United States
Environmental Protection
Agency
Research and Development
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
EPA/600/S-92/048 October 1992
ENVIRONMENTAL
RESEARCH BRIEF
Waste Reduction Activities and Options for a
Transporter of Bulk Plastic Pellets
Hanna Saqa and Daniel J. Watts*
Abstract
The U.S. Environmental Protection Agency (EPA) funded a
project with the New Jersey Department of Environmental
Protection and Energy (NJDEPE) to assist in conducting waste
minimization assessments at 30 small- to medium-sized busi-
nesses in the state of New Jersey. One of the sites selected
was a trucking company which specializes in the transportation
of dry bulk plastic pellets from the manufacturer to the user.
The assessment focused on the large volumes of hot water
which are used to clean the tank trucks between shipments. A
site visit was made in 1990 during which several opportunities
for waste minimization were identified. Options identified in-
cluded recirculation of the water and use of compressed gasses
as a partial replacement for the water stream used to clean the
trucks. Implementation of the identified waste minimization
opportunities was not part of the program. Percent waste
reduction, net annual savings, implementation costs and pay-
back periods were estimated.
This Research Brief was developed by the Principal Investiga-
tors and EPA's Risk Reduction Engineering Laboratory in Cin-
cinnati, OH, to announce key findings of this completed as-
sessment.
Introduction
The environmental issues facing industry today have expanded
considerably beyond traditional concerns. Wastewater, air
emissions, potential soil and groundwater contamination, solid
waste disposal, and employee health and safety have become
increasingly important concerns. The management and disposal
of hazardous substances, including both process-related wastes
* New Jersey Institute of Technology, Newark, NJ 07102
and residues from waste treatment, receive significant atten-
tion because of regulation and economics.
As environmental issues have become more complex, the
strategies for waste management and control have become
more systematic and integrated. The positive role of waste
minimization and pollution prevention within industrial operations
at each stage of product life is recognized throughout the
world. An ideal goal is to manufacture products while generat-
ing the least amount of waste possible.
The Hazardous Waste Advisement Program (HWAP) of the
Division of Hazardous Waste Management, New Jersey De-
partment of Environmental Protection and Energy, NJDEPE, is
pursuing the goals of waste minimization awareness and pro-
gram implementation in the state. HWAP, with the help of an
EPA grant from the Risk Reduction Engineering Laboratory,
conducted an Assessment of Reduction and Recycling Oppor-
tunities for Hazardous Waste (ARROW) project. ARROW was
designed to assess waste minimization potential across a
broad range of New Jersey industries. The project targeted 30
sites to perform waste minimization assessments following the
approach outlined in EPA's Waste Minimization Opportunity
Assessment Manual (EPA/625/7-88/003). Under contract to
NJDEPE, the Hazardous Substance Management Research
Center at New Jersey Institute of Technology (NJIT) assisted
in conducting the assessments. This research brief presents
an assessment of the transportation of dry plastic pellets from
the manufacturer to the user (1 of the 30 assessments per-
formed) and provides recommendations for waste minimization
options resulting from the assessment.
Methodology of Assessments
The assessment process was coordinated by a team of techni-
cal staff from NJIT with experience in process operations,
Printed on Recycled Paper
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basic chemistry, and environmental concerns and needs. Be-
cause the EPA waste minimization manual is designed to be
primarily applied by the in-house staff of the facility, the degree
of involvement of the NJIT team varied according to the ease
with which the facility staff could apply the manual. In some
cases, NJITs role was to provide advice. In others, NJIT
conducted essentially the entire evaluation.
The goal of the project was to encourage participation in the
assessment process by management and staff at the facility.
To do this, the participants were encouraged to proceed through
the organizational steps outlined in the manual. These steps
can be summarized as follows:
• Obtaining corporate commitment to a waste minimization
initiative
• Organizing a task force or similar group to carry out the
assessment
• Developing a policy statement regarding waste minimiza-
tion for issuance by corporate management
• Establishing tentative waste reduction goals to be achieved
by the program
• Identifying waste-generating sites and processes
• Conducting a detailed site inspection
• Developing a list of options which may lead to the waste
reduction goal
• Formally analyzing the feasibility of the various options
• Measuring the effectiveness of the options and continuing
the assessment.
Not every facility was able to follow these steps as presented.
In each case, however, the identification of waste-generating
sites and processes, detailed site inspections, and development
of options was carried out. Frequently, it was necessary for a
high degree of involvement by NJIT to accomplish these steps.
