Control Techniques for Coagulation‐Filtration

Hannah, S. A.; Cohen, Jesse M.; Robeck, Gordon G.

doi:10.1002/j.1551-8833.1967.tb03502.x

Cited by 24 publications

(9 citation statements)

References 24 publications

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“…More recently, temperature effects on coagulation were mentioned in an article on coagulation control parameters written by Hannah et a1. 3 They conducted a limited number of coagulation studies on one water sample at various temperatures. Results indicated that under cold-temperature conditions, efficiency of turbidity removal decreased.…”

Section: Research and Technologymentioning

confidence: 99%

Temperature Effects on the Use of Metal‐Ion Coagulants for Water Treatment

Morris¹,

Knocke²

1984

Journal AWWA

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The effects of low‐temperature conditions on the use of alum and ferric chloride for the removal of turbidity were studied. Experimental work involved the use of these coagulants for the removal of kaolin from water samples under both extreme‐low‐temperature and room‐temperature conditions. Analysis of data from a full‐scale treatment plant that experienced failure at low temperature was also included. Temperature effects on coagulation were significant, with low‐temperature conditions producing sharp decreases in turbidity removal efficiency. Alum coagulation was most severely affected. Precipitation studies showed that temperature did not significantly inhibit the rate of metal‐ion precipitation.

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Section: Research and Technologymentioning

confidence: 99%

Temperature Effects on the Use of Metal‐Ion Coagulants for Water Treatment

Morris¹,

Knocke²

1984

Journal AWWA

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“…little quantitative data were presented. 7 With the current need to control the One major operational difficulty that water treatment plants face in attempting to meet the THM standards is related toseasonal fluctuations in water quality. For example, changes in water temperature appear to affect the kinetics and equilibrium of metal hydroxide precipitation, resulting in a potentially adverse effect on coagulation systems.…”

mentioning

confidence: 99%

Effects of Low Temperature on the Removal of Trihalomethane Precursors by Coagulation

Knocke¹,

West²,

Hoehn³

1986

Journal AWWA

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This study showed that the trihalomethane (THM) concentration in finished water that had ken treated at 35.6" F (2°C) was significantly lower than in water treated at 71.6" F (22°C). Water temperature did not appear to affect the removal of total organic carbon (TOC) during coagulation with metal ion salts, but color removal was slightly reduced at low temperatures. The efficiency of coagulation for removing TOC, color, and THM formation potential improved when the water was treated at pH 5 rather than pH 7, regardless of temperature. Removal of low-molecular-weight organic substances was found to be more difficult at 35.6" F (2°C) than at 71.6" F (22°C). The data obtained suggest that reduced THM concentrations in finished water during winter are strictly a function of the reduced rate of THM formation.Campet alaconcluded that although low temperature did not affect the flocculation step of treatment, settling efficiency was impaired. Morris and Knocke6 presented quantitative results showing that low temperatures reduced the efficiency of metal ion coagulants for removal of turbidity from surface waters. They concluded that low temoeratures at times During the past ten years, considerable research has been conducted to determine how the disinfection of drinking water with chlorine can lead to the formation of potentially carcinogenic compounds, particularly trihalomethanes (THMs). Studies have also been conducted to evaluate methods of removing THMs from water with treatment methods such as air stripping' :' and adsorption by activated carbon columns." -" In addition, significant research has focused on methods of removing the organic precursors of THMsmethods such as the optimization of coagulation-flocculation systems.promoted the formation of extremely ciency and poor coagulation. Earlier work small particles, which did not settle mentioned possible problems with tur-well. Thus, their results showed that bidity removal when alum coagulation temperature affected both the flocculawas used at low temperatures, although tion and settling phases of treatment. little quantitative data were presented.7With the current need to control the One major operational difficulty that water treatment plants face in attempting to meet the THM standards is related toseasonal fluctuations in water quality. For example, changes in water temperature appear to affect the kinetics and equilibrium of metal hydroxide precipitation, resulting in a potentially adverse effect on coagulation systems.6 The flocculation and sedimentation stages of water treatment can also be affected by water temperature as a result of changes in solution viscosity and density. Until recently, temperature variations were not recognized as one of the potential causes of water treatment plant ineffi-APRIL 1986 Figure 1. Effect of incubation temperature on the rate of THM formation in Harwood' s Mill Reservoir water treated with 60 mg alum/L at pH 7 Figure 2. Effect of alum dose and temperature on turbidity removal from Chickahominy River water by coagulation ...

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“…The silting index may therefore be used to control coagulant overdosing. Shull 136 has described a procedure similar to the determination of the silting index of Hannah et al 135 He compared the time required to filter, at constant pressure, a 200-ml sample of jar test supernatant through a 0.45-fim membrane filter, to the time required to filter an equal volume of distilled water. The ratio was defined as the "filterability number", and was related to ZP measurements.…”

Section: Crc Critical Reviews In Environmental Controlmentioning

confidence: 99%

“…Hannah et al 135 evaluated the particle content of aqueous suspensions by passing the coagulated suspension through a millipore filter at constant pressure. The flow rate decreases as the test proceeds and is recorded as a function of time.…”

Section: Crc Critical Reviews In Environmental Controlmentioning

confidence: 99%

Granular media filtration in water and wastewater treatment: Part 2∗

Jackson¹,

Letterman

1980

C R C Critical Reviews in Environmental Control

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VII. POLYELECTROLYTES AS FILTER AIDSThe importance of surface chemistry to the process of granular media filtration was noted in Section V of Part I of this article. Beneficial changes in the surface chemical properties of granular media and suspended solids can be brought about by the addition of an appropriate chemical reagent (an inorganic and/or an organic coagulant/ flocculant, for example) to the wastewater stream. Although seldom taken into consideration in the models proposed to explain particle deposition and removal, chemicalaided granular media filtration is, in fact, widely practiced to improve the performance of full-scale filtration units.This section deals with the role and use of chemicals as filtration aids, with their selection, point and mode of application, and the methods used to determine the dose of chemical needed to optimize filter performance. Chemicals referred to by trade name in the text are identified according to structure in Appendix B.

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Control Techniques for Coagulation‐Filtration

Cited by 24 publications

References 24 publications

Temperature Effects on the Use of Metal‐Ion Coagulants for Water Treatment

Temperature Effects on the Use of Metal‐Ion Coagulants for Water Treatment

Effects of Low Temperature on the Removal of Trihalomethane Precursors by Coagulation

Granular media filtration in water and wastewater treatment: Part 2∗

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