Enhanced waste activated sludge dewaterability by the ozone-peroxymonosulfate oxidation process: Performance, sludge...

Area of Science:

• Environmental Science
• Water Treatment Engineering
• Chemical Oxidation Processes

Background:

• Sludge dewatering is crucial for reducing disposal costs and environmental impact.
• Conventional dewatering methods often face limitations in efficiency.
• Advanced oxidation processes offer potential for enhanced sludge treatment.

Purpose of the Study:

• To investigate the effectiveness of ozone-peroxymonosulfate (O3/PMS) oxidation for improving sludge dewaterability.
• To elucidate the mechanisms behind the enhanced dewatering performance.
• To assess the impact of O3/PMS treatment on sludge contaminants.

Main Methods:

• Sludge conditioning using ozone (O3) and peroxymonosulfate (PMS) at varying dosages.
• Measurement of capillary suction time (CST) and dewatered sludge cake water content (Wc).
• Analysis of sludge properties including zeta potential, particle size, and extracellular polymeric substances (EPS) composition and structure.
• Quantification of heavy metals and polycyclic aromatic hydrocarbons (PAHs) in treated sludge.

Main Results:

• Optimal O3/PMS dosage (30 mg/g TS O3 and 0.4 mmol/g TS PMS) reduced CST from 70.5 s to 26.7 s and Wc from 81.93% to 65.65%.
• Treatment increased sludge zeta potential, particle size, and fluidity, while decreasing hydrophilic EPS components and altering EPS protein secondary structure.
• Concentrations of most heavy metals and PAHs were reduced, with decreased heavy metal stability and toxicity (except for Zn).

Conclusions:

• Ozone-peroxymonosulfate (O3/PMS) advanced oxidation is a highly effective method for enhancing sludge dewaterability.
• The improved dewatering is attributed to alterations in sludge physicochemical properties and EPS structure.
• O3/PMS treatment offers environmental benefits by reducing sludge contaminants and their associated risks.