Utilization of post-fermentation sludge as a soil structure and strength conditioner

Area of Science:

• Soil Science
• Environmental Engineering
• Materials Science

Background:

• Limited research exists on the impact of digestate on soil structural and mechanical properties.
• Existing studies primarily focus on digestate's effects on soil organic carbon, chemistry, and microbiology.

Purpose of the Study:

• To investigate the influence of varying digestate application rates (1-15%) on soil structure and strength.
• To analyze these effects across diverse soil types with different compositions (grain size, pH, organic matter).

Main Methods:

• Scanning electron microscopy (SEM) for structural analysis.
• Nitrogen adsorption and mercury porosimetry for pore characteristics.
• Bulk density and mechanical stability tests for strength assessment.

Main Results:

• Digestate generally increased total porosity, average pore diameter, and total pore volume while decreasing bulk density.
• A significant decrease in specific surface area was observed in clayed soils with high initial surface area.
• Digestate application enhanced the mechanical strength of fragile sandy soil aggregates.

Conclusions:

• Digestate positively alters pore and surface characteristics, enhancing mechanical strength, particularly in sandy soils.
• Digestate application shows potential for improving the stability and structure of less productive soil areas.