A stochastic model for suspended solids settling velocity

1983 ◽  
Vol 18 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Christopher G. Uchrin ◽  
Walter J. Weber
Keyword(s):  
Stochastic Model ◽  
Suspended Solids ◽  
Settling Velocity

Effect of Starch on the Flocculation and Settling Behaviour of Titanium Dioxide Suspensions

1974 ◽  
Vol 9 (1) ◽  
pp. 154-171
Author(s):  
S.N. Ray ◽  
C. Hsi ◽  
B.C. -Y. Lu
Keyword(s):  
Titanium Dioxide ◽  
Suspended Solids ◽  
Settling Velocity ◽  
Pollution Abatement ◽  
Paper Mills ◽  
Paper Making ◽  
Jar Test ◽  
Settling Behaviour ◽  
Dimensionless Function ◽  
Flocculation Rate

Abstract This study concerns the problem of removal of suspended solids from the effluent streams of paper mills by chemical treatment. As titanium dioxide is one of the ingredients used in paper mills and present in the effluent streams, its flocculation and settling behaviour were investigated. Jar test experiments were conducted using alum and organic polyelectrolyte as the flocculants. As starch is also used in the paper making process, its influence on the flocculation and settling behaviour of titanium dioxide was conducted with the concentration of starch varying between 0–3% of the dry solids. The experimental results on flocculation are expressed in terms of dimensionless function Gθϕ and flocculation rate constants. The fraction of solids settled is presented in terms of the settling velocity. Concentration of starch was found to have a significant influence. The amount of alum required could be reduced by 75% by using starch 0.6% of the amount of titanium dioxide in the suspension and at the same time improving the settling velocity two folds. A possible application of this finding in pollution abatement is discussed.

Methods for determining the settling velocity profiles of solids in storm sewage

1996 ◽  
Vol 33 (9) ◽  
pp. 117-125 ◽  
Author(s):  
Emmanuelle Aiguier ◽  
Ghassan Chebbo ◽  
Jean-Luc Bertrand-Krajewski ◽  
Peter Hedges ◽  
Naomi Tyack
Keyword(s):  
Suspended Solids ◽  
Settling Velocity ◽  
Test Procedure ◽  
Velocity Profiles ◽  
Test Methods ◽  
Efficient Treatment ◽  
Experimental Procedure ◽  
Comparative Tests ◽  
Settling Process ◽  
Settling Characteristics

Recently, research has shown that a settling process is an efficient treatment for the removal of suspended solids from storm sewage. In order to design settling tanks, there is a need to determine the settling velocity characteristics of these solids. Devices and test methods for measuring settling velocities of solids in storm sewage have been developed by researchers. A literature review has revealed that the settling velocity profiles obtained with some methods (Chebbo, 1992), (Michelbach and Wohrle, 1993) and (Tyack et al., 1993) are very different. In order to explain why the results are different and to quantify the influence of the experimental procedure on the settling velocity grading curves, we have compared the selected methods when tested with the same sample and we have studied the effects of the conservation of the sample before the test, of the concentration of solids in the device and of the nature of the water on the settling velocity profiles. The results of the comparative tests indicate that the settling velocities are significantly lower with both the Cergrene and Aston methods than with the UFT test procedure. Moreover, the study has shown that the settling characteristics of solids change with time, that the use of sewage liquor rather than demineralised water or drinking water can change the results of the measurement and that the higher the concentration of solids, the greater the velocity of settled particles.

Patterns of gross deposition in reservoirs enriched in inorganic tripton

2001 ◽  
Vol 58 (11) ◽  
pp. 2177-2188 ◽  
Author(s):  
Steven W Effler ◽  
Carol M Matthews (Brooks) ◽  
David A Matthews
Keyword(s):  
New York ◽  
Suspended Solids ◽  
Inorganic Material ◽  
Settling Velocity ◽  
Particulate Phosphorus ◽  
Overlying Water ◽  
Longitudinal Gradients ◽  
The Individual ◽  
Carbon Particulate ◽  
Inorganic Components

Magnitudes and patterns in the deposition of chlorophyll (Chl), organic carbon, particulate phosphorus (PP), and suspended solids are documented for seven New York reservoirs based on analyses of metalimnetic and near-bottom sediment trap collections. Inorganic material dominated the trap collections and caused a decoupling of the downward fluxes of Chl and PP because of major contributions of inorganic components to P deposition. These contributions were manifested in the stoichiometry of trap collections, the much higher estimates of settling velocity (SV) for PP compared with Chl, and differences in patterns of Chl and PP deposition within individual reservoirs and among these systems. Most of the deposited phosphorus in these reservoirs (71–98%) was associated with nonphytoplankton particles. In contrast to the other constituents, the estimates of SV for Chl were lower and more uniform; nearly 50% of the individual estimates (n = 188) were between 0.15 and 0.25 m·day–1. Longitudinal gradients in sediment deposition occurred as a result of gradients in both overlying water concentrations and settling characteristics of the particles. Seasonal and vertical patterns in trap collections and budget calculations indicate that resuspension contributed to deposition, to varying extents, in all of the reservoir basins.

