Self-Cleaning Networks Put to the Test

Blokker, Mirjam; Vreeburg, J.H.G.; Schaap, Peter G.; Horst, P.

doi:10.1061/40927(243)468

Cited by 11 publications

(8 citation statements)

References 3 publications

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“…A number of studies reported similar minimum flow velocities for particle resuspension, varying from 0.10 to 0.25 m/s, depending on the material and conditions tested [25][26][27]. Blokker et al [28,29] suggested a minimum velocity of 0.2 m/s based on field studies in the Netherlands. The knowledge of a minimum flow velocity to resuspend particles inspired the design of self-cleaning pipes [28][29][30], composed of branched distribution systems with pipes of small diameters to maintain a high flow velocity (initial design flow velocity of 0.4 m/s) and keep particles in suspension.…”

Section: Impact Of Hydraulic Conditions On Particle Deposition and Re-suspensionmentioning

confidence: 99%

“…Blokker et al [28,29] suggested a minimum velocity of 0.2 m/s based on field studies in the Netherlands. The knowledge of a minimum flow velocity to resuspend particles inspired the design of self-cleaning pipes [28][29][30], composed of branched distribution systems with pipes of small diameters to maintain a high flow velocity (initial design flow velocity of 0.4 m/s) and keep particles in suspension. In our study, the smallest pipe studied had a diameter of 152 mm.…”

Section: Impact Of Hydraulic Conditions On Particle Deposition and Re-suspensionmentioning

confidence: 99%

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Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

Prest¹,

Schaap²,

Besmer³

et al. 2021

Water

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Spatial and short-term temporal changes in water quality as a result of water age and fluctuating hydraulic conditions were investigated in a drinking water distribution system. Online measurements of total and intracellular adenosine tri-phosphate (ATP), total and intact cell concentrations measured with flow cytometry (FCM), turbidity, and particle counts were performed over five weeks at five subsequent locations of the distribution system. The high number of parallel FCM and ATP measurements revealed the combined effect of water age and final disinfection on spatial changes in microbiology in the system. The results underlined that regular daily dynamics in flow velocities are normal and inevitable in drinking water distribution systems, and significantly impact particle counts and turbidity. However, hydraulic conditions had no detectable impact on the concentration of suspended microbial cells. A weak correlation between flow velocity and ATP concentrations suggests incidental resuspension of particle-bound bacteria, presumably caused by either biofilm detachment or resuspension from sediment when flow velocities increase. The highly dynamic hydraulic conditions highlight the value of online monitoring tools for the meaningful description of short-term dynamics (day-scale) in drinking water distribution systems.

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Section: Impact Of Hydraulic Conditions On Particle Deposition and Re-suspensionmentioning

confidence: 99%

Section: Impact Of Hydraulic Conditions On Particle Deposition and Re-suspensionmentioning

confidence: 99%

Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

Prest¹,

Schaap²,

Besmer³

et al. 2021

Water

View full text Add to dashboard Cite

show abstract

“…In looped sections of the network, an increase of the temporal scale only resulted in a small increase in number of pipes observed to exhibit proposed self-cleaning velocities which might be due to the extremely looped nature of the selected DMA. This indicates that to achieve self-cleaning velocities and reduce discolouration risk, branched network layouts may offer an improved design [17,26,27]. The more complex metric of Figure 7 investigated the stochastic stop-start motion of the velocity in individual pipe sections followed by a period that might facilitate both particle aggregation (increased mass due to flocculation) and settling.…”

Section: Discussionmentioning

confidence: 99%

The impact of drinking water network model spatial and temporal scale on hydraulic metrics indicating discolouration risk

Lokk,

Blokker,

Boxall

et al. 2022

Proceedings - 2nd International Join Conference on Water Distribution System Analysis (WDSA)& Computing and Control in the

