Ozonation application in activated sludge systems for a textile mill effluent

Area of Science:

• Environmental Science
• Chemical Engineering
• Water Treatment Technologies

Background:

• Textile wastewater contains recalcitrant organic compounds and color, posing environmental challenges.
• Chemical Oxygen Demand (COD) and color are key indicators of textile effluent pollution.
• Biological treatment alone may not sufficiently remove all pollutants.

Purpose of the Study:

• To investigate the efficacy of partial ozonation in textile wastewater treatment.
• To compare pre-ozonation and post-ozonation strategies for optimizing COD and color removal.
• To evaluate the economic feasibility of ozonation in textile effluent polishing.

Main Methods:

• Partial ozonation applied at the inlet (pre-ozonation) and outlet (post-ozonation) of a biological treatment system.
• Optimization of ozone contact time.
• Measurement of Chemical Oxygen Demand (COD) and color removal efficiencies.

Main Results:

• Pre-ozonation achieved 85% color removal and 19% COD reduction in 15 minutes, with limited removal of soluble inert COD.
• Post-ozonation demonstrated higher effectiveness in breaking down refractory organic compounds and achieving near-complete color removal.
• Post-ozonation resulted in a 14% reduction in soluble inert COD and was more economical, using approximately 50% less ozone.

Conclusions:

• Post-ozonation is a more effective strategy than pre-ozonation for polishing textile wastewater, offering superior COD and color removal.
• Ozonation, particularly post-ozonation, serves as an efficient polishing step for textile wastewater treatment.
• The polishing effect of post-ozonation presents an economically attractive solution for reducing residual COD and color in textile effluents.