Evaluating the Impact of Rainfall Characteristics on TSS and VSS Removal Efficiencies: A Comparative Analysis of Sewage Pump Stations in Kajang, Malaysia

This study evaluates the sediment control performance of two sewage pump stations (PS) configurations, PS-1 and PS-2, in Langat Kajang, Malaysia, under varying rainfall conditions. The primary focus is on the removal efficiencies of Total Suspended Solids (TSS) and Volatile Suspended Solids (VSS). Over 100 days (24 July 2023–31 October 2023), operational data were analyzed using Principal Component Analysis (PCA) and Agglomerative Hierarchical Clustering (AHC). PCA results revealed that the first two principal components accounted for 77.83% of the total variance, distinguishing the influence of rainfall intensity on TSS dynamics. PS-1, equipped with a grit chamber (GC), consistently demonstrated superior sediment control, removing 11.89 tonnes of grit from January to August 2024. Conversely, PS-2, lacking a GC, exhibited significant sediment accumulation and resuspension, with negative TSS removal values during moderate-to-high rainfall events. Statistical validation via the Kruskal–Wallis H test yielded a K-statistic of 193.098 (p < 0.0001), confirming substantial differences in TSS and VSS removal between the systems. The findings underscore the critical role of GCs in enhancing sediment removal and operational reliability. This study recommends continuous monitoring and retrofitting of vulnerable PS configurations, such as PS-2, with advanced sediment control mechanisms. Additionally, the results have significant implications for updating national PS design guidelines to mitigate challenges posed by increasing rainfall variability and urbanization.