A Stochastic Model for Primary Settlers

1970 ◽  
Vol 5 (1) ◽  
pp. 129-170
Author(s):  
D.P. Singh ◽  
A.W. Bryson ◽  
P.L. Silveston
Keyword(s):  
Stochastic Model ◽  
Stochastic Models ◽  
Suspended Solids ◽  
Sewage Treatment ◽  
Sewage Treatment Plant ◽  
Treatment Plant ◽  
Second Order ◽  
Order Model ◽  
First Order ◽  
The Mean

Abstract Stochastic models of process units are useful where the flow and concentrations in a feed stream vary appreciably over long time periods in a random way. Models yield not only the mean, but provide a measure of the variation around the mean. Assuming sedimentation can be described by a rate equation, stochastic models are developed for zero, first and second order rate processes. The zero order model can be rejected because it cannot be made to fit plant data, while the second order model was not developed further because of its complexity. The rate parameter for the first order model was evaluated from 1968 suspended solids data for the Kitchener Sewage Treatment Plant and found to have zero variance. Testing the model against 1966 and 1967 data and shorter period for 1968 showed that the model predicted suspended solids and BOD removals differing on the average from plant results by 10%. The first order stochastic model gives, thus, a satisfactory representation of primary settler performance.

The use of ozone during advanced primary treatment of wastewater for its reuse in agriculture: an approach to enhance coagulation, disinfection and crop productivities

2008 ◽  
Vol 57 (6) ◽  
pp. 955-962 ◽  
Author(s):  
A. E. Campos-Reales-Pineda ◽  
M. T. Orta de Velásquez ◽  
M. N. Rojas-Valencia
Keyword(s):  
Suspended Solids ◽  
Settling Velocity ◽  
Total Suspended Solids ◽  
Primary Treatment ◽  
Turbidity Removal ◽  
Helminth Eggs ◽  
Ozone Dose ◽  
Reduced Toxicity ◽  
Solids Removal ◽  
Plant Germination

The purpose of this work was to evaluate the effect that ozone (O3) has on the advanced primary treatment (APT) and disinfection of wastewaters for their reuse in agriculture. The enhancement and optimization of APT was done by applying low O3 doses during coagulation. By applying an ozone dose of 2 mg/L during APT, the required coagulant dose may be reduced by up to 25% to achieve a similar turbidity removal (and up to 50% for total suspended solids removal), when compared to a conventional APT treatment. When the same coagulant dose was applied (60 mg/L), the volume of settleable solids was reduced from 31.0 to 25.5 mL/L, and the settling velocity increased from 0.111 to 0.139 m/min. Disinfection was also improved by the use of ozone, which leads to better plant germination rates than when using chlorination, because of reduced toxicity of the ozonated effluents. Additionally, helminth eggs content was reduced by applying ozone.

Characterization of Suspended Solids in Urban Wet Weather Discharges

1992 ◽  
Vol 25 (8) ◽  
pp. 171-179 ◽  
Author(s):  
G. Chebbo ◽  
A. Bachoc
Keyword(s):  
Suspended Solids ◽  
Settling Velocity ◽  
Specific Mass ◽  
Urban Stormwater ◽  
Catchment Basin ◽  
Rainfall Events ◽  
Median Diameter ◽  
Geographical Position ◽  
Very High

The objective of this study is to reach a better understanding of the main characteristics of urban stormwater discharge pollution, by providing information on:–paniculate pollution, its importance in relation to dissolved pollution and its abatement through decantation,–the grain size, the specific mass and the settling velocity of these solids. The first part of this paper is given over to the presentation of the sites chosen and of the experimental methods put into operation. In the second part we go on to analyze the results obtained for ten rainfall events over four different sites, according to their geographical position, to the type of network and to the size of the catchment basin. It is quite clear from the results obtained that the solids are the main vector of pollution. These solids are very fine (median diameter = 25 to 44 µn) and generally have a very high settling velocity (median settling velocity = 4 to 11 m/h). Thus it can be stated that decantation represents an efficient method to combat the pollution in urban stormwater discharge and this has been proved experimentally.

scholarly journals Bioremediation of hydrocarbon-rich wastewater by aerobic granules of oil degrading bacterial strains in salinity influence

2021 ◽  
Author(s):  
Sayanti Ghosh ◽  
Saswati Chakraborty
Keyword(s):  
Suspended Solids ◽  
Extracellular Polymeric Substances ◽  
Settling Velocity ◽  
Biomass Concentration ◽  
Granule Size ◽  
Air Flow Rate ◽  
Salt Tolerant ◽  
Bacterial Strains ◽  
Nacl Concentration ◽  
Hydrocarbon Removal

