Effect of liquid-to-solid ratio on semi-solid Fenton process in hazardous solid waste detoxication

Area of Science:

• Environmental Science and Engineering
• Chemical Engineering
• Waste Management

Background:

• Hazardous solid waste poses significant environmental and health risks.
• Conventional slurry-based treatment methods often require high liquid-to-solid ratios (L/S), increasing operational costs and complexity.
• The semi-solid Fenton process (SSFP) offers a potential alternative for efficient hazardous waste detoxification.

Purpose of the Study:

• To investigate the impact of the liquid-to-solid ratio (L/S) on the efficiency of the semi-solid Fenton process (SSFP) for hazardous solid waste detoxification.
• To evaluate the removal of o-nitroaniline (ONA) and total organic carbon (TOC) from simulated solid waste residue (SSWR).
• To develop an optimized operation strategy for SSFP, including multi-stage applications.

Main Methods:

• Box-Behnken design (BBD) and response surface methodology (RSM) were employed to optimize key SSFP factors.
• Evaluated ONA and TOC removal efficiencies at various initial ONA concentrations (100 mg kg⁻¹, 1 g kg⁻¹, 10 g kg⁻¹, 100 g kg⁻¹) and L/S ratios.
• Developed a cubic empirical model to predict optimal L/S based on initial ONA concentration.

Main Results:

• Higher L/S ratios resulted in decreased removal rates for both TOC and ONA.
• A predictive model successfully correlated initial ONA concentration with optimal L/S for SSFP.
• The optimized multi-SSFP strategy achieved a total L/S of ≤ 3.8, significantly lower than conventional slurry systems (≥ 5).

Conclusions:

• SSFP is an effective and environmentally friendly method for detoxifying hazardous solid waste contaminated with organic pollutants like ONA.
• The study demonstrates the feasibility of achieving efficient hazardous waste treatment with reduced water usage.
• Optimized SSFP presents a promising approach for sustainable hazardous solid waste management.