Basic Studies on the Dual-Polymer Flocculation of Iron Hydroxide
©2017
Textbook
42 Pages
Summary
The efficiency of synthetic flocculants in flocculation processes has been identified by several authors over the years, and this makes it applicable in the industry. Nowadays, studies are focused on the combination of polymers for optimal performance. In this study, the physicochemical conditioning of iron hydroxide suspension (obtained sludge from the lignite mined sites in the Lusatia region of Germany) was investigated with flocculants of different properties as single polymer conditioning (C492 and A130) and as dual-polymer conditioning (C492+N300, A130+N300 and C492+A130) using Jar test. C492 is a cationic flocculant, A130 is an anionic flocculant, and N300 is a non-ionic flocculant. Turbidity of the supernatant and the sludge volume index were the assessing parameters considered under dosage range of 0.4, 0.8, 1.2, 2.0, 2.8 and 3.6 mg/gTS. The obtained optimization results were compared to the actual separation with respect to specific filtration resistance from pressure filtration. The obtained results show some interesting differences which are discussed in this book.
Excerpt
Table Of Contents
Adesipo, Adegbite Adeleke: Basic Studies on the Dual-Polymer Flocculation of Iron
Hydroxide, Hamburg, Anchor Academic Publishing 2017
Buch-ISBN: 978-3-96067-199-2
PDF-eBook-ISBN: 978-3-96067-699-7
Druck/Herstellung: Anchor Academic Publishing, Hamburg, 2017
Bibliografische Information der Deutschen Nationalbibliothek:
Die Deutsche Nationalbibliothek verzeichnet diese Publikation in der Deutschen
Nationalbibliografie; detaillierte bibliografische Daten sind im Internet über
http://dnb.d-nb.de abrufbar.
Bibliographical Information of the German National Library:
The German National Library lists this publication in the German National Bibliography.
Detailed bibliographic data can be found at: http://dnb.d-nb.de
All rights reserved. This publication may not be reproduced, stored in a retrieval system
or transmitted, in any form or by any means, electronic, mechanical, photocopying,
recording or otherwise, without the prior permission of the publishers.
Das Werk einschließlich aller seiner Teile ist urheberrechtlich geschützt. Jede Verwertung
außerhalb der Grenzen des Urheberrechtsgesetzes ist ohne Zustimmung des Verlages
unzulässig und strafbar. Dies gilt insbesondere für Vervielfältigungen, Übersetzungen,
Mikroverfilmungen und die Einspeicherung und Bearbeitung in elektronischen Systemen.
Die Wiedergabe von Gebrauchsnamen, Handelsnamen, Warenbezeichnungen usw. in
diesem Werk berechtigt auch ohne besondere Kennzeichnung nicht zu der Annahme,
dass solche Namen im Sinne der Warenzeichen- und Markenschutz-Gesetzgebung als frei
zu betrachten wären und daher von jedermann benutzt werden dürften.
Die Informationen in diesem Werk wurden mit Sorgfalt erarbeitet. Dennoch können
Fehler nicht vollständig ausgeschlossen werden und die Diplomica Verlag GmbH, die
Autoren oder Übersetzer übernehmen keine juristische Verantwortung oder irgendeine
Haftung für evtl. verbliebene fehlerhafte Angaben und deren Folgen.
Alle Rechte vorbehalten
© Anchor Academic Publishing, Imprint der Diplomica Verlag GmbH
Hermannstal 119k, 22119 Hamburg
http://www.diplomica-verlag.de, Hamburg 2017
Printed in Germany
i
Abstract
The efficiency of synthetic flocculants in flocculation process has been identified by
several authors over the years, and this makes it applicable in the industry. Nowadays,
studies are now focused on the combination of polymers for optimal performances. In
this study, the physicochemical conditioning of ferric hydroxide suspension (obtained
sludge from the lignite mined sites in the Lusatia region of Germany) was investigated
with polymers of different properties as single polymer conditioning (C492 and A130)
and as dual-polymer conditioning (C492+N300, A130+N300 and C492+A130) using Jar
test. C492 is a cationic flocculants, A130 is an anionic flocculants, and N300 is a non-
ionic flocculants. Turbidity of the supernatant and the sludge volume index (SVI) were
the considered assessing parameters under a dosage range of 0.4, 0.8, 1.2, 2.0, 2.8
and 3.6 mg/gTS. The obtained optimization results was compared to the actual
separation with respect to specific filtration resistance from pressure filtration. The result
shows that C492+N300 has no significant positive effect compare to C492 for the
physicochemical optimization while A130+N300 produced a lower SVI but more turbid
supernatant compare to A130. Based on the obtained values and observation of the
types of flocs formed during the flocculation processes, it could be deduced that
polymer bridging predominates with C492 and N300 while charge neutralization
predominates with A130 flocculants. And based on their actual separation process,
C492+N300 has the lowest specific filtration resistance during the actual separation
which indicates better filterability. And in most cases, the physicochemical optimization
result does not correlates with the actual separation result. However, in general, the
higher the dosage, the more compacted the flocs structure generated and the lower the
filtration resistance. Also, worthy of note as could be evident from this study is that the
timing for pressure filtration is not a determinant for its specific filtration resistance.
