Nitrogen removal in Myriophyllum aquaticum wetland microcosms for swine wastewater treatment: N-labelled nitrogen mass balance analysis.

BACKGROUND

Ecological treatments are effective for treating agricultural wastewater. In this study, wetland microcosms vegetated with Myriophyllum aquaticum were designed for nitrogen (N) removal from two strengths of swine wastewater, and N-labelled ammonium (NH -N) was added to evaluate the dominant NH -N removal pathway.

RESULTS

The results showed that 98.8% of NH -N and 88.3% of TN (TN: 248.6 mg L ) were removed from low-strength swine wastewater (SW1) after an incubation of 21 days, with corresponding values for high-strength swine wastewater (SW2) being 99.2% of NH -N and 87.8% of TN (TN: 494.9 mg L ). Plant uptake and soil adsorption respectively accounted for 24.0% and 15.6% of the added N. Meanwhile, above-ground tissues of M. aquaticum had significantly higher biomass and TN content than below-ground (P < 0.05). N mass balance analysis indicated that gas losses contributed 52.0% to the added N, but the N O flux constituted only 7.5% of total gas losses. The dynamics of NO -N and N O flux revealed that strong nitrification and denitrification occurred in M. aquaticum microcosms, which was a dominant N removal pathway.

CONCLUSION

These findings demonstrated that M. aquaticum could feasibly be used to construct wetlands for high N-loaded animal wastewater treatment. © 2016 Society of Chemical Industry.