Biofilm induced microplastics and microbial metabolites release from Polypropylene Random pipes in drinking water...

While plastic pipes are extensively employed in water infrastructure owing to their durability and corrosion resistance‌, their long-term deployment in drinking water distribution systems (DWDS) fosters biofilm proliferation through microbial colonization. However, biofilm-induced material alterations and the concurrent release of microplastics (MPs) and microbial secondary metabolites remain undercharacterized. To elucidate biofilm-mediated corrosion in polypropylene random copolymer (PPR) pipes and their implications for water safety, this research employed a multi-methodological framework of high-resolution scanning electron microscopy (SEM), flow cytometric quantification coupled with 16S rRNA sequencing, and gas chromatography-mass spectrometry (GC-MS). The results demonstrate that biofilm colonization induces progressive surface deterioration, with SEM revealing sequential roughness increase (60 days), microcracks formation (90 days), and pore formation (120-150 days). Biofilm-induced corrosion increased microplastics release (2.1-fold versus control) and enhanced leaching of microbial metabolites, including organophosphate flame retardants (TEP 18-fold, TCEP 5.2-fold), phthalates (DEHP 14-fold), and antioxidant derivatives (2,4-DTBP 20-fold, BHB 41-fold). PPR-degrading bacterial communities were dominated by Sphingobium, Bradyrhizobium, Comamonadaceae, and Sediminibacterium. GC-MS analysis detected released compounds with microbial degradation pathways evidenced by dodecanal accumulation (11-fold) and 1-dodecanol depletion (0.04-fold). These findings confirmed that biofilm development accelerate PPR material aging through both biofilm-induced corrosion and biochemical degradation, while introducing multiple water quality risks. These findings revealed that biofilm development accelerates PPR material aging through synergistic biofilm-induced corrosion and biochemical degradation, concurrently introducing multiple water quality risks via significantly elevated contaminant release. This study elucidates the mechanisms and quantifies the impacts of biofilm-induced corrosion in PPR pipes, highlighting the urgent need for biofilm control or material improvements in end DWDS.