Advanced wastewater treatment by integrated vertical flow constructed wetland with vetiveria zizanioides in north China

The use of tail water for irrigation is becoming increasingly common. However, raw tail water is often contaminated and can cause environmental harm and pose health risks. Nevertheless, it is often used without any significant pre-treatment, a practice mistakenly considered safe. The aim of this study is to explore the removal efficiency of Integrated Vertical Flow Constructed Wetland (IVFCW) with Vetiveria zizanioides, an economically sound, low-tech and easily maintainable treatment system that would allow safe and sustainable use of tail water for landscape irrigation for COD, NH3-N, TN at different hydraulic retention time and different temperature in north China. The IVFCW can remove about 71% of the chemical oxygen demand, 67% of NH3-N and 80% of TN after five days at the hydraulic load of 0.6~0.8m3/m2.d in summer; But at low temperature, all kinds of pollutants has a lower removal efficiency compared with summer. At 10°C, the highest removal ratio of CODCr, NH3-N, TN are only 51.71%, 19.87%, and 29.76%, respectively.