Comparative Analysis of Locally Sourced Adsorbents for Iponda and Idominasi, Abandoned Gold Mine Wastewater Bioremediation in Osun State, Nigeria

Abstract

This study investigates and compares the effects of Neem leaf (NL) and coconut husk (CCH) adsorbents in reducing the levels of heavy metal concentration and elemental content in wastewater from two specific abandoned gold mining sites, namely Iponda (Iponda  wastewater- IPWW) (longitude 4°43'18''E, Latitude 7°43'57''N ) and Idominasi (Idominasi wastewater -IDWW) (longitude 4°42'0''E, Latitude 7°40'59''N). Preparation of locally sourced adsorbents, bioremediation process through adsorption and physico-chemical analysis of the treated wastewater samples were carried out. Adsorbents were prepared from washed, air-dried neem leaves, grinded to 40 microns size to facilitate penetration of the adsorbate.  In addition, washed and airdried CCH was carbonized in an electric muffle furnace at between 300 0C and 350 0C over a period of 30 minutes, and then granulated and sieved with a mesh size of 40 µm to ensure uniform size. Measured dosages of adsorbent (0.5 g, 0.75 g, and 1 g) were added to a 50 ml volume of wastewater and the mixture was agitated at different speeds ranging from 30 rpm to 120 rpm.  The treated wastewater samples were then subjected to various physico-chemical analytical tests to determine the effect of the adsorbents on the reduction of the heavy metal concentration and elemental content of the wasted water samples. The results of this study demonstrate that both NL and CCH adsorbents have a significant impact on the wastewater from the two abandoned gold mining sites, IPWW and IDWW. This impact is reflected in the reduction of heavy metal and other element concentrations in the wastewater. Furthermore, it can be concluded that the bioremediation process is more effective when utilizing NL compared to carbonized CCH. Locally sourced cheap non-edible biomass materials hitherto considered as wastes have proved to be highly effective and efficient when used as adsorbents in the treatment of wastewater from abandoned gold mining sites. This is evident from the results obtained from this study.