a 2.5 m³ fish tank at 10–15 m³/h, operated as a fully closed loop (zero deliberate water exchange; only evaporation replaced with tap water). Hydroponic control: 29 boxes / 1 row / 1.2 m³ LECA, fed from a separate 0.3 m³ reservoir at 5 m³/h, fertilized 2–3×/week to EC ~2.5 mS/cm.
Compared with:
- todo Rakocy, Masser & Losordo (SRAC Publication #454) — general aquaponics system integration reference cited for the concept definition (p.149, secondary).
- todo Wilson 2005, Aquaponics Journal — cites a feedlot-aquaculture fish:vegetable production ratio of 1 kg fish : 7 kg vegetable biomass and commercial-scale Australian aquaponic barramundi operations (p.149, 155, secondary figures).
Linked claims
- Aquaponic systems recycle a majority of feed-derived nitrogen into edible plant biomass
- Fish-derived nutrient water is potassium-limited relative to hydroponic fertilizer
- Aquaponic fruit yield can approach conventional hydroponic yield despite lower nutrient concentration
Citations to chase
- todo Vymazal (2007) — constructed wetland nutrient removal rates, used as comparison benchmark (p.155)
- todo Headley, Herity & Davison (2005) — treatment-bed depth effects in subsurface-flow wetlands (p.155-156)
- todo Garcia et al. (2004) — shallow vs deep reed-bed contaminant removal (p.156)
- todo Wenger (2003) — unpublished diploma thesis, source of the 2003 tomato-variety comparison (Fig. 4), 5 cultivars, secondary to this paper
- todo Gnauck (2005) — unpublished thesis, source of the 0.26 kg feed m⁻³ LECA d⁻¹ nitrification-capacity figure (secondary)
- todo Wilson (2005), Aquaponics Journal — Australian commercial barramundi aquaponics and the 1:7 fish:vegetable production ratio (secondary)
- todo Rakocy, Masser & Losordo — SRAC Publication #454, aquaponics system integration review
Extraction notes
Type classification: quasi-experiment. The authors collected their own primary data (Table 1 water-quality monitoring, Table 2 NPK mass balance, tissue K analysis) from a real system they designed and operated, so this is primary research, not a review. It is not experiment because there is no randomisation and no independently replicated treatment units — each crop had exactly one aquaponic run and one hydroponic run, and for two of three crops (tomato, cucumber) these ran sequentially rather than concurrently. It is not exploratory because the comparison is explicitly hypothesis-driven and designed from the outset (“we compared plant productivity in aquaponic and in conventional hydroponic systems”, p.149) rather than a purely descriptive pilot. This matches the schema’s quasi-experiment test exactly: “Treatments compared but without randomisation or true replication.”
WARN-MATERIAL — EC unit ambiguity (affects EC cell in all 3 trial rows): Table 1 (p.152) prints the EC row’s unit as “mS cm⁻¹” with tolerance limit “<1200” and observed ranges 350–680 (tilapia) / 400–1103 (perch). Taken literally as mS/cm this is physically implausible for freshwater fish culture (roughly 10x seawater conductivity — would be lethal, and a “<1200 mS/cm tolerance limit” is meaningless). Section 2.1 (p.151) separately states the hydroponic fertilizer target as “an electrical conductivity of 2.5 mS cm⁻¹” — a plausible greenhouse hydroponic EC — and fish water is expected to sit below that. This is only consistent if Table 1’s own unit is actually µS/cm (a common µ→m glyph substitution in PDF text extraction from Elsevier’s older typesetting). Recorded EC assuming µS/cm (0.35–0.68 / 0.40–1.10 dS/m); the literal “mS cm⁻¹” reading (350–1103 dS/m) is the alternative candidate, noted in each trial row’s remarks for the user to verify against the original PDF glyph if it matters for downstream analysis.
Bibliographic discrepancy (metadata only, does not affect any trial data): the PDF’s own printed running header/footer reads “Desalination 247 (2009) 148–157” on every page, but both zotero-export.csv and a live CrossRef query (https://api.crossref.org/works/10.1016/j.desal.2008.03.048) agree on Volume 246, Issue 1-3, pages 147-156. Per instructions, zotero-export.csv/CrossRef is treated as authoritative for the frontmatter and Metadata block; the PDF’s own 247/148-157 is recorded here for transparency and left unresolved — possibly an artifact of this paper’s dual life as both a conference-proceedings chapter (it was “Presented at Multi Functions of Wetland Systems… 2007, Legnaro (Padova) Italy”) and a journal special-issue article.
