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PH09 Plant Ecotoxicology
(PH122) Suitability of treated domestic wastewater from pilot-scale constructed wetland treatment systems for irrigation reuse.
Gallagher, J1, Garber, K1, Jones, R1, Rodgers, Jr., J1, 1 Clemson University, Pendleton, South Carolina, U.S.A.
ABSTRACT- Recent droughts and demands for water have emphasized the need to reuse domestic wastewater. Therefore, suitability of primary and secondary domestic wastewater treated in pilot-scale constructed wetland treatment systems (CWTS) for potential irrigation reuse for consumable crops and golf courses was evaluated in this research. A weight-of-evidence approach for "suitability" was defined by the Food and Agriculture Organization of the United Nations (FAO), United States Department of Agriculture (USDA), and University of California (UC) irrigation standards, human health standards for irrigation reuse of mature plants (< 100 fecal coliform cfu / 100 mL), potential phytotoxicity to Bermuda grass (Conydon dactylon L.) and lettuce (Lactuca sativa L.), potential toxicity to Ceriodaphnia dubia Richard and Pimephales promelas Rafinesque, and by meeting NPDES permit limits for discharge. The domestic wastewater characteristics treated in CWTS achieved the FAO, USDA, and UC irrigation guidelines, except for potassium, magnesium, and nitrate. For the irrigation experiments involving mature lettuce, Bermuda grass, and treated domestic wastewater from pilot-scale CWTS, less than 100 fecal coliform cfu / 100 mL were enumerated on 23 of the 24 watered (spray or drip irrigation) samples. No phytotoxicity (germination and growth) was observed in the 21-day irrigation experiments with C. dactylon and treated domestic wastewater. Germination of lettuce (L. sativa) was significantly inhibited by both treated wastewaters in the 14-day experiments. Early seedling growth of L. sativa was not significantly affected by these treatments (p-value = 0.15). No toxicity was observed to C. dubia and P. promelas from treated secondary domestic wastewater. The treated primary and secondary domestic wastewater characteristics achieved the NPDES discharge permit limits except for total phosphorus and fecal coliforms. A weight-of-evidence approach for evaluating suitability of renovated water will increase reuse opportunities based on water quality characteristics and integrative measures such as toxicity.
Key words: wetlands, suitability, reuse, wastewater
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