Column studies on the removal of chromium from waste water by mango seed shell activated carbon

Abstract

The effects of time and carbon height on the removal of chromium from wastewater were investigated in fixed down flow adsorption columns containing mango seed shell activated carbon (MSSAC) for the purpose of converting the waste to wealth. The Hutchin’s bed depth service time (BDST) model was used to study the columns performance at 10% and 90% breakthrough concentrations. The BDST model constants were determined. The BDST equation obtained at flow rate of 1.61l.hr and influent chromium concentration of 3.151mg/L was used to predict the adsorbent performance at other flow rates and initial chromium concentrations. Results obtained revealed that there was a gradual decrease in the percentage of chromium adsorbed with time; the percentage adsorbed became zero at 72.33, 467.5 and 572 hours respectively for 3cm, 3.5cm and 4cm carbon heights. The breakthrough curves for chromium adsorption deviated from the characteristic S-curve for most dynamic studies because 100% removal of chromium was not attained even at the commencement of the column operation because of the high initial concentration of the adsorbate adopted in this study. It was observed that for a given breakthrough concentration, the service time decreased with increase in both flow rate and initial chromium concentration. Chi-square test performed on the developed BDST models revealed the reliability of the models for the prediction of the columns performance particularly at lower breakthrough concentrations. It was therefore recommended that MSSAC can be used for the removal of chromium from wastewater in adsorption columns; however there is the need for pilot studies on live wastewater to investigate the effect of interference.

Keywords: Column Adsorption, Activated carbon, mango seed shells, wastewater, pilot studies