Treatment of Pagla Sewage Treatment Plant Effluent by Multimedia Filter and Activated Carbon Filter

Abstract

The Pagla Sewage treatment plant is the oldest wastewater treatment plant in Dhaka city, situated in Narayanganj. It was first operational in 1968 and has been in service ever since. The plant aims to treat only domestic wastewater This includes wastewater from sinks, bathrooms, garages etc..It was initially designed for 500,000 citizens, but by 1992, it was rehabilitated by JICA, to treat a capacity of 120,000 m3/day. The plant has been designed considering influent BOD5 of 200mg’l, and effluent BOD5 of 50 mg/l. Although the initial plan was the treatment of domestic wastewater, recent studies reveal a higher amount of pollutants in the influent section, pointing towards possible mixing of industrial waste in the inlet. The PSTP was not initially designed to handle industrial waste. The industrial waste may include toxic chemicals, heavy metals and other non-treatable substances, that PSTP cannot possibly treat. The lack of efficiency of PSTP needs to be addressed in such a way, that the old treatment plant can keep running at least close to it’s initial capacity and goals. Modifications on certain aspects of the plant can significantly increase it’s capability. Studies have shown that the 8 lagoons in the PSTP are not able to function at their design capacity. Although immediate cleaning is recommended along with other upgrades, it is an expensive price to pay for an old plant. Due to the building of new plants like Dashenkandhi and Gandharpur Water treatment plants, it may seem uneconomical to spend so much money on PSTP. The study aims to improve the quality of the effluent of PSTP by the use of a multimedia filter bed, and an activated carbon filter bed, which is a much cheaper alternative to other expensive upgrades. This Study aims to deliver a prospect and possibility to accomplish just that. In order to better grasp the use of the multimedia and activated carbon filter, the research aims to obtain the filter efficiency. The filter efficiency refers to the removal of a non-desirable parameter in a sample water, by the use of the filters. It provides more information on how effective the filter is, at removing a particular parameter, by running the water through it.