Jayasekara, J. M. P. M.Najim, M. M. M.2024-11-292024-11-292024Jayasekara J. M. P. M.; Najim M. M. M. (2024), Investigating the effluent quality of a sewage treatment plant in the Kelaniya area: A temporal analysis, Proceedings of the International Conference on Applied and Pure Sciences (ICAPS 2024-Kelaniya) Volume 4, Faculty of Science, University of Kelaniya Sri Lanka. Page 206http://repository.kln.ac.lk/handle/123456789/28951Sewage treatment focuses on effectively removing contaminants from sewage to produce an effluent that is safe for discharge into the environment or reuse. Monitoring the effluent quality of a wastewater treatment plant is crucial for maintaining the treated effluent quality. There are growing concerns about the potential environmental impacts of the selected sewage wastewater treatment plant (SWWTP). However, there is a lack of comprehensive research to assess the actual impact of SWWTP on the local environment. Hence, the current study investigated the quality of the effluent of the selected SWWTP. This study was conducted by analysing variations of effluent quality parameters over 6 months (August 2023 to January 2024). Water samples were collected monthly and analysed for key water quality indicators using APHA methods. Temperature, pH, Dissolved Oxygen (DO), Biological Oxygen Demand (BOD), Chemical Oxygen Demand (COD), Total Suspended Solids (TSS), Total Dissolved Solids (TDS), conductivity, salinity, and flow velocity were measured as key water quality indicators. The values of each parameter were compared with the tolerance limits for the discharge of wastewater or effluent into Inland Surface Waters presented by the National Environmental (Protection and Quality) Regulations. The temporal variations of the studied parameters of water samples were statistically analysed using a One-way ANOVA. Results suggest that COD values exceeded the standard values in August (654±16.8 mg/L), October (336.5±35.4 mg/L), November (273±16.8 mg/L), and January (95.2±11 mg/L). TSS values exceeded the standard values in August (87±14.2 mg/L) and October (60±1.74 mg/L) and Dissolved oxygen did not reach the standard values in October (4.47±0.09 mg/L) and November (4.46±0.03 mg/L). Nitrate concentration exceeded the standard values in August (16±1.14 mg/L) and January (13.54±1.04 mg/L). All the other parameters lay within the range of standard values. The cluster analysis of water quality parameters was used to identify the similarities between the sampling sites, and it revealed that effluent released into the environment in August has very different water quality values than other sampling months. All the parameters except pH exhibit significant temporal fluctuations. Low DO level suggested limitations in the aeration process or overload of the organic matter. Low DO levels can affect microbial activities and chemical reactions. Ultimately this can lead to elevated levels of COD and BOD. In addition, sand filtration and carbon filtration are not sufficient to remove soluble organic matter in the water. Therefore, it can be concluded that this treatment plant has some environmental implications due to high COD, TSS, DO, and nitrate levels. Further analysis of each step of the wastewater treatment plant is needed to thoroughly understand the causes of variations in the water quality parameters.Standard values, Temporal variations, Treated effluent, Wastewater treatment plant, Water quality parameters