Subsurface flow constructed wetland model for phytoremediation of chromium from tannery wastewater using Echinodorus palaefolius

Abstract

In the leather tanning process or tannery, Cr solution is usually used to modify leather properties. This results in Cr containing wastewater, which becomes a crucial issue. One promising method for removing Cr from tannery wastewater is by using subsurface flow constructed wetland (SSF-CW). A combination of adsorption and phytoremediation that occurs in the SSF-CW removes Cr from wastewater. In this research, the effect of vegetation and media on Cr removal was investigated. Echinodorus palaefolius was used as a phytoremediation agent, while wood charcoal and natural zeolite were used as media. The experiment was conducted in 4-different SSF-CW reactor configurations, namely CTT (wood charcoal-zeolite; no plant), CDT (wood charcoal-zeolite; with plant), ZDT (zeolite; with plant) and ADT (wood charcoal; with plant). Each reactor was filled with 70 L Cr contained water that was recirculated within the reactor for 15 days. Evidence revealed that Echinodorus palaefolius significantly increases the removal of Cr from wastewater, compared to that of without those plants (wood charcoal-zeolite medium only). Using an initial concentration of Cr of 2.05 mg/L, removal percentage is 63.7, 86.83, 70.37, and 83.05% for CTT, ZDT, ADT, and CDT, respectively. It is also found that zeolite media performed much better than charcoal. A combination of zeolite medium and Echinodorus palaefolius (ZDT) produced the highest Cr removal. In addition to that, despite its Cr intoxication indication, the Echinodorus palaefolius was able to grow/regenerate during the experiment.