Enhancing Nitrogen and Phosphorus Removal by Applying Effective Microorganisms to Constructed Wetlands

Abstract

Rainfall occurs frequently in South China and results in recurring of drainage/discharge of nitrogen and phosphorus-rich water from paddy fields, which may cause serious non-point source pollution of receiving waters such as rivers. Moreover, time intervals between individual rainfall events are short (often only several days). Thus, not only is the treatment of discharge water needed, but a more rapid form of treatment is desired as well. On the basis of the literature, constructed wetlands could remove nitrogen and phosphorous from paddy field drainage/outflow, and effective microorganisms (EM) could also be added to enhance the removals. A field experiment was conducted to demonstrate the wetland effectiveness and EM enhancement. The experiment was conducted from June to October in 2016. By applying EM to constructed wetlands, after 8 days, concentrations of total nitrogen (TN), ammonium nitrogen (NH4 +-N), nitrate nitrogen (NO3 −-N), and total phosphorus (TP) were reduced by 88%, 91%, 89%, and 50%, respectively. Within the first 4 days, TN and TP concentrations were reduced by 78% and 40%, respectively, with EM application, in comparison to 50% and 20%, respectively, without EM application, representing additional respective reductions of 28% and 20% by applying EM. The results from the field experiment indicated a significant improvement of phosphorus and nitrogen removals by applying effective microorganisms.