[not reported] fields, grouped:
- Fish: Initial Stock density, FCR, SGR, Fish size initial/final, Fish survival rate, Fish weight gain, Total Feed (kg) as a stated total, Feed routine (frequency), % of body weight ration, N/P/K composition of feed (only a water-release fertilizer coefficient is given, from a separate sub-experiment — see below)
- Water: Water temperature (only a qualitative “higher water temperature in aquaponic” claim exists, attached to the secondary/2003 tomato-variety experiment, not this paper’s own 2005 trial), Average room Temperature, Lat/Long
- Plant: Plants/m², SPAD, Plant height, Leaf count, Plant fresh weight (g/plant — only area-based yield given), Plant dry matter (%), tissue N and P (Methods states these were analysed for tomato biomass via Kjeldahl/AAS/ICP, but no numeric values are reported in Results — only tissue K appears)
- Design: Replicates (n) — implied to be a single pooled system per treatment by the design description, but never stated as a number
Separate sub-experiment (not given its own trial row, no plant component): fish-feed fertilizer coefficients (46±4 g N, 6.0±0.8 g P, 1.0±0.4 g K released into water per kg fish feed) were determined using two replicate batches of tilapia (25 fish totalling 1330 g; 31 fish totalling 1730 g) in 220-L glass aquaria with an unplanted LECA nitrification filter, fed ad libitum for 14 days (consuming 330 g and 436 g feed respectively). This is methodologically important context for interpreting the main trials’ nutrient-input calculations but does not itself produce a CSV row (no crop grown).
New tags introduced: Meta/Fish/Perch (Eurasian perch, Perca fluviatilis) and Meta/Plant/Aubergine — checked TAGS.md conventions were not directly available to cross-reference during this extraction; flagging for the batch-level tag audit in case these are new facets.
Wikilink candidates needing a canonical-form decision: “Feed Conversion Rate (FCR)” used per existing vault convention (not applicable here since FCR is NR, but referenced in the Experiment data callout for completeness).
Source: Graber and Junge - 2009 - Aquaponic Systems Nutrient recycling from fish wa.pdf
Data Tables
Structured data extracted from this paper into the vault's
trials.csv/plant_measurements.csvdatasets. Fields the paper didn't report are omitted. Download the full datasets (measurements).
Trial Parameters
graberAquaponicSystemsNutrient2009-T1
Fish
| Field | Value |
|---|---|
| Fish | Tilapia (Oreochromis niloticus), natural strain imported from Lake Turkana, Kenya |
| Protein | 45 |
| Feed regime | Ad libitum; Trouvit Tilapia Starter pellets, 3.5 mm, 45% raw protein (p.150) |
| Fish biomass created (kg) | 88 |
| Fish trial duration (days) | 105 |
Water
| Field | Value |
|---|---|
| Water recycle | UNIT CONVERSION ONLY: 10-15 m3/h -> 166.7-250 |
| Water volume in the system | 2500 (fish tank only, 2.5 m3; UNIT CONVERSION ONLY: m3->L) |
| Water type | Fish tank effluent / RAS water, closed recirculating loop (zero daily water exchange except evaporation replacement with tap water) (p.150) |
| Daily Water exchange rate | 15 |
| Aq pH | 6.8-7.8 |
| pHOptimal | 7-8 (Table 1 tolerance limit, applies to both tilapia and perch culture) |
| Dissolved Oxigen | 2.6-4.8 |
| EC | 0.35-0.68 (dS/m; UNIT CONVERSION ONLY assuming microS/cm source unit, see WARN-MATERIAL in remarks) |
| TAN / NH4-N | 0.03-0.88 |
| NO2-N | 0.08-0.57 |
| NO3-N | 1.9-42 |
Plant
| Field | Value |
|---|---|
| Plant | Aubergine |
| Details | Varieties ‘Gilo Brasil’ and ‘Red Egg’ contributed 69% of the 78.9 kg overall aubergine yield on only 1/3 of the planted area (data not shown, p.154); fruit yield reportedly depended mainly on variety rather than production system (AP vs HYD). |
| Days Plant after transplant | 105 |
System & Setup
| Field | Value |
|---|---|
| System type | LECA (light-expanded clay aggregate) planted trickling filter used simultaneously as hydroponic-style grow bed, RAS-integrated (p.149-150) |
| Media Details | LECA filled 30 cm deep in green PVC boxes (0.4x0.6x0.4 m); Aquaponic: 74 boxes in 2 rows, 3.0 m3 total LECA; Hydroponic control: 29 boxes in 1 row, 1.2 m3 LECA (p.150, Figs 1-2) |
| Climate control | Y (Greenhouse (adjoining greenhouse, Waedenswil, Zurich); no temperature/humidity setpoints reported (p.150, Fig.1)) |
