Confidence votes 4.8K. The base meanining of un pigeonnier is a dovecote (a structure where doves, or similar birds, are bred or housed). But you will also find un pigeonnier used to mean a garret-flat, or any small flat near the top of a building (especially if it is a low-rent sort of place).
Duckweed creates an anaerobic environment. When it comes to wastewater lagoons, the lack of dissolved oxygen is bad. (Read our previous article, Troubleshooting Low Lagoon Dissolved Oxygen, for an in-depth look.) Duckweed is a DO killer, blocking the oxygen-transferring interface between the surface of the lagoon and the atmosphere.
Duckweed can survive across a pH range from five to nine, but grows best in the 6.5 to 7.5 range. When the pH is below 7.0, ammonia can be kept in its ionized state as ammonium ion, which is the preferred form of nitrogen for the plants. typical duckweed wastewater treatment plant will yield a daily harvest of up to one ton of duckweed plants (wet weight) per hectare. This can, in turn, produce up to 100 kilograms of fish or 90 kilograms of dried, high-protein duckweed meal each day.