United States
Environmental Protection
Agency
Risk Reduction
Engineering Laboratory
Cincinnati, OH 45268
Research and Development
EPA/600/SR-93/008 March 1993
Project Summary
Pollution Prevention Opportunity
Assessment
USDA Beltsville Agricultural
Research Center
Beltsville, Maryland
A pollution prevention opportunity
assessment (PPOA), performed during
the spring of 1991, Identified opportu-
nities for waste reduction at the U.S.
Department of Agriculture's Beltsville
Agricultural Research Center (BARC),
Beltsville, MD. These opportunities In-
volved general hazardous materials
handling and use, total Kjeldahl nitro-
gen (TKN) analyses, and high perfor-
mance liquid chromatography (HPLC)
analyses.
One pollution prevention option ap-
plicable to total Kjeldahl analyses In-
volved use of an automated nitrogen
analyzer. Acid and base wastes are vir-
tually eliminated, and chemical and la-
bor costs are reduced significantly.
Other pollution prevention options for
total Kjeldahl analysis included use of
phenate autoanalyzer, micro analysis,
and alternate catalyst. Pollution pre-
vention options for HPLC included solid
phase extraction, supercritical fluid ex-
traction, solvent recovery, and column/
particle size reduction.
77i/s Project Summary was developed
by EPA's Risk Reduction Engineering
Laboratory, Cincinnati, OH, to an-
nounce key findings of the research
project that Is fully documented In a
separate report of the same title (see
Project Report ordering Information at
back).
Introduction
EPA has developed a systematic ap-
proach to identify, evaluate, and imple-
ment options to reduce or eliminate
hazardous waste. The approach is pre-
sented in a guidance document entitled
"Waste Minimization Opportunity Assess-
ment Manual" (EPA/625/7-88/003). The
procedure described in the EPA manual
provides detailed worksheets and a pro-
cess/option evaluation method for use in
industrial settings. For BARC, appropriate
worksheets were used to quantify waste
generation, evaluate options, and calcu-
late payback. To encourage use of this
manual, EPA is conducting a series of
pollution prevention assessment projects.
BARC employs approximately 1000 sci-
entists and technicians who perform re-
search work in all areas related to the
Agricultural Research Service activities.
State-of-the-art research is conducted on
livestock diseases, animal and human nu-
trition, animal genetics and physiology,
plant productivity and diseases, and a host
of other topics. The pollution prevention
assessment was conducted for the U.S.
Environmental Protection Agency's (EPA)
Risk Reduction Engineering Laboratory
(RREL) under the purview of the Waste
Reduction Evaluations at Federal Sites
(WREAFS) Program of EPA's Pollution
Prevention Research Branch. This report
summarizes the application of the EPA
procedure to selected processes at BARC.
Procedure
EPA's systematic assessment procedure
can be used by a facility's own employees
to identify pollution prevention opportuni-
ties. As a structured program, it provides
intermediate milestones and a step-by-
step procedure to (1) understand the
facility's processes and wastes, (2) iden-
tify options for reducing waste, and (3)
determine whether the options are techni-
cally and economically feasible enough to
p Printed on Recycled Paper
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justify implementation. The Waste Minimi-
zation Opportunity Assessment Manual
contains a set of 19 worksheets designed
to facilitate the pollution prevention as-
sessment procedure. This procedure con-
sists of four major steps:
• Planning and organization—organiz-
ing and goal setting.
• Assessment—carefully reviewing a
facility's operations and wastestreams
and identifying and screening poten-
tial options to minimize and prevent
wastes.
• Feasibility analysis—evaluating the
technical and economic feasibility of
the options selected and subsequently
ranking the options.
• Implementation—procuring, installing,
implementing, and evaluating (at the
discretion of the facility).
As the result of discussion with the
BARC environmental staff, researchers,
and EPA personnel, the investigation fo-
cussed on:
• general hazardous materials handling
and usage,
• TKN analyses, and
• HPLC analyses.
