Enzyme　induced　carbonate　precipitation　(EICP)　based　on　self-extracted　crude　soybean　urease　solution　(CSUS)　is　a　promising　method　for　soil　improvement.　However,　the　deionized　water-extracted　CSUS　usually　contains　a　large　amount　of　impurities　that　easily　lead　to　bioclogging　during　the　biogrouting　process,　resulting　in　a　nonuniform　biomineralization　effect.　In　this　study,　a　purification　method　using　inorganic　flocculants　is　proposed　to　extract　CSUS　with　relatively　high　purity　and　urease　activity　(UA)　for　EICP　method.　Seven　commonly　used　inorganic　flocculants　were　adopted　in　this　study,　including　KAl(SO4)2•12H2O,　AlCl3•6H2O,　Al2(SO4)3•18H2O,　Fe2(SO4)3,　poly　aluminum　chloride,　poly　ferric　sulfate,　and　poly　aluminum　ferric　chloride.　Three　sets　of　tests,　including　CSUS　extraction　tests,　solution　tests,　and　sand　column　treatment　tests,　were　conducted　to　investigate　the　feasibility　and　validity　of　this　purification　method.　The　test　results　show　that　inorganic　flocculants　could　effectively　reduce　the　turbidity　of　the　extracted　CSUS,　avoid　the　bioclogging　during　biogrouting,　and　thus　improve　the　biomineralization　effect　of　the　CSUS-based　EICP　method.　Compared　with　deionized　water-based　CSUS,　at　least　60%　of　the　impurities　in　CSUS　can　be　removed　at　optimal　flocculant　contents　when　the　soybean　powder　content　is　100　g/L.　On　the　other　hand,　the　flocculants　would　also　cause　a　reduction　in　the　UA　of　the　extracted　CSUS.　Considering　the　UA,　turbidity,　and　biomineralization　effect　of　the　extracted　CSUS,　the　optimal　inorganic　flocculants　and　their　contents　are　recommended　to　be　3.0　g/L　for　KAl(SO4)2•12H2O,　2.0　g/L　for　AlCl3•6H2O,　2.5　g/L　for　Al2(SO4)3•18H2O　under　the　tested　conditions,　respectively.　©　2024