Overflow Rate Research Articles

Using Top-of-Froth Conductivity to Infer Water Overflow Rate in a Two-Phase Lab-Scale Flotation Column

The metallurgical performance of a flotation machine is largely defined by phenomena occurring in the froth zone. The water content in the froth affects recovery by influencing froth stability and mobility and, at the same time, reduces grade by mechanical entrainment of gangue particles in the overflow water. Efficient operation requires a compromise between the water carried by bubbles from the collection zone and that which overflows. It is believed that the most suitable operating strategy could be based on the measurement of froth water content, as a strong correlation with water overflow is anticipated. This work reports the testing results of an in situ electrical conductivity sensor continuously measuring the froth zone water content in a laboratory-scale flotation column. The test program included simultaneous measurement of froth conductivity and water overflow rates for changes in gas flow rate and frother concentration. The results show a stronger dependence of the measured top-of-froth water content on frother concentration than on the gas flow rate. A relatively linear trend was shown between top-of-froth water content and water overflow rate for a given air rate and frother.

Interrogating common clarification models for unit operation systems with dynamic similitude

Surface overflow rate (SOR), plug flow reactor (PFR) and continuously stirred tank reactor (CSTR) are common models for clarification unit operations (UO). With wide deployment in engineering practice and regulation, through tools from spreadsheets to complex numerical codes, these models are formulated based upon conceptualized system geometry (e.g., rectangular channel) and idealized hydrodynamics (plug flow or well-mixed conditions). Yet the hydrodynamics and geometry of actual UO systems can be complex and substantially different from these assumptions. As a result, the applicability and generalizability of these models require critical and systematic interrogation. This study examines the predictive capability and generalizability of these common models for a hydrodynamic separator (HS), tanks, rectangular clarifiers and an urban drainage basin based on physical model data and high-fidelity large-eddy simulation (LES). Moreover, this study presents a novel application of dynamic similitude to developing a more generalized and physically interpretable model based on the hypothesis that PM and PM-partitioned constituent separation in a UO can be approximated solely through the dimensionless settling velocity W (Hazen number). Based on this hypothesis and dynamic similitude, a similarity modified gamma model (SMG) is proposed and tested. With dynamic similitude and W, results show common models are not robust and generalizable for predicting PM separation with error ranging from 30 to 50% and can significantly oversize a clarifier up to 904%. The non-linear characteristics of PM separation are shown to have a critical role in clarifications system design scalability and economics. In contrast, the SMG model is robust and generalizes the PM separation for geometrically similar systems, irrespective of particle density, particle size distribution (PSD), and loading conditions. The developed theory and proposed SMG model also can simplify and reduce the effort as well as expense of physical model testing while serving as an adjuvant for numerical simulations of clarification systems. Results also reveal commercial HS systems do not outperform simple plain tank geometries. The complex turbulence vortical structures pose significant challenges for UO system analysis and design.

Evaluation of the Hydrological Performance of Infiltration Trench with Rainfall-Watershed-Infiltration Trench Experimental Setup

Urbanization and population growth result in an increase of insufficient groundwater recharge. In order to overcome the adverse effects of urbanization, low impact development (LID) best management practices (BMPs) are introduced. LIDs are nature-based solutions, also called green infrastructures, that have the ability to control both the amount and the quality of stormwater runoff. Rain barrels, vegetative swale, green roofs, bioretention, permeable pavement, and detention ponds are among the examples of LIDs. Within this context, the infiltration trench is also one of the important LID types and is widely implemented in settlement areas. Field-scale experiments may not be sufficient in determining the design criteria of infiltration trenches. Controlled experiments should be conducted in order to identify the optimum design criteria of infiltration trenches for best practices. In this study, the hydrological performance of the infiltration trench is investigated by conducting experiments using an open-lab large-scale rainfall-watershed-infiltration trench (RWI) experimental setup. The RWI experimental setup is built at the Avcılar Campus of Istanbul University-Cerrahpaşa and consists of an artificial rainfall system, an impermeable drainage area, and an infiltration trench. The effect of gravel size, berm height, and rainfall type on the hydrological behavior of the infiltration trench is tested by conducting several experiments. During these experiments, the overflow rate and the drainage rate are measured at the exit of the pipes, located on the front wall and on the base of the infiltration trench, respectively. Results show that the magnitude and lag time of the overflow rate hydrograph are affected by rainfall intensity, gravel size, and berm height significantly. On the other hand, minor changes on the drainage rate hydrograph are observed under different rainfall intensities, gravel sizes, and berm heights. Based on the outcomes of this study, the engineering design guidelines of infiltration trenches are elaborated.

