Beyond −10 Metres Water Head

2016 ◽  
pp. 214-222
Keyword(s):  
Water Head

scholarly journals Gravity-Driven Membrane Reactor for Decentralized Wastewater Treatment: Effect of Reactor Configuration and Cleaning Protocol

Membranes ◽  
2021 ◽  
Vol 11 (6) ◽  
pp. 388
Author(s):  
Ihtisham Ul Haq Shami ◽  
Bing Wu
Keyword(s):  
Wastewater Treatment ◽  
Municipal Wastewater ◽  
Economic Feasibility ◽  
Reactor Configuration ◽  
Membrane Performance ◽  
Decentralized Wastewater Treatment ◽  
Water Head ◽  
Cake Layer ◽  
Gravity Driven ◽  
Cleaning Protocol

In this study, three gravity-driven membrane (GDM) reactors with flat sheet membrane modules and various biocarriers (synthetic fibers, lava stones, and sands) were operated for municipal wastewater treatment. The effects of water head, periodically cleaning protocol, and operation temperature on the GDM reactor performance were illustrated in terms of membrane performance and water quality. The results indicated that: (1) the cake layer fouling was predominant (>~85%), regardless of reactor configuration and operation conditions; (2) under lower water head, variable water head benefited in achieving higher permeate fluxes due to effective relaxation of the compacted cake layers; (3) the short-term chemical cleaning (30–60 min per 3–4 days) improved membrane performance, especially when additional physical shear force was implemented; (4) the lower temperature had negligible effect on the GDM reactors packed with Icelandic lava stones and sands. Furthermore, the wastewater treatment costs of the three GDM reactors were estimated, ranging between 0.31 and 0.37 EUR/m3, which was greatly lower than that of conventional membrane bioreactors under lower population scenarios. This sheds light on the technical and economic feasibility of biocarrier-facilitated GDM systems for decentralized wastewater treatment in Iceland.

scholarly journals Laboratory test and numerical simulation of composite geomembrane leakage in plain reservoir

2021 ◽  
Vol 13 (1) ◽  
pp. 651-662
Author(s):  
Jinping Luo ◽  
Guoxiang Huang ◽  
Yanni Shao ◽  
Jian Liu ◽  
Quanyi Xie
Keyword(s):  
Laboratory Test ◽  
Water Shortage ◽  
Seepage Discharge ◽  
Threshold Distance ◽  
Water Head ◽  
Large Populations ◽  
Key Issues ◽  
Single Factor Analysis ◽  
The Impact ◽  
Leakage Location

Abstract Plain reservoir plays an important role in alleviating water shortage in plain areas which are generally crowded with large populations. As an effective and cheap anti-seepage measure, geomembrane is widely applied in plain reservoirs. Therefore, it is necessary to investigate the seepage discharge caused by composite geomembrane leakage. The laboratory test and numerical calculation are carried out in this paper to analyze the influence of three factors (i.e., water head, leakage size, and leakage location) on seepage discharge. It is found from the results of the orthogonal and single-factor analysis that the impact order of the three factors on the seepage discharge of plain reservoir is: distance from dam toe > water head > leakage size. Moreover, the seepage discharge increases as the water head, leakage size, and leakage quantity increase, in a linear relation. The opposite trend can be sawed in the seepage discharge when the distance from dam toe rises. Furthermore, a threshold distance is innovatively presented based on the results of numerical analysis. The ranking of three factors has enlightening significance for future scholars to track and study key issues of the leakage of composite geomembrane. The threshold distance presented in this paper is beneficial for engineers to manage and maintain the reservoir. Generally, the findings of this study can be beneficial to deepen the understanding of the influence of composite geomembrane leakage on the plain reservoirs.

