Please use this identifier to cite or link to this item: https://doi.org/10.21256/zhaw-18461
Title: Influence of pH change on the phosphorus cycle in aquaponics
Authors : Gartmann, Florentina
Schmautz, Zala
Junge, Ranka
et. al : No
Conference details: 9th International Phosphorus Workshop (IPW9), Zurich, 8 - 12 July 2019
Publisher / Ed. Institution : ZHAW Zürcher Hochschule für Angewandte Wissenschaften
Issue Date: 2019
License (according to publishing contract) : CC BY 4.0: Attribution 4.0 International
Type of review: No review
Language : English
Subjects : Aquaponics; PH change; Phosphorus cycle
Subject (DDC) : 577: Ecology
630: Agriculture
Abstract: In fish farming, large amounts of phosphorus (P) are accumulating in the discharge, which on one side poses a problem due to eutrophication potential, but on the other side opens a chance for recycling of this critically limiting nutrient. In aquaponics (AP), which is the combined cultivation of fish (aquaculture) and plants (hydroponic) in one water cycle, plants assimilate P present in aquaculture discharge. The aim of this study was to investigate the P-cycling in aquaponic in order to be able to further optimise P utilisation. For this, the effect of pH manipulation on the system was examined. Three replicates of semi-commercial size aquaponic systems, stocked with Nile tilapia (Oreochromis niloticus), and planted with lettuce (Salanova® Batavia) were monitored from 22th September to 8th November 2017. The pH was adjusted to 6.0±0.2 by adding acid (HCl) during weeks 1 and 2, and to 7.3±0.3 by adding bases (KOH and Ca(OH)2) during weeks 3 and 4. Ortho-P and total-P from different sampling points in the system (system water, sludge, and deposits) were analysed. In addition, biomass production of fish and lettuce, and its nutrient content was compared between the triplicates. The P balance showed that 41% and 8% of the total P inputs provided by feed and water were absorbed by fish and plants, respectively. 27% of P accumulated in the system water, and 24% in form of deposits (biofilm on sump and fish tank surface and deposits on digester heater). Furthermore, digested sludge contained more ortho-P (14-55% of total-P) than fresh sludge (5-10% of total-P). In addition, around 90% of total-P was present as ortho-P in a system water. The ortho-P concentrations after the manipulations of pH in the aquaponic system water surprisingly increased with increasing pH. This is probably due to the complex dynamics between P and Ca. The established P mass balance identified and quantified several P pools, demonstrating that aquaponics systems can maximize overall P utilization if a digester is included into the loop.
Departement: Life Sciences and Facility Management
Organisational Unit: Institute of Natural Resource Sciences (IUNR)
Publication type: Conference poster
DOI : 10.21256/zhaw-18461
URI: https://digitalcollection.zhaw.ch/handle/11475/18461
Appears in Collections:Publikationen Life Sciences und Facility Management

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