[Experimental study on stabilization of sewage sludge by MOC]

Area of Science:

• Environmental Engineering
• Materials Science

Context:

• Sewage sludge disposal presents environmental challenges due to high moisture content and heavy metal contamination.
• Effective stabilization is crucial for safe land application or disposal.

Purpose:

• To investigate the efficacy of magnesium oxychloride cement (MOC) as a stabilization agent for sewage sludge.
• To determine optimal MOC to sludge ratios and assess its impact on sludge properties and heavy metal leachability.

Summary:

• MOC effectively reduces sludge moisture content through water absorption by MgCl2 (1.55 mL/g) and hydration reactions.
• The hydration process forms a robust crystal structure (3 and 5 phases), yielding high compressive strength (85.14 kg/cm²).
• Optimal MOC/sludge ratio is 3/100 with MgO/MgCl2 ratio of 3/1, forming a Mg-Si-Al gel that immobilizes heavy metals.

Impact:

• Sludge treated with MOC shows significantly reduced heavy metal concentrations (Cu, Zn, Cd, Cr, As) below leachability standards.
• MOC stabilization offers a promising solution for managing sewage sludge, enhancing its environmental safety.
• The developed method improves sludge compressive strength and reduces moisture, facilitating easier handling and disposal.