Water Infiltration into Soil in Response to Ponded-Water Head

1991 ◽  
Vol 55 (6) ◽  
pp. 1511-1515 ◽  
Author(s):  
D. Swartzendruber ◽  
W. L. Hogarth
Keyword(s):  
Water Infiltration ◽  
Water Head

Observations on some basal failures in sheeted excavations

1970 ◽  
Vol 7 (2) ◽  
pp. 136-144 ◽  
Author(s):  
V. Milligan ◽  
K. Y. Lo
Keyword(s):  
Shear Strength ◽  
Ground Water ◽  
Groundwater Level ◽  
Soil Conditions ◽  
Remedial Measures ◽  
Factors Influencing ◽  
Water Head ◽  
The Stability ◽  
Made In

In excavations below groundwater level, instability of the base may result from the inflow of water into the excavation. The most important factors influencing the stability are the ground water and detailed soil conditions at the site.Construction problems encountered in excavations in clay strata, underlain by pervious water bearing layers, are described. The remedial measures adopted in each case are also discussed. From a study of the observations made in the case records, it is suggested that excavation in intact clays may be carried out to depths exceeding that limited by the ratio of t/h = 0.5, where t is the distance from the bottom of the excavation to the top of the water bearing stratum, and h is the water head at the top of the water bearing stratum, provided that the clay is not disturbed during construction so that the shear strength of the clay is preserved.

scholarly journals A Study on the Effects of Model Structure and Demand Allocation on Water Network Modeling

2020 ◽  
Vol 42 (3) ◽  
pp. 110-120
Author(s):  
Seonghan Kim ◽  
Kwansue Jung ◽  
Sukmin Yoon ◽  
No-Suk Park
Keyword(s):  
Steady State ◽  
Network Modeling ◽  
Extended Period ◽  
Model Structure ◽  
Water Network ◽  
Detailed Model ◽  
Water Head ◽  
Models Comparison ◽  
The Difference ◽  
Steady State Simulation

Objectives:In order to reduce the uncertainty of the pipe network modeling, the model structure was basically included all distribution pipes and several models were proposed according to the location of the water meters.Methods:For models verification, first, a steady state simulation of each model was made by constructing a model including all water supply pipes (All-meters Model), which are the bases of 3 simplified models, and considering the location of all water meters. The network analysis was performed by dividing into the steady state and the extended period simulation.Results and Discussion:From the results of models comparison, ‘All-meters Model’ and ‘All-connections Model’ were found to obtain more accurate results for constructing a water network model for simulation of water quality events in distribution network. When constructing an ‘All-meters Model’ in all networks, the model becomes complicated and data management does difficult. Therefore this study suggests a hybrid model construction.Conclusions:It would be reasonable to construct a detailed model (All-meters or All-connections Model) in looped network in which the water flow path can be changed according to the difference of water head, and a skeletonized model (Street-meters aggregation or Reduced-meters Model) for a branch network that does not have a significant impact on demand allocations.

scholarly journals Modification of Classical Horseshoe Spillways: Experimental Study and Design Optimization

2019 ◽  
Vol 5 (10) ◽  
pp. 2093-2109
Author(s):  
Vahid Hassanzadeh Vayghan ◽  
Ali Saber ◽  
Soroosh Mortazavian
Keyword(s):  
Hydraulic Jump ◽  
Design Parameters ◽  
Hydraulic Structures ◽  
Flow Conditions ◽  
Design Factor ◽  
Flow Passage ◽  
Water Head ◽  
Cubic Polynomial ◽  
Polynomial Models ◽  
Discharge Efficiency

Investigation of the hydraulic aspects of spillways is one of the important issues regarding hydraulic structures. This study presents a modified horseshoe spillway (MHS) constructed by adding a flow passage and an internal weir in the bed of a classical horseshoe spillway (CHS). This modification increased the discharge efficiency and eliminated the rooster-tail hydraulic jump in CHSs. Eighteen laboratory-scale MHSs in various geometric sizes, six various CHSs, and a rectangular weir of the same width were constructed and tested under the same flow conditions. Results showed that in terms of discharge efficiency and water head reduction, CHSs and MHSs were superior to the rectangular weir. Compared to CHSs, the increased discharge flowrate in MHSs due to the internal weirs could further reduce the water head and thus increased their overall efficiencies. Design parameters effecting spillways’ discharge efficiencies were investigated based on dimensional analysis. The internal to external weir length ratio in MHSs was found to be a key design factor. To determine the optimal geometric design of CHS and MHS models, cubic polynomial models considering dimensionless parameters and their interactions were fitted to the experimental results. The cubic models revealed that higher discharge efficiencies in MHSs tended to occur at relatively low water heads and high internal to external weir lengths ratios.