A ragged porous hollow tubular carbon nitride towards boosting visible-light photocatalytic hydrogen production in water and seawater

Photocatalytic water splitting to produce hydrogen, especially seawater, shows great economic value and development prospects to deal with the energy crisis. In this paper, urea and melamine were employed as base precursor materials to obtain four different morphologies of tubular g-C3N4: stacked rectangular thin plates with flocculent structure, ragged porous hollow tubes, porous hollow tubes and tetragonal hollow prismatic tubes by simply regulating the heating rate. Among them, the ragged porous hollow tubular g-C3N4 (TCN-1.5) exhibit an amazing hydrogen evolution rate of 8683 μmol h−1 g−1 from water, which is 19.3 times that of the massive g-C3N4 (449 μmol h−1 g−1), and still maintain a high hydrogen evolution rate (6782 μmol h−1g−1) from sea water. The analysis results show that by controlling the change of the heating rate, the ammonia overflow rate can be effectively controlled to produce abundant voids and pits to form volume defects, which can exhibit higher specific surface area and serve as a highly active center for the catalytic reaction and effectively improve the photocatalytic performance. This study provides a simple design idea to construct a novel type of ragged porous hollow tubular g-C3N4 for efficient photocatalytic hydrogen production from water and seawater.

The coupled model of transient non-equilibrium interphase mass transfer rate of sliding bubble and two-phase flow in variable gradient drilling

The aim of this research is to investigate the influence of key parameters of variable gradient drilling by injecting hollow-glass spheres (Referred to as HGS, it is a low-density and micron-sized hollow glass sphere) on the interphase mass transfer rate of the surface boundary layer of the sliding bubble in the annulus and the flow law of the two-phase flow in the wellbore after the gas intrusion occurred. Firstly, the key parameters of variable-gradient drilling, such as HGS volume fraction, HGS density, the depth of the filter separator, were coupled with the model of non-equilibrium interphase mass transfer rate and the mathematical model of two-phase flow to establish a new two-phase flow model of transient non-equilibrium interphase mass transfer for variable-gradient drilling. Secondly, the existing classic model and measured data were used for comparative analysis with the model in this paper, and then the accuracy of the model in this paper was verified. Thirdly, based on the on-site data, the numerical calculations and sensitivity analysis were carried out using the model in this paper. Finally, a comparative analysis of the interphase mass transfer rate was performed under equilibrium and non-equilibrium conditions. In addition, the influence on non-equilibrium interphase mass transfer rate of surface boundary layer of the bubble, bottom hole pressure, overflow rate and overflow rate exerted by different separator positions, HGS volume fraction, HGS density, and pumping rate was studied. The results indicated that the interphase mass transfer rate under the non-equilibrium condition was lower than that under the equilibrium condition when the both were at the same well depth or at the same circulation time. The interphase mass transfer rate enhanced with the increase of pumping rate, the depth of filter separator and HGS density, but decreased with the increase of HGS volume fraction. The bottom-hole pressure was negatively correlated with the depth of the filter separator and the volume fraction of HGS, on the contrary, it was positively correlated with the HGS density. Similarly, the gas void fraction, overflow rate and overflow were positively correlated with the depth of filter separator and HGS volume fraction, but negatively correlated with the HGS density. This research can provide a certain theoretical reference for variable gradient drilling.

ANALYSIS OF FLOW AND PARTICLE SETTLING IN A CONTINUOUS SETTLING TANK: CFD STUDY

In the present work, the hydrodynamics and particle separation in a settling tank were studied using the Euler-Euler and Euler-Lagrange approaches. The computational fluid dynamics (CFD) model was validated using data obtained from an ultrasonic velocity profiler. The presence of the particles and their impact on the flow patterns were investigated. The presence of the particles in the settling tank lead to changes in the flow patterns. This phenomenon was evaluated through experiments and simulations. The behavior of different particles was studied using discrete phase model tracking. The effects of the feedwell diameter and height on the flow patterns were studied to select the optimized feedwell parameters. The dependency of the direction of the motion of the particles on the terminal settling velocity and the overflow rate was explored. Since the local conditions inside the settling tank are important, the effects of the flow rate, particle density, and concentration were studied in terms of the separation efficiency.

