Case Study of a Restored Wetland Best Management Practice

Abstract

A restored drained wetland should provide a comparable environment to remove nonpoint source nitrogen (N) from animal feeding operation (AFO) runoff as an equivalent constructed wetland. Our research addresses the N removal efficiency of the drained and restored Long Acres Wetland (LAW) to its modeled constructed wetland equivalents, and the relationship of the five denitrifying variables of bacteria population size, bacteria-pollutant contact, N Cycle continuity, kinetics, and bacteriapollutant contact time to rate their relative influence on N removal. Although, we found restoration improved percent total nitrogen removed (%TNR) from 90.9% to 94.6%, analysis of variance (ANOVA) of the actual drained versus actual restored %TNR datasets indicated no statistical difference. However, ANOVA of the actual restored versus modeled restored %TNR datasets showed a significant statistical difference, indicating that the actual restored LAW was not operating at its theoretical optimal efficiency. Subsequent ANOVA of the denitrifying variables' preversus post-restoration datasets indicated that restoration had favorably influenced all denitrifying variables except bacteria-pollutant contact. Our results suggest lack of mixing was the limiting factor negating all other enhanced variables potential treatment contributions. Nevertheless, the actual drained LAW significantly removed N, indicating that drained wetlands maybe removing considerable N from polluted runoff.