However, in a haze, choice of dual-polymer flocculation should be based on the
properties of the flocculants, appropriate dosing concentration and the desired
assessing parameters.
Keywords: solid-liquid separation, flocculation, synthetic flocculants, dual-polymer,
pressure filtration
ii
Table of Contents
Abstract ... i
List of Figures ...iv
List of Tables ... v
1.
Introduction ... 1
1.1 Study Objectives ... 2
2.
Literature Review ... 4
2.1 Solid Liquid Separation ... 4
2.2 Theory of Flocculation ... 5
2.2.1 Flocculation and Energy Barrier ... 5
2.2.2 Flocculants ... 6
2.2.3 Flocculation Mechanisms ... 7
2.2.4 Factors Affecting Flocculation ... 10
2.3 Flocculation Assessment ... 10
2.4 Charge Characterization ... 10
2.5 Filtration Technique ... 11
2.5.1 Pressure Filtration ... 12
2.5.2 Specific Filtration Resistance ... 13
2.5.3 Tendency of Deviation ... 14
3.
Materials and Methods ... 15
3.1 Materials ... 15
3.2 Method ... 15
3.2.1 Charge Quantification ... 15
3.2.2 Flocculation Tests (Jar Test) ... 17
3.2.3 Pressure Filtration ... 18
iii
4.
Result and Discussion ... 20
4.1 Physicochemical Optimization Process Results ... 20
4.1.1 Optimum Dosage for Single Polymer Conditioning ... 20
4.1.2 Optimum Dosage for Dual Polymer Conditioning ... 21
4.2 Comparison of the Physicochemical Results ... 23
4.3 Pressure Filtration Process ... 24
4.3.1 Single Polymer Filtration Result ... 24
4.3.2 Dual polymer Filtration Result ... 25
4.4 Comparison of the Specific Filtration Resistance ... 26
5.
Conclusions and Further Studies ... 28
References ... 29
Appendix ... 33
iv
List of Figures
Figure 1: Solid-Liquid separation process ... 4
Figure 2: A) Potential energy representation. B) The electrical charge of particles ... 6
Figure 3: The graphical representation of flocculation ... 8
Figure 4: Formation of floc ... 9
Figure 5: Curves showing the various tendency of deviation from the normal ... 14
Figure 6: Working principles of particle charge detector (Product sheet manual) ... 16
Figure 7: Set-up for Jar-Test experiment using Flocculator ... 17
Figure 8: Schematic diagram of the pressure filtration apparatus ... 19
Figure 9: Graphical representation of the physiochemical process for C492 and A130 21
Figure 10: Dual polymer flocculation for C492+N300, A130+N300 and C492+A130 ... 22
Figure 11: Specific Filtration Resistance for C492 and A130 ... 25
Figure 12: Specific Resistance value for C492+N300, A130+N300 and C492+A130 ... 25
v
List of Tables
Table 1: The "best" Floc Characteristics for different separation processes ... 11
Table 2: Typical dosage range for dewatering process of biosolids. ... 12
Table 3: Properties of the different flocculants employed in this study ... 15
Table 4: The physicochemical pre-treatment result ... 20
Table 5: Parameters for calculating the specific filtration resistance ... 24
Table 6: The specific filtration resistance for all the flocculants considered ... 24
Table 7: Specific filtration resistance at optimum dosage ... 26
Table 8: Correlation between SFR and assessed parameters ... 27
1
1.
