Floating wetlands for wastewater treatment in Montes Claros (MG), Brazil
We have deployed floating wetlands (AFIs) at the secondary clarifiers (number 6 in the figure below) of a wastewater treatment plant in Montes Claros (MG).
We initially used two aquatic plant species: the water hyacinth (Eichornia crassipes) and the water lettuce (Pistia stratiotes).
The floating wetlands (15 AFIs with E. crassipes plus a nursery AFI in clarifier #1 and 15 AFIs with P. stratiotes plus a nursery AFI in clarifier #2) were installed in June 2021 (figure below).
Problems with the installation led to a low survival rate, especially of the water lettuce. In July, we began experimenting with a third species: the Vetiver grass – Vetiveria (Chrysopogon) zizanioides (figure below).
Re-deployment was undertaken in August 2021. We staggered AFIs with E. crassipes and V. zizanioides in clarifier #1 and P. stratioides and V. zizanioides in clarifier #2 (figure below).
Below is a view of the experiment one month after re-deployment (September 8). Survival rate was high for E. crassipes and V. zizanioides, but low for P. stratioites.
E. crassipes and V. zizanioides continue to develop at fast pace by the end of September.
By early October, we begun pruning of E. crassipes on both the experimental and nursery AFIs in clarifier #1. Almost 4 kg of excess biomass was removed on October 7.
A month later, another 20kg of excess biomass of E. crassipes was removed from clarifier #1.
We will provide more updates as the experiment progresses.