Abstract
The aim was to assess the ability of microcosms (laboratory-scale shallow ponds) as a
post polishing stage for the remediation of artificial textile wastewater comprising two
commercial dyes (basic red 46 (BR46) and reactive blue 198 (RB198)) as a mixture.
The objectives were to evaluate the impact of Lemna minor L. (common duckweed) on
the water quality outflows, the elimination of dye mixtures, organic matter and nutrients
as well as the impact of synthetic textile wastewater comprising dye mixtures on the L.
minor plant growth. Three mixtures were prepared providing a total dye concentration
of 10 mg/l. Findings showed that the planted simulated ponds possess a significant (p
< 0.05) potential for improving the outflow characteristics and eliminate dyes,
ammonium-nitrogen (NH4-N) and nitrate-nitrogen (NO3-N) in all mixtures compared
with the corresponding unplanted ponds. The removal of mixed dyes in planted ponds
was mainly due to phyto-transformation and adsorption of BR46 with complete
aromatic amine mineralisation. For ponds containing 2 mg/l of RB198 and 8 mg/l of
BR46, removals were around 53%, which was significantly higher than those for other
mixtures: 5 mg/l of RB198 and 5 mg/l of BR46, and 8 mg/l of RB198 and 2 mg/l of
BR46 achieved only 41% and 26% removals, respectively. Dye mixtures stopped the
growth of L. minor and the presence of artificial wastewater reduced their development.