| Nutrient supplemented | N (Aquaponic received NO added fertilizer by design - only fish-derived nutrients from RAS effluent (p.149-150, Section 2.1). Hydroponic control WAS fertilized (EC target 2.5 mS/cm, 2-3x/week) - see remarks, not applicable to this AP-treatment row.) |
| Equipment | SC1000 continuous sensors (Hach Lange sc-sensors 3798-S EC, phD-S pH, 1200-S redox, LDO dissolved O2), logged every 15 min; WTW Multiline 350i handheld multi-electrode meter (daily backup); Hach Lange LCK photometric test kits read on Cadas30 photometer (dissolved ions); irrigation pumps (10-15 m3/h to aquaponic LECA rows via 0.11 m orange PVC sewage piping, 6 cm drilling holes; 5 m3/h to hydroponic row) |
| Control Parameters | Table 1 tolerance limits: NH4-N <1.0 mg/l; NO2-N <0.2 mg/l; NO3-N <150 mg/l; pH 7-8; EC <1200 (unit ambiguous, see remarks); O2 >6 mg/l |
| Combination | Tilapia and aubergine; aquaponic vs hydroponic (sequential growing cycles, not concurrent) |
Site
| Field | Value |
|---|---|
| Region | Europe |
| Country | Switzerland |
Results & Statistics
| Field | Value |
|---|---|
| Measured Unit | g FW m-2 d-1 (fruit production rate); kg FW (fruit production total, see remarks) |
| Statistically analysed | N |
| AP | 90 |
| HYD | 82 |
Experimental Remarks: TRIAL DEFINITION: T1 = Aquaponic aubergine culture (tilapia RAS, LECA trickling-filter grow beds), 19.07.2004-~01.11.2004, 105 d. Paired control = Hydroponic aubergine on the same LECA-box design fed mineral fertilizer (EC ~2.5 mS/cm), recorded in HYD column, run 07.04.2004-~20.07.2004 (105 d). Only one aquaponic treatment for this crop, so one row. | Hydroponic control ran 07.04.2004-~20.07.2004 (105 d); Aquaponic ran 19.07.2004-~01.11.2004 (105 d). The two arms were run SEQUENTIALLY in the same greenhouse space, not concurrently side-by-side (Table 2, p.153). Season/weather conditions therefore differ between the paired AP and HYD runs for this crop. | WARN-MATERIAL EC unit: Table 1 (p.152) prints the EC row unit as ‘mS cm-1’ with tolerance ‘<1200’ and ranges 350-680 (tilapia) / 400-1103 (perch). Read literally as mS/cm this is physically implausible for freshwater RAS fish culture (350-1103 mS/cm would be roughly 10x seawater conductivity, lethal to tilapia/perch; a <1200 mS/cm ‘tolerance limit’ is meaningless for fish). Section 2.1 (p.151) separately and unambiguously states the HYDROPONIC fertilizer target as ‘an electrical conductivity of 2.5 mS cm-1’ - a plausible greenhouse hydroponic EC. Table 1’s fish-water range sitting below that hydroponic target only makes sense if Table 1’s own unit is actually microS/cm (a common mu-to-m glyph substitution in PDF text extraction from this era of Elsevier typesetting), i.e. 0.35-0.68 / 0.40-1.10 mS cm-1 (dS/m). Recorded EC assuming microS/cm (defensible reading, physically consistent); the literal ‘mS cm-1’ reading is the other candidate and is recorded here for the user to verify against the original PDF glyph. Affects EC cell in all 3 trial rows (same Table 1 source). | MINOR (informational, not a conflict): Table 1 O2 range for tilapia culture (2.6-4.8 mg/l) sits BELOW the paper’s own stated tolerance limit of >6 mg/l (p.152) - fish were kept under below-target dissolved oxygen for this trial; this is the paper’s own reported finding, not an extraction contradiction. | WARN-MINOR RANGE (water quality): range only, no trial mean reported (Table 1, p.152); N=sample count given in table, not applied here | WARN-MINOR (bibliographic, does not affect any data cell): the PDF’s own printed running header/footer reads ‘Desalination 247 (2009) 148-157’ throughout, but CrossRef (queried live at https://api.crossref.org/works/10.1016/j.desal.2008.03.048) and zotero-export.csv both give Volume 246, Issue 1-3, pages 147-156. Frontmatter/Metadata use the CrossRef-confirmed 246/147-156 per instructions (zotero-export.csv is authoritative over the PDF); the PDF’s own 247/148-157 is recorded here for transparency, unresolved as to why the printed article disagrees with its own registered metadata (possibly a proceedings/special-issue cross-listing artifact). | NO COLUMN (Table 2, p.153, full figures for cross-check): Aubergine HYD: Fruit Production 40.2 kg FW total; Total System Removal N=1.0,P=0.20,K=1.3 g/m2/d; Fruit Harvest Removal N=0.26,P=0.02,K=0.2 g/m2/d; Nutrient recycling 25%N/9%P/16%K. Aubergine AP: Fruit Production 38.6 kg FW total; Fish Feeding Load 1.58 kg/d; Total System Removal N=3.3,P=0.41,K=- g/m2/d; Fruit Harvest Removal N=0.29,P=0.02,K=0.2 g/m2/d; Nutrient recycling 9%N/5%P/-%K. Planted area HYD=AP=5.0 m2. No