INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
INTERNATIONAL
CLEANER
PRODUCTION
INFORMATION
CLEARINGHOUSE
CASE STUDY #240
1. Headline: EP3 - Pollution Prevention Assessment for an
Oil Extraction and Soap Manufacturing Facility
2. Background:
What is EP3?
The United States Agency for International Development
(USAID) is sponsoring the Environmental Pollution
Prevention Project (EP3) to establish sustainable programs
in developing countries, transfer urban and industrial
pollution prevention expertise and information, and
support efforts to improve environmental quality. These
objectives are achieved through technical assistance to
industry and urban institutions, development and delivery
of training and outreach programs, and operation of an
information clearinghouse.
EP3's Assessment Process
EP3 pollution prevention diagnostic assessments consist of
three phases: pre-assessment, assessment, and post-
assessment. During pre-assessment, EP3 in-country
representatives determine a facility's suitability for a
pollution prevention assessment, sign memoranda of
agreement with each facility selected, and collect
preliminary data. During assessment, a team comprised of
US and in-country experts in both pollution prevention and
the facility's industrial processes gathers more detailed
information on the sources of pollution, reducing this
pollution. Finally, the team prepares a report for the
facility's management detailing its findings and
recommendations (including cost savings, implementation
costs, and payback times). During post-assessment, the EP3
in-country representative works with the facility to
implement the actions recommended in the report.
Summary
This assessment evaluated a facility that extracts and
refines olive oil and manufactures domestic soap from
resulting side products. The objective of the assessment
was to identify actions that would: (1) reduce the
quantity of toxics, raw materials, and energy used in the
manufacturing process, thereby reducing pollution and
worker exposure, (2) demonstrate the environmental and
economic value of pollution prevention methods to the soap
industry, and (3) improve operating efficiency and product
quality.
The assessment was performed by an EP3 team comprised of
an expert in oil extraction and soap manufacturing and a
pollution prevention expert.
Facility Background
This facility extracts and refines oil from spent olive
oil pressing waste (grignon) for sale as consumable oil.
Any oils that cannot be used for consumption are used in
the manufacture of soap. The facility operates three eight-
hour shifts, employing eighty permanent workers and eighty
seasonal workers. Sales exceeded $ 2.6 million during 1992-
1993 operating season.
The facility is the only company in the area that extracts
olive oil from grignon. It represents approximately 30
percent of the national market for oil seed refining and
sells about 15 percent of the nation's bar soap used
primarily for clothes laundering.
3. Cleaner Production Principle: The assessment identified
various cleaner production applications including: process
modification, good housekeeping, new technology,
recycling, and material substitution.
4. Description of Cleaner Production Application:
Overall, the assessment identified 13 pollution prevention
opportunities that could provide first year savings of $
420,000 (US) for a one-time investment of $ 236,000 (US).
If implemented, these changes could reduce energy and
water use per unit output, reduce contaminated wastewater,
and improve product quality.
Manufacturing Process
The plant has five main unit operations: grignon drying,
oil extraction, recovery of hexane, oil refining, and soap
making (a detailed process flow chart is available from
the EP3 Clearinghouse).
Each day, raw grignon is ground and dried in three large
hot air rotary dryers to 7 percent moisture before the
extraction process begins. The plant operates two systems
of six 13-ton extractor/desolventizer vessels. Each system
uses three tanks at a time in series for oil extraction.
The grignon is placed in the tanks, and an un-metered
amount of hexane is added through the top of the first
tank. It extracts oil as it percolates through the
grignon. The mixture of hexane and olive oil (called
miscella) flows to fill the second tank, overflows, and
then fills the third before going to temporary storage to
await separation.
The miscella drains from the extractors and is pumped to
the evaporators. The evaporators use non-contact steam to
evaporate the hexane from the mixture.
The neutralization process separates the oil from the
waste, called "soap stock." The neutralized oil is then
decolorized and deodorized. The refined oil is sold for
consumption.
Oil of insufficient quality for refining and the soap
stock from the neutralizing step in refining and the soap
stock from the neutralizing step in refining are used as
feed for soap making. In large, steam-heated cylindrical
tanks, oil and/or soap stock mix with sodium hydroxide,
salt, and a variable amount of water, reacting to form a
soap that floats on top of the tank. The wet soap is
filtered, steam heated, and vacuum-dried. The soap next
passes through a high-shear mixing machine to an extruder
where it is cooled and molded into a continuous
rectangular solid. The soap bar is cut, inspected, dried,
and boxed for shipment.
Existing Pollution Problems
At the time of the assessment, there were a number of
pollution problems at the facility, including: (1)
excessive hexane emissions during oil extraction, (2)
particulate and NOx emissions from boilers, (3) fire
hazard from dried grignon, (4) excessive waste water from
hexane evaporation, (5) oil loss to the water stream, and
(6) excessive fatty acids dumped directly into the sea.
Pollution Prevention Opportunities
Overall, the assessment identified 13 pollution prevention
opportunities that could provide first year savings of $
426,000 (US) for a one-time investment of $ 236,000 (US).
The predicted savings could rise dramatically by including
the avoided capital costs for a waste water pre-treatment
station designed for pre-assessment operating conditions.
Below is a list of pollution prevention opportunities in
order of unit operation processes.
Summary of Recommended Pollution Prevention Opportunities
--Grignon Drying--Leave 12 percent residual moisture
instead of the current 7% reduces hexane emissions from
extraction and particulate and NOx emissions from boilers.
