Removing Color Caused by Humic Acids

Edwards, Gerald A.; Amirtharajah, Appiah

doi:10.1002/j.1551-8833.1985.tb05508.x

Cited by 116 publications

(59 citation statements)

References 8 publications

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“…An analysis of Figures 2-5 reveals two regions in which coagulation with Fenton's reagent and subsequent fl occulation and fl otation produce removal effi ciencies greater than or equal to 50% and 60% for the fi rst (lower pH) and second (higher pH) region, respectively. Similar behaviour was observed by Edwards and Amirtharajah (1985), who also worked with water sample with true colour of 100 HU (caused by the addition of humic acid) and turbidity equal to zero, using aluminium sulphate (alum) as a coagulant. These researchers concluded that in the fi rst region, corresponding to approximate coagulation pH values of 3.6 to 4.6 in the current study (Figures 2-5), the hydrolysing species adsorption mechanism was probably dominant, causing charge neutralisation of HS molecules.…”

Section: Coagulation Diagramssupporting

confidence: 72%

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Influence of the apparent molecular size of humic substances on the efficiency of coagulation using Fenton's reagent

Julio

Bernardo

2013

An. Acad. Bras. Ciênc.

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This work used Fenton's reagent as a coagulating agent in the treatment of water samples with high true colour caused by humic substances (HS) extracted from peat. In addition, the effects of the apparent molecular size of HS on coagulation, fl occulation and fl otation were studied. To that end, four distinct water samples having the same true colour were prepared using HS with different molecular sizes, which were obtained by ultrafi ltration fractioning. Through optimisation of coagulant dosage and coagulation pH, as well as posterior construction of coagulation diagrams for each water sample, it was verifi ed that the sample prepared with the smallest apparent molecular size of HS was the most diffi cult to treat, requiring higher coagulant (Fenton's reagent) dosages than samples prepared with larger HS molecular sizes. Furthermore, fi ltration experiments after dissolved air fl otation (DAF) were carried out in an attempt to simulate conventional treatment. The most representative results in fi ltered water were: apparent colour ≤ 3 HU; turbidity < 0.5 NTU; and residual iron concentration < 0.005 mg/L. The absorbance and total organic carbon values of fi ltered water samples were also very low, suggesting that the formation of disinfection by-products with chlorine would likely be insignifi cant.

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Section: Coagulation Diagramssupporting

confidence: 72%

“…Furthermore, coagulant dosages (Fenton) were lower in the fi rst region than for the second region. As observed by Edwards and Amirtharajah (1985), it seems to have a restabilisation region between the two regions in which the coagulation resulted effi cient.…”

Section: Coagulation Diagramsmentioning

confidence: 75%

Influence of the apparent molecular size of humic substances on the efficiency of coagulation using Fenton's reagent

Julio

Bernardo

2013

An. Acad. Bras. Ciênc.

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“…La nature ainsi que la concentration des matières organiques doivent également être prises en compte (VIK et ai, 1985) et l'on peut noter comme pour l'effet de la temperature, que l'ajout de matières minérales permet d'améliorer le rendement d'élimination des substances organiques (EDWARD et AMIRTHARAJAH, 1985). HUNDT et O'MELIA (1988) Les essais de floculation ont été réalisés sur jar-test Hydrocure FLH6.…”

Section: Pour Pallier Ces Inconvénients Le Service Des Eaux De La VIunclassified

“…Une simulitude apparaît ici, avec les travaux d 'EDWARD et AMIRTHARAJAH (1985) dont il ressort que le rendement d'élimination des colloïdes organiques peut être amélioré par un ajout de matières minérales.…”

Section: Residue Curves (Expérimental Dose -Calculated Dose) Versus Cunclassified

Modélisation mathématique du taux de coagulant dans une station de traitement d'eau