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Matching model complexity to application and ensuring sufficient complexity to capture the emergent behaviour of interest is a perennial challenge. In this paper we define a model as the variables, parameters and factors that represent a particular place, time and situation, not the software or algorithms. Specifically, we explore the cross products of spatial and temporal scaling of water demands within extended period 1D network model simulations to predict the hydraulic conditions within individual drinking water pipes and the association of this with discolouration risk. High spatial scale hydraulic models investigated include mapping each customer with a unique demand node instead of the current practice of aggregated demand to nodes at the ends of pipe lengths. For demand profiling we compare top-down DMA inlet patterns at 15-minute resolution with bottom-up stochastic demand patterns down to 1 second timesteps. The value of the resulting increases in resolution of hydraulic model outputs are captured in a range of pipe specific metrics that are likely to be indicative of discolouration risk. Unlike water quality surrogate of water age or chlorine residual that aggregate time and pipe effects from source to point of interest, discolouration risk has been shown to be primarily a function of the hydraulic conditions in a specific length of pipe. Hence the additional effort to achieve high-resolution modelling simulations are perhaps warranted to manage discolouration. Results review proposed discolouration metrics by correlating with consumer reported discolouration events, showing how these change as a function of spatial and temporal resolution. For example, increasing temporal scale from 15 minutes to 1-minute results in a 15-fold increase in identifying flow reversal locations that can facilitate settling of network discolouration material and therefore pose a discolouration risk. High temporal scale is shown to capture the on/off nature of customer demands and the significant impact on peak velocities that are shown suppressed when using aggregated profiles. This work provides an indication of the optimal level of model resolution required to differentiate pipes according to discolouration risk and hence improve targeting of pro-active maintenance and discolouration management efficiency.

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“…[2,3]). This formed the basis for design and application of self-cleaning networks in The Netherlands that have been applied in The Netherlands since the 1990 and that have been shown to reduce the number of customer complaints [4]. These observations also suggests that can be described with a predictive model .…”

Section: Introductionmentioning

confidence: 88%

Aquarellus: a numerical too to calculate accumulation of particulate matter in drinking water distribution systems

Van Summeren,

Dash,

Morley

et al. 2022

Proceedings - 2nd International Join Conference on Water Distribution System Analysis (WDSA)& Computing and Control in the

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Despite preventive measures, turbid (vernacular: “discolored”) distributed drinking water is still a common cause for customer complaints across the world. Discoloration events are caused by the accumulation of particulate matter in drinking water distribution systems (DWDSs) and subsequent remobilization during hydraulic events [1], although uncertainties remain concerning the specific accumulation and transport processes. For Dutch DWDSs, it is plausible that microscopic particles originating at treatment plants contribute substantially to the particulate matter that resides in DWDSs, and that physical processes within the distribution network are cardinal in the subsequent transport during distribution. Aquarellus, a predictive numerical tool has been developed to predict the accumulation of particulate material in DWDSs. It integrates hydraulic calculations using the EPANET toolbox with a particle transport module that is based on a description of gravitational settling, particle stagnation, bed load transport, and resuspension of particles in distribution pipes, depending on the shear stress near the pipe wall [2]. The performance of the multi-core calculations allows for simulating distribution network sizes that are common to Dutch water utilities (100s of km total pipe length). The user can assign the injection of multiple particle species corresponding to temporal patterns at multiple source locations. A graphical user interface handles user IO and the visualization of geographical maps as well as time-dependent build-up of particulate material across the distribution network and within individual pipes. To characterize particle properties (critical input parameters) encountered in Dutch DWDSs, we performed lab experiments on 9 samples from 3 water utilities to determine particle size distributions, mass density, mobility thresholds, and a measure for gravitational settling. Using the outcomes of these lab experiments, a sensitivity test with a range of input parameters was performed in Aquarellus. This helped determine how the variation in the relevant input parameters influence the calculated spatial patterns of accumulated particulate matter ̶ a measure for the discoloration risk. We compared the modeling results to turbidity measurements from systematic cleaning actions in a real-life Dutch distribution network (Spijkenisse). Finally, we will discuss the potential for applying the tool to assist the planning of cleaning actions and monitoring programs.

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Self-Cleaning Networks Put to the Test

Cited by 11 publications

References 3 publications

Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

Dynamic Hydraulics in a Drinking Water Distribution System Influence Suspended Particles and Turbidity, But Not Microbiology

The impact of drinking water network model spatial and temporal scale on hydraulic metrics indicating discolouration risk

Aquarellus: a numerical too to calculate accumulation of particulate matter in drinking water distribution systems

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