308 E. Lancaster Avenue
Wynnewood, PA 19096

Municipal Water Treatment

The first use of activated carbon for water treatment dates back to more than 2000 years ago when the product was used in char form. Powdered Activated Carbon (PAC) became commercialized during the 20th century for water treatment to remove taste and odor contaminants. Granular Activated Carbon (GAC) came into use after World War II.
Major Grades Supplied

Major grades supplied by Carbochem for municipal water treatment:

  • Carbochem® LQ-325: PAC
  • Carbochem® LQ-900S: GAC for regular filter operation
  • Carbochem® BAC-820: Biologically activated GAC for deep bed filters

Operating conditions that make GAC cost-effective:

  • Year round treatment to achieve high quality water
  • Dual filter media

Operating conditions that make PAC cost-effective:

  •  Seasonal demand for specific treatment (such as removing MIB, Geosmin)
Activated Carbon Evaluation and Cost Optimization
  • Requires performance testing which is specific for the contaminant involved (such as MIB, Geosmin) and  reliable analytical techniques
  • Pitfalls producing unreliable results:
  1. Threshold Odor Test has limitations in terms of reproducibility due to the “fatigue factor” and the subjective nature of the test.  In addition, it does not provide an absolute result for a specific compound and therefore has a limited degree of accuracy.
  2. The use of TOC as a surrogate for MIB or Geosmin is not meaningful or reliable since the PAC needs to be filtered before the measurement can be taken, which removes the undissolved organic carbon component and thus effectively only the DOC is measured. DOC consists of a wide range of molecular weight compounds with different functionalities to MIB and Geosmin, so the resulting adsorption result will not be representative of MIB and Geosmin.
  3. The same applies to Tannin Value, as the Tannin Value is only an indicator of tannin removal and has no meaningful correlation to any other performance criterion. Tannin Value is highly dependent on the source of tannic acid used and the correct correlation of the isotherm data to the definition of tannin value given in the Test Protocol.  As a result of these limitations, the tannin value is unreliable and inconsistent which does not make it a valid standard.
Primary Treatment Objectives
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TOC reduction

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Taste and odor removal, such as Geosmin and MIB
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Pesticide removal, such as Atrazine

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Decolorization

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Removal of disinfection byproduct precursors

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Reduction of turbidity (filtration mechanism)
Key Quality Properties of GAC Related to Performance
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Iodine Number: indication of micropore content and surface area

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Abrasion Number: Hardness and degree of attrition including reactivation yield

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Apparent Density: Volume activity and design parameters

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Water Soluble Ash: Level of extractables which can impact water quality

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Pore Size: Needs to be compatible with the dimensions of the contaminant

Origins and Properties of Activated Carbon

Activated Carbon 101: Explore activated carbon's fascinating history and unique properties.