Extraction of crude soybean urease using ethanol and its effect on soil cementation

One nature-based soil improvement method is the Enzyme Induced Carbonate Precipitation (EICP) approach using the crude soybean urease solution. This study aims to investigate the extraction of soybean urease using different contents of ethanol, and its effect on the cementation of EICP-treated sand. Crude urease enzyme was extracted from the soybean powder using the grinding-extraction method with distilled water containing ethanol. The activity of crude soybean urease extracted with various ethanol contents was studied. Sand columns treated using the crude soybean urease were tested to evaluate the calcium carbonate precipitation and unconfined compressive strength. The test results show that the proposed extraction method using ethanol can produce clearer crude urease solution from soybean powder. The urease activity and turbidity of the extracted urease enzyme solution are highly dependent on the content of ethanol, with the optimal ethanol content of 20%∼30% (v/v) for the preparation of 100 g/L crude soybean urease solution. The extracted relatively clear urease solution contributes to improve the uniformity of calcium carbonate distribution and thus the strength of the EICP-treated sand column.