Properties of flocs produced by water treatment coagulants

2001 ◽  
Vol 44 (10) ◽  
pp. 231-236 ◽  
Author(s):  
J. Gregory ◽  
V. Dupont
Keyword(s):  
Test Procedure ◽  
Dynamic Monitoring ◽  
Optical Technique ◽  
Water And Wastewater Treatment ◽  
Aluminium Sulfate ◽  
Jar Test ◽  
Water And Wastewater ◽  
Clay Suspensions ◽  
Polyaluminium Chloride ◽  
Floc Breakage

Hydrolyzing coagulants are extensively used in water and wastewater treatment, often under conditions where hydroxide precipitation is important, giving “sweep flocculation”. Pre-hydrolyzed coagulants, such as polyaluminium chloride (PACl) are also widely used and have several advantages over traditional additives, such as aluminium sulfate. Their action is usually discussed in terms of cationic species and charge neutralization. However, precipitation may also be important and this aspect has not been considered in detail. The present work has compared the action of alum and three commercial PACl products on model clay suspensions. The conventional jar test procedure has been used, along with measurements of settled floc volume and dynamic monitoring of floc formation and break-up by an optical technique. The latter method gives very useful information on the nature of the flocs produced and their response to different shear conditions. It is clear from the results that the PACl products form larger and stronger flocs than alum. With all coagulants floc breakage appears to be essentially irreversible. Sediment volumes are slightly lower for flocs produced by PACl than by alum, but the value is proportional to the dosage in all cases.

Properties of flocs formed using different coagulants

2002 ◽  
Vol 2 (5-6) ◽  
pp. 95-101 ◽  
Author(s):  
M.A. Yukselen ◽  
J. Gregory
Keyword(s):  
Shear Rate ◽  
Continuous Monitoring ◽  
Test Procedure ◽  
Cationic Polyelectrolyte ◽  
Aluminium Sulphate ◽  
Jar Test ◽  
Average Shear ◽  
Break Up ◽  
Polyaluminium Chloride ◽  
Floc Breakage

The effects of shear on the formation and break-up of flocs generated using aluminium sulphate (“alum”), polyaluminium chloride and a cationic polyelectrolyte have been investigated using conventional jar test procedure and by continuous optical monitoring. Using the experimentally determined optimum dosage, the breakage of flocs was followed at a high stirring speed, corresponding to average shear rate (G) of about 330-520 s-1. Most of the breakage occurred within a few seconds of increasing the shear rate. After each breakage the stirring rate was reduced to the original value to allow the flocs to re-grow. For alum and polyaluminium chloride, it was found that only limited re-growth of flocs occurred indicating a significant irreversibility of the floc break-up process. Residual turbidity increased after floc breakage and re-growth, indicating a reduction in sedimentation rate of the re-grown flocs, consistent with the continuous monitoring results. For the cationic polyelectrolyte, the re-growth of flocs occurred to a much greater extent and floc breakage was almost fully reversible.

Synthesis, Characterization, and Flocculation Properties of Branched Polyacrylamide

2012 ◽  
Vol 476-478 ◽  
pp. 2311-2316 ◽  
Author(s):  
Wei Min Sun ◽  
Guang Cheng Zhang ◽  
He Lin Li ◽  
Dong Dong Li ◽  
Pei Pei Li ◽  
...  
Keyword(s):  
Nuclear Magnetic Resonance ◽  
Fourier Transform ◽  
Water Soluble ◽  
The Self ◽  
Solution Polymerization ◽  
Solution Ph ◽  
Water And Wastewater Treatment ◽  
Water And Wastewater ◽  
Acrylamide Monomer ◽  
Clay Suspensions

A water soluble branched polyacrylamide has been synthesized through solution polymerization. The polymerization was initiated by potassium diperiodatocuprate, K5[Cu(HIO6)2](Cu(III)), in alkaline medium and capable of initiating the self condensation vinyl polymerization of acrylamide monomer. The polymer obtained was characterized using Fourier-transform infrared (FTIR) spectroscopy and nuclear magnetic resonance (NMR) spectroscopy. Its flocculation properties were evaluated with clay suspensions using standard jar tests. The concentration of monomers, concentration of initiators, reaction temperature and solution pH on the influence of intrinsic viscosity and flocculation properties of production were studied. The results demonstrate that the branched polymer can be used as a kind of novel flocculant in water and wastewater treatment.

