Evaluation of the Characteristics of Pollutant Discharge in Tomato Hydroponic Wastewater (HWW) for Sustainable Water Management in Korea

Abstract

In South Korea, the use of hydroponic cultivation has been on the rise. However, this system produces a large amount of wastewater. In this study, the amount of wastewater generated by hydroponic tomato cultivation is identified, and a management plan is proposed. Based on the analysis of 103 tomato HWW samples, it was found that the electrical conductivity (EC) was 4.25 ± 1.01 dS/m, the nitrogen (N) content was 411.21 ± 122.64 mg/L, and the phosphorus (P) content was 47.74 mg/L, which caused eutrophication. Therefore, agricultural reuse and HWW treatment were proposed. Regarding the annual HWW load, 1 ha of hydroponics discharges 964.26 kg/ha of N, 111.95 of P, 937.46 of K, 795.14 of Ca, 313.83 of Mg, and 405.40 of S. The trace elements were heavy metals, which were calculated as Fe—4.03, Mn—0.77, Zn—1.08, B—2.25, Cu—0.38, and Mo—0.05 kg/ha. Since wastewater is a national source of drinking water, it needs to be collected and treated. Inter-item correlation analysis showed that most of the fertilizer components were correlated with the EC concentrations. This study can be used to determine the concentrations required for agricultural reuse and to determine the treatment capacity in HWW management.