General Hazardous Materials
Handling and Usage
The BARC facility generates approxi-
mately 5,300 gal of hazardous waste an-
nually at a disposal cost of approximately
$423,000. A strong site-wide hazardous
waste management program is led by the
Safety, Occupational Health, and Environ-
mental Section Office. This program in-
cludes state-of-the-art marshalling facilities
for solvent bulking, site-wide hazardous
waste training, the presence of collateral
hazardous waste duty officers in each re-
search institute, an electronic mail system
for trading chemicals onsite, recycling pro-
grams, and others. An existing strong in-
centive for pollution prevention on the site
is the charge-back policy, by which man-
agement units are assessed for disposal
costs. This incentive, coupled with the en-
vironmental ethic of many researchers and
their desire to minimize raw material costs,
has already led to significant pollution pre-
vention onsite. Additional approaches to
pollution prevention were identified in this
study.
Total KJeldahl Nitrogen
The Kjeldahl method is a widely used
standard method of chemical analysis, first
described in 1883, for determining protein
nitrogen in grains, meats, and other bio-
logical materials. Samples requiring analy-
sis are oxidized in hot, concentrated
su If uric acid, with bound nitrogen converted
to ammonium ions. Subsequent steps in-
clude treatment with an excess of strong
base, distillation, and titration of the liber-
ated ammonia.
Quantities of reagent used for the
Kjeldahl procedure vary based on the ni-
trogen content of the sample being ana-
lyzed. Samples with low nitrogen content
require increased sample size for analy-
sis. These samples use macro-Kjeldahl
techniques that generate approximately
500 to 600 ml of waste per sample.
Samples in which the nitrogen content is
higher allow for a smaller sample size;
therefore, the micro-Kjeldahl analysis is
appropriate. Micro-Kjeldahl wastes are es-
timated at 50 to 100 ml per sample.
Wastes requiring disposal after a Kjeldahl
analysis consist of the digest, which is
alkaline and contains metals used as cata-
lysts, and the distillate, which is either
acidic or basic. The total acid and base
wastestreams for 1990 for BARC were
approximately 850 gal.
High Performance Liquid
Chromatography
Laboratories at BARC extensively em-
ploy HPLC in their work. Like other forms
of chromatography, HPLC is used to sepa-
rate, isolate, and identify components of
mixtures. Compounds of interest are sepa-
rated on a column containing solid adsor-
bent based on differing affinities for the
packing material. Solvents are used to
introduce samples and to elute materials
through and off the column. A pump is
required for solvent flow. Sensitive detec-
tors identify and quantify compounds elut-
ing from the column. Before using HPLC,
a preparative or extractive procedure iso-
lates a specific analyte or characteristic
class of compounds. Organic solvents are
used for these extractions.
Approximately 2,600 gal of solvent waste
was generated by BARC during 1990. A
significant amount of this total stems from
the use of organic solvents in HPLC and
in sample preparation.
The sample preparation step isolates
either components of interest or
interferents for the sample matrix before
analysis and quantitation through HPLC.
At BARC, the main procedures used are
liquid-liquid or solid-liquid extraction. Aque-
ous samples may be extracted with an
organic liquid, or samples may be ex-
tracted directly with solvent. Secondary
extractions may also be performed. Ex-
traction solvents used at BARC include
chloroform, hexane, methanol, and meth-
ylene chloride. Extractions and prepara-
tive procedures account for a significant
percentage of solvent wastes generated
at BARC.
Hazardous wastes generated directly as
a result of HPLC analyses consist of the
solvents used as mobile phase to intro-
duce and elute analytes through the chro-
matography column. Typical solvents used
include aqueous mixtures of methanol,
acetonrtrile, etc. The nature of the HPLC
effluent leads to its categorization as a
hazardous waste because of its flamma-
bility and, possibly, other characteristics
of hazardous waste.
