[en] The growth of duckweed (Lemna minor), depending on biotic and abiotic factors (i.e. temperature, light intensity, photoperiod, pH, nutrients), is an important compartment of the treatment process in wastewater floating macrophytes ponds. Excess or shortage of this biomass might be responsible of the dysfunction of such ponds. Modeling these duckweed ponds through mass balances based on Petersen’s matrix should help in an optimal management of such facilities. This article focused on (i) the influence of light intensity on the growth, and (ii) the mortality of Lemna minor under a constant temperature. Experiments were carried out in a growth chamber using a pilot consisting of transparent cubic tanks, with an initial fresh Lemna minor biomass. In order to monitor Lemna minor biomass, digital image processing was achieved in addition to fresh weight and dry weight measurements methods. The results showed that Lemna minor reached a maximum growth rate (0.19 d-1) for light intensities ranging between 250 μmol.m-².s-1 and 300 μmol.m-². s-1. Light intensities from 300 μmol.m-².s-1 to 400 μmol.m-².s-1 induced a slight growth inhibition. This inhibition was strongly marked at 450 μmol.m-².s-1. As for mortality, very low levels (< 0.05 d-1) were determined. These results thus provide a contribution in the modeling of duckweed waste stabilization ponds.
Vasel, Jean-Luc ; Université de Liège - ULiège > DER Sc. et gest. de l'environnement (Arlon Campus Environ.) > DER Sc. et gest. de l'environnement (Arlon Campus Environ.)
Language :
English
Title :
Monitoring the influence of light intensity on the growth and mortality of duckweed (Lemna minor) through digital images processing
Alternative titles :
[fr] Suivi de l'influence de l'intensité lumineuse sur la croissance et la mortalité des lentilles d'eau (Lemna minor) par traitement d'images
Publication date :
August 2013
Number of pages :
10+3
Event name :
10th IWA Specialist Group Conference on Ponds Technology: Advances and Innovations in Pond Treatment Technology