Does a constructed wetland work in winter?

Yes, of course. A constructed wetland operates without any issues in winter. The primary role in wastewater treatment is played by bacteria, just as in conventional biological wastewater treatment plants, which are present in the root bed regardless of whether plants are there or not. Bacteria survive in the filter bed of the constructed wetland all year round. The only thing that happens in winter is that bacteria lower their metabolism proportionally to the temperature, thereby reducing treatment efficiency by roughly 5%. As designers, we know this, which is why we design the treatment plants specifically for the harsher winter periods.