Two common reasons for needing outside participation were a
shortage of technical staff within the company and a need to
develop an agenda for technical action before corporate com-
mitment and policy statements could be obtained.
It was not a goal of the ARROW project to participate in the
feasibility analysis or implementation steps. However, NJIT
offered to provide advice for feasibility analysis if requested.
In each case, the NJIT team made several site visits to the
facility. Initially, visits were made to explain the EPA manual
and to encourage the facility through the organizational stages.
If delays and complications developed, the team offered assis-
tance in the technical review, inspections, and option develop-
ment.
No sampling or laboratory analysis was undertaken as part of
these assessments.
Facility Background
The facility is the home base of a medium sized trucking-
transportation company, which specializes in transporting dry,
bulk plastic pellets of several types including polypropylene,
pplyvinyl chloride, and polystyrene. The company is respon-
sible for the movement of the pellets from the plastic manufac-
turer to their customers. The economics of manufacture and of
the use of large quantities of the pellets favor such bulk
transportation. There are significant quality issues which re-
quire segregation of different types and composition of pellets,
contamination may result in inferior quality of products by the
user of the pellets. The transportation company then must
scrupulously clean the tankers between each load. It was
reported that some customers will refuse a shipment if a single
foreign pellet is observed.
At this facility, other activities including vehicle maintenance
occur. The waste reduction opportunities assessment was car-
ried out only on the plastic pellet handling and cleaning section
of the facility at the request of the management. There was
very little input received from the management. The identifica-
tion of options and of necessary additional information was
carried out by the assessment team.
The facility houses administrative buildings, a 2-bay mainte-
nance garage, parking areas, and the tank cleaning operation.
The site is bordered by a small stream. About 200 people are
employed at the rural location.
Operational Processes
The process of cleaning the trucks' tanks involves use of
filtered water from a 250-ft deep well which is on the property.
The water is heated in a Karcher unit and sprayed through a
revolving head. The head is lowered into the body of the tank
through the port on the top. Multiple nozzles on the head are
designed to assure that the water streams are directed at all
areas of the truck interior. The water exits the tank, carrying
the pellets, through a 4-in. drain at the rear of the tank. The
drain is fitted with a "sock-like" bag filter to capture the pellets
which are removed from the truck by this procedure. The
capture pellets are recovered, segregated by type, and returned
to the manufacturer or sold to brokers for reuse. On average 2
or 3 tank trucks are cleaned by this process each day. Average
daily water use is about 10,000 gal. About 5 gal of pellets are
recovered each day.
Existing Waste Management Activities
From a broad industry-wide perspective it seems that activities
of this company are supportive of many commonly encouraged
principles of pollution prevention. Shipment of materials in bulk
eliminates the need for packaging materials and eliminates
substantial quantities of waste. Careful attention to product
quality and prevention of cross contamination of materials is
critical to minimize product and process failures by the ultimate
manufacturer. Such failures also contribute to the waste stream.
This facility takes care to recover and return to the manufacturing
stream the excess pellets which would otherwise contaminate
other materials or be discarded as waste. This tank cleaning
activity illustrates a less commonly recognized principle—that
many pollution prevention benefits require action by someone
in the raw materialAransportation/production chain which results
in a waste stream.
The rinse water is collected in a sump after passing through
the bag filter at the exit port of the tank. The sump has a float
which triggers a pump to move the collected water to a storm
water catch basin in a paved area. This water, as well as storm
water runoff, is drained into a pair of underground settling
tanks. The outflow of these tanks enters a stream which borders
the property. Periodically (approximately once each year), the
settling tanks are cleaned and any solid residue is sent offsite
as nonhazardous waste. While the vehicle maintenance area
was not a part of this assessment, it was learned that waste
and used oil, oil filters, and other vehicle fluids from this facility
are drummed and sent offsite for treatment.
It was observed that occasionally the water from the tank
cleaning had a grayish color after passing through the bag filter
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at the exit port of the tank. It was observed that the effluent
from the settling tanks also had the grayish color. It was
concluded that any waste minimization options should address
this issue.
Waste Minimization Opportunities
The type of waste currently generated by the facility, the
source of the waste, the quantity of the waste and the annual
treatment and disposal costs are given in Table 1. This particular
facility presents a dilemma in determination of waste manage-
ment costs. The present water handling system commingles
the tank cleaning water and storm water runoff at the settling
tanks and it is difficult to ascribe costs to each individual
source. It is estimated that the annual solids removal costs are
$1500. A very high estimate is that 25% of the solids come
from the tank cleaning operation.
