EICP Treatment of Soil by Using Urease Enzyme Extracted from Watermelon Seeds

Abstract

As part of an effort to lower the cost of urease enzyme used in enzyme induced carbonate precipitation (EICP) for soil improvement, urease enzyme was extracted from watermelon seeds. EICP is a biologically-based ground improvement technique in which a solution containing calcium, urea, and urease enzyme is used to induce calcium carbonate precipitation in a granular soil, enhancing strength, and stiffness. To reduce the enzyme cost by obtaining it from a waste material, the effectiveness of urease enzyme extracted from watermelon seeds, a urease-rich agricultural waste, was evaluated. Low-tech methods were employed for extraction and purification of the enzyme. The extracted enzyme, which showed urease activity of around 611 U/ml, was used to treat Ottawa 20/30 sand. Results of scanning electron microscope imaging and energy dispersive X-ray analysis demonstrated calcium carbonate precipitation. The ratio of the precipitated carbonate content to the theoretical maximum was found to be around 64%.