ABSTRACT
The As levels fluctuated over time, especially in zeolite wetlands where these levels mainly decreased (Fig. 1). Each type of wetland presented a different
1 INTRODUCTION
Constructed wetlands are low-cost green systems successfully applied in water treatment. They are able to remove different pollutants including arsenic (As) (Lizama Allende et al. 2011), but very little is known about their efficiency and reliability for this purpose. Surface flow wetlands have been mostly used to metals and metalloids remove, however subsurface flow wetlands could be more effective since they allow contact between wastewater and wetland substrate. The use of alternative substrates to the conventional gravel has been suggested to enhance performance (Ye et al. 2003). Furthermore, cocopeat, zeolite and limestone have potential to enhance As removal (Lizama Allende et al. 2011), although this potential has not been tested under highly acidic conditions, which is often associated to the presence of As and metals (e.g. acid mine drainage).