Bazer-Bachi¹,

Puech-Coste²,

Aim³

et al. 2005

rseau

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Les auteurs, après une synthèse bibliographique sur la coagulation, présentent deux modèles mathématiques reliant la dose optimale d'un coagulant, le sulfate d'aluminium, à la qualité de l'eau brute.Un premier modèle applicable aux eaux dont la turbidité est inférieure à 20 NTU tient compte de quatre variables caractéristiques de l'eau brute qui sont : la turbidité, la résistivité, la température, la teneur en matières organiques.Le second modèle, utilisable pendant les périodes de crue, intègre un cinquième descripteur : la nature de la suspension minérale.Des essais effectués sur l'usine de Clairfont, qui alimente la rive gauche de Toulouse, montrent que ces modèles sont parfaitement adaptés pour automatiser l'injection du coagulant.When the source of supply of a water treatment plant has a streaming behaviour, it is sometimes difficult to adjust correctly the coagulant dose by jar-testing alone.Following this remark, the municipal water utilities of Toulouse city (France) has decided to conduct a study on the modelisation of coagulant dose as a function of the quality of raw water.This study started first by a bibliographic survey to find the main parameters which affect the flocculation mechanisms, followed by a hydrologic study of the upper Garonne river to characterize as well as possible its behavior.This was following by a study of the influence of certain parameters on the efficiency of coagulation by aluminium sulfate on synthetic waters having characteristics close to those of the Garonne river (BAZER-BACHI, 1986). This work showed the rote of the turbidity, of the resistivity, of the temperature and of the nature of mineral suspension. It also indicated the non-linearity between the optimum coagulant dose and these parameters as well as the interactions between them.These conclusions led us to use a second degree polynomial model, as : k k kY = bo + ∑ bi Xi + ∑ bii X2i + ∑ bij Xi Xj i = 1, j = 2, i ≠ jData were collected from modified jar-test on water from the Garonne River, characterized by physico-chemical (turbidity, temperature, pH, resistivity, CEC, MES, colloid titralion, organic matters) and chemical analyses (mineralisation). As the hydrological study showed that the nature of colloid suspension changed only during storm events, the modelisation was divided in two sub-groups :- a « CALME » model, comprising four variables (turbidity, resistivity, temperature, organic matters), for low turbidity waters (below 20 NTU),- a « CRUES » a model, using a fifth parameter representative of the nature of suspension (the ratio between colloid titration and turbidity).The « CALME » model, which fitted very well, showed the primordial influence of the temperature and organic matters, and then of the turbidity. Removal of resistivity was not advisable, as this parameter showed strong interactions with turbidity and organic matters (fig. 3, 4).The « CRUES » model showed the primordial role of the turbidity followed by the temperature and then by organic matters. The tw...

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“…Charge neutralization/complexation is believed to preferentially occur at acidic pH [9][10][11], while physical enmeshment and/or adsorption commonly occurs under conditions favoring metal hydroxide precipitation, and humic substances are primarily transferred onto freshly formed precipitate [9,10,12,13]. When FeCl 3 is employed in enhanced coagulation for HA removal, good performance has been gained at acidic pH and large doses, where in pH-coagulant concentration domains fresh iron hydroxide precipitation is formed [4][5][6].…”

Section: Introductionmentioning

confidence: 99%

Effect of polyferric chloride (PFC) doses and pH on the fractal characteristics of PFC–HA flocs

Wang

Feng

Dentel

et al. 2011

Colloids and Surfaces A: Physicochemical and Engineering Aspect

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a b s t r a c tChanges in the fractal characteristics of PFC-HA flocs with polyferric chloride (PFC) doses and coagulation pHs were investigated in this study. A type of PFC coagulant with a hydrolysis degree (B*) of 0.6027 and a Fe(III) concentration of 0.202 mol/L was employed to coagulate HA solutions at five constant coagulation pHs. Zeta potential tests were employed to reveal the coagulation mechanisms. The physical properties of flocs formed in the coagulation process were analyzed by their CCD image morphology, size distribution, and fractal dimensions. Next, microscopic observations and nitrogen-adsorption-desorption methods were conducted to characterize the pore structure and surface fractal dimensions of powders prepared from these flocs through a cryofixation-vacuum-freeze-drying procedure. The PFC doses and coagulation pHs had an obvious effect on the physical characteristics of PFC-HA flocs and their corresponding powders. Generally, in the low PFC dose range, PFC-HA flocs formed under acidic coagulation pHs and charge neutralization mechanisms were larger, had less irregular boundaries or surfaces (lower D 1 value), a more compact structure (lower D 2 value) and more irregular pore surface or pore size distribution in their dried powder than those formed under neutral and alkaline coagulation pHs and physical enmeshment and/or fresh precipitate adsorption mechanisms involved in the coagulation process. After the PFC doses exceeded this range, a gradual reversal phenomenon occurred. Furthermore, there were different specific PFC dosages that were above the critical reversal point for each property of these flocs or powders, such as the median diameter, one-dimensional fractal dimension, two-dimensional fractal dimension, and pore surface fractal dimension. In addition to these characteristics, the most compact PFC-HA flocs were formed at coagulation pH = 6.00 ± 0.05 and a PFC dosage of 4.04 × 10 −4 mol/L (Fe 3+ ), and the loosest flocs were produced at coagulation pH = 7.00 ± 0.05 and a PFC dose of 1.01 × 10 −4 mol/L (Fe 3+ ).

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Removing Color Caused by Humic Acids

Cited by 116 publications

References 8 publications

Influence of the apparent molecular size of humic substances on the efficiency of coagulation using Fenton's reagent

Influence of the apparent molecular size of humic substances on the efficiency of coagulation using Fenton's reagent

Modélisation mathématique du taux de coagulant dans une station de traitement d'eau

Effect of polyferric chloride (PFC) doses and pH on the fractal characteristics of PFC–HA flocs

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