dedicated trials.csv column for area-normalized NPK removal/recycling rates; AP/HYD generic columns instead carry the primary fruit yield rate (g FW/m2/d). | UNIT CONVERSION ONLY: fish tank irrigation rate 10-15 m3/h -> 166.7-250 L/min; hydroponic reservoir rate 5 m3/h -> 83.3 L/min; fish tank 2.5 m3 -> 2500 L; DO/TAN/NO2/NO3 mg/l recorded as-is (mg/L ~ ppm 1:1 equivalence for dilute aqueous solution, ppm column). | NOT DERIVED, left NR: Initial Stock density (fish tank volume 2.5 m3 given, but no fish count/weight-at-stocking for the main trial system, only for the separate 220-l aquaria fertilizer-coefficient sub-experiment); FCR (Fish Feeding Load kg/d x Duration would give a total feed input, and Fish biomass created is given, but Total Feed itself is never stated as a total - not computed); SGR; Fish size initial/final; Fish survival rate; Fish weight gain (g/fish - fish counts not given); Total Feed (kg) as a stated total (only the daily rate kg feed/d is given in Table 2 - see NO COLUMN note for the rate); % of body weight (ad libitum feeding, no ration % given); N/P/K composition of feed as % (the paper instead gives ‘nutrient release into the water by feeding 1 kg fish feed’ = 46+/-4 g N, 6.0+/-0.8 g P, 1.0+/-0.4 g K per kg feed - this is a water-release fertilizer coefficient from a separate 220-l aquaria sub-experiment with 2 replicate tilapia batches (25 fish/1330 g and 31 fish/1730 g, ad libitum for 14 d, consuming 330 and 436 g feed respectively), NOT total feed composition; recorded here as NO COLUMN, not entered as Protein/N/P/K feed-% since equating water-release with total feed content would be an assumption the paper does not make). | Fish Category, Water classification, Plant Category: NR - paper does not use a categorisation term for these. | Replicates (n): NR - the paper never states a replicate count; system description (Fig.2: 2 aquaponic LECA rows sharing one fish-tank water supply, sampled only at the main reservoir, vs 1 hydroponic row) implies a single pooled system per treatment rather than independently replicated experimental units, consistent with the quasi-experiment classification, but this is inferred from the design description, not a stated number. | Fish Production (kg FW, Table 2) mapped to ‘Fish biomass created (kg)’ as the closest schema fit - the paper frames it analogously to ‘Fruit Production’ (total biomass produced during the trial window), not explicitly defined by the authors as final-minus-initial biomass. | Separate methodological context (NOT this trial, no plant component, not given its own row): fertilizer coefficients (46+/-4 g N, 6.0+/-0.8 g P, 1.0+/-0.4 g K released per kg fish feed) were determined in a 220-l glass-aquaria sub-experiment with unplanted LECA nitrification filter, 2 replicate tilapia batches (25 fish/1330 g total and 31 fish/1730 g total), fed ad libitum 14 d, consuming 330 g and 436 g feed respectively (p.151, Section 2.2-3).
graberAquaponicSystemsNutrient2009-T2
Fish
| Field | Value |
|---|---|
| Fish | Eurasian perch (Perca fluviatilis), obtained from Percitech S.A., Switzerland |
| Protein | 45 |
| Feed regime | Ad libitum; Trouvit Tilapia Starter pellets, 3.5 mm, 45% raw protein (p.150) |
| Fish biomass created (kg) | 27 |
| Fish trial duration (days) | 67 |
Water
| Field | Value |
|---|---|
| Water recycle | UNIT CONVERSION ONLY: 10-15 m3/h -> 166.7-250 |
| Water volume in the system | 2500 (fish tank only, 2.5 m3; UNIT CONVERSION ONLY: m3->L) |
| Water type | Fish tank effluent / RAS water, closed recirculating loop (zero daily water exchange except evaporation replacement with tap water) (p.150) |
| Daily Water exchange rate | 41 (see remarks - includes soil-culture irrigation offtake, not pure evaporation-replacement) |
| Aq pH | 6.19-7.41 |
| pHOptimal | 7-8 (Table 1 tolerance limit, applies to both tilapia and perch culture) |
| Dissolved Oxigen | 6.7-7.5 |
| EC | 0.40-1.10 (dS/m; UNIT CONVERSION ONLY assuming microS/cm source unit, see WARN-MATERIAL in remarks) |
| TAN / NH4-N | 0.06-0.68 |
| NO2-N | 0.01-0.18 |
| NO3-N | 12.1-95 |
Plant
| Field | Value |
|---|---|
| Plant | Tomato |
| Details | Cultivar not stated for this 2005 trial. A separate, earlier 2003 tomato-variety trial (Fig.4, citing Wenger 2003 diploma thesis [ref 14]) tested 5 named cultivars (Grapella, Rose of Berne, Frog King, Golden Orb, Sweet from Hungary) in the same system design; all yielded more fruit in aquaponic than hydroponic, partly attributed to higher aquaponic water temperature and faster initial growth (p.154-155). This 2003 data is SECONDARY (from a companion thesis, not this paper’s own directly-measured 2005 tomato trial) and is not entered as trial data here. |