Synthesis, Characterization and Floculating Properties of Coply(AM-DAC) in Water and Wastewater Treatment

2011 ◽  
Vol 396-398 ◽  
pp. 1369-1374 ◽  
Author(s):  
Wein Min Sun ◽  
Guang Cheng Zhang ◽  
Meng Meng Su ◽  
He Lin Li ◽  
Xia Lei
Keyword(s):  
Wastewater Treatment ◽  
Fourier Transform ◽  
Sodium Sulfite ◽  
Ammonium Persulfate ◽  
Solution Polymerization ◽  
Water And Wastewater Treatment ◽  
Turbidity Removal ◽  
Initiation System ◽  
Water And Wastewater ◽  
Clay Suspensions

A cationic polymeric flocculant was synthesized through solution polymerization. The polymerization was initiated by acrylamide and Aacryloxyethyltrimethyl Ammonium Chloride(DAC) monomers, and ammonium persulfate and sodium sulfite as redox initiation system. The copolymer obtained was characterized by Fourier-transform infrared (FTIR) spectroscopy. Its flocculating properties were evaluated by turbidity removal with clay suspensions, turbidity and COD removal with sewage using standard jar tests. The results demonstrate that the copolymer can be used as a kind of cationic polymeric flocculant in water and wastewater treatment.

Ecofriendly Flocculation of Bentonite Suspensions by Two Anionic Polysaccharides: Carboxylated Chitosan (CC) and Sodium Carboxymethyl Starch (CMS-Na)

2014 ◽  
Vol 955-959 ◽  
pp. 321-325
Author(s):  
Bing Bing Zhang ◽  
Jing Bai ◽  
Guang Jin Yuan ◽  
Yan Yan Jia ◽  
Zhe Xiang Han ◽  
...  
Keyword(s):  
Colloidal Particles ◽  
Laser Light ◽  
Test Procedure ◽  
Carboxymethyl Starch ◽  
Jar Test ◽  
Anionic Polysaccharides ◽  
Low Energy Consumption ◽  
Scattering Measurements ◽  
Clay Suspensions ◽  
Sodium Carboxymethyl Starch

Growing demand for ecofriendly technologies promotes the interest in investigation of natural flocculants and their derivatization aimed to dewatering of colloidal stable clay suspensions in a low energy consumption and environmentally friendly way. The present work used two negatively charged polysaccharides carboxylated chitosan (CC) and sodium carboxymethyl starch (CMS-Na) as flocculants and bentonite as colloidal particles system to study the influence of their charge characteristics on flocculation efficacy. Flocculation studies between negatively charged polysaccharides and negatively charged bentonite colloidal particles were systematically investigated through standard jar test procedure and laser light scattering measurements. It was found that the investigated negatively charged polysaccharides showed high flocculation performance for bentonite suspensions at less amount anionic polysaccharides doses but obvious deteriorative performance even antiflocculation process appeared at large amount anionic polysaccharides dosage.

Formation, breakage and re-formation of flocs formed by cationic starch

2013 ◽  
Vol 68 (6) ◽  
pp. 1352-1358 ◽  
Author(s):  
Qintie Lin ◽  
Huanlong Peng ◽  
Qinlu Lin ◽  
Guangcai Yin
Keyword(s):  
Large Scale ◽  
Separation Efficiency ◽  
Test Procedure ◽  
Mixing Conditions ◽  
Cationic Starch ◽  
Jar Test ◽  
Strong Shear ◽  
Alkaline Conditions ◽  
Polymer Flocculant ◽  
Floc Breakage

The efficiency of flocculation can be significantly improved through floc breakage and re-formation under appropriate conditions. To obtain a better understanding of the mechanisms involved and to relate floc properties to separation efficiency, the effects of mixing conditions on the formation, breakage and re-formation of flocs formed by kaolin and cationic starch were investigated through conventional jar test procedure and continuous optical monitoring. It has been found that the breakage of flocs was fully reversible and the polymer flocculant could resist strong shear; even having been sheared for four times, the flocculation index (FI) value would be higher than that of the original flocs. The results indicated flocs formed at neutral and alkaline conditions had better shear resistance than those at acidification conditions, and the mode of floc rupture was large-scale fragmentation.

Chemical Water and Wastewater Treatment VIII

2015 ◽  
Vol 4 (0) ◽  
pp. 9781780402840-9781780402840
Author(s):  
H. Hahn ◽  
E. Hoffman ◽  
H. Odegaard
Keyword(s):  
Wastewater Treatment ◽  
Water And Wastewater Treatment ◽  
Water And Wastewater ◽  
Chemical Water

Water and Wastewater Treatment for a Small Island Resort

1989 ◽  
Vol 21 (2) ◽  
pp. 189-193 ◽  
Author(s):  
B. Rigden
Keyword(s):  
Wastewater Treatment ◽  
Reverse Osmosis ◽  
Small Island ◽  
Rotating Biological Contactor ◽  
Water And Wastewater Treatment ◽  
Water And Wastewater ◽  
Operational Data ◽  
Reverse Osmosis Desalination

The design of a reverse osmosis desalination unit and a rotating biological contactor for water and wastewater treatment for a small island resort is described. Some operational data are presented and recommendations for design flows and loadings are made.

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