Nutrients and Trace Metals in Tomato Packinghouse Wastewater: Source Characterization, Leaching Assessment, and Remediation.

Managing about 150 million liters of wastewater generated during washing of tomatoes in packinghouses each year is one of the major concerns for the Florida tomato industry. This is because of the urban encroachment of agricultural lands resulting in close proximity of packinghouses to residential areas and increased regulations on disposal of wastewater to protect Florida’s environmentally sensitive water bodies. Our objectives in this study were to 1) identify the sources of phosphorus and trace metals (copper, nickel, zinc) in packinghouse wastewater, 2) conduct leaching studies to determine the leaching potential of wastewater applied contaminants, and 3) remediate wastewater containing these contaminants using chemical amendments. To achieve these objectives, we collected wastewater samples at different locations in the tomato packinghouses such as dump tank and wash tank and analyzed for nutrients and trace metals. For the leaching study, we packed 12 PVC soil columns (30 cm diameter and 50 cm long) and conducted leaching studies and determined the distribution and transport of contaminants in the soil columns. To explore the scope of chemical amendments in remediating wastewater containing these contaminants, we conducted batch chemical studies with different chemicals such as alum, ferric chloride, and lime and compared the contaminant removal efficiencies. Results of this study will help to develop best management practices to use wastewater generated in tomato packinghouses and environmentally and economically sustain the tomato industry.