Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System
Abstract
:1. Introduction
2. Materials and Methods
2.1. Solid Waste Samples
2.2. Determination of Elemental Concentrations
2.3. Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS)
2.4. P K-edge X-ray Absorption Near Edge (XANES) Spectroscopy
2.5. Statistical Analyses
3. Results
3.1. Elemental Composition
3.2. Pyrolysis-Field Ionization Mass Spectrometry (Py-FIMS)
3.3. P K-edge X-ray Absorption Near Edge (XANES) Spectroscopy
4. Discussion
4.1. Organic Matter Composition
4.2. P XANES Spectroscopy
5. Conclusions
- The methodological approach of using Py-FIMS and XANES spectroscopy as methods to determine organic matter composition and P speciation of solid African catfish RAS waste samples was appropriate. It revealed insight into the distribution of organic matter compound classes in solid waste of three different fish stocking densities and provided evidence for the occurrence of exclusively Ca-bound P compounds in African catfish RAS waste.
- The high amounts of sterols, fatty acids and alkylaromatics in the solid waste of all three stocking densities of African catfish RAS determined by Py-FIMS reflect the plant-based feed of the fish. To assess the suitability of African catfish RAS solid waste as organic soil amendment and to prevent possible negative effects of sterols on the N-cycle in soil, further research is needed, especially on soils that have been amended by solid waste from African catfish RAS. Alternatively to direct land application of this waste, some pretreatments such as anaerobic digestion for biogas production or vermifiltration, should be tested.
- The stocking density had an influence on feed input, water exchange rates and total oxygen concentrations in the tested African catfish RAS systems. These three factors, alone and in combination, alter solid waste composition, and its applicability as soil amendment if originating from extensive or (semi)intensive catfish aquaculture.
- XANES spectroscopy detected exclusively Ca-associated P compounds in solid African catfish RAS waste of three different fish stocking densities. Ca-phosphate minerals as a major constituent of many bio-waste material P fertilizers have beneficial properties when applied on soils. Thus, solid African catfish RAS waste can be considered as possible addition to traditional organic P fertilizers. However, this first investigation of African catfish RAS waste with P XANES spectroscopy would benefit from the application of more different complementary techniques, such as solution 31P nuclear magnetic resonance (NMR) spectroscopy and sequential P fractionation to get a more comprehensive view on P speciation.
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Parameter | Unit | EAS | SIAS | IAS |
---|---|---|---|---|
N | % | 5.2 ± 0.2 | 5.4 ± 0.2 | 5.1 ± 0.3 |
S | % | 0.9 ± 0.0 | 0.9 ± 0.0 | 1.0 ± 0.1 |
C:N | ratio | 7.9 ± 0.2 | 7.4 ± 0.2 | 7.8 ± 0.2 |
P | % | 1.4 ± 0.1 | 1.7 ± 0.1 | 1.6 ± 0.1 |
Al | % | 0.1 ± 0.0 | 0.1 ± 0.0 | 0.0 ± 0.0 |
Fe | % | 0.2 ± 0.0 | 0.3 ± 0.0 | 0.3 ± 0.0 |
Ca | % | 3.4 ± 0.1 | 4.2 ± 0.2 | 3.9 ± 0.1 |
Mg | % | 0.2 ± 0.0 | 0.2 ± 0.0 | 0.2 ± 0.0 |
K | % | 0.2 ± 0.0 | 0.3 ± 0.0 | 0.5 ± 0.0 |
Sample | VM | TII | %TII From Compound Classes | |||||||||
---|---|---|---|---|---|---|---|---|---|---|---|---|
(%) | (106 counts mg−1) | CHYDR | PHLM | LDIM | LIPID | ALKYL | NCOMP | STEROL | AMID | SUBER | FATTY | |
EAS | 78.5 a | 958.5 a | 2.3 a | 2.3 a | 0.8 a | 3.6 a | 6.1 a | 1.1 a | 14.4 a | 2.6 a | 0.7 a | 12.2 a |
SIAS | 77.2 a | 1467.8 b | 2.5 a | 2.5 a | 1.2 c | 3.7 a | 6.2 a | 1.3 b | 14.1 a | 2.8 a | 0.8 b | 7.4 b |
IAS | 85.8 b | 1396.3 b | 2.7 a | 2.4 a | 1.0 b | 3.7 a | 6.0 a | 1.4 b | 14.2 a | 2.9 a | 0.8 b | 7.2 b |
Sample | Ca Phytate | CaHPO4 | Ca Hydroxyapatite | R-Factor |
---|---|---|---|---|
in % | ||||
EAS | 87 | 6 | 7 | 0.0094 |
SIAS | 53 | 47 | 0.0267 | |
IAS | 76 | 24 | 0.0102 |
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Prüter, J.; Strauch, S.M.; Wenzel, L.C.; Klysubun, W.; Palm, H.W.; Leinweber, P. Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System. Agriculture 2020, 10, 466. https://doi.org/10.3390/agriculture10100466
Prüter J, Strauch SM, Wenzel LC, Klysubun W, Palm HW, Leinweber P. Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System. Agriculture. 2020; 10(10):466. https://doi.org/10.3390/agriculture10100466
Chicago/Turabian StylePrüter, Julia, Sebastian Marcus Strauch, Lisa Carolina Wenzel, Wantana Klysubun, Harry Wilhelm Palm, and Peter Leinweber. 2020. "Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System" Agriculture 10, no. 10: 466. https://doi.org/10.3390/agriculture10100466
APA StylePrüter, J., Strauch, S. M., Wenzel, L. C., Klysubun, W., Palm, H. W., & Leinweber, P. (2020). Organic Matter Composition and Phosphorus Speciation of Solid Waste from an African Catfish Recirculating Aquaculture System. Agriculture, 10(10), 466. https://doi.org/10.3390/agriculture10100466