WATER QUALITY PARAMETERS FOR VEGETABLE WASHWATERS

Total Suspended Solids (TSS), Total Dissolved Solids (TDS), and Turbidity are all measures of water clarity. TSS is a measure of the concentration of solids (mg/L) with particle size greater than 1-1.2 microns. Particles smaller than that are considered dissolved solids and are quantified as TDS in mg/L. A Turbidity measurement is another way to quantify the solid load of water and is measured in nephelometric turbidity units (NTU); examples of solutions with different turbidity measures are shown in Figure 1. Vegetable washwaters often contain high TSS and have high turbidity. The main component of the solid load is the soil that is washed from the vegetables. Suspended solids are considered problematic in wastewater because they reduce water clarity, clog plumbing and irrigation lines, interfere with disinfection technologies, and add sediment to aquatic systems (CCME 2006; MOECC 2003). The solids can also contain other unwanted Figure 1: Examples of solutions with varying turbidity, from left to right: 10 NTU, 20 NTU, 100 NTU, and 800 NTU (photo credit: HMGA)