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Water
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Smart Hydraulics in Wastewater Transport
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Smart Hydraulics in Wastewater Transport

A special issue of Water (ISSN 2073-4441). This special issue belongs to the section "Hydraulics and Hydrodynamics".

Deadline for manuscript submissions: closed (31 December 2018) | Viewed by 25674

Special Issue Editor

Prof. Francois Clemens

E-Mail Website
Guest Editor
Delft University of Technology, P.O. Box 5048, 2600 GA Delft, The Netherlands
Interests: hydraulics; measuring techniques; asset management

Special Issue Information

Dear Colleagues,

In the engineering and operation of systems for wastewater collection, transportation and treatment, applied hydraulics is of undisputed importance. As most existing infrastructure is designed based on relatively simple design rules aiming at robustness, it is no surprise that applying more advanced means (e.g., 3D CFD simulations, advanced measuring techniques and modern process control) can help to increase the effectiveness and efficiency of wastewater systems on one hand, while at the other hand these advanced means can provide valuable insight for new designs.

When talking about “smart” hydraulics in wastewater, one can think of several interpretations:

  1. Using advanced hydraulic calculations in designing and operating wastewater systems (e.g., flow patterns in reactors).
  2. Using advanced measuring techniques (e.g., PIV, PTV) for design purposes.
  3. Applying knowledge on hydraulic phenomena hitherto ignored or avoided (e.g., vortices or pre-rotation pump sumps) because of a limited understanding of their benefits or the risk they represent to damaging equipment or endanger system performance.

The proposed Special Issue on “Smart Hydraulics in Wastewater” aims at (but is not limited to) addressing the afore mentioned fields of interest. Manuscripts may address fundamental and applied research, while well documented case studies are welcomed as well. As a lot of challenges with respect to wastewater hydraulics are related to multiphase flows, contributions in this field of interest are encouraged.

Prof. Francois Clemens
Guest Editor

Manuscript Submission Information

Manuscripts should be submitted online at www.mdpi.com by registering and logging in to this website. Once you are registered, click here to go to the submission form. Manuscripts can be submitted until the deadline. All submissions that pass pre-check are peer-reviewed. Accepted papers will be published continuously in the journal (as soon as accepted) and will be listed together on the special issue website. Research articles, review articles as well as short communications are invited. For planned papers, a title and short abstract (about 100 words) can be sent to the Editorial Office for announcement on this website.

Submitted manuscripts should not have been published previously, nor be under consideration for publication elsewhere (except conference proceedings papers). All manuscripts are thoroughly refereed through a single-blind peer-review process. A guide for authors and other relevant information for submission of manuscripts is available on the Instructions for Authors page. Water is an international peer-reviewed open access semimonthly journal published by MDPI.

Please visit the Instructions for Authors page before submitting a manuscript. The Article Processing Charge (APC) for publication in this open access journal is 2600 CHF (Swiss Francs). Submitted papers should be well formatted and use good English. Authors may use MDPI's English editing service prior to publication or during author revisions.

Keywords

  • wastewater
  • hydraulics
  • experiments
  • field observations
  • calculation methods
  • algorithms

Published Papers (6 papers)

