Effectiveness of Manual Bar Screen in Separating Solid Waste from Municipal Sewers of Khulna City

doi:10.34104/ajeit.020.031041

Abstract

In Bangladesh, disposal of raw sewage directly into the streams is a common culture. Installing a complete wastewater treatment plant everywhere is not possible for developing or least developed countries. Bar screen can be advantageous in separating solid waste from the raw sewage. Solid waste separation from municipal sewage can play an important role in improving the environmental condition. The objective of this study was to observe the effect of bar screen in raw sewage pretreatment. This study was carried out in Khulna city area to investigate the condition of forty-seven outfalls through which the raw sewage is being disposed to the streams. As part of the study, a bar screen was temporarily installed on a drain inside Khulna University of Engineering & Technology campus. The capability and effect of the temporarily installed bar screen were observed and studied over a period of time. From twelve hours of observation of the installed bar screen, around 20% removal found for BOD and COD. Reduction of electrical conductivity (EC) and total dissolved solids (TDS) found near 20% also. Removal percentage of BOD, COD, EC, and TDS obtained higher after one hour of installing the bar screen while 24 hours of observation exhibited a comparatively lower rate of removal. The optimum condition of the bar screen notified at 12 hours which indicated the incorporation of cleaning procedure after every twelve hours to sustain the performance. Furthermore, the differences between raw sewage and bar screen treated sewage were studied; and the possibility of using bar screens on every outfall of Khulna city area was discussed in this study.

Highlights

Each and every element of raw sewage does carry disadvantages related to the environment
The sewers of Khulna City were taken into consideration for this study to investigate the effectiveness of manual bar screen which leads the separation of solid waste from raw sewage
Due to lack of awareness, the drains of Khulna city have been used to collect solid wastes of diverse nature. This can be remedied by screening out the solid wastes from sewage by bar screens

Summary

Introduction

Each and every element of raw sewage does carry disadvantages related to the environment. This study carries the importance of removing solid waste from municipal sewage before disposing it to the streams by implementing raw sewage pretreatment system. The sewers of Khulna City were taken into consideration for this study to investigate the effectiveness of manual bar screen which leads the separation of solid waste from raw sewage. The city is bounded by Rupsha River on east and south side, Mayur River on west and by Bhairab River by north side. It is the capital of Khulna Division and a major industrial and commercial center. Khulna City Corporation (KCC) covers a total area of 64.78 square kilometers (Bangladesh Bureau of Statistics, 2011). The population of the KCC area is about 0.75

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