Comparative phytoremediation efficiency of Lemna minor and Hydrilla verticillata for removing linear alkylbenzene sulphonate (LAS)

Linear alkylbenzene sulfonate (LAS), a widely used anionic surfactant, can adversely affect aquatic systems. This study compared the LAS-removal performance of the floating macrophyte Lemna minor and the submerged macrophyte Hydrilla verticillata using a 3 × 3 factorial design (0, 20, and 40 ppm LAS; 0, 5, and 10 days; n = 3). After 10 days, both plant-associated systems removed more than 80% of LAS. L. minor achieved the highest observed removal (90.12% at 40 ppm), compared with 81.90% for H. verticillata, but this performance came at the cost of greater biomass loss. Biomass declined by approximately 28% in L. minor and 25% in H. verticillata at 40 ppm, and biomass was negatively associated with removal efficiency (Spearman ρ = −0.82 and −0.79, respectively; p < 0.05). Future work must incorporate abiotic/plant-free controls, increased replication, complete LAS mass balances, and analyses of microbial communities, biofilms, and transformation products, alongside mixed-species or staged systems. Validation using real detergent wastewater under flow-through or pilot-scale conditions is essential to assess treatment robustness, harvesting needs, and practical operational constraints.