『Abstract
In situ denitrification walls and biofilters made of wood chips
are being implemented as innovative technologies for the removal
of nitrates in tile drainage water from farms to reduce pollution
of surface waters and the hypoxia problem in the Gulf of Mexico.
Although fairly effective in removing nitrates, not much is known
about the effectiveness of the biofilters in removal of herbicides,
pesticides, and antibiotics in the drainage water. Using weathered
wood chips obtained from an in situ denitrification wall, four
common pollutants tested sorbed strongly to wood chips in the
following order: enrofloxacin＞monensin A＞atrazine＞sulfamethazine.
Of the four chemicals tested, enrofloxacin was found to desorb
the least by water extraction. The apparent hysteresis index for
atrazine was found to be lower than that for enrofloxacin and
sulfamethazine indicating greater sorption-desorption hysteresis
for atrazine than enrofloxacin and sulfamethazine. Consecutive
steps of water desorption and organic solvent extraction indicated
that more than 65％ of the sorbed atrazine, 70％ of sulfamethazine,
90％ of enrofloxacine, and 80％ of monensin A were retained in wood
chips. Results of this study showed that wood chip denitrification
walls or biofilters have an added benefit in retaining herbicides
and antibiotics and therefore can act as a barrier to reduce pollution
of surface water and groundwater.
Keywords: Atrazine; Sulfamethazine; Enrofloxacin; Monensis A;
Denitrification wall; Wood chips; Sorption; Desorption』
1. Introduction
2. Materials and methods
2.1. Chemicals
2.2. Sorbents
2.3. Sorption and desorption of chemicals onto woodchips and
soils
2.4. Effect of wood chip particle size on sorption of atrazine
2.5. Sample preparation and chemical analysis
2.6. Chemical analysis
3. Results and discussion
3.1. Sorption experiments
3.2. Desorption experiments
3.3. Effect of wood chips particle size on atrazine sorption
3.4. Extraction of sorbed chemicals from wood chips
4. Conclusion
Acknowledgments
References