Santa Cesarea Terme, a sulphuric acid speleogenetic system intensely influenced by marine waters

2021 ◽  
Author(s):  
Ilenia M. D'Angeli ◽  
Jo De Waele ◽  
Adriano Fiorucci ◽  
Bartolomeo Vigna ◽  
Stefano M. Bernasconi ◽  
...  
Keyword(s):  
Sulphuric Acid ◽  
Southern Italy ◽  
Sea Water ◽  
Sampling Site ◽  
Seasonal Effects ◽  
Water Sampling ◽  
Marine Waters ◽  
Water Head ◽  
Marine Influence ◽  
By Products

<p>Santa Cesarea Terme (SCT) karst system opens along the Adriatic coastline of Apulia (southern Italy) and is composed of four sub-horizontally caves Fetida, Sulfurea, Gattulla and Solfatara. Being influenced by rising sulphidic waters, it is used as thermal spa for human health treatments. The caves show interesting signs of hypogene sulphuric acid speleogenetic (SAS) activity such as peculiar morphologies and mineralogical by-products. From the geomorphological standpoint it is possible to observe ceiling cupolas, megacusps (former megascallops), rising channels, submerged feeders, weathered walls, replacement pockets, whereas for mineralogy sulphur, gypsum and jarosite deposits have been recorded. Despite the presence of extensive SAS features, SCT is also intensely influenced by marine water.</p><p>All these observations induced us to conduct a long-lasting (2015-2018) geochemical monitoring to understand intensity and tendency of the two main domains (rising acidic vs. marine).</p><p>Water sampling was done every 3-4 months at 4 sites in Fetida (2 in areas influenced by sea water movements, and 2 in the innermost zone, less but still influenced by sea), and 1 site in Gattulla. Moreover, 1 sampling site located along the coastline (sea water) was constantly monitoring for comparative reasons.</p><p>Collected groundwaters exhibit mean temperatures of 23 °C (7 °C higher than average annual air temperature) and circumneutral pH. All samples belong to the Na-Cl-SO<sub>4</sub> type of waters. Sea waters display the highest pH (ranging between 8.15 and 8.20), [Na<sup>+</sup>], [K<sup>+</sup>], [Mg<sup>2+</sup>], [Cl<sup>-</sup>], [SO<sub>4</sub><sup>2-</sup>], and total dissolved solids (TDS), and on the other hands one of the innermost sampling site in Fetida Cave showed the highest values of temperature (29 °C), [HS<sup>-</sup>], [Ca<sup>2+</sup>] and the lowest pH (6.76). In addition, the Ba<sup>2+</sup>/Sr<sup>2+ </sup>ratio compared with Ca<sup>2+</sup>/HCO<sub>3</sub><sup>-</sup> or Ca<sup>2+</sup>/SO<sub>4</sub><sup>2-</sup> clearly exhibit the presence of two main domains: rising acid and marine. In particular, the samples collected in the Adriatic Sea are always in the domain of marine influence, whilst all the others from Gattulla and Fetida, depending on sampling conditions (tides, waves, etc..), can fall in both domains.</p><p>Our investigations demonstrated rising sulphidic fluids to reach the surface through deep tectonic fractures and karst flowpaths, but seasonal effects due to modest water head variations (tides) and meteomarine conditions affect the geochemical variability, even in the innermost portion of the caves, inducing these slightly thermal acidic fluids to partially mix with marine waters.</p>

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