Table 2 shows the opportunities for waste minimization recom-
mended for the facility. The type of waste, the minimization
opportunity, the possible waste reduction and associated sav-
ings, and the implementation cost along with the payback time
are given in the table. The quantities of waste currently gener-
ated at the facility and possible waste reduction depend on the
level of activity of the facility. All values should be considered
in that context. It must be frankly stated that any waste reduc-
tion option at this facility will result in no savings by standard
calculation methods. It will be a net cost to evaluate and install
any new procedures and technology. Not every pollution pre-
vention option necessarily results in a cost savings. However,
other savings not quantifiable by this study include a wide
variety of possible future costs which will be incurred if the
facility cannot discharge into the stream, or costs which may
be incurred as a result of cleanup liability in the future.
As discussed previously, the pollution prevention challenge
identified at this facility has to do with the cause and resolution
of the gray color in the effluent water from the tank cleaning
process. It is assumed that the color represents small quantities
of material which are derived from the plastic pellets. Two
possibilities were identified. It is possible that some types of
pellets have a water-soluble additive which is removed by the
water used in the cleaning. This was considered to be a
remote possibility, however, based upon the relatively small
quantity of pellets which remain in the tanks and the relatively
large volume of water which is used in the cleaning.
The other possibility identified was that the color actually results
from the presence of powdery fines from the pellets themselves.
Such fines could result from grinding of the pellets against
each other while they bump along the road as well as during
filling and emptying procedures. Such fines are likely to be
electrostatically charged and retained on the surface of the
tank. Alternatively, the pellet rubbing could occur during the
actual cleaning operation. This was seen as a less likely
possibility for the same reasons as described above—the small
quantity of pellets which remain in the tank prior to the cleaning
operation.
One pollution prevention possibility is to develop a system to
allow recycling of the water used in the cleaning operation.
Presumably the fines (if that is the explanation) will settle out,
given enough time. They could also be removed by filtration,
coagulation, orflocculation. It appears uneconomical to construct
a treatment system for this application. Addition of a storage
tank with a second and finer filter to be used after the bag filter
may address this situation. The water could be reused several
times because its function in this application is primarily to
push material.
Another option which should be evaluated is to remove any
fines which may be adhering to the walls of the tank using air
rather than water. Use of a directional nozzle, similar to that
used presently to direct water streams, could assure coverage
of the entire interior of the tank. It would be necessary to have
a fine filter, and preferably a high volume vacuum filter at the
exit port of the tank to capture the fines which would be
passing out of the tank. Because of the potential for electrostatic
charges on the fines, it may be preferable to ground the tank to
dissipate this charge.
Regulatory Implications
There do not seem to be significant regulatory implications
which would impede pollution prevention initiatives at this facility.
It is likely that increased emphasis on the quality of water
discharged directly to the stream will encourage pollution pre-
vention at this facility. Careful and regular attention should be
given to discharge requirements to assure compliance with all
regulations.
This Research Brief summarizes a part of the work done under
cooperative Agreement No. CR-815165 by the New Jersey
Institute of Technology under the sponsorship of the New
Jersey Department of Environmental Protection and Energy
and the U.S. Environmental Protection Agency. The EPA Project
Officer was Mary Ann Curran. She can be reached at:
Pollution Prevention Research Branch
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, OH 45268
* Mention of trade names or commercial products does not constitute endorse-
ment or recommendation for use.
Table 1. Summary of Current Waste Generation
Waste Generated
Aqueous Discharge to
Settling Tank
Source of Waste
Annual Quantity
Generated
Annual Waste
Management Costs
Effluent from the tank cleaning
operation
2,500,000 gal
$375
GOVERNMENT PRINTING OFFICE: 1994 - 550-4*7/80161
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Table 2. Summary of Recommended Waste Minimization Opportunities
Waste Stream
Reduced
Minimization Opportunity
Annual Waste Reduction
Quantity Percent
Tank Cleaning Effluent
Installation of storage tank,
filter, and pump to allow
removal of the fines and recycling
of the water. *
2,000,000 gal
Net Implementation Payback
Annual Savings Cost Years *
80
$300
$10,000
33
Installation of air pressure/
vacuum recovery system for
removal of fines from the tank.
It is not known if all of the
pellets could be removed in this
way as well. It is possible that
the water wash could be eliminated.
Assume that water wash is
still needed, then there will
be no savings. If it is not
needed, then the savings will
be 100%.
4,000
0-13
* Savings result from reduced raw material and treatment and disposal costs when implementing each minimization opportunity independently.
This option reduces the amount of fresh water needed but does not reduce water usage or contamination by fines.
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
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