Phosphate and Nitrate Removal from Aqueous Solution by Carbonated and Uncarbonated African Nutmeg (Monodora Myristica) Shell

Abstract

This study was aimed at investigating the possibility of using Monodora myristica shell for the absorption of phosphate and nitrate from wastewaters.  Four categories of the shell (untreated raw shell, treated raw shell, untreated carbonated shell and treated carbonated shell ) were used for the investigation. Three different concentrations (2.5 %, 5 % and 10 %) of the respective shells were used for the study. The results revealed that none of the different modifications of the shell had phosphate absorption capacity. All the different shell modifications showed remarkable nitrate absorption capacity from solution.  The findings also revealed a saturation time of 3 h for nitrate absorption at shell concentrations of 5 % to 10 % and a saturation time of 5 h at shell concentration of 2.5 %. At the end of 3 h contact time, nitrate concentration in the presence of the untreated carbonated shell was  observed to decrease from 231.47 mg/L to 63.10 mg/L and 28.57 mg/L, at shell concentrations of 5 % and 10 %, respectively. In the presence of the treated carbonated shell, after 3 h contact time, nitrate levels showed significant decreases from 231.47 mg/L to 169.99 mg/L and 56.83 mg/L, respectively. Similarly, after 3 h contact time, nitrate levels in the presence of the untreated and treated shells showed decreases from 231.47 mg/L to  167.63 mg/L and 158.81 mg/L, and from 231.47 mg/L to 56.83 mg/L and 45.59 mg/L, at shell concentrations of 5 % and 10 %, respectively. The study was able to give an insight into the potential use of the Monodora myristica shell as a bio adsorbent in nitrate removal from wastewaters.

Keywords: Absorbent Monodora myristica, nitrate, phosphate, wastewater