In water treatment applications all the three varieties of activated carbon (Coconut Shell activated carbon, Coal activated carbon & Wood activated carbon) are used depending upon the nature of treating potable water and waste water. Hence there is a need for a comparative study of various types of carbon based on their specifications.
The following table shows the technical difference between the three types of activated carbons based on density, hardness and other parameters
| SR NO |
CHARACTER |
COCONUT SHELL ACTIVATED CARBON |
COAL ACTIVATED CARBON |
WOOD ACTIVATED CARBON |
| 1 |
DENSITY |
0.48 TO 0.58 GM/CC (VERY HIGH) |
0.38 TO 0.48 GM/CC (HIGH) |
0.25 TO 0.30 GM/CC (LOW) |
| 2 |
HARDNESS |
98 % MIN (VERY HIGH) |
90 – 95 % (HIGH) |
85% MIN (LOW) |
| 3 |
ASH |
VERY LOW – 3 % MAX |
HIGH – 10 % MAX |
VERY HIGH – 15 % MAX |
| 4 |
POROSITY |
MORE MICROPORES |
MORE MESOPORES & LESS MICROPORES |
MORE MESOPORES & MACROPORES |
| 5 |
WETTABILITY |
VERY HIGH |
NORMAL |
LOW |
| 6 |
HEAVY METALS |
NOT TRACEABLE |
PRESENT |
LOW |
| 7 |
BACK WASHING |
NEGLIGIBLE LOSS OF MATERIAL |
LOW LOSS OF MATERIAL |
– |
| 8 |
OPERATION COST |
LOW |
NORMAL |
HIGH |
| 9 |
AVAILABILITY |
RENEWABLE SOURCE (AGRICULTURAL BYPRODUCT) |
FOSSILE (LIMITED AVAILABILITY) |
RENEWABLE BUT DEPLETING |
| 10 |
BEST SUITABLE FOR |
DECHLORINATION |
ODOUR REMOVAL |
DECOLORIZATION IN POWDER FORM |
| 11 |
APPLICATION (MESH WISE) |
WATER TREATMENT |
EFFLUENT TREATMENT |
ETP |
| 8 X 16, 12 X 30, 8 X 30 |
8 X 30 , 12 X 40 , MINUS 325 |
MINUS 200 |
| WATERTREATMENT BLOCKS |
|
|
| 35 X 70, 80 X 325 |
|
|
Choosing the best solution
Porosity plays a vital role in choosing the right type of carbon. While Coconut activated carbon contains many micropores, Coal activated carbon contains mainly mesopores as well as as micropores whereas wood activated carbon contains mesopores & macropores only. If the molecular size of the impurities are less than 100 angstroms then coconut carbon can be preferred. Likewise if the molecular size of the impurities are between 100 and 1000 angstroms we can use coal carbon. And if the molecular size of the impurities are greater than 1000 angstroms Wood carbon can be considered.
In general
- Wood activated carbon is most suitable for decolorization in powder form.
- Coal activated carbon is suitable for odor removal.
- Coconut activated carbon is suitable for dechlorination.
Cost wise coconut shell activated carbon is little bit expensive compared to coal & wood activated carbon. ”If we are to fill up a vessel of a given volume, the weight of coconut activated carbon required is more due to its high density”. But at the same time there is a negligible loss of material during back washing for coconut activated carbon due to its high hardness. Thus operation cost is low. Wettability is very high, and ash content is very low in Coconut activated carbon. Since it is a renewable source. It is preferable for drinking water treatment and RO water applications. Having said that Coconut activated carbon is best suited for drinking water products.
Coal activated carbon is used in drinking water projects. Apart from that, there are few other industrial applications like Effluent treatment and Waste water treatment. This type of carbon can be best suited for odor removal and cost effective applications.
Wood activated carbon is mainly used in POWDER applications where “decolorization” plays a vital role.
Choosing the right form of activated carbon products mainly depends upon your applications and cost of operation. Professional guidance is the best way to ensure the right product for a particular application.
