Sewage sludge nutrient solubilization using a single-stage microwave treatment

Area of Science:

• Environmental Science
• Chemical Engineering
• Water Treatment

Background:

• Sewage sludge treatment is crucial for environmental protection.
• Nutrient recovery from sludge offers sustainable resource management.
• Advanced Oxidation Processes (AOPs) show promise for sludge treatment.

Purpose of the Study:

• To investigate the efficiency of a single-stage MW/H2O2/H+-AOP for sewage sludge treatment.
• To evaluate nutrient (phosphate, ammonia) and chemical oxygen demand (COD) recovery.
• To determine the impact of temperature and acid addition on process outcomes.

Main Methods:

• A single-stage advanced oxidation process (MW/H2O2/H+-AOP) was employed.
• Experiments were conducted at varying temperatures (60-120°C).
• The influence of inorganic acid addition was assessed.

Main Results:

• Higher soluble phosphate was achieved at 100-120°C in the single-stage process compared to lower temperatures.
• Acid addition at 120°C significantly increased soluble phosphate yield.
• Soluble ammonia and COD increased with temperature, with a COD solubilization threshold at 80°C; higher temperatures led to further oxidation to CO2.

Conclusions:

• The single-stage MW/H2O2/H+-AOP is effective for sludge treatment and nutrient recovery.
• Optimizing temperature and acid addition enhances soluble phosphate and ammonia recovery.
• Temperature control is vital to balance COD solubilization and prevent over-oxidation.