Review of bio-enzyme for soil improvement

Traditional soil stabilizers, such as cement and lime, typically entail substantial energy consumption and environmental pollution. In contrast, bio-enzyme has emerged as a promising alternative, aligning with the imperatives of sustainable development, cost-effectiveness, and environmental friendliness. Bio-enzymes are primarily one or more protein molecules that catalyzes chemical reactions in the soil to form a cementing bond that stabilizes the soil structure and reduces the soil’s affinity for water. Currently, a plethora of studies on bio-enzyme have been conducted by scholars worldwide, yet there remains a notable absence of the systematic organization and comprehensive review of these findings. This study offers a thorough examination of bio-enzyme technology, encompassing its biochemical properties, mechanisms, the engineering properties of stabilized soil, bio-enzymatic composites, and its engineering applications. And current trends and future prospects of bio-enzyme are also scrutinized. This forward-looking study indicates that bio-enzyme functions through mechanisms such as cation exchange, specific binding, and surfactants, among others to diminish the electric double layer thickness and hydrophilicity of soil, consequently enhancing engineering properties of soil. And the improvement performance can be influenced by various factors, including soil properties, enzyme dosage, specificity, and sample preparation, etc. It is also noted that the composites of bio-enzyme with conventional stabilizers tend to enhance improvement performance more efficiently. The engineering applications of bio-enzyme have demonstrated its superiority over traditional stabilizers in soil improvement. However, the performance of treated soils with available bio-enzyme remains limited, highlighting the necessity for extracting novel bio-enzyme form plants/animals and determining its mechanisms and engineering mechanical properties. It is also essential to develop more bio-enzymatic composites and conduct application in-situ to develop relevant standards and application guidelines.