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Abstract
Nutrient-rich wastewater from concentrated animal feeding operations (CAFOs) is one of the largest sources of surface water contamination in the US. This study evaluated biochar as a media in vegetated constructed treatment wetlands (CTWs) for CAFO wastewater treatment. A wood biochar was found to adsorb up to 0.28 mg NH4 +-N per g biochar but no NO3- or PO43-. It was subsequently used in a greenhouse experiment, conducted with four simulated CTWs: R1 biochar with aqueous plants; R2 - biochar, gravel and plants; R3 - biochar; and R4 - gravel and plants. The reactors were monitored for their removal of solids, nutrients and metals from swine wastewater as well as plant growth. Overall, there were no statistical differences between the mass of pollutants (TS, COD, NH4+-N, PO43--P, K, Na) removed by R1 and R2, but for almost all parameters (except PO43--P and Na) they outperformed R3 and R4. Plant growth was greatest in R1 and least in R4. These findings show that incorporation of biochar into CTW media can significantly improve treatment of wastewater. Additional studies using other types of biochar could yield even better results