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Title: Preliminary laboratory evaluation of iron-bearing reactive media for pesticide water treatment

item Allred, Barry
item RACHARAKS, RATANACHAT - The Ohio State University

Submitted to: Applied Engineering in Agriculture
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 7/22/2014
Publication Date: 1/31/2015
Citation: Allred, B.J., Racharaks, R. 2015. Preliminary laboratory evaluation of iron-bearing reactive media for pesticide water treatment. Applied Engineering in Agriculture. 30(6):859-867.

Interpretive Summary: Improved methods are needed to treat ground and surface waters contaminated with agricultural pesticides. Laboratory contaminant removal batch tests were used to evaluate four iron-based filter materials for water treatment of organochloride pesticides (2,4-D, alachlor, and atrazine). These batch tests determined that porous iron composite (PIC) worked best. Laboratory saturated solute transport column tests were then carried out to further assess the filter treatment capabilities of PIC to remove organochloride pesticides from water. The column tests showed PIC capable of treating waters with high organochloride pesticide (2,4-D, alachlor, and atrazine) concentrations to the extent that the reduced pesticide levels achieved are able to meet USEPA drinking water standards. The column tests also indicate that PIC degrades organochloride pesticides quickly, with only 4 min. of PIC to solution exposure time needed to remove almost all of the 2,4-D, alachlor, and atrazine originally present. Furthermore, pH adjustment was not required in order for PIC to be effective in removing organochloride pesticides from water. The overall laboratory findings in regard to PIC water treatment of organochloride pesticides are promising, but must be considered very preliminary. Additional research should focus on isolating the degradation products of chemical interactions between PIC and organochloride pesticides, precise determination of the process or processes by which PIC degrades organochloride pesticides, measurement of the minimum exposure time required by PIC to treat organochloride pesticide contaminated waters, and rigorous, long duration testing at actual field sites.

Technical 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 initiated to assess the water treatment capabilities of four iron-based filter materials to remove three different organochloride pesticides. The iron-based filter materials evaluated were zero valent iron (ZVI), porous iron composite (PIC), sulfur modified iron (SMI), and iron oxide/hydroxide (IOH). The three organochloride pesticides tested on the iron-based filter materials were 2,4-D, alachlor, and atrazine. The laboratory investigation included contaminant removal batch tests and low-to-high flow rate saturated solute transport column tests. Results of replicated contaminant removal batch tests indicate, that of the four iron-based filter materials 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, effluent 2,4-D, alachlor, and atrazine concentrations exiting the PIC column were less than 0.3 ppb, even when the column retention time was only 4 minutes. 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.