Enhancing Bioflocculation in High-Rate Activated Sludge Improves Effluent Quality Yet Increases Sensitivity to Surface Overflow Rate

Enhancing Bioflocculation in High-Rate Activated Sludge Improves Effluent Quality Yet Increases Sensitivity to Surface Overflow Rate

Models of Wet Basin Design Response with Residence Time Metrics for Presumptive Guidance

Wet basins manage hydrologic quantities, particulate matter (PM), and chemicals. Residence time (RT) and hydraulic residence time (HRT) are common metrics to index presumptive water chemistry and PM load response. Models for the response of basin designs were studied. Basin hydrodynamics (based on geometry, inlet layout, and baffles), and PM separation based on influent particle-size distribution (PSD) were indexed with RT and HRT. PM separation and economics were examined for seven basin designs (HRT=0.25–21 days). Scaled designs were patterned geometrically from an existing basin that was oversized based on flows and PSDs. Computational fluid dynamics (CFD) with continuous simulation, surface overflow rate (SOR), and first-order decay models were studied. Basin geometrics, PM separation, and constituent RT were modeled across a representative wet season. The results demonstrate that PM separation is sensitive to influent PSD and basin sizing for 1–5-day HRTs, with less sensitivity to PSD for larger volumes of 5–21-day HRT. Constituent RT (based on PM) varies in the wet season and remains below the HRT. Basin retrofit geometry and inlet layout impact constituent RT and PM separation. HRT alone, from any model tested herein, is not recommended in assessing basin treatment for less than a 5-day HRT, or if the PSD is unknown. For basins with greater than 1-day HRT, transport behavior is approximated reasonably assuming steady flow. Although PM separation is insensitive to HRT beyond a 5-day design, increasing basin size impacts economics. Results indicate that the 14-day basin HRT is not an optimal benchmark for treatment.

A Review of the Reliability of Integrated IR Laser Diodes for Silicon Photonics

With this review paper we provide an overview of the main degradation mechanisms that limit the long-term reliability of IR semiconductor lasers for silicon photonics applications. The discussion is focused on two types of laser diodes: heterogeneous III–V lasers bonded onto silicon-on-insulator wafers, and InAs quantum-dot lasers epitaxially grown on silicon. A comprehensive analysis of the reliability-oriented literature published to date reveals that state-of-the-art heterogeneous laser sources share with conventional laser diodes their major epitaxy-related degradation processes, such as the generation of non-radiative recombination centers or dopant diffusion, while eliminating cleaved facets and exposed mirrors. The lifetime of InAs quantum dot lasers grown on silicon, whose development represents a fundamental step toward a fully epitaxial integration of future photonic integrated circuits, is strongly limited by the density of extended defects, mainly misfit dislocations, protruding into the active layer of the devices. The concentration of such defects, along with inefficient carrier injection and excessive carrier overflow rates, promote recombination-enhanced degradation mechanisms that reduce the long-term reliability of these sources. The impact of these misfits can be largely eliminated with the inclusion of blocking layers.

UAV Assisted Wireless Network

With the increasing demand of social network service, the unmanned aerial vehicle has been used as a base station to assist terrestrial base station to improve wireless network performance. UAV base station provides high efficiency and wider data transmitting range due to the small size and flexibility of UAV. However, UAV wireless network faces few challenges. Energy efficiency is hard to achieve due to small battery capacity. The base station performance is also very important. It can be determined by aircraft’s flying stability, the performance of air to ground communication and the limitation of wireless coverage of UAV. In order to achieve optimal UAV deployment, improving deployment delay, communication coverage and UAV number limitation are important. Trajectory optimizing problems also need to be considered. This article analyzes UAV assisted wireless networks through investigating UAV energy efficiency, UAV aided network performance, optimal deployment methods and flight trajectory. It is shown that energy efficiency can be optimized by applying LoS based channel in UAV trajectory planning. And inequality iteration algorithm proposed by former researchers is used to determine optimal flight trajectory. This method is efficient because of cellular network’s interference-free ability. As for performance, channel selection methods are used to reduce overflow rate and boost data-received size. These methods are analyzed and proved to be effective for improving UAV aided wireless network performance.

