Abstract:
This study presents a comprehensive analysis of the efficiency and compliance of the I-9 Sewage Treatment Plant (STP) in Islamabad, Pakistan, from 2022 to 2024. Total of 30 samples were collected using grab sampling method (sampling from particular location at particular time to avoid variation in the readings. 15 samples were collected from effluents and 15 samples from influent for the analysis of parameters including pH which remained consistently within the permissible range (6-9) and TSS(mg/L) removal was stable over the three years with mean ranks of (22.00 in 2022, 20.33 in 2023, and 26.67 in 2024) as well as the Means ranks of turbidity(NTU) increased from 14.60 in 2022 to 18.67 in 2023 and 35.73 in 2024 which shows declining in plants ability to filter out. Mean values of EC is 16.00 in 2022, 19.53 in 2023, and 33.47 in 2024, Means values of COD (mg/L) 16.00 in 2022, 19.53 in 2023, and 33.47 in 2024, and Mean values of BOD (mg/L) increased from 11.60 in 2022 to 23.30 in 2023 and 34.10 in 2024. The compliance assessment of national (NEQs, EPDA) and international (CPCB, MDPI) regulatory standards revealed frequent exceedances of permissible limits, particularly for Turbidity NTU (against the local EPDA standard of 10 NTU), COD mg/L, and BOD mg/L throughout 2022 and 2023. However, the 2024 data indicated a marked improvement, with BOD and COD values showing a significant decline towards compliance, suggesting recent enhancements in the biological treatment process. Results suggest that Sewage Treatment Plant should be monitored on regular basis to maintain maximum microbial growth and dissolved oxygen level needs to be adjusted in aeration tanks according to the results. Install a flow equalization tank and make sure to obtain routine compliance reporting.