| Days Plant after transplant | 67 |
System & Setup
| Field | Value |
|---|---|
| System type | LECA (light-expanded clay aggregate) planted trickling filter used simultaneously as hydroponic-style grow bed, RAS-integrated (p.149-150) |
| Media Details | LECA filled 30 cm deep in green PVC boxes (0.4x0.6x0.4 m); Aquaponic: 74 boxes in 2 rows, 3.0 m3 total LECA; Hydroponic control: 29 boxes in 1 row, 1.2 m3 LECA (p.150, Figs 1-2). A second, non-amended natural-soil control row was also grown alongside for tomato only (irrigated every few days with fish water per irrigation need), see remarks. |
| Climate control | Y (Greenhouse (adjoining greenhouse, Waedenswil, Zurich); no temperature/humidity setpoints reported (p.150, Fig.1)) |
| Nutrient supplemented | N (Aquaponic received NO added fertilizer by design - only fish-derived nutrients from RAS effluent (p.149-150, Section 2.1). Hydroponic control WAS fertilized (EC target 2.5 mS/cm, 2-3x/week) - see remarks, not applicable to this AP-treatment row.) |
| Equipment | SC1000 continuous sensors (Hach Lange sc-sensors 3798-S EC, phD-S pH, 1200-S redox, LDO dissolved O2), logged every 15 min; WTW Multiline 350i handheld multi-electrode meter (daily backup); Hach Lange LCK photometric test kits read on Cadas30 photometer (dissolved ions); irrigation pumps (10-15 m3/h to aquaponic LECA rows via 0.11 m orange PVC sewage piping, 6 cm drilling holes; 5 m3/h to hydroponic row) |
| Control Parameters | Table 1 tolerance limits: NH4-N <1.0 mg/l; NO2-N <0.2 mg/l; NO3-N <150 mg/l; pH 7-8; EC <1200 (unit ambiguous, see remarks); O2 >6 mg/l |
| Combination | Eurasian perch and tomato; aquaponic vs hydroponic vs soil culture (sequential, not concurrent) |
Site
| Field | Value |
|---|---|
| Region | Europe |
| Country | Switzerland |
Results & Statistics
| Field | Value |
|---|---|
| Measured Unit | g FW m-2 d-1 (fruit production rate); kg FW (fruit production total, see remarks) |
| Statistically analysed | N |
| AP | 355 |
| HYD | 389 |
Experimental Remarks: TRIAL DEFINITION: T2 = Aquaponic tomato culture (perch RAS, LECA trickling-filter grow beds), 29.07.2005-~03.10.2005, 67 d. Paired control = Hydroponic tomato on the same LECA-box design fed mineral fertilizer (EC ~2.5 mS/cm), recorded in HYD column, run 23.05.2005-~05.07.2005 (43 d) - a SHORTER window than its paired aquaponic run. A third, non-quantified soil-culture control (irrigated every few days with fish water) was also grown for tomato only (p.150, Fig.2); its fruit yield appears only as a bar in Fig.3 with no table/text numeric value, so per ‘never read values off a figure’ it is NOT extracted - recorded here as context only. Only one aquaponic treatment for this crop, so one row. | Hydroponic control ran 23.05.2005-~05.07.2005 (43 d); Aquaponic ran 29.07.2005-~03.10.2005 (67 d) - started ~3-4 weeks after HYD ended, and ran 24 d LONGER than its own paired control (Table 2, p.153). Sequential, not concurrent; duration mismatch between AP (67d) and HYD (43d) is as-reported, not an error. | WARN-MATERIAL EC unit: Table 1 (p.152) prints the EC row unit as ‘mS cm-1’ with tolerance ‘<1200’ and ranges 350-680 (tilapia) / 400-1103 (perch). Read literally as mS/cm this is physically implausible for freshwater RAS fish culture (350-1103 mS/cm would be roughly 10x seawater conductivity, lethal to tilapia/perch; a <1200 mS/cm ‘tolerance limit’ is meaningless for fish). Section 2.1 (p.151) separately and unambiguously states the HYDROPONIC fertilizer target as ‘an electrical conductivity of 2.5 mS cm-1’ - a plausible greenhouse hydroponic EC. Table 1’s fish-water range sitting below that hydroponic target only makes sense if Table 1’s own unit is actually microS/cm (a common mu-to-m glyph substitution in PDF text extraction from this era of Elsevier typesetting), i.e. 0.35-0.68 / 0.40-1.10 mS cm-1 (dS/m). Recorded EC assuming microS/cm (defensible reading, physically consistent); the literal ‘mS cm-1’ reading is the other candidate and is recorded here for the user to verify against the original PDF glyph. Affects EC cell in all 3 trial rows (same Table 1 source). | WARN-MINOR RANGE (water quality): range only, no trial mean reported (Table 1, p.152); N=sample