Eutrophication is an ongoing environmental issue that can negatively impact aquatic ecosystems. Eutrophication occurs because a surplus of nutrients, such as nitrogen and phosphorus, reaches water bodies. Denitrification is the process responsible for the majority of nitrogen removal in wetlands. Since organic carbon can benefit nitrogen removal, it is relevant to investigate how total organic carbon (TOC) affects the removal of nitrogen. Therefore, the aim of this project is to determine whether relationships between different purification processes, concentrations of nutrients and water color in constructed wetlands can be established, and to further examine those relationships. The study was conducted by quantitatively compiling, analysing and visualizing data collected from previous studies. The parameters analysed were total nitrogen (TN), total phosphorus (TP), water color and TOC in the inflow and outflow of each wetland. Higher concentrations of TN, TOC, and TP in the inflow were shown to result in a higher efficiency in reducing the nutrient concentrations of each nutrient in the wetlands. There were both positive and negative correlations between different nutrients entering the wetlands. Nitrogen removal did not increase at higher concentrations of TOC or TP in the inflow, but the nitrogen removal slightly decreased at higher concentrations of water color which might indicate that composition of the organic matter has an effect on nitrogen removal.