Evaluation of hydraulic performance indices for retention ponds

2015 ◽  
Vol 72 (1) ◽  
pp. 10-21 ◽  
Author(s):  
Arash Farjood ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin ◽  
Keith N. Adams ◽  
Sher Khan
Keyword(s):  
Hydraulic Performance ◽  
Hydraulic Efficiency ◽  
Hydraulic Analysis ◽  
Performance Indices ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Moment Index ◽  
Selection Of

Abstract Comprehensive hydraulic analysis of sediment retention ponds is commonly achieved through interpretation of residence time distribution and derivation of indices associated with short-circuiting and mixing. However, the availability of various indices indicates the need for careful selection of the most appropriate indices. This study compares some of the commonly used hydraulic performance indices, together with a new short-circuiting index, τ5, for five different flow regimes in a model sediment retention pond. The results show that τ5 was the best measure for short-circuiting. Among the mixing indices, only the Morril index correctly represented the physical behaviour of the experiments. In addition, two hydraulic efficiency indices, λ and a moment index (MI) were assessed and showed a good correlation with the short-circuiting and mixing indices, but MI was more reproducible than λ. Based on these results, this study recommends using τ5, Morril index and MI for analysis of hydraulic performance in sediment retention ponds.

scholarly journals Experimental investigation of the effect of temperature differentials on hydraulic performance and flow pattern of a sediment retention pond

2018 ◽  
Vol 77 (12) ◽  
pp. 2896-2906 ◽  
Author(s):  
Ehsan Hendi ◽  
Asaad Y. Shamseldin ◽  
Bruce W. Melville ◽  
Stuart E. Norris
Keyword(s):  
Residence Time ◽  
Hydraulic Performance ◽  
Effect Of Temperature ◽  
Sediment Retention ◽  
Small Temperature ◽  
Thermally Induced ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds ◽  
Counter Current

Abstract Existing studies on sediment retention ponds (SRPs) have examined the effects of pond layout, inlet and outlet geometry and the installation of baffles on the performance of the SRPs. However, the effects of a temperature difference between the ambient water in the pond and the inflow are often neglected, and the buoyancy forces arising from these differences in temperature can potentially change the flow in the pond and hence its hydraulic performance. This study has experimentally evaluated the effect of these temperature differences on the flow field and residence time in a retention pond for a range of temperature differences. As expected a cold inflow sinks to the bottom of the pond while a hot inflow remains at the surface, but in both cases the inflow flows more rapidly towards the outlet than is the case for isothermal inflow. A counter-current was observed at the bottom or the surface of the pond for colder or hotter influents, respectively. These thermally induced flows significantly reduced the residence time of the pond, reducing the hydraulic performance of the pond and causing severe short-circuiting. The results have also shown that the temperature differences in the pond decrease with time, yet small temperature differences persist with the pond remaining thermally stratified.

scholarly journals Effect of baffles on the hydraulic performance of sediment retention ponds

2016 ◽  
Vol 75 (9) ◽  
pp. 1991-1996
Author(s):  
Sher Khan ◽  
Bruce W. Melville ◽  
Mudasser Muneer Khan ◽  
Muhammad Shoaib ◽  
Asaad Shamseldin
Keyword(s):  
Physical Model ◽  
Residence Time ◽  
Hydraulic Performance ◽  
Large Area ◽  
Sediment Retention ◽  
Retention Pond ◽  
Retention Ponds ◽  
Sediment Retention Ponds

An investigation of the effect of baffles on retention pond performance using a physical model of an existing sediment retention pond is presented. Analysis of residence time (RTD curves) was used to compare the hydraulic performance of different arrangements of baffles in the pond. Five different arrangements for the design of baffles were studied. The results show that placing a single baffle to deflect the influent to a sediment retention pond does not improve pond performance; rather, it stimulates short-circuiting. This is contradictory to the literature and is considered to be a consequence of the model pond incorporating sloping walls, which is a novel aspect of this study. Most of the previous studies have neglected the effects of battered walls. Conversely, the inclusion of more than two baffles was found to increase the hydraulic performance. The results reported here are limited to small and narrow ponds where a large portion of the pond is batter (i.e. made up of sloping walls). For large area ponds, batter effects may be negligible and are likely to be different from those reported here.

The effect of different baffles on hydraulic performance of a sediment retention pond

2015 ◽  
Vol 81 ◽  
pp. 228-232 ◽  
Author(s):  
Arash Farjood ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin
Keyword(s):  
Hydraulic Performance ◽  
Sediment Retention ◽  
Retention Pond

scholarly journals Hydraulic investigation of the impact of retrofitting floating treatment wetlands in retention ponds

2019 ◽  
Vol 80 (8) ◽  
pp. 1476-1484 ◽  
Author(s):  
Sher Khan ◽  
Muhammad Shoaib ◽  
Mudasser Muneer Khan ◽  
Bruce W. Melville ◽  
Asaad Y. Shamseldin
Keyword(s):  
Root Length ◽  
Longitudinal Axis ◽  
Hydraulic Performance ◽  
Treatment Wetlands ◽  
Experimental Investigations ◽  
Retention Pond ◽  
Retention Ponds ◽  
Floating Treatment Wetlands ◽  
The Impact ◽  
Stormwater Retention

