Treatment of pre-treated liming wastewater in tannery by mixed banana peel adsorbent in column filtration studies

Abstract

Liming is considered the first chemical treatment in the tanning industry where the animal’s outer covering is treated with sodium sulfide and hydrated lime. Generated wastewater from liming operations contains a large amount of soluble sulfide. Upon acidification, the emitted soluble sulfide in wastewater poses an environmental threat generating gaseous hydrogen sulfide. In this study, a combination of chemically and thermally activated banana peel adsorbent was utilized to eliminate soluble sulfide from the tannery liming wastewater in the column experiment. The prepared absorbents were assessed by a scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDS) for characterization. Results indicate that the column analysis at optimum adsorbent dose and flow rate showed a significant reduction of sulfide (95.8 %), biochemical oxygen demand (93.3 %), chemical oxygen demand (93.2 %), and total dissolved solids (99.6 %). SEM micrographs of the treated adsorbent illustrated the adsorption of sulfide and other pollutants confirming the presence of various elements in the EDS spectrum. The mechanism of higher sulfide removal efficiency is explained through the pH point of zero charge (pHpzc). The liming wastewater treatment with the proposed method showed acceptable outcomes compared to the previous studies. Hence, the present investigation illustrates a promising sustainable approach using modified banana peel adsorbent to treat tannery liming wastewater.