--Oil extraction: Hexane washing--purchase and instal a
heat exchanger to pre-heat the gringnon and hexane to 60
degrees C - reduces hexane emissions. The implementation
costs are $12,000 (US) with a financial benefit of
$213,000 (US) combined and a payback period of 3 months.
--Oil extraction: Hexane Distribution--Design build and
install a hexane distribution manifold for each extractor
reduces hexane emissions. the implementation costs are
$24,000 (US) with a financial benefit of $213,000 (US)
combined and a payback period of 3 months.
--Oil extraction: Control hexane feed rate-- purchase and
install flow meters for each extractor - reduces hexane
emissions. The implementation cost is estimated at
$14,500 (US) with a financial benefit of $213,000 (US)
combined and a pay back period of 3 months.
--Oil extraction: Vapor vent condensing--Purchase a shell
and tube condenser to maintain a negative pressure
(vacuum) on the system -reduce hexane emissions. The
implementation cost is $7,000 (US) with a financial
benefit of $213,000 (US) combined and a payback period of
3 months.
--De-solventizing Grignon: Steam measuring: Purchase and
install flow meters and pressure gauges - reduces hexane
emissions. Implementation cats of $15,500 (US) with a
financial benefit of $21,000 (US) combined and a payback
period of 1.5 years combined.
--Miscella Distillation:
1. Hexane evaporation--Purchase and install a heat
exchanger to pre-heat the miscella with the hot oil
exciting the stripper - reduces hexane air emissions;
reduces by 95% the volume of hexane contaminated
waste water (equivalent to 91,200 kg of hexane and
96,000 cubic meters of water per year.
Implementation of $8,000 (US) and a financial benefit
of $162,000 (US) and a pay back period of 1 year.
2. Water Cooling: purchase and install an
efficient cooling tower with a fan- same as
above.Implementation costs of $58,000 (US) with a
financial benefit of $162,000 (US) combined and a
payback period of 1 year.
3. Hexane vent recovery: Purchase and install a
mineral oil absorber - same as above. Implementation
costs $58,000 (US) with a financial benefit of
$162,000 (US) combined and a payback period of about
1 year.
--Refining oil neutralization wash water centrifuge--
purchase and install wash water flow controller and meter
- reduces waste water volume. Implementation costs $4000
(US) with a financial benefit of $6000 (US) and a payback
period of 9 months.
--Decolorization--
1. Purchase and install a shell and tube heat
exchanger to cool oil before storage - reduces
loading on decolorizing system and reduces waste
volume. Implementation costs of $7000 (US) with a
financial benefit of $18,000 (US) and a payback
period of less than 5 months.
2. Increase the holding time in the bleacher from
15 minutes to 30 minutes reducing operating wastes
and costs in decolorization. No implementation costs
providing an immediate benefit of $18,000 (US).
--Deodorization purchase and install two shell and vacuum
condensers - reduces fatty acids dumped into the sea.
Implementation costs of $29,000 (US) and financial benefit
of $6,000 (US) and a payback period of 5 years.
The total costs of these opportunities is estimated at
$236,000 (US) and $426,000 (US).
A number of the recommendations can help the facility
produce superior oil for consumption, including (1)
cooling the oil from the oil/hexane Stripper, (2) adding
process flow meters and controls in the refining stage,
and (3) upgrading equipment in the deodorizing process. In
addition, several of the recommendations will reduce waste
water volume by nearly 50 percent, and lower the COD
level, hydrocarbon loading, and the amount of solids in
the waste water. These changes could help the facility
improve its competitiveness in the domestic and export
markets.
If implemented, these pollution prevention improvements
will reduce hexane emissions to the atmosphere and to
waste water by over 160,000 kilograms; reduce waste water
volume by 96,000 cubic meters per year; reduce particulate
and NOx emissions; and reduce the risk of fire or
explosion from hexane.
Implementation Status
The facility has appointed a follow-up team that is
working under the supervision of the local EP3 office and
a specialized local consultant in order to implement the
assessment's recommendations. After setting priorities
relative to the implementation plan, actual execution
began. The follow-up team is conducting experiments to
determine the most suitable way of obtaining 12 percent
moisture level in the dried grignon and whether such a
moisture level yields the desired results, for both oil
extraction and combustion purposes. Two shell-and-tube
heat exchangers have been purchased to pre-heat hexane
(before extraction) to 60 degrees C and are scheduled for
installation by the end of September 1994. The follow-up
team is screening for appropriate flow meters and pressure
gauges to ensure better measurement and control of its
production operations. The facility has also purchased two
NIAGARA filters to reduce the volume of waste water and
hexane losses in its deodorizing operation effluents.
5. Economics: See above.
6. Advantages: See above
7. Constraints: See above.
8. Contacts:
EP3 Clearinghouse (UNITED STATES)
TEL: 1 (703) 351-4004
FAX: 1 (703) 351 6166
Internet: apenderg@habaco.com
9. Keywords: oil extraction, soap, oil, process
modification, recycling, good housekeeping, material
substitution, EP3, grignon, hexane, NOx, deodorizing,
olive oil, USAID
10. Reviewer's comments: This case study was carried out in a
developing country in which EP3 has an established
programme. It was submitted to UNEP IE and edited for the
ICPIC diskette in August 1995. It has not undergone a
formal technical review.