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.

Analysis of the methods for determining the settling characteristics of sewage and stormwater solids

1998 ◽  
Vol 37 (1) ◽  
pp. 53-60 ◽  
Author(s):  
Emmanuelle Lucas-Aiguier ◽  
Ghassan Chebbo ◽  
Jean-Luc Bertrand-Krajewski ◽  
Benoit Gagné ◽  
Peter Hedges
Keyword(s):  
Total Mass ◽  
Settling Velocity ◽  
Test Procedure ◽  
Test Methods ◽  
The Other ◽  
Test Procedures ◽  
Experimental Procedure ◽  
Comparative Tests ◽  
Sewer Networks ◽  
Settling Characteristics

In order to optimise the design and the management of sewer networks and settling tanks, there is a need to determine the settling velocity characteristics of sewage and stormwater solids. Devices and test methods for measuring settling velocities of these solids have been developed (Chebbo, 1992), (Michelbach and Wohrle, 1993) and (Tyack et al., 1993). In order to quantify the influence of the experimental procedure on the settling velocity grading curves, we have compared three selected methods (Cergrene, Aston, Camp) when tested with the same sample with the method developed by UFT (Michelbach and Wohrle, 1993). The results of the comparative tests indicate that the settling velocities are significantly higher with the UFT test procedure than the other methods. This is mainly explained by the fact that the UFT method takes only settleable solids into account. When the calculations of the four methods are made with the total mass of SS, the study has shown that the settling velocity curves of the same samples are different. The differences vary between the nature of the samples and the test procedures which were compared. The influence of the experimental procedure for separating a sample by settling velocities fractions is demonstrated. In conclusion, we explain the need to develop an international test procedure in order to be able to compare the results.

On-line determination of sludge settling velocity for flux-based real-time control of secondary clarifiers

2006 ◽  
Vol 54 (11-12) ◽  
pp. 249-256 ◽  
Author(s):  
A. Lynggaard-Jensen ◽  
L. Lading
Keyword(s):  
Wastewater Treatment ◽  
Wastewater Treatment Plant ◽  
Control Algorithm ◽  
Suspended Solids ◽  
Settling Velocity ◽  
Treatment Plant ◽  
On Line ◽  
Sludge Settling ◽  
Settling Characteristics

The state diagram for operation of secondary clarifiers is used to design a control algorithm for the return sludge pumping and determination of the actual hydraulic capacity of the biological step of a wastewater treatment plant. On-line input for the control algorithm is derived from a sludge volume sensor and a suspended solids sensor in the form of software sensors giving values for the sludge settling characteristics – settling velocity, sludge volume index, initial settling velocity and the exponent in the Vesilind equation – allowing the control to accommodate the ever changing settling characteristics and thereby keep the suspended solids flux in the clarifiers in balance for both dry weather flows and during rain events. The control algorithm has been implemented, tested and set into normal operation on a full scale wastewater treatment plant.

Behaviour of Mechanically Blended Return-Sludge in Absence of Substrate

1970 ◽  
Vol 5 (1) ◽  
pp. 34-54
Author(s):  
Shyam D. Bokil ◽  
Jatinder K. Bewtra
Keyword(s):  
Activated Sludge ◽  
Suspended Solids ◽  
Treatment Plant ◽  
Aeration Rate ◽  
Batch Experiments ◽  
Sludge Treatment ◽  
Waring Blender ◽  
Settling Characteristics

Abstract Nine sets of batch experiments, each of ten to twelve days duration, were conducted in the laboratory on return-sludge samples collected from activated sludge treatment plant at Windsor. The thickened sludge samples were blended daily in a waring blender and were continuously aerated in twelve-litres capacity jars. Parallel runs were made on control sludge samples which were not blended. Amongst the parameters varied were the speed and frequency of blending and the aeration rate. The effects of these variables on progressive bio-degradation of volatile suspended solids and the settling characteristics of the sludge were determined. Blended sludge showed significant improvement in the rate of bio-degradation and its settling characteristics as compared to the control unblended sludge

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.

On-line measurements of settling characteristics in activated sludge

1997 ◽  
Vol 36 (4) ◽  
pp. 307-312
Author(s):  
Michael R. Rasmussen ◽  
Torben Larsen
Keyword(s):  
Activated Sludge ◽  
Settling Velocity ◽  
Continuous Measurement ◽  
Batch Reactor ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Dynamic Variations ◽  
On Line ◽  
Settling Column ◽  
Settling Characteristics

An on-line settling column for measuring the dynamic variations of settling velocity of activated sludge has been developed. The settling column is automatic and self-cleansing insuring continuous and reliable measurements. The settling column was tested on sludge from a batch reactor where sucrose was added as an impulse to activated sludge. The continuous measurement of settling velocity revealed a highly dynamic response after the sucrose was added. The results were verified with simultaneous measurement of the initial settling rate. A 200 hour experiment showed variations in settling velocity, which was not apparent in the DSVI (Diluted Sludge Volume Index).