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Research

18 pages, 4681 KiB  
Article
Hydraulic Capacity and Efficiency of a Low-Speed Nonpressurized Coil Pump
by Radosław Matz, Ryszard Błażejewski, Tadeusz Nawrot and Maciej Pawlak
Water 2019, 11(8), 1659; https://doi.org/10.3390/w11081659 - 10 Aug 2019
Viewed by 3035
Abstract
The paper presents the results of an investigation on hydraulics of a low-speed coil pump for transport of liquids. One of the pump’s advantages is its wide range of potential inclination angles for its rotating shaft, from the horizontal to an almost vertical [...] Read more.
The paper presents the results of an investigation on hydraulics of a low-speed coil pump for transport of liquids. One of the pump’s advantages is its wide range of potential inclination angles for its rotating shaft, from the horizontal to an almost vertical position. A simplified hydraulic model was developed based on kinematic and geometrical considerations to determine the pump capacity. The model was verified under laboratory conditions using a low-speed coil pump composed of transparent PVC tube (15 mm outer diameter) wound around a cylindrical drum (104 mm external diameter; 550 mm long). Laboratory tests were performed for three angles of inclination of the axis of rotation (20°, 40°, and 60°) and four rotational speeds (10, 20, 30, and 40 rpm). The results of the tests showed satisfactory agreement with the hydraulic model predictions. Energetic efficiency was estimated on the base of electric power measurements and difference of water levels in the two arms of rotating transparent torus, partly filled with water. The hydraulic efficiency of the coil pump is increasing with decreasing rotational speed. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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16 pages, 2990 KiB  
Article
Sedimentation of Raw Sewage: Investigations For a Pumping Station in Northern Germany under Energy-Efficient Pump Control
by Martin Rinas, Jens Tränckner and Thilo Koegst
Water 2019, 11(1), 40; https://doi.org/10.3390/w11010040 - 26 Dec 2018
Cited by 8 | Viewed by 4724
Abstract
Flow control in wastewater pressure pipes can reduce energy consumption but increases the risk of sediment formation due to reduced flow velocity. In this work, the sedimentation behavior of dry and wet weather samples at the inflow of a wastewater pumping station is [...] Read more.
Flow control in wastewater pressure pipes can reduce energy consumption but increases the risk of sediment formation due to reduced flow velocity. In this work, the sedimentation behavior of dry and wet weather samples at the inflow of a wastewater pumping station is determined by settling column experiments. Based on the derived characteristic settling velocity (vs) distribution, the impact of energy-efficient flow control on sediment formation in pressure pipes (600 mm diameter) was quantified in comparison to a simple on/off operation. In parallel, the sediment formation for 2 years of pumping operation was monitored indirectly via the friction losses. For the investigated case, settling is strongly influenced by the inflow condition (dry, combined from road runoff). Under combined inflow, the proportion of solids with vs from 0.007 to 1.43 mm/s significantly increases. In energy-efficient mode with smoother operation and shorter switch-off sequences, the sediment formation is significant lower. The mean deposit’s height in energy-efficient control was calculated to 0.137 m, while in on/off operation the mean deposit’s height was 0.174 m. No disadvantages arise over a long period by installing the energy-efficient control. The decreased flow lead under the investigated conditions even to a reduced sediment formation. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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19 pages, 1061 KiB  
Article
Sensitivity Analysis of a Wall Boundary Condition for the Turbulent Pipe Flow of Herschel–Bulkley Fluids
by Dhruv Mehta, Adithya Krishnan Thota Radhakrishnan, Jules Van Lier and Francois Clemens
Water 2019, 11(1), 19; https://doi.org/10.3390/w11010019 - 22 Dec 2018
Cited by 6 | Viewed by 3508
Abstract
This article follows from a previous study by the authors on the computational fluid dynamics-based analysis of Herschel–Bulkley fluids in a pipe-bounded turbulent flow. The study aims to propose a numerical method that could support engineering processes involving the design and implementation of [...] Read more.
This article follows from a previous study by the authors on the computational fluid dynamics-based analysis of Herschel–Bulkley fluids in a pipe-bounded turbulent flow. The study aims to propose a numerical method that could support engineering processes involving the design and implementation of a waste water transport system, for concentrated domestic slurry. Concentrated domestic slurry results from the reduction in the amount of water used in domestic activities (and also the separation of black and grey water). This primarily saves water and also increases the concentration of nutrients and biomass in the slurry, facilitating efficient recovery. Experiments revealed that upon concentration, domestic slurry flows as a non-Newtonian fluid of the Herschel–Bulkley type. An analytical solution for the laminar transport of such a fluid is available in literature. However, a similar solution for the turbulent transport of a Herschel–Bulkley fluid is unavailable, which prompted the development of an appropriate wall function to aid the analysis of such flows. The wall function (called ψ 1 hereafter) was developed using Launder and Spalding’s standard wall function as a guide and was validated against a range of experimental test-cases, with positive results. ψ 1 is assessed for its sensitivity to rheological parameters, namely the yield stress, the fluid consistency index and the behaviour index and their impact on the accuracy with which ψ 1 can correctly quantify the pressure loss through a pipe. This is done while simulating the flow of concentrated domestic slurry using the Reynolds-Averaged Navier–Stokes (RANS) approach for turbulent flows. This serves to establish an operational envelope in terms of the rheological parameters and the average flow velocity within which ψ 1 is a must for accuracy. One observes that, regardless of the fluid behaviour index, ψ 1 is necessary to ensure accuracy with RANS models only in flow regimes where the wall shear stress is comparable to the yield stress within an order of magnitude. This is also the regime within which the concentrated slurry analysed as part of this research flows, making ψ 1 a requirement. In addition, when the wall shear stress exceeds the yield stress by more than one order (either due to an inherent lower yield stress or a high flow velocity), the regular Newtonian wall function proposed by Launder and Spalding is sufficient for an accurate estimate of the pressure loss, owing to the relative reduction in non-Newtonian viscosity as compared to the turbulent viscosity. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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33 pages, 6276 KiB  