Pollution prevention in HPLC begins with
an understanding of how the separation
process proceeds. The goal of the analyst
is to achieve the best separation in the
shortest time. To obtain this separation,
the analyst can change the following vari-
ables:
• mobile phase composition
• stationary phase composition
• temperature
• flowrate
• column configuration
• particle size
Each of these factors plays a significant
role in achieving the desired level of sepa-
ration. The first three variables control the
elution time of the component (i.e., the
time taken between component injection
and detection). The last three variables
control the width of the peak. As the peak
narrows, sensitivity increases since the
signal level rises above the detector's in-
strumental noise level. Additionally, a faster
eluting compound will have a narrower
peakwidth since broadening processes
have been curtailed.
Results and Discussion
During the course of the project, a num-
ber of generic laboratory pollution preven-
tion tools and techniques were identified.
These include waste management books
and manuals that describe common-sense
approaches to reducing wastes generated
by laboratories. Specific techniques and
references are contained in the project
report. One interesting concept is the pro-
cedure conducted at the end of laboratory
procedures that renders certain wastes
nonhazardous.
The project identified a number of im-
pediments to further pollution prevention
activities at BARC. Probably the biggest
impediment is the nature of waste gen-
eration onsite. Because a large number of
small quantity wastes streams are gener-
ated by the large number of laboratories,
standard waste reduction techniques ap-
plied at other sites are not directly appli-
cable. Other impediments to pollution
prevention include the need for new labo-
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ratory methods to be approved by inde-
pendent boards such as the Association
of Official Analytical Chemists (AOAC).
Therefore, changes in laboratory proce-
dures are difficult to implement.
General pollution prevention options
concerning hazardous materials handling
and use are given in Table 1. The major
pollution prevention initiative identified in
this report is a thorough audit of the types
and quantities of hazardous waste gener-
ated onsite. Until specific waste streams
are identified and quantified, it will be diffi-
cult to determine how much further
progress is feasible regarding pollution pre-
vention. Additional recommended initiatives
include further discussions with regulatory
agencies regarding laboratory treatment
options; centralizing various operations,
where feasible, to reduce the waste, in-
cluding a central chemical warehouse and
a centralized purchasing system; and fur-
ther education and training of site person-
nel. Additional pollution prevention
concepts for TKN and HPLC are con-
tained in Table 2.
The most interesting finding regarding
the TKN assessment was that methods
exist to virtually eliminate hazardous waste
generated by Kjeldahl analyses. Commer-
cially available automated microcomputer-
based systems use combustion techniques
to remove nitrogen from the sample and a
thermal conductivity detection system to
measure the released nitrogen. Nitrogen
concentrations are determined in less than
3 min according to one manufacturer's
literature. Acceptable sample sizes vary
from 1 mg to 1 g, depending on nitrogen
concentration and sample density. Some
of these units are currently in operation at
BARC, and scientists are pleased with
their operations. Scientists outside BARC
also praise the method, and method ap-
proval by the AOAC has been obtained
for certain analyses, with additional ap-
provals for other analyses expected shortly.
These analyzers provide a significant
health and safety improvement to labora-
tory workers because handling of hot ac-
ids and bases is eliminated and sulfur
trioxide fumes generated during digestion
are eliminated. Of course, suitable health
and safely precautions are needed be-
cause of the use of flammable gases with
the automatic analyzer. Disposal costs for
waste from the automated analyzer are
estimated at $0.65 per sample; those for
macro-Kjeldahl analysis, $2.85. Labor per
Kjeldahl analysis is estimated to be re-
duced by approximately 50% with the au-
tomated system. Acid and base waste
generation is virtually nonexistent; how
ever, copper filings and anhydrous chemi-
cals used for water removal must be
disposed of when spent. The $30,000 cost
for this instrument may limit its use in
laboratories performing a limited number
of analyses yearly. (Treatment steps for
TKN wastes are also discussed in the
complete Project Report.)
