Towards resilient municipal wastewater sewerage systems in khartoum: A surcharged flow measurement device

Abstract

Sewerage and sanitation-related disasters are becoming more frequent, especially in developing countries. The aftermath of natural disasters is no less devastating than the immediate destruction they cause. In this way, one of the most pressing needs in rapidly urbanizing cities, especially African capitals, is the efficient sanitary facilities in which the flow measurement is an essential element to evaluate the sewerage systems' performance. The traditional devices of measurements are not suitable due to the enormous discharge of sewage network and many solid particles in wastewater might cause a blockage in sewers. Consequently, the accuracy of measurement declines rapidly. This research aims to develop a flow-measuring device for full pipe flow, also known as sanitary sewer overflow. This particular case is an existing phenomenon that faces sewerage authorities worldwide and impacts the whole society. Flow measurement in such a situation is a formidable challenge and needs cutting-edge research to find fitting flowmeters. The device is a modified fiberglass-built venturi that was manufactured locally without the diverging part (cutthroat venturi). The manufacturing was both simple and achieved at a relatively low cost. Two sensors were used to measure the surcharged flow, one in the inlet section and the other in the throat. The modified venturi connects to an Arduino board that is programmed to output the differential pressure. To calibrate the device, a closed pipe submerged into a hydraulic flume channel is adopted to simulate the overflow sewers. To calculate the actual flow, a stopwatch was used together with the known volume of the channel to compute the actual flow, which was compared with the discharge measured by the device. The results showed an acceptable discharge coefficient “Cd” of about 0.9, which meets the standard discharge coefficient of the venturi meter.