Developing a reclamation strategy for softening nanofiltration brine: A scaling-free conversion approach via continuous two-stage electrodialysis metathesis

A significant amount of concentrated, scaling-prone brine can be generated during the conversion of unconventional water resources to freshwater, thus necessitating the zero discharge of concentrated brine to meet environmental and resource requirements. In this study, a two-stage feed-and-bleed electrodialysis metathesis (FB-EDM) process was implemented to reclaim softening nanofiltration (SNF) brine. To determine the optimized process parameters, experiments were conducted with various initial diluate to concentrate volume ratios (VD:VC), applied voltages, replenishment flow rates (Qrp), and initial diluate compartment concentration ratios (CD1:CD2). The results indicated that these parameters (except for the initial volume ratio) significantly influenced the FB-EDM process. The optimized conditions included a VD:VC of 2:1, voltage of 1.5 V per repeating unit, Qrp of 4 L/h, and CD1:CD2 of 1.5:1. The two-stage FB-EDM process operating under the optimized conditions achieved an energy consumption of <0.9 kWh/kg salt, and the total dissolved solids (TDS) in terms of Cl-type and Na-type salts reached 199.1 and 224.4 g/L, respectively; the corresponding overflow rates were 1.17 and 1.14 L/h, respectively. The developed system thus demonstrated approximately 85% TDS removal and ionic conversion of the brine; additionally, the self-crystallization of CaSO4·2H2O was realized by blending the Cl-type and Na-type salts. This process therefore represents a suitable method for converting SNF brine into highly-concentrated liquid salts, and provides a reclamation strategy for miscellaneous salts.

Decision Support Model for Ecological Operation of Reservoirs Based on Dynamic Bayesian Network

In this study, a model was proposed based on the sustainable boundary approach, to provide decision support for reservoir ecological operation with the dynamic Bayesian network. The proposed model was developed in four steps: (1) calculating and verifying the sustainable boundaries in combination with the ecological objectives of the study area, (2) generating the learning samples by establishing an optimal operation model and a Monte Carlo simulation model, (3) establishing and training a dynamic Bayesian network by learning the examples and (4) calculating the probability of the economic and ecological targets exceeding the set threshold from time to time with the trained dynamic Bayesian network model. Using the proposed model, the water drawing of the reservoir can be adjusted dynamically according to the probability of the economic and ecological targets exceeding the set threshold during reservoir operation. In this study, the proposed model was applied to the middle reaches of Heihe River, the effect of water supply proportion on the probability of the economic target exceeding the set threshold was analyzed, and the response of the reservoir water storage in each period to the probability of the target exceeding the set threshold was calculated. The results show that the risks can be analyzed with the proposed model. Compared with the existing studies, the proposed model provides guidance for the ecological operation of the reservoir from time to time and technical support for the formulation of reservoir operation chart. Compared with the operation model based on the designed guaranteed rate, the reservoir operation model based on uncertainty reduces the variation range of ecological flow shortage or the overflow rate and the economic loss rate by 5% and 6%, respectively. Thus, it can be seen that the decision support model based on the dynamic Bayesian network can effectively reduce the influence of water inflow and rainfall uncertainties on reservoir operation.

Capacity balancing for vanadium redox flow batteries through continuous and dynamic electrolyte overflow

The vanadium crossover through the membrane can have a significant impact on the capacity of the vanadium redox flow battery (VFB) over long-term charge–discharge cycling. The different vanadium ions move unsymmetrically through the membrane and this leads to a build-up of vanadium ions in one half-cell with a corresponding decrease in the other. In this paper, a dynamic model is developed based on different crossover mechanisms (diffusion, migration and electro osmosis) for each of the four vanadium ions, water and protons in the electrolytes. With a simple to use approach, basic mass transport theory is used to simulate the transfer of vanadium ions in the battery. The model is validated with own measurements and can therefore predict the battery capacity as a function of time. This is used to analyse the battery performance by applying an overflow from one half-cell to the other. Different constant overflow rates were analysed with regard to an impact of the performance and electrolyte stability. It was observed that a continuous overflow increases the capacity significantly but that the electrolyte stability plays an essential role using a membrane with a big vanadium crossover. Even with a good performance, a complete remixing of the tanks is necessary to prevent electrolyte precipitations. Therefore, a dynamic overflow was determined in such a way that the capacity of the battery is maximised while the electrolytes remain stable for 200 cycles.Graphic abstract

Quotation Strategies of Non-Truck Operating Common Carrier Based on Multivariate Statistical Regression and Triple Pricing Model