Abstract This paper describes the laboratory experimental investigations undertaken to analyse the influence of floating treatment wetlands (FTWs) on the hydraulic performance of a stormwater retention pond. Two experimental series were conducted, each focussed on investigating the influence of placing an FTW in a pond with firstly the inflow entering the retention pond from an inlet positioned 0.25 m offset from the longitudinal axis of the pond, and secondly the inlet positioned at the longitudinal axis of the pond. For both series of experiments, tests were undertaken at 1 l/s and 1.5 l/s, and with and without an artificial FTW installed. This study is the first to investigate the hydraulic impact of FTWs and their root systems on the performance of stormwater retention ponds. The results presented in this study suggest that FTWs are a viable method to minimise hydraulic inefficiencies, thereby increasing retention time and optimising hydraulic performance of stormwater retention ponds. The results highlight the importance of plant root characteristics. The optimal arrangement of root length is LR/DP = 0.5, where LR = root length and DP = pond depth. The results also indicate that the spatial variability of vegetation has a significant impact on the hydraulic performance of the pond.

Hydraulic Design of Inlet Guide Vane and its Full Flow Passage Numerical Simulation on Centrifugal Pump

2014 ◽  
Author(s):  
Hucan Hou ◽  
Yongxue Zhang ◽  
Zhenlin Li ◽  
Xin Zhou ◽  
Zizhe Wang
Keyword(s):  
Centrifugal Pump ◽  
Flow Rate ◽  
Guide Vane ◽  
Hydraulic Performance ◽  
Design Flow ◽  
Inlet Guide Vane ◽  
Hydraulic Efficiency ◽  
Flow Passage ◽  
Setting Angle ◽  
Hydraulic Design

In order to effectively improve hydraulic performance of centrifugal pump on off-conditions, the hydraulic design of inlet guide vane (IGV) was completed by adopting two dimensional theory in-house code based on one kind of IS series of centrifugal pump, which can achieve pre-whirl regulation of centrifugal pump. During design process the trailing edge of vane is assumed as equal velocity moment condition, and the distribution of vane setting angle along meridional streamline is also given as a quartic function firstly, the camber line is then drawn by point-by-point integration method and thickened at both sides along circumferential direction. With local vortex dynamics diagnosis theory, the optimal improvement of vane space shape can be finished by adjusting the design parameters of vane setting angle distribution coefficient ap. The full flow passage numerical simulations of centrifugal pump with IGV device are completed to analyze the influence of pre-whirl regulation on hydraulic performance of centrifugal pump under various pre-whirl angles. The results show that the pre-whirl regulation can improve the hydraulic performance of centrifugal pump on off-conditions. Under the positive pre-whirl regulation conditions, the best efficient point shift to small flow rate zone, and under the negative pre-whirl regulation conditions it moves to large flow rate zone. Compared with the pump without IGV device at the same flow rate condition of 0.8Q (Q the design flow rate), the hydraulic efficiency of centrifugal pump with IGV device improves obviously and reaches up to 1.43%. Meanwhile compared with that installed with the straight vanes designed based on the traditional theory, the inner flow field of centrifugal pump with the designed vanes improves and the overall hydraulic efficiency of centrifugal pump is somewhat increased.

scholarly journals Sorption and Degradation Potential of Pharmaceuticals in Sediments from a Stormwater Retention Pond

Water ◽  
2019 ◽  
Vol 11 (3) ◽  
pp. 526 ◽  
Author(s):  
Fan Liu ◽  
Asbjørn Nielsen ◽  
Jes Vollertsen
Keyword(s):  
Half Life ◽  
Pond Water ◽  
Organic Micropollutants ◽  
Partitioning Coefficient ◽  
Retention Pond ◽  
Retention Ponds ◽  
Water Partitioning ◽  
Stormwater Retention ◽  
Sorption Potential

Stormwater retention ponds commonly receive some wastewater through misconnections, sewer leaks, and sewer overloads, all of which leads to unintended loads of organic micropollutants, including pharmaceuticals. This study explores the role of pond sediment in removing pharmaceuticals (naproxen, carbamazepine, sulfamethoxazole, furosemide, and fenofibrate). It quantifies their sorption potential to the sediments and how it depends on pH. Then it addresses the degradability of the pharmaceuticals in microcosms holding sediment beds and pond water. The sediment-water partitioning coefficient of fenofibrate varied little with pH and was the highest (average log Kd: 4.42 L kg−1). Sulfamethoxazole had the lowest (average log Kd: 0.80 L kg−1), varying unsystematically with pH. The coefficients of naproxen, furosemide and carbamazepine were in between. The degradation by the sediments was most pronounced for sulfamethoxazole, followed by naproxen, fenofibrate, furosemide, and carbamazepine. The first three were all removed from the water phase with half-life of 2–8 days. Over the 38 days the experiment lasted, they were all degraded to near completion. The latter two were more resistant, with half-lives between 1 and 2 months. Overall, the study indicated that stormwater retention ponds have the potential to remove some but not all pharmaceuticals contained in wastewater contributions.

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