Abstract
Nitrification is one of the mechanisms to remove ammonium in constructed wetlands. An important factor affecting this biochemical process is the concentration of dissolved oxygen. This study proposed using hydrogen peroxide as a source of oxygen to ensure enough dissolved oxygen in saturated vertical flow constructed wetlands. Hydrogen peroxide is decomposed into water and oxygen in the presence of catalase in constructed wetlands. Three hydrogen peroxide concentrations, 0.6%, 1% and 2% (w/v) in the dosing solutions, were tested over three periods. The effects of hydrogen peroxide concentration on ammonia removal were assessed in terms of oxygen generation and potential impacts of hydrogen peroxide solution concentration on microorganisms and wetland plants. It was found that as hydrogen peroxide dosing concentration increased, concentration of nitrate in the effluent decreased while an increase in plant growth was observed. It was concluded that the use of hydrogen peroxide affected nitrification by shifting the primary ammonia removal mechanism from nitrification to plant uptake. A dosing solution of 1% was suggested since the greatest plant growth was measured and a uniform dissolved oxygen distribution was measured.