Combined with the existing transaction orders of carless carriers, the numerical information and text and information are extracted, and the related factors of line guide price are integrated, and the relationship between relevant factors and line guide price is studied. Using the unified unit and 0-1 text setting method, preprocessing data, eliminating the influence of numerical units, quantifying textual data, so that the data can be put into the relevant equations for testing. According to the characterization relationship between the guiding price and factors, a multivariate linear statistical regression model was established, and the statistical P value was used for testing to verify the availability of the model. The index of price overflow rate and equilibrium degree are put forward as the standard to evaluate whether the transaction price of an order is reasonable. The normal distribution of orders can be verified by looking at the scatter plot of the cumulative percentage of transactions and the price spillover rate of orders. According to the central limit theorem of large sample data with normal distribution, the sample can be sampled in sections and the summation can be taken as the transaction probability. According to the operation mode of the vehicle-free carrier platform, the transaction mode of three quotations is added to re-quote the line. The pricing obtained from multiple linear statistical regression is used as the benchmark, and the dynamic pricing strategy is re-customized according to the principle of the first quotation giving priority to lowering the price, the second quotation giving priority to stabilizing the transaction, and the third quotation giving priority to the success rate. The sensitivity analysis shows that the platform can get a revenue increase of 33%∼48% based on this new pricing strategy, and meanwhile improve the balance and stability of orders. The research report provides a calculation method of a new quotation model with high turnover rate and stable income for the non-truck operating common carrier platform, and has a guiding significance for the construction of the non-truck operating common carrier trading system, especially the rationality of the price formulation and the stability of the transaction order quantity.

Upflow Filtration System Using Fiber-Ball Filter Media for the Treatment of Nonpoint Pollution

Objectives : The objective of this study is to investigate the performance of the fiber-ball media upflow filtration system for non-point pollutants treatment.Methods : The additional air backwashing nozzle were installed between upper and lower fliter media cartridge. The effect of feed SS concentration, surface overflow rate, retention time, head loss on the removal efficiency were investigated respectively. Particle size distribution, SEM, and backwashing effect were also analyzed.Results and Discussion : The operated of upflow filter mean retention time, mean head loss were 1.99 min, 7.2 cm. On condition of SOR 480 m&lt;sup&gt;3&lt;/sup&gt;/m&lt;sup&gt;2&lt;/sup&gt;/day, results indicate that the range of removal efficiency of turbidity and SS were 76.8 ~ 93.21% (mean 88.3%) and 85.4 ~ 97.9% (mean 92.7%), respectively. The effluent turbidity and SS were under 15 NTU, 20 mg/L, respectively.Conclusions : Since turbidity can be continuously monitored in a filtration non-point pollution treatment system, turbidity can be used as a operation factor in evaluating operating conditions. The particle size the effluent larger than the influent was due to bonding, collision and adsorption between particles in the pores of the filter media. SEM analysis showed that after backwashing, very fine particles in the filter medium were not removed but adhered to the fiber yarn and remained. The average recovery rate of fiber-ball media filtration was 88.7%, which is evaluated as excellent in backwashing.

Settling velocity distribution of bioflocules generated with different carbon sources during the rearing of the river shrimp Cryphiops caementarius with biofloc technology

Controlling the concentration of bioflocs is one of the main concerns in aquaculture systems with Biofloc Technology (BFT). Biofloc accumulation deteriorates the water quality and can negatively affect the production rates of the farmed river shrimp. This study describes and characterizes the settling velocity distribution of bioflocs generated with the addition of two carbon sources (molasses and chancaca) when applying the BFT for the rearing of the river shrimp Cryphiops caementarius. This study revealed that bioflocs generated with different carbon sources have different settling velocity curves. Regarding the mass fraction settling velocities, there were significant differences (P < 0.05) for mean solids fraction at similar withdrawn times between molasses and chancaca. The average settling velocities for bioflocs were 0.1044 ± 0.1224 cm s−1 for molasses and 0.1131 ± 0.1225 cm s−1 for chancaca. Therefore, a settling device operating with a given overflow rate will more efficiently remove bioflocs generated with chancaca than with molasses. The settling velocity curves obtained in this research contain valuable information to select appropriate devices for bioflocs and suspended solids removal in aquaculture systems with BFT.

