Research on the purification effect of major pollutants in water by modular constructed wetlands with different filler combinations

Constructed wetland systems have been widely used in China due to their advantages of good treatment effect, low cost and environmental friendliness. However, traditional constructed wetlands have challenges in applications such as deactivation due to filler clogging, difficulty in filler replacement and low adaptability. To address the above problems, this research proposes the use of a modular filler design for constructed wetland based on the concept of assembly construction, which can quickly replace the clogged fillers without destroying the overall structure of the wetland. Four commonly used fillers were selected and applied to the pilot system of the assembled constructed wetland in this study. The goal was to investigate the purification effect of the constructed wetland system with different filler module combinations (CW1, CW2 and CW3) on the simulated wastewater. The results showed that there were significant differences in the removal effects of different filler combinations on different pollutants. The filler combination of CW1 was found to be the best for the removal of NH4+-N. In terms of total phosphorus and chemical oxygen demand, CW2 has the best removal effect. Therefore, the assembled constructed wetland is adjustable and substantially reduces the maintenance cost in the later stage after the filler is clogged, which provides technical guidance for its application in engineering.