Hydraulic performance of sewer pipes with deposited sediments

Abstract

This paper investigates in-sewer sediment deposit behaviour and its influence on the hydraulic performance of sewer pipes. This evaluation is based on experimental results regarding the mobility of non-cohesive and partly cohesive deposits in a partially full circular pipe. The focus of these tests is on the development of bed forms and friction characteristics. In particular, it is investigated to what extent the bed forms from the non-cohesive and (partly) cohesive sediments affect a sewer's discharge capacity. Based on the laboratory study results and on the existing criteria for sewer design, a generic assessment of a sewer's hydraulic performance is made. The relative discharge factor for a pipe with sediment deposit is analysed in terms of the thickness and roughness of the deposit.

Spatial Distribution, Adsorption/Release Characteristics, and Environment Influence of Phosphorus on Sediment in Reservoir

“…The initial concentration is the concentration in overlying water during the initial stage of experiment; the equilibrium concentration is the concentration in overlying water after 24 h; and, the amount of adsorption and release is the ability to adsorb or release P (<0 for release and >0 for adsorption). It can be easily seen in Figure 2 that there are high correlations between the initial concentration and equilibrium concentration, as well as the amount of adsorption and release, which is consistent with previous studies [21,24]. Qmax is the maximum adsorption (mg/kg); Kd is the adsorption efficiency (L/kg) calculated by Langmuir model; and, 1/n is the adsorption efficiency as The initial concentration is the concentration in overlying water during the initial stage of experiment; the equilibrium concentration is the concentration in overlying water after 24 h; and, the amount of adsorption and release is the ability to adsorb or release P (<0 for release and >0 for adsorption).…”

“…Qmax is the maximum adsorption (mg/kg); Kd is the adsorption efficiency (L/kg) calculated by Langmuir model; and, 1/n is the adsorption efficiency as The initial concentration is the concentration in overlying water during the initial stage of experiment; the equilibrium concentration is the concentration in overlying water after 24 h; and, the amount of adsorption and release is the ability to adsorb or release P (<0 for release and >0 for adsorption). It can be easily seen in Figure 2 that there are high correlations between the initial concentration and equilibrium concentration, as well as the amount of adsorption and release, which is consistent with previous studies [21,24]. Q max is the maximum adsorption (mg/kg); K d is the adsorption efficiency (L/kg) calculated by Langmuir model; and, 1/n is the adsorption efficiency as calculated by the Freundlich model.…”

“…The spatial distribution of P in sediments is shown in Figure 3 with ArcGIS, which shows an increasing trend from the entrance to the dam site, and that is consistent with the literature results [13]. This trend is in accordance with the hydraulic gradient, which contributes to sediment deposits [24,26]. The dam site (point 10) had the second highest content of sediment P, which reached 750.5 mg/kg.…”

Prediction of Sediment Accumulation Model for Trunk Sewer Using Multiple Linear Regression and Neural Network Techniques

“…In-sewer sediment is getting more scientific and operational interest in the last decade [1]; Sediments disposition in combined sewers is a critical aspect as it is a primary cause of several hydraulic and environmental problems such as blockage, reduction in hydraulic capacity, increase in the flooding frequency, sewer wall corrosion, shock loads to wastewater treatment plants and, erosion and resuspension of the deposited solids during wet weather flow (WWF) [2]. The reduction in hydraulic capacity in sewers containing sediment is significant reaching 10-20% for relatively small sediment/diameter values of 2-10% [3]. Hannouche et al [4] assert that the contribution of the sewer sediment resuspension to the total TSS of the wastewater is in order of 20-80%.…”

A Fuzzy Expert System for Prioritizing Rehabilitation of Sewer Networks

“…Their approach is based on regressive models using pipe age and specified for each material type. Banasiak (2008) investigated in‐sewer sediment deposit behavior and its influence on sewer pipe hydraulic performance and used laboratory study results to make a generic assessment of a sewer's hydraulic performance. Dridi et al (2008) used optimization techniques based on evolutionary algorithms as genetic algorithm (Adeli and Cheng, 1994a, 1994b) to schedule system pipe renewal.…”