Evaluating Porous Pavement for the Mitigation of Stormwater Impacts

Urban stormwater management is one of the biggest challenges facing modern cities. The current stormwater networks are likely to be insufficient under continuous urbanisation and the development of residential areas in addition to increases in rainfall intensity, especially in areas with relatively high slopes, which may thus be subject to flooding. This study aimed to mitigate the overflow rate of the selected case study area using a pervious inlets pavement technique based on porous asphalt concrete pavements with a reservoir layer. The current stormwater network system of the Al-Yarmouk quarter (located at the centre of Karbala City, Iraq) was evaluated by exposing it in simulation to a rainfall intensity equivalent to the 5-year return period and applying storm and sanitary analysis (SSA) and GIS software. The simulation results showed that constructing 50% of the road surface area (5% of the total studied area) with porous asphalt concrete with air voids of about 20% and variable reservoir thicknesses, could reduce water runoff entering the network significantly. Moreover, placing 240 mm, 328 mm and 400 mm of No.75 aggregate layer within reservoir depths would result in further mitigations of surface runoff quantity by about 15%, 30%, and 45%, respectively. A reservoir depth of 240 mm was found to reduce flooding quantities and times by about 71% and 18.29%, respectively, while creating a 328 mm reservoir depth under the porous asphalt results in quantity and time reductions of about 98.5% and 81%, respectively. No surface flooding was observed when reservoir depth was changed to 400 mm.

MITIGATING TSUNAMI DAMAGE BY PROMOTING GROUND EROSION

To reduce the damage caused when a tsunami overflows coastal dikes, this study performs hydraulic experiments and numerical simulations and proposes a new method for slowing the tsunami by intentionally eroding parts of the ground. The effectiveness of the proposed method is assessed, velocity-reduction mechanism is clarified, and reduced tsunami velocity is predicted. Using crushed expanded polystyrene (EPS) as the ground material, vertical erosion is enhanced and a large depression is formed that changes the flow from supercritical to subcritical, thereby decelerating it. Assuming a constant tsunami overflow rate, the tsunami velocity after deceleration can be predicted with [Formula: see text] uncertainty.

Physically-Based Particle Size Distribution Models of Urban Water Particulate Matter

A particle size distribution (PSD) of particulate matter (PM) is a primary metric to examine PM transport and fate, as well as PM-bound chemicals and pathogens in urban waters. To facilitate physical interpretation and data sharing, a series of concise analytical models are examined to reproduce unit operation (UO) influent and effluent PSD data and indices. The models are a (1) single-parameter exponential and two-parameter (2) gamma, (3) lognormal, and (4) Rosin-Rammler distributions. Two-parameter models provide physical interpretations for the central tendency of PM diameters, and shape as an index of PSD hetero-dispersivity. Goodness-of-fit is used to test models and PSDs. For influent data from two disparate areas, a paved source area and a larger watershed delivering unique PSDs, lognormal and gamma models provide consistent representation of influent and effluent complexity. In these areas, contrasting UOs (a clarification basin and a volumetric filter), subject to type I settling, scour, and filter PM elution, are differentiated based on flow, surface area, volume, and residence time. Surface overflow rate (SOR) as a common heuristic design tool for only type I settling is used to further test PSD models by simulating effluent PSDs for a scaled basin design. Lognormal and gamma models of SOR-generated effluent PSDs were not statistically different. In conclusion, two-parameter PSD models have physical interpretations and lower errors compared to an exponential model. Gamma and lognormal distributions are physically-based models that reproduce actual complex influent or effluent or through SOR as a tool for PSD transformation. Results indicate that PSD models and parameters can be applied to evaluate behavior of common UOs.

Design criteria for presedimentation basin treats: Shatt Al-Arab River water

The design of Pre-sedimentation basins is based on design criteria including surface overflow rate and detention time. The previous studies differ in specifying the criteria values and, subsequently, it is difficult to choose the suitable ones according to raw water source characteristics. The aim of this study is to specify the design criteria values for pre-sedimentation basin treats the water of Shatt Al-Arab River. To satisfy this aim, experimental work was conducted including 51 plain sedimentation experiments and 37 particles size distribution analyses. The work results were used to determine the values of surface overflow rate and detention time in terms of actual and theoretical efficiencies of pre-sedimentation basin. The study results indicated that to use a pre-sedimentation basin in treating the water of Shatt Al-Arab River and the other rivers which have suspended solids with d50 values vary over the range (7.4-20.9) µm at efficiency exceeds 50%, the surface overflow rate must be less than 0.5 m/day and the detention time must be greater than 12.3 hr.