Introduction
As the world population increases, demand for potable water increases, likewise the
generation of waste. This reveals that sludge in general; either as a result of mining or
as effluent from the industry, household or other sources requires proper treatment in
order to attain expected standard for water reuse and groundwater recharge. In solid-
liquid separation process; its efficiency and the quality of the separated liquid
(supernatant) is usually of interest considering the involved economic and
environmental consequences. Brostow, et al., (2009) noted that of several separation
processes; gravitation, coagulation, flocculation, etc. flocculation is the fastest. In the
treatment of suspensions and fine particle systems; it plays a significant role, and in
solid-liquid separation process; it remains indispensable for both upstream and
downstream (Oyegbile, et al., 2015).
Research has proven that solid-liquid separation can be improved by the use of
synthetic flocculants in flocculation process. It increases the effective particle size by
forming larger flocs and breaks down the suspension stability followed by the release of
the liquid phase. It is an efficient and cost-effective strategy and has become widely
employed in several industrial applications (Fan, et al., 2000). This is because it
generates larger flocs which can sediment and be separated easily. Polymers used in
flocculation can destabilize these particles either by bridging, charge neutralization,
depletion flocculation or electrostatic patch (Chaiwong & Nuntiya, 2008). Ebeling, et al.,
(2005) pointed out some advantages of the use of polymers over alum, ferric chloride
and other aids that have been in use before. Few of these includes its low dosage
requirement, reduction of sludge production, easier storage and mixing, no pH
adjustment requirement, its effectiveness for smaller particles and improvement of the
floc resistance to shear forces.
Over the last few decades, research has been focusing on the combination of polymers
for optimal performance. Several research works have discussed the benefits of using
two-component flocculants as compared to single component. Britt, (1973) was one of
the first groups of researchers to work on this topic and has been further investigated in
2
several other studies. Razali, et al., (2012) stated that dual flocculation provides a better
control of flocculation kinetics than single-flocculants as well as improved flocs
structure. In addition to that, research by Wu & Theo, (2009) on poly (ethylene oxide)
and carboxylate phenolic resin confirm that dual flocculants improve the richness of
flocculation but, it depends on the concentration of the two components used. They
noted that dual component flocculants may consist of two polyelectrolytes, two
polymers, or polyelectrolytes and a nano-colloid. They further stated that one of the
components adsorbs on the surface of the particles while the other bridges these
polymer-coated particles. Use of dual polymer can produce a synergetic effect and
complexation for flocculation process (Fan, et al., 2000); an example is an increase in
the bonding effect. In a similar work, Yu & Somasundaran, (1993) investigated on
alumina flocculation with polystyrene sulfonate and cationic polyacrylamide polymers
which confirms that the flocculation result obtained from two polymers premixed was
much lower than when the polymers were used individually.
1.1 Study Objectives
The general aim of this study is to compare the single and dual-polymer conditioning of
ferric hydroxide suspension with respect to the subsequent solid-liquid separation
efficiency by pressure filtration. The sludge is part of the waste product obtained from
the lignite mining areas in the Lusatia region of Germany). And the specific study
objectives include;
Physicochemical treatment of ferric hydroxide suspension using flocculants with
different charge densities.
Assessment of the physicochemical optimization process with respect to the
turbidity of the supernatant and the sludge volume index (SVI).
Determination of optimum flocculants dosage with respect to the measured
parameters and separation efficiency.
This will be achieved by the performance of a bench scale flocculation and dewatering
experiments in order to obtain the optimum dose. The experimental tasks involve
charge quantification of ferric hydroxide suspension using the particle charge detector
(PCD), determination of the charge densities of the flocculants that were selected using
Details
- Pages
- Type of Edition
- Erstausgabe
- Publication Year
- 2017
- ISBN (Softcover)
- 9783960671992
- ISBN (PDF)
- 9783960676997
- File size
- 7.4 MB
- Language
- English
- Publication date
- 2017 (November)
- Keywords
- Coagulation Solid-liquid separation Synthetic flocculant Pressure filtration Anionic flocculant Cationic flocculant Non-ionic flocculant Single polymer Suspension
- Product Safety
- Anchor Academic Publishing
