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Volatile Organic Compounds Removal Systems

Volatile Organic Compounds Removal Systems

What are Volatile Organic Compounds (chemicals) 

VOCs are a subset of volatile organic compounds with inherent physical and chemical properties that allow these compounds to move between water and air.

Volatile organic compounds (VOCs) are ground-water contaminants of concern because of very large environmental releases, human toxicity, and a tendency for some compounds to persist in and migrate with ground water to drinking-water supply wells. Some VOCs, such as chlorinated solvents, have been used in commerce and industry for almost 100 years and chloroform and other trihalomethanes (THMs) have undoubtedly been present in chlorinated drinking water since the first continuous municipal application of chlorination in 1908. The production and use of manmade organic compounds, many of which are classified as VOCs, increased by an order of magnitude between 1945 and 1985. Some VOCs have had, and continue to have, very large and ubiquitous usage.

In general, VOCs have high vapor pressures, low-to-medium water solubility and low molecular weights. Some VOCs may occur naturally in the environment, other compounds occur only as a result of manmade activities, and some compounds have both origins.

Volatile organic compounds are released into the atmosphere by anthropogenic and natural emissions which are important because of their involvement in photochemical pollution.

Volatile organic compounds are hydrocarbon compounds those have low boiling points, usually less than 100ºC, and therefore evaporate readily. Some are gases at room temperature. Propane, benzene, and other components of gasoline are all volatile organic compounds and can be isolated from the water phase of a sample by purging the water sample with inert gas, such as helium, and, subsequently, analyzed by gas chromatography.

Many VOCs are human-made chemicals that are used and produced in the manufacture of paints, adhesives, petroleum products, pharmaceuticals, and refrigerants. They often are compounds of fuels, solvents, hydraulic fluids, paint thinners, and dry-cleaning agents commonly used in urban settings. VOC contamination of drinking water supplies is a human-health concern because many are toxic and are known or suspected human carcinogens.

Removal of VOC'S from Water with Activated Carbon


What is Activated Carbon?

Activated carbon has an incredibly large surface area per unit volume, and a network of submicroscopic pores where adsorption takes place. Activated carbon is a material that is produced from carbonaceous source materials, such as coal, coconuts, nutshells, peat, wood, and lignite. The primary raw material used for activated carbon is any organic material with a high carbon content. The carbon-based material is converted to activated carbon through physical modification and thermal decomposition in a furnace, under a controlled atmosphere and temperature. The finished product has a large surface area per unit volume and a network of submicroscopic pores where adsorption takes place.

What are the Properties of Activated Carbon?

An activated carbon product can be characterized by its activity and physical properties. Activity properties include pore size distribution that defines the available pore volume of a carbon over three pore size regions: the micropore, misopore, and macropore regions:

  • Micropore region - less than 100 Angstroms
  • Mesopore region - between 100 and 1,000 Angstroms
  • Macropore region - greater than 1,000 Angstroms

Pore size distribution properties are key indicators of a carbon's potential performance for removing contaminants (adsorbates) from water. The molecules encountered in the gas phase are generally smaller than those in the liquid phase applications; therefore, a gas phase carbon has the majority of its pores concentrated in the micropore region.

A broad range of pore sizes are avaiable, both for ease of movement of adsorbates through the carbon pores and for the adsorption of particular molecular sizes. Liquid phase carbons often contain a broader pore size distribution to remove color bodies and larger organic materials, while maintaining some microporosity for the removal of taste and odor compounds.

Physical properties include surface area, product density, mesh size, abrasion resistance, and ash content.

Typical measured carbon properties include:

Iodine Number - standard testing done to estimate the surface area of the activated carbon by measuring iodine adsorption at a given set of standard testing conditions, reported in mg I2 adsorbed per gram carbon

Surface Area - amount of surface available for adsorption for a given mass of carbon, measured using techniques such as BET nitrogen adsorption; reported in units of m2/g

Product Density - several properties available, including apparent density which is the density of the carbon at maximum packing efficiency, reported in g/cc or lbs/cf

Mesh Size - measure of particle range of the granular product, usually reported as a range of sieve openings, such as 12 x 40 for a carbon that passes a 12 mesh screen, but is retained on a 40 mesh screen with a specification on the amount that can be retained on the larger opening screen or passing the smaller opening screen; basis is US sieve sizes Abrasion Number - measure of the ability of the carbon product to resist attrition; this important property permits one to understand how durable the activated carbon is in applications where backwashing is required, carbon will be transferred, or treatment velocities are above average

Ash Level - a measure of the non-carbon content of the activated carbon, all base materials have a certain ash constituency, with the content varying from base material to base material, for example, coconut shell carbon tends to have more alkali earth metals, while coal-based carbons have more heavy metals.

Table 
Typical Properties of Activated Carbons
Produced from Different Raw Materials

 

Coconut

Bituminous

Lignite

Iodine Number

1,100

950

600

Abrasion Number

85

75

60

Bulk Density as packed
in column lbs/ft3

25

25

23

% Ash

3

6.7

20.1

Granular Activated Carbon Filtratioon Systems

 

We offer skid mounted or containerize fully automatic coconut shell granular activated carbon filtration systems ranging from 50 liters per minute to 1000 liters per minute for removal of violate organic compounds.

 

Features & Benefits

 

  • Fully automatic
  • Skid or Containerized options
  • Heater or air condition options
  • Custom build and modular units
  • Compact footprint
  • High quality filtered water
  • Pressure driven filter systems
  • Fully instrumented and controlled complex process
  • Remote monitoring option
  • Development capability
  • Quality assurance and control management
  • Stainless steel, fiber glass and carbon steel with selective liners options
  • Service contract 

 

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                   Double VOC removal System                     Single VOC Removal System

 

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