Assessment of Central Effluent Treatment Plant (CETP) Performance and Surface Water Quality in Effluent Discharged Area at Savar Tannery Estate in Bangladesh

Abstract

An enormous amount of effluent that contains a number of harmful substances is produced by tannery industries. In Bangladesh, inadequately treated effluent discharge from the Central Effluent Treatment Plant (CETP) is a significant environmental and social issue. There is a Central Effluent Treatment Plant (CETP) at Savar Tannery Industrial Estate in Bangladesh to treat the composite tannery effluent, which consists of 132 tannery industries. The study is targeted to assess the performance of the Central Effluent Treatment Plant (CETP) and evaluate the surface water and groundwater quality in the effluent discharged area of the Savar tannery estate in Bangladesh. All the samples were collected three times (pre-monsoon, monsoon, and post-monsoon) in a year, from the monsoon of 2021 to the pre-monsoon of 2023.The composite effluent samples were collected before entering and discharging points of the CETP and analyzed for various physicochemical parameters to assess the performance of the CETP. There were five surface water samples collected from different locations, starting from the CETP discharge point and at different distances, i.e., 100, 500, 1000, and 2000 meters from the CETP discharge point, and the samples were named SW1, SW2, SW3, SW4, and SW5, respectively, as well as several groundwater samples collected around the CETP. The study results showed high values of EC, TSS, TDS, TH, BOD, COD, NO3 --N, SO4 2-,HCO3-, PO4 3-, Cl-, and metals (Na, Ca, Cr, Cu, Fe, Pb, and Zn) in the composite tannery influent and effluent collected from before entering and discharging points of the CETP tannery estate at Savar. The values of the physicochemical and anionic parameters were above the standard permissible limits of effluent discharge prescribed by the ISW-BDSECR (2023), DoE-BD (2023), and NEQS (2000). The higher values of TDS and TSS inthe tannery effluent were due to the presence of various organic and inorganic substances.The pH values were 8.6 and 7.5 in the influent and effluent, respectively, indicating a neutral to slightly alkaline range. The average values of DO, BOD, and COD were 0.7, 573, and 1646 mg/L in the influent and 0.9, 96.7, and 337 mg/L in the effluent, respectively, causing serious surface water pollution in the areas. Higher COD and BOD levels indicate reduced oxygen concentration, or lower DO values, in the influent and effluent. The average EC was 11430 μS/cm in the influent and 10190 μS/cm in the