scholarly journals Development and Validation of 2-Azaspiro [4,5] Decan-3-One (Impurity A) in Gabapentin Determination Method Using qNMR Spectroscopy

Molecules ◽  
2021 ◽  
Vol 26 (6) ◽  
pp. 1656
Author(s):  
Nataliya E. Kuz’mina ◽  
Sergey V. Moiseev ◽  
Mikhail D. Khorolskiy ◽  
Anna I. Lutceva
Keyword(s):  
Test Procedure ◽  
Active Pharmaceutical Ingredient ◽  
Test Methods ◽  
Intermediate Precision ◽  
Coefficients Of Variation ◽  
Validation Parameters ◽  
Limit Of Quantitation ◽  
Student’S T ◽  
Development And Validation ◽  
Student’S T Test

The authors developed a 1H qNMR test procedure for identification and quantification of impurity A present in gabapentin active pharmaceutical ingredient (API) and gabapentin products. The validation studies helped to determine the limit of quantitation and assess linearity, accuracy, repeatability, intermediate precision, specificity, and robustness of the procedure. Spike-and-recovery assays were used to calculate standard deviations, coefficients of variation, confidence intervals, bias, Fisher’s F test, and Student’s t-test for assay results. The obtained statistical values satisfy the acceptance criteria for the validation parameters. The authors compared the results of impurity A quantification in gabapentin APIs and capsules by using the 1H qNMR and HPLC test methods.

Analysis of Physical Structure and Chemical Composition of Oil-Water Transition Layer in Oil Gathering and Transportation System

2013 ◽  
Vol 652-654 ◽  
pp. 2566-2569
Author(s):  
Dan Dan Yuan ◽  
Hong Jun Wu ◽  
Hai Xia Sheng ◽  
Bao Hui Wang ◽  
Xin Sui
Keyword(s):  
Chemical Composition ◽  
Transition Layer ◽  
Suspended Solids ◽  
Solid Phase ◽  
Freezing Point ◽  
Analytical Data ◽  
Transportation System ◽  
Physical Structure ◽  
Efficient Treatment ◽  
Oil Water

he existence of oil-water transition layer brings a great trouble to the dehydration of oil gathering and transportation system. It leads to raising the electric current of dehydrator and becoming worse of the deoiling and dehydrating properties of the treatment equipment, resulting in the serious influences on oil recovery. For the efficient treatment of the transition layer, it is necessary clearly to understand the structure and composition of the layer. In this paper, the physical structure and chemical composition of the layer were systematically, layer by layer and phase by phase, analyzed by modern instrumental methods The results show that (1）the layer is an emulsion which is composed of oil, water and suspended solids. The water phase has characteristics of weak alkaline，high salinity and viscous polymer. The oil phase contains many natural emulsifiers such as colloid, asphaltene and so on. The solid phase mainly concludes FeS particle which plays a decisive role in suspended solids; (2) the typical transition layer is composed of water and oil which accounts for above 90%, the content of solid impurity, which controls the emulsion of the layer, is less than 10%. Compared with oil phase, the water content of typical transition layer is larger with the density of 0.9~1.0 g/L and high freezing point. The analytical data can be adopted for the treatment of oil-water transition layer and smoothly run operations for oil gathering and transportation.

The Effect of Extraneous Factors on the Development of Test Methods

1970 ◽  
Vol 185 (1) ◽  
pp. 519-524 ◽  
Author(s):  
M. A. W. Hall
Keyword(s):  
Test Methods ◽  
Test Unit ◽  
Comparative Testing ◽  
Comparative Tests ◽  
Objective Measurements ◽  
Test Programme ◽  
Simple Measurement ◽  
Consumer Magazine ◽  
Typical Test ◽  
The Way

Comparative testing of cars for a quarterly consumer magazine poses a particular set of problems. The main ones are time and the designing of apparatus to produce objective comparisons between cars. A subsidiary, but important, problem is the need to produce information which is technically valid and yet readily interpretable by a non-technical public. A test unit is described, and a typical test programme is outlined. Examples are given of the way in which particular problems have been overcome: in particular, the evolution of equipment for measuring acceleration, which has reduced the time necessary for testing by 75 per cent, is described. The development of comparative tests for handling is discussed, and the difficulty of defining a simple measurement of the noise inside a car is used as an example of the difficulty of producing objective measurements which correlate with subjective impressions. It is concluded that, whilst rationalization of test methods is often both desirable and practicable, it is sometimes necessary for individual organizations to retain their own particular methods.

Comparison and evaluation of empirical zone settling velocity parameters based on sludge volume index using a unified settling characteristics database

2003 ◽  
Vol 37 (16) ◽  
pp. 3821-3836 ◽  
Author(s):  
Dimosthenis.L Giokas ◽  
Glen.T Daigger ◽  
Marcos.von Sperling ◽  
Youngchul Kim ◽  
Panayotis.A Paraskevas
Keyword(s):  
Settling Velocity ◽  
Volume Index ◽  
Sludge Volume Index ◽  
Settling Characteristics

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.

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