On the Total Load Sediment Transport of Urban Wastewater Flows

Abstract

The objective of the present work is to determine the total load of the urban wastewater flow and compare the results with the proposed relations by previous researchers for calculating the total load. For this goal, the gradation curves of sediment have been analyzed. Field experimental data has been collected at the entrance grit chamber of the wastewater treatment plant in Khomein city, Iran. A rectangular concrete channel was prepared. The channel demonstrates a length of 18m, a width and depth of 0.5 m, and a longitude slope of 0.1%. The goal of this setup is to collect and measure the deposited sediment from the wastewater flow. A long-period accumulation test was planned to study the development of the sediment characteristics over 10 days. According to our observation, the PSDs range from 0.075 mm to 31 mm, and the solid particles are in the size range of 0.30 mm to 2 mm. For this goal, continuous hydraulic conditions were set up: flow rate, Q = 14.7 L/s, and longitude slope, S0 = 0.1% (0.001). Particle size distribution (PSD) was measured with use of gradation test. A total of 14 samples of the deposited material have been collected after 7 months at an interval of 15 days. Also, the mass rate of the total load of sediment transferred by the flow has been measured, and the results have been compared with 10 famous methods for calculating the total load by using d50. The results show that Ackers and White’s method [1] estimates the total load with a relative error of 9.34%. So, this method can be used to estimate the total load of the flow with high accuracy. Also, the distribution of sediment particle size in the urban wastewater flow has been achieved, and the range of particle diameters is between 0.075 mm to 31 mm.