Granulation of sewage and brewery sludge isolated oil degrader Brevibacterium and Staphylococcus were investigated in hydrocarbon-rich wastewater with 280 mg/L of hydrocarbon at 10-25 g/L NaCl salinity influence. Brevibacterium and Staphylococcus cultures were inoculated in aerobic granular reactors (AGRs) R1 and R2 which were operated with 24 h cycle time and 2 L/min air flow rate. Yellowish matured granules appeared within 15 days. R1 granules achieved stability till 15 g/L NaCl concentration but faced disintegration between 15-20 mg/L NaCl exposure which reduced granule size and hydrocarbon removal from 2.15-1.7 mm and 78-73%. R2 granules were more salt tolerant providing 2.5±0.5 mm granule size with 4±1 g/L volatile suspended solids (VSS) and 201±1 mg/g VSS extracellular polymeric substances (EPS) content achieving 81±0.7% hydrocarbon removal in 30 days. High granule stability and biomass concentration ensured less biomass washout from reactors. Granule settling velocity (GSV) in R1 and R2 reached 20±1 and 32±0.8 m/h which corresponded with granule size profiles. Kinetics analysis showed that at steady state, R1 and R2 were capable of 72 and 91% phenol removals in 30 and 24 h, respectively. Hence, the study provided salt tolerant oil degrading granules for refinery wastewater treatment.

Characterization of Solids Transferred into Sewer Trunks during Wet Weather

1990 ◽  
Vol 22 (10-11) ◽  
pp. 231-238 ◽  
Author(s):  
G. Chebbo ◽  
P. Musquere ◽  
V. Milisic ◽  
A. Bachoc
Keyword(s):  
Suspended Solids ◽  
Settling Velocity ◽  
Measurement Methods ◽  
First Results ◽  
Retention Basin ◽  
Wet Weather

The paper describes the choice of parameters used to characterise sewer sediments in trunk sewers. Different sampling and measurement methods are compared for a number of sites. The sampling arrangement in the BEQUIGNEAUX retention basin, situated in Bordeaux, is described as an example of the methods used. The first results of this study are reported in terms of size, vertical settling velocity and density of suspended solids. There is also a report on the reduction in pollution obtained by settlement of solids.

Quantification of Wind Induced Resuspension in a Shallow Lake

1985 ◽  
Vol 17 (6-7) ◽  
pp. 903-914 ◽  
Author(s):  
R. H. Aalderink ◽  
L. Lijklema ◽  
J. Breukelman ◽  
W. van Raaphorst ◽  
A. G. Brinkman
Keyword(s):  
Shallow Lake ◽  
Suspended Solids ◽  
Settling Velocity ◽  
Sediment Traps ◽  
Least Square ◽  
Horizontal Transport ◽  
Parameter Estimations ◽  
Experimental Time Series ◽  
Wave Induced ◽  
Least Square Values

The mass balance of suspended solids in a shallow lake was modelled as the net result of resuspension and settling. Four different formulations for the flux of resuspension were used. Two equations were based on the conception of wave induced resuspension, the other two used the flow field induced shear stress as the driving force for resuspension. Parameter estimations based on experimental time series of wind velocity and SS concentration produced lower least square values with the models based on flow induced resuspension. The model parameter representing settling was in reasonable accordance with the settling velocity obtained from sediment traps. The spread in results can be explained by a lack of homogeneity and horizontal transport.

A Water Elutriation Apparatus for Measuring Settling Velocity Distribution of Suspended Solids in Combined Sewer Overflows

2004 ◽  
Vol 39 (4) ◽  
pp. 432-438 ◽  
Author(s):  
Bommanna G. Krishnappan ◽  
Jiri Marsalek ◽  
Kirsten Exall ◽  
Robert P. Stephens ◽  
Quintin Rochfort ◽  
...  
Keyword(s):  
Velocity Distribution ◽  
Suspended Solids ◽  
Settling Velocity ◽  
Settling Chamber ◽  
Combined Sewer Overflows ◽  
Polymer Addition ◽  
Combined Sewer ◽  
Sewer Overflows ◽  
Settling Velocity Distribution ◽  
Chemical Distribution

Abstract An elutriation apparatus has been proposed for determining the settling velocity distributions of suspended solids in combined sewer overflows (CSOs). The apparatus consisted of a series of interconnected cylindrical settling chambers, through which the sample was drawn using a peristaltic pump attached to the outlet of the last settling chamber. Since the diameters of the cylinders were progressively increasing, sediment with different settling velocities settled in different cylinders. By measuring the amount of sediment in each cylinder, the settling velocity distribution was deduced. The apparatus was tested using samples from a CSO outfall in Hamilton, Ontario, Canada. The test results showed that the apparatus performed well for determining settling characteristics of suspended solids and chemical distribution in different settling fractions. The effectiveness of polymer addition to enhance flocculation and settling of CSOs was also tested in this apparatus. The elutriation apparatus proposed here offers several advantages over the traditional methods (i.e., settling columns) of measurements of settling velocity distributions. The main advantage is its ability to measure the distributions under dynamic conditions, i.e., in the presence of flow. Consequently, the elutriation apparatus reproduces flow conditions in actual settling tanks better than conventional settling columns.

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