TY - JOUR
T1 - Reuse of Carlton reject water
T2 - II. Fate and transport of 226Ra
AU - Sarkar, D.
AU - O'Connor, G. A.
AU - Ruple, G. J.
AU - Sartain, J. B.
PY - 1999
Y1 - 1999
N2 - The water treatment process known as electrodialysis reversal (EDR) is employed in Sarasota County, FL to create drinking water from groundwater sources that are non-potable. This process makes use of an antiscalant, Aquafeed 600, to prevent precipitation of calcium solids that clog the membranes. The reject water generated during the process is highly saline (TDS = 6500 mg L-1) and contains potentially problematic levels of the radionuclide 226Ra (≈ 15 pCi L-1; MCL = 3 pCi L-1). The present study was conducted to evaluate the possibility of using the reject water (with or without dilution by sewage effluent) to irrigate golf course turf and sod farms of Sarasota, FL in terms of 226Ra reactivity and contamination potentials. Glasshouse and field studies were conducted to determine the effects of various proportions of reject water (reject:effluent = 0:1, 1:2, 2:1, and 1:0) on soil and leaching water qualities with respect to 226Ra. The results indicated that 226Ra accumulated throughout the soil profile, and that only small amounts of 226Ra escaped into the drainage water. Even for the undiluted reject water treatment, the measured activity of 226Ra in the drainage water at 30% leaching fraction was less than the required maximum contamination level (MCL) of 3 pCi L-1. Steady-state fate modeling, using the computer code MINTEQA2, suggested that radium adsorption on sand was the primary mechanism responsible for 226Ra retention in the soil column. In the absence of competing Ca, 100% of the 226Ra was predicted to sorb on sandy soil at neutral pH. The presence of Ca decreased overall retention of 226Ra, due to competition for similar surface sites. The 226Ra concentration in the system was too low to induce direct precipitation of radium salts. Radium adsorption on sand was influenced by pH of the soil solution, with more radium adsorbed at higher pH. Under steady-state conditions, the predicted 226Ra concentrations in drainage waters at 30% and 15% leaching fractions were in good agreement with the experimental values for all irrigation treatments considered. At the model-predicted rate of radium accumulation, it will take between 110 and 680 years to reach the soil radium cleanup standard of 5 to 30 pCi g1 in the columns even when pure reject water is used for irrigation.
AB - The water treatment process known as electrodialysis reversal (EDR) is employed in Sarasota County, FL to create drinking water from groundwater sources that are non-potable. This process makes use of an antiscalant, Aquafeed 600, to prevent precipitation of calcium solids that clog the membranes. The reject water generated during the process is highly saline (TDS = 6500 mg L-1) and contains potentially problematic levels of the radionuclide 226Ra (≈ 15 pCi L-1; MCL = 3 pCi L-1). The present study was conducted to evaluate the possibility of using the reject water (with or without dilution by sewage effluent) to irrigate golf course turf and sod farms of Sarasota, FL in terms of 226Ra reactivity and contamination potentials. Glasshouse and field studies were conducted to determine the effects of various proportions of reject water (reject:effluent = 0:1, 1:2, 2:1, and 1:0) on soil and leaching water qualities with respect to 226Ra. The results indicated that 226Ra accumulated throughout the soil profile, and that only small amounts of 226Ra escaped into the drainage water. Even for the undiluted reject water treatment, the measured activity of 226Ra in the drainage water at 30% leaching fraction was less than the required maximum contamination level (MCL) of 3 pCi L-1. Steady-state fate modeling, using the computer code MINTEQA2, suggested that radium adsorption on sand was the primary mechanism responsible for 226Ra retention in the soil column. In the absence of competing Ca, 100% of the 226Ra was predicted to sorb on sandy soil at neutral pH. The presence of Ca decreased overall retention of 226Ra, due to competition for similar surface sites. The 226Ra concentration in the system was too low to induce direct precipitation of radium salts. Radium adsorption on sand was influenced by pH of the soil solution, with more radium adsorbed at higher pH. Under steady-state conditions, the predicted 226Ra concentrations in drainage waters at 30% and 15% leaching fractions were in good agreement with the experimental values for all irrigation treatments considered. At the model-predicted rate of radium accumulation, it will take between 110 and 680 years to reach the soil radium cleanup standard of 5 to 30 pCi g1 in the columns even when pure reject water is used for irrigation.
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M3 - Article
AN - SCOPUS:33747488938
SN - 0096-4522
SP - 38
EP - 44
JO - Annual Proceedings Soil and Crop Science Society of Florida
JF - Annual Proceedings Soil and Crop Science Society of Florida
IS - 58
ER -