A number of techniques can help pre-
vent the pollution associated with HPLC
analyses. Solid phase extraction (SPE)
techniques can reduce solvent usage by
over 95% when performing certain extrac
Table 1. General Pollution Prevention Options for BARC
Pollution Prevention Techniques
Training and assessments
Process or equipment modification
Waste segregation
BARC Options
Expand on the existing pollution prevention ethic with further education and training. Successful efforts are
already underway including paper recycling and source reduction in individual operations.
Appoint a pollution prevention "officer" within each research institute to assist researchers with reduction and
recycling initiatives. Pollution prevention representatives from all the institutes could meet periodically to
discuss and compare efforts among institutes. Such information transfer, crucial for the adoption of pollution
prevention throughout the BARC, reduces repetitive pollution prevention development efforts. For example,
DOE's Sandia National Laboratories has a pollution prevention network where 60 people throughout the
laboratories are points of contact
Develop and implement a plan to conduct periodic laboratory pollution prevention laboratory assessments
using suitable, in-house expertise. Such assessments may uncover additional pollution prevention opportun-
ities over time, and emphasize BARC's commitment to pollution prevention; they can also be used to
monitor the success of pollution prevention efforts.
Keep abreast of commercially available technology changes as they relate to laboratory pollution prevention.
When new technology is too expensive for individual laboratories to implement, consider pooling resources
and locating instruments at a centralized facility, which may be used by several laboratories.
Reduce atmospheric emissions of chemicals from laboratories as part of a comprehensive pollution prevention
program. Glassware and automated extraction systems to reduce these emissions are commercially available.
In addition, for some samples, emissions can be reduced through solid phase extraction techniques as opp-
osed to classical liquid evaporation techniques that release the solvent carrier into the fume hood and subse-
quently to the atmosphere
Segregate hazardous from nonhazardous wastes. Hazardous waste volumes are often unnecessarily increased
due to the addition of wastestreams that are not hazardous. Segregation alone can significantly reduce haz-
ardous waste generation rates and disposal costs.
Pollution prevention policy
Require each laboratory to have a written waste management/reduction policy. Minimum requirements would
include annual chemical inventories, the dating of chemicals as received, etc.
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Table 2. TKN and HPLC Pollution Prevention Options
Pollution Prevention Options
Nature of Capital Net Payback
Waste Stream Pollution Investment Operating Period
Affected Prevention Option ($} Cost Savings ($/yr) (yr)
TKN
Nitrogen autoanalyzer
Phenate autoanalyzer
Micro analysis
Alternate catalyst
HPLC
Acid/base
Acid/base
Acid/base
Metal catalysts
Equipment
Equipment
Procedure
Equipment/
procedure
30,000
30,000
Negligible
N/A
11,700
4,050
350
N/A
2.56
7.41
0
N/A
Solid Phase Extraction
Supercritical Fluid Extraction *
Solvent Recovery
Column/Particle Size Reduction *
Solvent
Solvent
Solvent
Solvent
Equipment/
procedure
Equipment/
procedure
Equipment
Equipment
N/A
30,000
12,000
<800
N/A
20,000
N/A
4,200
N/A
1.5
N/A
0.19
' Based on literature specifying at least 150 extractions per week
• Based on one BARC laboratory that conducts 1000 HPLC analyses per month
tions. SPE employs small disposable col-
umns containing sorbent of which ana-
lytes of interest can be bonded and then
eluted off the sorbent. One to two millili-
ters of solvent and an SPE filter or car-
tridge can accomplish the same function
as 200 to 300 ml of solvent in a standard
HPLC system.
Supercritical fluid extraction (SFE) is an
innovative technique that offers great
promise for replacing chlorinated solvent
extractions in the relatively near future.
SFE requires a gas compressed above its
critical temperature and pressure points.
