Reuse of Carlton reject water: I. Effects on bermudagrass yield

Sarasota County, FL is contracted to provide wastewater (sewage) effluent for the irrigation of local golf courses. However, the county produces less wastewater effluent during summer months, and occasionally fails to meet its obligation to the golf courses. A water treatment process known as electrodialysis reversal (EDR) is employed in the Carlton facility of Sarasota County to create drinking water from groundwater sources that are non-potable due to high salt content. This process makes use of an antiscalant, Aquafeed 600, to prevent precipitation of calcium solids that clog the membranes. The end products of EDR are desalinized, potable water and a saline reject water (TDS = 6500 mg L^-1; EC = 5.9 dS m^-1). This study was conducted to determine the feasibility of using EDR reject water to supplement the traditional wastewater effluent for turfgrass irrigation and to assess the effect of reject water on bermudagrass growth. The study (1996-98) consisted of Tifway and FLoraTeX® bermudagrass grown in soil columns, irrigated with four mixtures of reject:effluent (0:1, 1:2, 2:1, and 1:0) and maintained at two leaching fractions (0.15 and 0.30). Perennial ryegrass, a cool season turfgrass, was overseeded during the winter months (December-February) of years 1 and 2. Yield data for the first two years indicated no significant reduction in bermudagrass yield at either leaching fraction, regardless of the proportion of reject water in the irrigation water. In the third year, however, Tifway bermudagrass yields for the 1:0 and the 2:1 reject:effluent treatments at 0.15 leaching fraction were significantly less than for the 0:1 and the 1:2 reject:effluent treatments. There was no significant difference in the yield of FLoraTeX® bermudagrass, suggesting greater salt tolerance than for the Tifway bermudagrass. Reduction in perennial ryegrass yield with application of reject water (in all proportions) indicated potential problems if using reject water during winter overseeding with ryegrass or similar, less salt-tolerant, turfgrass species.