count given in table, not applied here. Perch water-quality range (Table 1) is pooled across BOTH tomato and cucumber trials (‘Perch (Tomatoes, Cucumbers)’ is a single combined column in Table 1, p.152) and cannot be disaggregated by crop; the identical range is therefore also applied to T3 (cucumber). This is a reporting-granularity limitation of the source, not a value conflict. | Daily Water exchange rate 41% is explicitly stated (p.152) to include water used to irrigate the parallel soil-culture control (‘During tomato experiments, a total of 49.17 m3 or 0.734 m3 d-1 of fish water was used to irrigate the soil cultures, which explains the higher water consumption in the second experiment’) - i.e. this 41% is NOT solely fish-tank evaporation replacement, unlike the 15%/9% figures for aubergine/cucumber which the text attributes ‘only due to water evaporation in aquaponic’ (p.152). | NO COLUMN (Table 2, p.153, full figures for cross-check): Tomato HYD: Fruit Production 73.6 kg FW total, Planted area 2.8 m2; Total System Removal N=1.5,P=0.29,K=3.0 g/m2/d; Fruit Harvest Removal N=0.52,P=0.11,K=0.8 g/m2/d; Nutrient recycling 34%N/37%P/28%K. Tomato AP: Fruit Production 116.1 kg FW total, Planted area 4.9 m2; Fish Feeding Load 0.89 kg/d; Total System Removal N=0.6,P=neg.(negative value due to data uncertainty, per table footnote),K=- g/m2/d; Fruit Harvest Removal N=0.43,P=0.07,K=0.4 g/m2/d; Nutrient recycling 69%N, >100%P (table shows a value >100; text p.154 explains: ‘a percentage of more than 100 was calculated, due to the soil irrigation with fish water, where nutrient loss could not be calculated exactly’ - this is the AUTHORS’ own stated data-uncertainty caveat, not a contradiction to flag), -%K. In summer 2005 about 1/3 of NPK removal by the hydroponic system was achieved by tomato fruit (p.154). | Potassium tissue content (mineral, plant.csv): aquaponic tomato fruit = 22.0 g K/kg dry matter vs hydroponic = 40.8 g K/kg dry matter (p.154-155, Section 3.3), explicitly linked by the authors to fish water containing ~45x lower potassium than the hydroponic fertilizer (factor-3 lower N, factor-10 lower P, factor-45 lower K vs hydroponic, p.154) - this caused a stated poorer tomato quality in aquaponic. See out/graberAquaponicSystemsNutrient2009.plant.csv. | Sensory taste-test (n=19, variety ‘Grappella’ only, not a plant analyte, NO COLUMN): 15% preferred aquaponic tomato taste, 21% hydroponic, 47% soil-cultivated, 17% detected no difference (p.155). | UNIT CONVERSION ONLY: fish tank irrigation rate 10-15 m3/h -> 166.7-250 L/min; fish tank 2.5 m3 -> 2500 L; DO/TAN/NO2/NO3 mg/l recorded as-is (mg/L ~ ppm 1:1 equivalence for dilute aqueous solution). | NOT DERIVED, left NR: Initial Stock density (fish tank volume 2.5 m3 given, but no fish count/weight-at-stocking for the main trial system, only for the separate 220-l aquaria fertilizer-coefficient sub-experiment); FCR (Fish Feeding Load kg/d x Duration would give a total feed input, and Fish biomass created is given, but Total Feed itself is never stated as a total - not computed); SGR; Fish size initial/final; Fish survival rate; Fish weight gain (g/fish - fish counts not given); Total Feed (kg) as a stated total (only the daily rate kg feed/d is given in Table 2 - see NO COLUMN note for the rate); % of body weight (ad libitum feeding, no ration % given); N/P/K composition of feed as % (the paper instead gives ‘nutrient release into the water by feeding 1 kg fish feed’ = 46+/-4 g N, 6.0+/-0.8 g P, 1.0+/-0.4 g K per kg feed - this is a water-release fertilizer coefficient from a separate 220-l aquaria sub-experiment with 2 replicate tilapia batches (25 fish/1330 g and 31 fish/1730 g, ad libitum for 14 d, consuming 330 and 436 g feed respectively), NOT total feed composition; recorded here as NO COLUMN, not entered as Protein/N/P/K feed-% since equating water-release with total feed content would be an assumption the paper does not make). | Fish Category, Water classification, Plant Category: NR - paper does not use a categorisation term for these. | Replicates (n): NR - see T1 remark, same system-design reasoning applies. | Methods (p.152) states elemental composition (C, N, P) of tomato biomass was analysed by an external lab (Labor fuer Boden und Umweltanalytik, Zurich) via Kjeldahl/AAS/ICP, but no N or P tissue-content numbers are actually reported in Results - only the K figure above appears. [not reported]: tissue N, tissue P.
