Page 373 - Solid Waste Analysis and Minimization a Systems Approach

IMPLEMENTATION AND APPROACH 351

Use of alternative abrasives—The use of alternative abrasive media can be used in
many of these types of applications such as switching to a steel shot or grit because,
overall, these abrasives are more cost-effective. The steel shot or grit can be used
over 3000 times before having to be replaced. To reuse the abrasive, a capture and
separation system consisting of an enclosure, bar grading, screw conveyors, and a
wash system would need to be installed. The steel shot or grit abrasive is more
expensive ($0.30 per pound f.o.b. [freight on board]), but can be reused many times
to make it more cost-beneficial. Additional investigation into the cost of the equip-
ment and the feasibility is needed to determine if this option is viable.

Collect sand and reuse—Another option to reduce sand blast waste is to vacuum up
used sand back into the feed hopper and reuse for next job. This option is not very
feasible because of the contamination present in the used sand and the inability to
separate the particles from the concrete blast and the sand used for sand blasting.
The sand also pulverizes when shot at concrete at a high pressure, and therefore
would not be reusable.

Workers use shop towels throughout the facility to clean various items and to
wipe their hands. These towels become soiled and greasy and are disposed of with
the municipal solid waste. Approximately 5000 lb of shop towel waste is generated
each year.

Launder on site—The rags could be laundered on site using a standard washer and
dryer for reuse. By purchasing a washer and dryer (about $1200), one person from
the facility could be assigned the duty to wash and dry the towels. More durable
rags should be purchased to be able to withstand repeated washings. Drawbacks
for this option include the need for additional labor to wash and dry the towels, and
the possibility of discharging oil, which is an environmental and regulatory
concern.

Use laundry service—Laundry services exist that will wash and deliver fresh towels
to industrial customers. The average cost for laundering industrial shop towels is
$0.75 per pound. Assuming the amount of shop towels that would need to be pur-
chased is 1500 lb, below is a simplified cost analysis:

Laundry service 1500 lb × $0.75 per pound = $1,125 per year

Potential cost savings
Assuming a purchase cost of $0.50 per pound, the savings in purchase of shop towels
would be

$0.50 per pound × (5000 − 1500) lb = $1750

3
Disposal of the current shop towels is assumed to be one 20 yd dumpster at $224 per
haul. The overall estimated cost savings for this option is

$1750 + $224 − $1125 = $849 per year