Fruit and vegetable wash-water characterization, treatment feasibility study and decision matrices

Abstract

On average, it is estimated that up to 5 L of wastewater is generated per kilogram of produce in post-harvest processing of fruit, leafy greens, and root vegetables. The typical wastewater parameters vary in concentration (solids content, COD, BOD, nitrogen, phosphorus) based on the produce being processed. The challenge for producers and regulators is that the selection of the appropriate treatment technology is challenging, so decision matrices were developed to narrow down the treatment selections. Wash-waters for different types of fruit and vegetables from two different operation types, washing only versus washing and processing were investigated. Bench-scale treatments selected for testing included settling, coagulation and flocculation with settling, centrifuge, dissolved air flotation, electrocoagulation, screening, and hydrocyclone. The developed decision matrices summarize the removal effectiveness of the different treatments for typical wastewater parameters and serve as a reference tool in understanding wash-water treatment technologies and their effectiveness in treating various wash-waters.