graberAquaponicSystemsNutrient2009-T3
Fish
| Field | Value |
|---|---|
| Fish | Eurasian perch (Perca fluviatilis), obtained from Percitech S.A., Switzerland |
| Protein | 45 |
| Feed regime | Ad libitum; Trouvit Tilapia Starter pellets, 3.5 mm, 45% raw protein (p.150) |
| Fish biomass created (kg) | 4 |
| Fish trial duration (days) | 42 |
Water
| Field | Value |
|---|---|
| Water recycle | UNIT CONVERSION ONLY: 10-15 m3/h -> 166.7-250 |
| Water volume in the system | 2500 (fish tank only, 2.5 m3; UNIT CONVERSION ONLY: m3->L) |
| Water type | Fish tank effluent / RAS water, closed recirculating loop (zero daily water exchange except evaporation replacement with tap water) (p.150) |
| Daily Water exchange rate | 9 |
| Aq pH | 6.19-7.41 |
| pHOptimal | 7-8 (Table 1 tolerance limit, applies to both tilapia and perch culture) |
| Dissolved Oxigen | 6.7-7.5 |
| EC | 0.40-1.10 (dS/m; UNIT CONVERSION ONLY assuming microS/cm source unit, see WARN-MATERIAL in remarks) |
| TAN / NH4-N | 0.06-0.68 |
| NO2-N | 0.01-0.18 |
| NO3-N | 12.1-95 |
Plant
| Field | Value |
|---|---|
| Plant | Cucumber |
| Details | Used as the ‘model culture’ to evaluate TOTAL nutrient recycling capacity including non-fruit green biomass (see remarks); cultivar not stated. Late-year (autumn/winter) planting date associated with lowest recycling rates of the three crops (p.153). |
| Days Plant after transplant | 42 |
System & Setup
| Field | Value |
|---|---|
| System type | LECA (light-expanded clay aggregate) planted trickling filter used simultaneously as hydroponic-style grow bed, RAS-integrated (p.149-150) |
| Media Details | LECA filled 30 cm deep in green PVC boxes (0.4x0.6x0.4 m); Aquaponic: 74 boxes in 2 rows, 3.0 m3 total LECA; Hydroponic control: 29 boxes in 1 row, 1.2 m3 LECA (p.150, Figs 1-2) |
| Climate control | Y (Greenhouse (adjoining greenhouse, Waedenswil, Zurich); no temperature/humidity setpoints reported (p.150, Fig.1)) |
| Nutrient supplemented | N (Aquaponic received NO added fertilizer by design - only fish-derived nutrients from RAS effluent (p.149-150, Section 2.1). Hydroponic control WAS fertilized (EC target 2.5 mS/cm, 2-3x/week) - see remarks, not applicable to this AP-treatment row.) |
| Equipment | SC1000 continuous sensors (Hach Lange sc-sensors 3798-S EC, phD-S pH, 1200-S redox, LDO dissolved O2), logged every 15 min; WTW Multiline 350i handheld multi-electrode meter (daily backup); Hach Lange LCK photometric test kits read on Cadas30 photometer (dissolved ions); irrigation pumps (10-15 m3/h to aquaponic LECA rows via 0.11 m orange PVC sewage piping, 6 cm drilling holes; 5 m3/h to hydroponic row) |
| Control Parameters | Table 1 tolerance limits: NH4-N <1.0 mg/l; NO2-N <0.2 mg/l; NO3-N <150 mg/l; pH 7-8; EC <1200 (unit ambiguous, see remarks); O2 >6 mg/l |
| Combination | Eurasian perch and cucumber; aquaponic vs hydroponic (sequential, immediately consecutive) |
Site
| Field | Value |
|---|---|
| Region | Europe |
| Country | Switzerland |
Results & Statistics
| Field | Value |
|---|---|
| Measured Unit | g FW m-2 d-1 (fruit production rate); kg FW (fruit production total, see remarks) |
| Statistically analysed | N |
| AP | 80 |
| HYD | 125 |
Experimental Remarks: TRIAL DEFINITION: T3 = Aquaponic cucumber culture (perch RAS, LECA trickling-filter grow beds), 22.11.2005-~03.01.2006, 42 d. Paired control = Hydroponic cucumber on the same LECA-box design fed mineral fertilizer (EC ~2.5 mS/cm), recorded in HYD column, run 11.10.2005-~22.11.2005 (42 d) - ending the day the aquaponic run began. Only one aquaponic treatment for this crop, so one row. | Hydroponic control ran 11.10.2005-~22.11.2005 (42 d); Aquaponic ran 22.11.2005-~03.01.2006 (42 d), starting the day HYD ended (Table 2, p.153). Sequential (immediately consecutive), not concurrent. | WARN-MATERIAL EC unit: Table 1 (p.152) prints the EC row unit as ‘mS cm-1’ with tolerance ‘<1200’ and ranges 350-680 (tilapia) / 400-1103 (perch). Read literally as mS/cm this is physically implausible for freshwater RAS fish culture (350-1103 mS/cm would be roughly 10x seawater conductivity, lethal to tilapia/perch; a <1200 mS/cm ‘tolerance limit’ is meaningless for fish). Section 2.1 (p.151) separately and unambiguously states the HYDROPONIC fertilizer target as ‘an electrical conductivity of 2.5 mS cm-1’ - a plausible greenhouse hydroponic EC. Table 1’s fish-water range sitting below that hydroponic target only makes sense