Comparison of Canna indica and Acorus calamus for surfactant removal in biochar augmented constructed wetlands

Abstract

Surfactants get discharged indiscriminately in wastewater which increased several fold during COVID-19, raising environmental concerns. In this study, two locally available plant species Canna indica and Acorus calamus were compared for the sodium dodecyl sulfate (SDS, − a chemical surfactant) removal in vertical flow constructed wetlands (VFCWs) augmented with biochar. The dose-response relationship was studied for 144 days in four phases by varying the SDS concentration at 10, 25, 50, and 100 ppm in wastewater. The mean SDS removal efficiencies varied from 85 % - 98 % during the different phases. The results suggested that planted artificial wetlands acted more stable than unplanted ones, although the removal efficiencies of the planted and unplanted were found similar (97.9 % - 98.4 %) in phase 4. Further, GC–MS analysis confirmed C₂ products formed during SDS degradation indicating mineralization of SDS. The bioconcentration factor (BCF) and translocation factor (TF) studies revealed no accumulation of SDS in the roots of both plants as BCF _(root) < 1 whereas, the aerial part of C. indica showed bioaccumulation of SDS with BCF _(aerial) values nearly 1. TF for SDS was >1 in the case of both plants, among which translocation of SDS in C. indica with biochar amendment (TF = 17.8) was found to be highest. TF values indicated that biochar may have supported the uptake and translocation of SDS in C. indica whereas biochar has not supported the pollutant transfer in A. calamus. In terms of plant health, C. indica showed better growth and higher biomass increase than the A. calamus. The results implicate that C. indica with biochar-amended CW systems has great potential and can be recommended for efficient removal and uptake of SDS.