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Super Absorbent Polymers & Waste Stabilization
The use of super absorbent polymer (superabsorbent polymer or SAP) in waste stabilization offers many advantages over more conventional absorbents. These advantages include:
- Minimal increase in waste volume or weight
- Lower transport fees due to less loads
- Lower total landfill disposal fees due since waste volume has not expanded
- Faster processing time and consummate labor savings
- No exothermic reaction to release organics or PCBs into the environment.
- Ability to bind most soluble Heavy Metals to prevent leaching
Conventional absorbents include lime kiln dust, Portland cement, dried corn cob, shredded newspaper, bentonite clay and saw dust. These conventional absorbents are relatively cheap – priced in the $20 to $50 per ton range.
Why would someone use a super absorbent polymer that can cost $2.00/lbs or more?
The waste Project Manager needs to evaluate all the key cost parameters of the particular waste stream to determine if the use of SAP is appropriate and cost effective.
In the case of radioactive waste, where loads must be shipped long distances and landfill costs can reach $1000 per cubic yard or more, the use of super absorbent polymer to prevent volume expansion is quickly realized in cost saving. Let’s assume one pays $400 to dispose of a single 55-gallon drum of liquid radwaste at an authorized landfill. The relative savings from using SAP becomes quickly apparent:
|
Waste Lock® SAP |
Bentonite Clay |
|
Absorbent |
Absorbent |
Absorbent Amt Req’d |
25 lbs |
150 lbs |
Cost per pound |
$3.00 / lbs |
$ 0.30 /lbs |
Total Absorbent Cost |
$ 75.00 |
$ 45.00 |
Volume Expansion |
Negligible |
3x (Tripled) |
Final Waste Volume |
55 gallons |
3 X 55 gallons |
Disposal Cost per Drum |
$ 400.00 |
$ 1200.00 |
Total Cost of Disposal |
$ 462.50 |
$ 1245.00 |
Savings from use of Waste Lock® = $782.50 |
In the above case, the cost of the absorbent required is 67% greater when Waste Lock® Super Absorbent Polymer is used versus inexpensive bentonite clay. However, the saving are rapidly wiped out when one considers the costs associated with greatly expanding the waste volume and/or weight.
Further savings can be realized when one also considers faster processing times, labor cost savings and lower transport fees. The following case shows project at the remediation of a Manufactured Gas Plant (MGP) site where Waste Lock® Super Absorbent Polymer was successfully used to stabilize soil/sludge for transport to a hazardous disposal landfill:
Waste Solidification (Waste Lock® vs. Lime Kiln Dust) |
Waste Lock® versus Mineral Absorbent |
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Type of Waste: |
MGP Sludge |
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For |
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For |
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LKD |
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Waste Lock® |
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Project Waste Volume |
200 |
yds³ |
200 |
yds³ |
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Waste Density (lbs/yd³) |
2165 |
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2165 |
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Waste Qty (Tons) |
216.5 |
|
216.5 |
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% Water in Waste |
50% |
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50% |
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Absorbent Costs |
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Amount Absorbent Needed per Ton |
500 |
lbs. |
20 |
lbs. |
Cost of Absorbent per weight unit |
$ 38.00 |
/ T |
$ 2.10 |
/ lbs |
Cost of Absorbent per Ton of Waste |
$ 9.50 |
|
$ 42.00 |
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Total Absorbent Needed for Project |
108,250 |
lbs |
4,330 |
lbs |
(Tons Waste X Absorbent per Ton) |
54.1 |
Tons |
2.2 |
Tons |
Project Cost of Absorbents |
$ 2,057 |
|
$ 9,093 |
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Transport & Disposal Costs |
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Landfill Disposal Fee |
$ 35.00 |
/ T |
$ 35.00 |
/ T |
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Transport Cost to Dispoal Facility |
$ 45.00 |
/ T |
$ 45.00 |
/ T |
(Located 150 miles away) |
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Total Waste (Original + Absorbent) |
270.6 |
Tons |
218.7 |
Tons |
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Transport + Disposal Costs |
$ 21,650 |
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$ 17,493 |
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Labor Costs |
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Minutes to Process One Ton Waste |
60 |
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15 |
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Workers Used |
2.5 |
|
2.5 |
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Man-Hours to Process One Ton Waste |
2.5 |
|
0.625 |
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Cost per Man-Hour (Wages + Benefits) |
$ 38.00 |
|
$ 38.00 |
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Total Labor Cost for Project |
$ 20,568 |
|
$ 5,142 |
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(Tons X Man-Hour Costs) |
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Cost of Transport Disposal |
$ 21,650 |
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$ 17,493 |
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Cost of Absorbents Consumed |
$ 2,057 |
|
$ 9,093 |
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Total Labor Costs |
$ 20,568 |
|
$ 5,142 |
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Total Project Cost |
$ 44,274 |
|
$ 31,728 |
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Absorbents plus Transport/Landfill Fees |
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Savings from use of Waste Lock® |
$ 12,546 |
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This spreadsheet shows the significant savings of using the Super Absorbent Polymer for stabilization. Actual savings may be somewhat higher if:
- Waste must be disposed of in B-25 or other metal boxes at landfill. Volume expansion will directly impact waste packaging costs.
- The faster processing rate with Super Absorbent Polymer ends the project quicker and frees up the project resources and assets to be quickly mobilized on another project generating company revenue.
In conclusion, the use of Super Absorbent Polymers like Waste Lock® Super Absorbent Polymer can often yield better economics over less expensive and less sophisticated absorbents (like saw dust, clay, LKD, etc…) when the full project costs of the alternatives are compared.
10 October 2007
Martin Matushek
M² Polymer Technologies, Inc.
West Dundee, IL |
