Evaluation of Multiple Contaminants Removal Efficiency by Zeolite and Steel making Slag for Double Sheeted PRB

Abstract

Artificial island is constructed with dredged materials and landfill waste. However these materials could be considered as the main sources for contamination as they might contain ammonium, cadmuim and phosphate. Also previous researchers show that costal sediments in South Korea were contaminated by ammonium, phosphate and cadmium (Song, 2003). Littoral area of sea could be happened by sudden accident but almost all contamination are caused by artificial behavior. Double sheeted permeable reactive barrier system containing zeolite and steel making slag is possible to be applied to filter multiple contaminants at the same time. Sequential batch test was firstly performed to select reaction order between zeolite and slag (Test ZS), slag and zeolite (Test SZ) and mixed two materials. In case of phosphate and cadmium removal rate (%), there was no difference between two modules. However in case of ammonium removal rate (%), test ZS showed better removal rate than that of Mixed and test SZ. Column test 1 was performed to reconfirm removal efficiency depending on reaction order under flow through condition. Among three test methods in sequential batch test, two test mothods, test ZS and test SZ, which showed highest and lowest removal efficiency of ammonium, were tested. Because lower removal efficiency of ammonium than that of other contaminant in sequential batch test was obtained, only ammonium breakthrough curve was obtain in column test 1. The result was analyzed by two-site nonequilibrium model and it showed high reliability (R2). Test ZS showed high removal efficiency than that of test SZ and it was similar to sequential batch test. Column test 2 was performed to evaluate removal efficiency of multiple contaminants by column test ZS which consists of different depth of zeolite and steel making slag under flow-through condition. In this test four test methods, 10:0, 8:2, 5:5, 7:3, were tested and through obtained breakthrough curve, retardation factor (Rf) partitioning coefficient (β), and mass transfer coefficient (ω) were analyzed. In the case of ammonium, breakthrough curve was delayed more with increasing zeolite depth and retardation factor (Rf) of 10:0, 8:2, 5:5, 3:7 were 185.9, 111.2, 109.1, 67.3. In the case of phophate, breakthrough curve was delayed more with decreasing zeolite depth and retardation factor (Rf) of 10:0, 8:2, 5:5, 3:7 were 0, 38.25, 120, 122.4. In the case of cadmuim, breakthrough curve was delayed more with decreasing zeolite depth and retardation factor (Rf) of 10:0, 8:2, 5:5, 3:7 were 48.95, 101.3, 156.1, 207.1. After column test 2, linear relationship between Rf, ω and β and it is possible to predict other column test method parameter without other tests.