Unveiling microplastic pollution in Rawal Lake: Assessment and treatment in different environmental compartments

Microplastics have been an emerging concern in freshwater environments, particularly lakes and reservoirs. In Pakistan, limited research has been carried out on MPs' distribution in water, sediments and fish. This study aims to quantify and characterize MPs in water, sediments, and fish samples of Rawal Lake. An effective treatment process for the removal of MPs from water through magnetic extraction and chemical coagulation was an imperative objective. MPs quantification and identification were done via a stereomicroscope and the polymer characterization was done using ATR-FTIR. Findings revealed that the average abundance of MPs in water was 71 ± 12.94 items/500 ml, 114 ± 23.02 items/100 g in sediments, and in fish, 17 ± 4.65 items/fish samples. Fibers and filaments were abundant in water samples, whereas fragments and fibers were abundant in sediments and fish samples. The ATP-FTIR analysis of visible MPs was identified as (PET, PPS, PVA and PIB), (PET, PP, PE, PPS, EDPT, VCVA and PIB) and (PET, PE, PPS, PIB) in water, sediment and fish samples, respectively. However, PET was the most dominant polymer in all compartments. MPs removal rate through magnetic extraction using commercially available iron ore was observed to be 85% for different polymer types. However, the chemical coagulation process showed high removal efficiency at different concentrations of coagulants. The high removal efficiency for PET, PPS, and PIB was 88.90%, 99% and 66.98% with T1: Alum + PS (150 + 15 mg/L). The high removal rate for PT and PPS was 88.88% and 83% with T2: FeCl₃ + PS (111 + 15 mg/L). Moreover, the high removal rate for PET, PPS, and PIB was 88%, 84%, and 99% with T3: Alum + FCl₃ + PS (150 + 111.68 + 15 mg/L), respectively. Overall, the study provides a better understanding of microplastic contamination and a novel approach for the removal of microplastics in different environmental compartments.