Tuesday, November 3, 2009
Convention Center, Exhibit Hall BC, Second Floor
Water reuse is a growing practice and Florida leads the nation in using recycled water for various purposes. The overall objective of this study was to determine the inorganic (nutrients, trace metals) and organic (pesticides) compounds in recycled water ponds of five working commercial horticultural nurseries. The recycled water was characterized to determine the extent and variability of nutrients, metals, bacteria, and pesticides using EPA approved methods. The pH of recycled water at four sites was alkaline (8.1–9.3) while pH at one site was neutral (6.5). The EC values of recycled water at all sites were low and ranged from 0.311 to 0.362 dS/m. Total P in the recycled water ranged from 0.35 to 1.0 mg/L and 87 to 96% of total P was present as orthophosphate. Total Kjeldahl N values in all recycled water ponds ranged from 1.47 to 2.17 mg/L. Total coliforms and E. coli were between 20 to 50 colony forming units/100 mL of recycled water. Concentrations of trace metals in recycled water were low and of targeted analysis of 11 trace metals, only two metals, B and Zn, were above the method detection limits with concentrations of 0.104 to 0.153 mg/L for B and 0.123 to 0.211 mg /L for Zn. Among organo-chlorine pesticides detected, endrin aldehyde was the only pesticide detected in all nursery recycled water ponds, with concentrations of 0.04 to 0.10 µg/L in four recycled water ponds while one pond had an elevated concentration of 1.62 µg/L. Other detected pesticides in recycled water were methoxychlor, endosulfan sulfate, DDE, and α–chlorodane and the concentrations of these individual pesticides were less than 0.20 µg/L. In summary, the concentrations of various inorganic and organic compounds in recycled water from nursery ponds are very low and do not appear to be problematic for irrigation purposes.