Use of Modified Pine Bark for Removal of Pesticides from Stormwater Runoff

Pesticide entrainment in stormwater runoff can contribute to non-point source pollution of surface waters. Granular activated carbon has been successfully used for removing pesticides from wastewater. However, implementation of granular activated carbon sorption media in stormwater filtration systems comes with high initial capital investment and operating costs. Modified pine barks offer attractive alternative sorption media for use in stormwater filtration systems. Pine barks constitute a significant fraction of underutilized low-value waste materials from the forest products industry. The majority of the waste bark is used as a low-grade thermal fuel. We evaluated the effectiveness of modified pine bark for removing pesticides from water under dynamic conditions by percolating water solutions of pesticides through fixed bed columns of the test materials. We found that bark modified by grinding and treatment with an aqueous solution of N-methylpyrrolidinone (NMP), or with an NMP solution of stearic acid, or a methanol solution of sodium methylate is very effective in removing chlorpyrifos, chlorothalonil, and dichlobenil. Removal for chlorpyrifos was 88% to 96%; for chlorothalonil, 84% to 92%; and for dichlobenil, 39% to 90%. These results indicate that modified pine bark is as effective as granular activated carbon in removing hydrophobic pesticides from water and may be used as a less expensive alternative sorption medium for removal of pesticides from stormwater runoff.