Effect of polyaluminum chloride on enhanced softening for the typical organic-polluted high hardness North-China surface waters

Yan, Mingquan; Wang, Dongsheng; Ni, Jinren; Qu, Jiuhui; Yan, You; Chow, Christopher W.K.

doi:10.1016/j.seppur.2008.02.014

Cited by 26 publications

(15 citation statements)

References 23 publications

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“…Similar results are obtained by Yan et al (2008) who studied the treatment of organic-polluted high hardness surface water using enhanced softening via precipitation employing different coagulants, such as FeCl3, AlCl3 and polyaluminum chloride (PACl), in bench scale experiments. Higher elimination of natural organic matter (NOM) (UV254 removal attained ~50%) was obtained under enhanced softening with coagulant injection conditions as compared with conventional coagulation at natural pH or by softening alone without coagulation.…”

Section: Om Removal Under Softening Conditionssupporting

confidence: 80%

Combining lime softening with alum coagulation for hard Ghrib dam water conventional treatment

Ghernaout¹

2018

Int. j. adv. appl. sci.

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This work aims to control the efficiency of water softening as an inherent phenomenon in the coagulation process or, in other words, to evaluate the softening process as a secondary reaction which is producing simultaneously with the main reaction as the coagulation process. Ghrib Dam water is wellknown for its high hardness ranging from 750 to 900 mg/L as CaCO3. That is, this water is unpleasant to the domestic consumption. Conventional water treatment at the Ghrib Station is based on coagulation using aluminum sulfate [Al2 (SO4)3.18H2O] (alum) as a single coagulant. Alum has a minimal effect on the total hardness and its human toxicity is not yet doubtful. This research introduces the concept of the replacement of alum by lime and sodium hydroxide (NaOH) in coagulation process at the Ghrib Station. Coagulation experiments on jar test using the three reagents (alum, lime, and NaOH) are performed and physicochemical analyses are conducted to evaluate the possibility of alum partial or total replacement for improving the treatment effectiveness in hardness reducing. The obtained results show that hardness is decreased at its half by combining simultaneously the three chemical products: alum = 15, lime = 100, NaOH = 100 mg/L. Additional survey is required to examine the complicated interaction in the Ca 2+ /Mg 2+ -DOM-Al ternary system to comprehensively define the contributions of the two mechanisms -lime softening and coagulation -to organic matter removal by coagulation.

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Section: Om Removal Under Softening Conditionssupporting

confidence: 80%

Combining lime softening with alum coagulation for hard Ghrib dam water conventional treatment

Ghernaout¹

2018

Int. j. adv. appl. sci.

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“…The treatment of organic-polluted high-hardness surface water by enhanced softening via precipitation using PACl, FeCl 3 and AlCl 3 has been investigated and reported in our previous paper [25]. It is found that higher removal of natural organic matter (NOM) (UV 254 removal reaches about 50%) is achieved by enhanced softening with PACl addition as compared with conventional coagulation at natural pH or by softening alone without coagulation.…”

Section: Enhanced Softening With Coagulantmentioning

confidence: 99%

“…The performance of enhanced softening is affected significantly by magnesium content in raw water [25]. For water with higher content of Mg 2+ , the inflexion pH for favorable NOM removal is lower.…”

Section: Enhanced Softening With Coagulantmentioning

confidence: 99%

Natural organic matter (NOM) removal in a typical North-China water plant by enhanced coagulation: Targets and techniques