The gas is thus transformed into a
supercritical fluid exhibiting high diffusion
coefficients and low viscosities. These
properties allow for very efficient transfer
of solutes from the sample matrix into the
supercritical fluid. Carbon dioxide is typi-
cally used, and modifiers may be added
to selectively extract fractions or compound
classes from a sample. Varying the tem-
perature and pressure (density) of the
supercritical fluid also can allow for very
selective extractions. For example, low
density carbon dioxide extraction is simi-
lar to that for hexane, whereas higher
density carbon dioxide extracts similarly
to benzene. SFE also offers shorter ex-
traction times compared with organic sol-
vents. After the extraction, supercritical
carbon dioxide returns to a gaseous state
at room temperature and pressure. Given
a capital cost of $30,000 for instrumenta-
tion, the payback period (based on an
average workload of 150 extractions/wk)
would be less than 1V4 yr. This relatively
short payback is because both the pur-
chase of organic solvents and disposal
costs are eliminated.
Additional source reduction methods are
available for HPLC analyses. The majority
of analyses involve the use of HPLC col-
umns, with a typical column packing of 5
u, C on silica. The column configuration
is also standard at 4.6 mm i.d. x 25 cm
length with typical flowrates of approxi-
mately 1 mL/min. Switching to a smaller
column internal diameter while holding the
column length and particle size constant
will reduce solvent consumption as shown
below:
Flowrate Comparisons
Column Dimensions Flowrate
[i.d., (mm) x length (cm)] [mL/min]
4.6 x 25 1.0
2.0 x 25 0.2
1.0 x 25 0.05
The narrower column reduces the
amount of sample needed and, hence,
reduces the waste from the sample prepa-
ration step. The narrower column can af-
fect sensitivity, however. To prevent
column overloading, the sample size and
analyte level are smaller.
The analyst may also choose to reduce
the packing particle size from 5 u. to 3 u..
This change enhances sensitivity by nar-
rowing the analyte peakwidths. Further-
more, solvent consumption can be reduced
if the column length is lessened. A shorter
column length should produce shorter elu-
tion times while preserving the separation
resolution.
By converting to a different column in-
ner diameter or length, waste reduction of
approximately 80% per HPLC analysis (at
negligible additional column costs) are fea-
sible. These techniques may not be fea-
sible for all HPLC analyses performed at
BARC, however.
Additional source reduction methods and
recycling techniques for extraction and
HPLC waste are contained in the Project
Report.
Conclusions and
Recommendations
Pollution prevention at laboratory facili-
ties similar to BARC is a difficult process
because of the distribution of small-quan-
tity waste generators. Nevertheless, sig-
nificant pollution prevention progress can
be made. Source reduction and treatment
techniques are available that will reduce
waste overall, and specifically waste for
TKN and HPLC analyses. The total quan-
tity of wastes generated at BARC by TKN
and HPLC analyses has not been quanti-
fied. In addition, some identified source
reduction techniques may not be economi-
cally feasible unless implemented at a cen-
tralized facility. Therefore, specific
estimates of waste reduction at this site
have not been projected for many of the
options in Table 2. The Project Report
contains sufficient information so that the
reader can determine economic payback
periods based on savings per individual
(unit) analysis.
The full report was submitted in fulfill-
ment of Contract 68-C8-0062, WA 3-70
by Science Applications International Cor-
poration under the sponsorship of the U.S.
Environmental Protection Agency.
•U.S. Government Printing Office: 1993 — 750-071/60213
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This Project Summary was prepared by the staff of Science Applications Interna-
tional Corporation, Cincinnati, OH 45203
James S. Bridges is the EPA Project Officer (see below).
The complete report, entitled "Pollution Prevention Opportunity Assessment:
USDA Beltsville Agricultural Research Center,. Bertsville, Maryland,"
(Order No. PB92-146843; Cost: $19.50, subject to change) will be
available only from:
National Technical Information Service
5285 Port Royal Road
Springfield, VA 22161
Telephone: 703-487-4650
The EPA Project Officer can be contacted at:
Risk Reduction Engineering Laboratory
U.S. Environmental Protection Agency
Cincinnati, Ohio 45268
United States
Environmental Protection Agency
Center for Environmental Research Information
Cincinnati, OH 45268
Official Business
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