Water reuse in closed hydroponic systems: Comparison of GAC adsorption,ion exchange and ozonation processes to treat recycled nutrient solution |
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| Affiliation: | 1. LIWET, Department Of Industrial Biological Sciences, Ghent University, Campus Kortrijk, Graaf Karel De Goedelaan 5, B-8500 Kortrijk, Belgium;2. Department of Civil Engineering and Architecture, University of Catania, Viale A. Doria 6, 95125, Catania, Italy;1. Division of Marine Bioscience, College of Ocean Science and Technology, Korea Maritime and Ocean University, Busan 606-791, Republic of Korea;2. Inland Research Institue, National Institute of Fisheries Science, Changwon 51688, Republic of Korea;1. Norwegian Veterinary Institute, P.O. Box 750 Sentrum, 0106 Oslo, Norway;2. Akva Design AS, Havnegata 46, 8900 Brønnøysund, Norway;3. IRIS – International Research Institute of Stavanger, P.O. Box 8046, 4068 Stavanger, Norway;1. Soils Department, Faculty of Agriculture, Mansoura University, 35516, Mansoura, Egypt;2. Agricultural Botany Department, Faculty of Agriculture, Mansoura University, 35516, Mansoura, Egypt;3. Department of Agricultural and Biological Engineering, University of Florida, Gainesville, FL, 32611, United States |
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| Abstract: | In this study, the removal of root exudates from recycled nutrient solution (RNS) in hydroponic systems was investigated by using alternative advanced treatment processes. In particular, the performance of adsorption on granular activated carbon (GAC adsorption), ion exchange (using Amberlite IRA96) and ozonation was evaluated. The characterization of a RNS from a lettuce hydroponic company showed the occurrence of several organic acids including benzoic, maleic, palmitic, stearic, phthalic, succinic, acrylic, adipic, myristic, mannonic, oleic, arachidic and acetic acid. Furthermore, benzoic, acrylic, myristic and palmitic acid were detected even after the RNS treatment by GAC adsorption, ion exchange or ozonation. Further experiments were performed to evaluate the removal efficiency of root exudates from RNS by the selected treatment processes. For this purpose benzoic acid (BA), which is a potent growth inhibitor, was selected as target compound. Benzoic acid occurring at 23 μg/L in the RNS was completely removed by GAC adsorption, ion exchange or ozonation process. In addition, GAC adsorption was the most efficient technique for organic matter removal. Indeed, the COD removal efficiency was 74%, 67% and 22% for GAC adsorption, ozonation and ion exchange treatments, respectively. The results from UV–vis absorbance measurements corroborated the best performance of activated carbon in organic compounds removal from RNS. For instance, the absorbance removal at 280 nm reached 82%, 51% and 27% after GAC adsorption, ozonation and ion exchange treatments, respectively. |
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| Keywords: | Closed hydroponic Root exudates Activated carbon Ion exchange resin Ozonation |
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