Yan

Wang²,

Ni³

et al. 2009

Separation and Purification Technology

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a b s t r a c tSeasonal coagulation objectives for a typical North-China water treatment plant with micro-polluted and high alkalinity source waters are proposed in this paper. These are based on a yearlong data collection period where raw water characteristics, trihalomethanes formation potential (THMFP) and coagulation features were investigated using a jar test procedure, resin absorption and ultrafiltration fractionations. Three approaches beyond simply increasing the coagulant dose were used to achieve optimized coagulation. One is coagulation by adjusting the pH of the raw water when metal salt coagulants (FeCl 3 and AlCl 3 ) are used. At pH levels of about 5.0 for FeCl 3 and about 5.8 for AlCl 3 , the highest removal of natural organic matter (NOM) was obtained, which is twice that without pH control. The second is enhanced coagulation through coagulant optimization based on raw water characteristics. A high efficient composite polyaluminum chloride (HPAC) coagulant was developed for the water taking the advantages of polyaluminum chloride (PACl) and other additives. HPAC exhibited 30% more efficiency than AlCl 3 , FeCl 3 and polyaluminum chloride (PACl) in dissolved organic carbon (DOC) removal and was also very effective in turbidity removal. The third is enhanced softening with coagulant addition. Higher removal of NOM is achieved by enhanced softening with coagulant addition conditions as compared with conventional coagulation at natural pH. Especially with PACl addition, it can enhance the formation of Mg(OH) 2 precipitate and remove NOM efficiently at a relatively lower pH range (pH < 10). By this approach, the pH for enhanced softening can be decreased significantly into a practical operation pH range for high-hardness water at a treatment plant.

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“…So far, various methods, including adsorption (6), ion exchange (8), nanophotocatalysis (9), membrane (10,11) and ultrasonic technologies (11), electrocoagulation (12), coagulation and enhanced coagulation (13) have been employed for the removal of humic substances from water, among which the advanced oxidation processes (AOPs) have been introduced as a suitable option for the removal or destruction of the humic substances compared to other common methods (coagulation, ion exchange, membrane filtration, and adsorption) (6). Synthesis of hydroxyl radicals with high oxidative power in AOP has caused these treatment processes to be known as one of the most practical physicochemical treatment procedures (14).…”

Section: Introductionmentioning

confidence: 99%

Sonocatalytic Degradation of Humic Substances From Aquatic Environments Using MgO Nanoparticles

Soltani¹,

Safari²,

Rezaee³

et al. 2017

Avicenna J Environ Health Eng

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Humic substances are considered as one of the major natural organic contaminants in water resources. Presence of such substances in the drinking water supply resources results in poor water quality and jeopardizes the consumer's health. In the present study, sonocatalytic decomposition of the humic substances by using MgO nanoparticles was investigated under the radiation of the ultrasonic waves. Accordingly, the X-ray diffraction (XRD) and scanning electron microscopy (SEM) techniques were used to determine characteristics of the nanoparticles. Furthermore, the effects of various parameters, including the amount of nanoparticles, initial pH, initial concentration of humic substances, contact time, as well as the power and frequency of ultrasonic waves on the efficiency of the sonocatalytic decomposition of humic substances were investigated. Results of the present study showed that the efficiency of sonocatalytic decomposition of humic substances was reduced by increasing the initial pH and initial concentration of the humic substances; while, the increased amount of the nanocatalyst resulted in the increased efficiency of decomposition. Furthermore, the obtained results indicated that the MgO sonocatalytic process could decompose the humic substances with the efficiency of 78.5% under optimal conditions (pH:7, initial concentration of humic substances: 20 mg/L, concentration of nanoparticles:1 g/L, power: 100%, frequency: 37 kHz and contact time:120 min). Based on the obtained results, the sonocatalytic method using MgO can remove humic substances and other similar organic matters from the aquatic environments with a high efficiency.

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Effect of polyaluminum chloride on enhanced softening for the typical organic-polluted high hardness North-China surface waters

Cited by 26 publications

References 23 publications

Combining lime softening with alum coagulation for hard Ghrib dam water conventional treatment

Combining lime softening with alum coagulation for hard Ghrib dam water conventional treatment

Natural organic matter (NOM) removal in a typical North-China water plant by enhanced coagulation: Targets and techniques

Sonocatalytic Degradation of Humic Substances From Aquatic Environments Using MgO Nanoparticles

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