Preliminary Laboratory Evaluation ofIron-Bearing Reactive Media forPesticide Water Treatment

Abstract

Abstract. Agricultural pesticides are often found in ground and surface waters, and if present in high enough concentrations, create risks to human and ecological health. Filter treatment systems can potentially remove pesticides from water. Therefore, a laboratory investigation was conducted to assess the water treatment capabilities of four iron-bearing reactive media to remove three different organochloride pesticides. The iron-bearing reactive media evaluated were zero valent iron (ZVI), porous iron composite (PIC), sulfur modified iron (SMI), and a synthetic goethite - iron oxide/hydroxide (SG). The three organochloride pesticides tested for removal by the four iron-bearing reactive media were 2,4-D, alachlor, and atrazine. The laboratory investigation included contaminant removal batch tests and saturated solute transport column tests at two hydraulic retention times. Results of replicated contaminant removal batch tests indicate, that of the four iron-bearing reactive media evaluated, PIC is clearly the most effective for water treatment of 2,4-D, alachlor, and atrazine. The initial batch test concentration for each of the three pesticides was 500 ppb, and the replicated PIC batch tests averaged more than 98% removal for alachlor and greater than 99% removal of 2,4-D and atrazine. Pesticide water treatment capabilities for PIC were further assessed by comparing results between control (no filter material - empty column) and PIC saturated solute transport column tests. In contrast to an influent concentration entering the PIC column of 500 ppb for each of the three pesticides, the effluent 2,4-D, alachlor, and atrazine concentrations exiting the PIC column were less than 0.3 ppb, even when the hydraulic retention time was only 4 min. Importantly, all PIC column test effluent pesticide concentrations were well below USEPA drinking water standards. Consequently, this preliminary laboratory assessment indicates that the PIC filter material exhibits promise for organochloride pesticide water treatment; however, more laboratory and field testing is needed to fully determine PIC capabilities.