if Table 1’s own unit is actually microS/cm (a common mu-to-m glyph substitution in PDF text extraction from this era of Elsevier typesetting), i.e. 0.35-0.68 / 0.40-1.10 mS cm-1 (dS/m). Recorded EC assuming microS/cm (defensible reading, physically consistent); the literal ‘mS cm-1’ reading is the other candidate and is recorded here for the user to verify against the original PDF glyph. Affects EC cell in all 3 trial rows (same Table 1 source). | WARN-MINOR RANGE (water quality): range only, no trial mean reported (Table 1, p.152); N=sample count given in table, not applied here. Perch water-quality range (Table 1) is pooled across BOTH tomato and cucumber trials (‘Perch (Tomatoes, Cucumbers)’ is a single combined column in Table 1, p.152) and cannot be disaggregated by crop; the identical range from T2 is applied here. Reporting-granularity limitation of the source, not a value conflict. | Source text (Table 2 raw extraction, p.153): the Hydroponic cucumber row appears to be missing one placeholder relative to the Aubergine/Tomato hydroponic rows (which show two consecutive dashes for Fish Feeding Load and Fish Production, both NA since hydroponic has no fish); read here as an extraction/typesetting quirk, not a genuine table discrepancy, and both Fish Feeding Load and Fish Production for the Cucumber HYD control are treated as NA, consistent with the other two crops’ hydroponic rows. | NO COLUMN (Table 2, p.153, full figures for cross-check): Cucumber HYD: Fruit Production 25.6 kg FW total, Planted area 4.9 m2; Total System Removal N=0.3,P=0.06,K=0.7 g/m2/d; Fruit Harvest Removal N=0.12,P=0.03,K=0.2 g/m2/d; Nutrient recycling 36%N/48%P/25%K. Cucumber AP: Fruit Production 48.2 kg FW total, Planted area 14.4 m2; Fish Feeding Load 0.26 kg/d; Total System Removal N=0.4,P=0.07,K=- g/m2/d; Fruit Harvest Removal N=0.08,P=0.02,K=0.1 g/m2/d; Nutrient recycling 17%N/27%P/-%K. Cucumber achieved the lowest recycling rates overall: authors attribute this to lowest feed input and moderate fruit yield from a late-year (autumn) start (p.153). Whole-plant (non-fruit) recycling: standing green biomass at end of culture = 68 kg (AP) / 24 kg (HYD), i.e. 141%/95% of respective fruit yield; including this green biomass, total P recycling reaches ~100% (HYD, by design with fertilizer) and 50% (AP) (p.154). No dedicated column for whole-plant biomass recycling or green-biomass mass. | UNIT CONVERSION ONLY: fish tank irrigation rate 10-15 m3/h -> 166.7-250 L/min; fish tank 2.5 m3 -> 2500 L; DO/TAN/NO2/NO3 mg/l recorded as-is (mg/L ~ ppm 1:1 equivalence for dilute aqueous solution). | NOT DERIVED, left NR: Initial Stock density (fish tank volume 2.5 m3 given, but no fish count/weight-at-stocking for the main trial system, only for the separate 220-l aquaria fertilizer-coefficient sub-experiment); FCR (Fish Feeding Load kg/d x Duration would give a total feed input, and Fish biomass created is given, but Total Feed itself is never stated as a total - not computed); SGR; Fish size initial/final; Fish survival rate; Fish weight gain (g/fish - fish counts not given); Total Feed (kg) as a stated total (only the daily rate kg feed/d is given in Table 2 - see NO COLUMN note for the rate); % of body weight (ad libitum feeding, no ration % given); N/P/K composition of feed as % (the paper instead gives ‘nutrient release into the water by feeding 1 kg fish feed’ = 46+/-4 g N, 6.0+/-0.8 g P, 1.0+/-0.4 g K per kg feed - this is a water-release fertilizer coefficient from a separate 220-l aquaria sub-experiment with 2 replicate tilapia batches (25 fish/1330 g and 31 fish/1730 g, ad libitum for 14 d, consuming 330 and 436 g feed respectively), NOT total feed composition; recorded here as NO COLUMN, not entered as Protein/N/P/K feed-% since equating water-release with total feed content would be an assumption the paper does not make). | Fish Category, Water classification, Plant Category: NR - paper does not use a categorisation term for these. | Replicates (n): NR - see T1 remark, same system-design reasoning applies.
Plant Measurements
| Trial | System | Category | Analyte | Value | Unit | Sig. | Location |
|---|---|---|---|---|---|---|---|
| graberAquaponicSystemsNutrient2009-T2 | AP | mineral | Potassium (K) in fruit | 22.0 | g/kg DM | NR | p.154-155, Section 3.3 |
| graberAquaponicSystemsNutrient2009-T2 | HYD | mineral | Potassium (K) in fruit | 40.8 | g/kg DM | NR | p.154-155, Section 3.3 |