Agro-industrial wastewater treatment and biomass production using macrophyte Lemna minor in sequencing batch reactor experiments.

Conventional methods often fail to treat high-load agro-industrial wastewater, whereas plant-based systems offer superior pollutants removal and high-value biomass. This study investigated the performance of Lemna minor in sequencing batch reactors for treating dairy, citrus juice and chili sauce wastewater. It also evaluated the effect of NH4-N addition and wastewater dilution with a chemical medium or tap water on pollutants removal and biomass characteristics. According to the results, COD removal ranged between 59% ± 12% and 91% ± 6% while nitrogen supply did not significantly affect the plant's ability to remove organic load. NH4-N removal exceeded 60% in all bioreactors. Citrus juice and chili sauce were the most suitable types of wastewater for biomass production while nitrogen addition enhanced the biosynthesis of proteins, lipids and lutein. The use of a chemical medium to dilute the agro-industrial wastewater in the bioreactors at a ratio of 1:3 (25% wastewater and 75% medium) enhanced macrophyte growth, resulting in higher growth rates. The biochemical composition of the biomass varied depending on the wastewater types used with total protein and lipid content ranged up to 36% and 54%, respectively. The lutein concentrations ranged between 2.52 and 9.61 mg g-1. L minor showed high assimilation efficiency in treating nutrient-rich agro-industrial wastewater, simultaneously generating biomass with significant potential for commercial valorization.