Article
A Case Study of a Small Diameter Gravity Sewerage System in Zolkiewka Commune, Poland
by Tadeusz Nawrot, Radosław Matz, Ryszard Błażejewski and Marcin Spychała
Water 2018, 10(10), 1358; https://doi.org/10.3390/w10101358 - 29 Sep 2018
Cited by 7 | Viewed by 4466
Abstract
This article presents a small diameter gravity sewerage system in a rural area. In this system, domestic wastewater was preliminarily treated in septic tanks equipped with outlet filters, so the effluent features were similar to those of clear water. Additionally, some outlets were [...] Read more.
This article presents a small diameter gravity sewerage system in a rural area. In this system, domestic wastewater was preliminarily treated in septic tanks equipped with outlet filters, so the effluent features were similar to those of clear water. Additionally, some outlets were equipped with floating-ball check valves to avoid backflow. One of the pressure mains was used as a gravity collector conveying septic tank effluent in the direction of the pumping station during pump idle time. The operation of the system was simulated using SWMM computer code. The simulation results were validated for data obtained from part of a sewerage system in Kolonia Zolkiew and Rozki village consisting of two pumping stations and 86 serviced households using polyethylene pipes of outer diameter 50–63 mm. The results of the measurement of the outflows from one pumping station are presented. The simulation results showed good agreement with the empirical data, especially after several simulation days. The greatest discrepancy during the start-up period was the consequence of the initial conditions describing the empty pipework. Thanks to storage in the pump sumps, septic tank and pipes, as well as their smart operation, a relatively uniform inflow to the pumping stations was achieved. Simulations in SWMM showed that there is still potential to optimize the sewerage system through more adequate pump selection and pipe diameters. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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13 pages, 2362 KiB  
Article
Rheology of Un-Sieved Concentrated Domestic Slurry: A Wide Gap Approach
by Adithya Krishnan Thota Radhakrishnan, Jules Van Lier and Francois Clemens
Water 2018, 10(10), 1287; https://doi.org/10.3390/w10101287 - 20 Sep 2018
Cited by 4 | Viewed by 2954
Abstract
Information on the rheology of domestic slurries is essential in designing pipeline transportation in novel sanitation systems. As concentrated slurries in their original collected state have wide particle size distribution, with particles up to 2 mm, a wide gap rheometer is used to [...] Read more.
Information on the rheology of domestic slurries is essential in designing pipeline transportation in novel sanitation systems. As concentrated slurries in their original collected state have wide particle size distribution, with particles up to 2 mm, a wide gap rheometer is used to acquire the rheograms. Rheograms obtained from a wide gap rheometer require a method to convert the rotational velocity to the shear rate, and this method must be robust to noisy data and yield stress in the slurry. For this purpose, a Tikhonov regularisation method is chosen as it suits the criteria the best. Using this, the rheograms are obtained for various total suspended solids (TSS) concentrations of slurries. A Herschel-Bulkley rheological model is used to represent the rheology of the slurries. The influence of the change in concentration of the slurries is represented through its influence on the Herschel-Bulkley parameters. The consistency index K exponentially increases with the concentration. The yield stress τ y , is 0 at low concentrations, and above 2.0% TSS (wt./wt.) exponentially increases with the concentration. The behaviour index n , is 1 at low concentrations, and above 2.6% TSS (wt./wt.) it decreases in an inverse power law with the concentration to reach a sort of plateau. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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22 pages, 8466 KiB  
Article
A Wall Boundary Condition for the Simulation of a Turbulent Non-Newtonian Domestic Slurry in Pipes
by Dhruv Mehta, Adithya Krishnan Thota Radhakrishnan, Jules Van Lier and Francois Clemens
Water 2018, 10(2), 124; https://doi.org/10.3390/w10020124 - 30 Jan 2018
Cited by 15 | Viewed by 6267
Abstract
The concentration (using a lesser amount of water) of domestic slurry promotes resource recovery (nutrients and biomass) while saving water. This article is aimed at developing numerical methods to support engineering processes such as the design and implementation of sewerage for concentrated domestic [...] Read more.
The concentration (using a lesser amount of water) of domestic slurry promotes resource recovery (nutrients and biomass) while saving water. This article is aimed at developing numerical methods to support engineering processes such as the design and implementation of sewerage for concentrated domestic slurry. The current industrial standard for computational fluid dynamics-based analyses of turbulent flows is Reynolds-averaged Navier–Stokes (RANS) modelling. This is assisted by the wall function approach proposed by Launder and Spalding, which permits the use of under-refined grids near wall boundaries while simulating a wall-bounded flow. Most RANS models combined with wall functions have been successfully validated for turbulent flows of Newtonian fluids. However, our experiments suggest that concentrated domestic slurry shows a Herschel–Bulkley-type non-Newtonian behaviour. Attempts have been made to derive wall functions and turbulence closures for non-Newtonian fluids; however, the resulting laws or equations are either inconsistent across experiments or lack relevant experimental support. Pertinent to this study, laws or equations reported in literature are restricted to a class of non-Newtonian fluids called power law fluids, which, as compared to Herschel–Bulkley fluids, yield at any amount of applied stress. An equivalent law for Herschel–Bulkley fluids that require a minimum-yield stress to flow is yet to be reported in literature. This article presents a theoretically derived (with necessary approximations) law of the wall for Herschel–Bulkley fluids and implements it in a RANS solver using a specified shear approach. This results in a more accurate prediction of the wall shear stress experienced by a circular pipe with a turbulent Herschel–Bulkley fluid flowing through it. The numerical results are compared against data from our experiments and those reported in literature for a range of Reynolds numbers and rheological parameters that are relevant to the prediction of pressure losses in a sewerage transporting non-Newtonian domestic slurry. Nonetheless, the application of this boundary condition could be extended to areas such as chemical and food engineering, wherein turbulent non-Newtonian flows can be found. Full article
(This article belongs to the Special Issue Smart Hydraulics in Wastewater Transport)
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