Physicochemical changes in microplastics and formation of DBPs under ozonation

Area of Science:

• Environmental Science
• Water Treatment Technology
• Polymer Chemistry

Background:

• Microplastics (MPs) are a growing environmental concern due to their persistence and widespread pollution.
• Conventional water treatment methods like coagulation and sedimentation are insufficient for complete MP removal.
• Understanding MP behavior during advanced water treatment is crucial for assessing risks.

Purpose of the Study:

• To investigate the morphological changes of thermoplastic polyurethane (TPU) and polyethylene (PE) microplastics during ozonation.
• To evaluate dissolved organic carbon leaching and chloroform formation from these MPs after subsequent chlorination.
• To assess the impact of ozone pretreatment on disinfection byproduct (DBP) generation.

Main Methods:

• Ozonation of TPU and PE microplastics.
• Analysis of surface morphology and chemistry changes post-ozonation.
• Chlorination of ozonated and un-ozonated MPs.
• Quantification of chloroform and other disinfection byproducts (DBPs).

Main Results:

• Ozonation altered the surface appearance and chemistry of TPU and PE MPs, with more significant changes observed in TPU.
• Ozone pretreatment notably increased chloroform (CHCl₃) generation from TPU during chlorination.
• The presence of bromide ions led to the formation of various DBPs, with TPU-O exhibiting the highest total DBP yield.

Conclusions:

• Ozonation modifies microplastic properties, influencing their reactivity during water disinfection.
• The formation of DBPs during chlorination is exacerbated by ozone pretreatment, particularly for TPU.
• This research provides critical data for the environmental risk assessment of MPs in drinking water treatment processes.