Soil stabilisation using AMD sludge, compost and lignite: TCLP leachability and continuous acid leaching

Area of Science:

• Environmental Science
• Soil Science
• Remediation Technology

Background:

• Industrial by-products offer a low-cost soil remediation strategy.
• Acid mine drainage (AMD) sludge and carbonaceous materials were investigated for metal stabilization.

Purpose of the Study:

• To evaluate the efficacy of AMD sludge, zero-valent iron, and carbonaceous materials for As and Cu remediation.
• To assess the performance of these materials under different leaching conditions.
• To provide engineering recommendations for field application.

Main Methods:

• Soil incubation experiments (9 months).
• Toxicity Characteristic Leaching Procedure (TCLP) tests.
• Column leaching experiments under acidic conditions.

Main Results:

• AMD sludge significantly sequestered As and Cu, comparable to zero-valent iron.
• Carbonaceous materials provided marginal benefits alone but enhanced Cu leachability reduction with AMD sludge.
• Combined AMD sludge and compost application was more effective than AMD sludge with lignite under acid leaching.
• Concerns regarding Ca and Al release necessitate careful management.

Conclusions:

• AMD sludge is a viable material for in situ metal stabilization.
• Compost addition can enhance the effectiveness of AMD sludge for copper remediation.
• Lignite may increase metal mobility; careful material selection and application are crucial.
• Engineering considerations for field deployment and environmental impact mitigation are essential.