Investigation on removal effect of microplastics and influencing factors of modified rainwater bioretention system
Polyethylene(hydrophobic)and polystyrene latex microspheres(hydrophilic),two kinds of microplastics widely used and frequently detected in water environment,were selected as representatives.The effect of the rainwater bioretention system consisting of 90%sandy soil and 10%feedwater sludge under different hydraulic retention time,ionic strength,pH and cation type was studied.The results showed that when the abundance of two kinds of microplastics in the water was 5.0×104,5.3×104 i-tems/L and HRT was 10 min,respectively,the beginning and complete penetration time of microplastics in the modified rainwater bioretention system was significantly delayed than that in the traditional rainwa-ter bioretention system.In the modified rainwater bioretention system,after HRT increased from 10 min to 30 min,polyethylene began to penetrate from 90 min(9 FVs)to 360 min(12 FVs),and polystyrene la-tex microspheres began to penetrate from 40 min(4 FVs)to 240 min(8 FVs).At high ionic strength(50.0 mmol/L),the system has a stronger ability to trap microplastics;pH and cation type have no sig-nificant influence on the retention effect of microplastics.
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