Bioremediation of Heavy Metal Contaminated Mine Wastes using Urease Based Plant Extract

Abstract

Acid mine drainage occurrence is a serious environmental problem by mining industry, it usually contains high levels ofmetal ions, such as iron, copper, zinc, aluminum, and manganese, as well as metalloids of which arsenic is generally of thegreatest concern. An indigenous plant extract was used to produce calcium carbonate from Canavalia ensiformis aseffective biomaterial, and its ability to form the calcium carbonate under stable conditions was compared to that ofpurified urease. X-ray diffraction and scanning electron microscopy were employed to elucidate the mechanism of calciumcarbonate formation from the crude plant extracts. The results revealed that urease in the plant extracts catalyzed thehydrolysis of urea in liquid state cultures and decreased heavy metal amounts in the contaminated soil. The heavy metalamounts were decreased in the leachate from the treated mine soil; 31.7% of As, 65.8% of Mn, 50.6% of Zn, 51.6% of Pb,45.1% of Cr, and 49.7% of Cu, respectively. The procedure described herein is a simple and beneficial method of calciumcarbonate biomineralization without cultivation of microorganisms or further purification of crude extracts. This studysuggests that crude plant extracts of Canavalia ensiformis have the potential to be used in place of purified forms of theenzyme during remediation of heavy metal contaminated soil.