Evaluation of Lemna minor phytoremediation performance for the treatment of dairy wastewater

The aim of the study was to evaluate the efficiency of Lemna minor to purify synthetic dairy wastewater (SDW) and real dairy wastewater (RDW), both diluted and undiluted. Results showed that Lemna significantly reduced electrical conductivity (EC); the removal efficiency for EC was 19.4% in RDW and 9.8% in SDW. Higher values were recorded for diluted real dairy wastewater (DRDW) (41%) and for diluted synthetic dairy wastewater (DSDW) (35.8%). Total suspended solids were slightly reduced in RDW (14%) and SDW (13.5%), compared to DSDW (25%) and DRDW (29%). Greater removing efficiency of chemical oxygen demand was recorded in DRDW (60%) and DSDW (55.5%) compared to RDW (27.6%) and SDW (27%). In RDW, nitrogen and phosphorus removal were 24.8 and 37.4% and in SDW were 25 and 48.6%, respectively, compared to much higher results in diluted effluents, and nitrogen removal was 65.4% in DRDW and 63.5% in DSDW, but the best results were recorded for phosphorus removal in DSDW (78.8%) and DRDW (87%). The higher elimination of all the parameters investigated in the units populated with duckweed compared to the control attests to the effectiveness of L. minor in the phytoremediation of dairy wastewater, especially when reducing the primary pollutant load.