HBI-94-007-02, Pub. 10/31/94
The amount of pollutants and waste generated by industrial facilities has become an increasingly costly problem for manufacturers and a significant stress on the environment. Companies, therefore, are looking for ways to reduce pollution at the source as a way of avoiding costly treatment and reducing environmental liability and compliance costs.
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 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 U.S. and in-country experts in both pollution prevention and the facility's industrial processes gathers more detailed information on the sources of pollution, and identifies and analyzes opportunities for 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.
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:
Overall, the assessment identified 13 pollution prevention pollution opportunities that could provide first year savings of $420,000 for a one-time investment of $236,000. If implemented, these changes could reduce energy and water use per unit output, reduce contaminated wastewater, and improve product quality.
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 the 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.
The plant has five main unit operations:
EPA is sponsored by the U.S. Agency for International Development.
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 noncontact 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 solid for consumption.
Oil of insufficient quality for 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.
At the time of the assessment, there were a number of pollution problems at the facility, including:
The assessment identified 13 pollution prevention opportunities that could provide first year savings of $426,000 for a one-time investment of $236,00.
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. Table 1 presents the pollution prevention opportunities in order of unit operation processes.
| Unit Operation | Pollution Prevention Action and Environmental/Product Quality Benefit | Cost | Financial Benefit | Payback Period |
|---|---|---|---|---|
| Grignon Drying | Leave 12 percent residual moisture instead of the current 7 percent - reduces hexane emissions from extraction and particulate and NOx emissions from boilers. | $0 | Not directly quantifiable. | Not Applicable |
| Oil Extraction: Hexane Washing | Purchase and install a heat exchanger to pre-heat the grignon and hexane to 60 degrees C - reduces hexane emissions. | $12,000 | $213,000 combined | 3 months |
| Oil Extraction: Hexane Distribution | Design, build, and install a hexane distribution manifold for each extractor - reduces hexane emissions. | $24,000 | $213,000 combined | 3 months |
| Oil Extraction: Control Hexane Feed Rate | Purchase and install flow meters for each extractor - reduces hexane emissions. | $14,500 | $213,000 combined | 3 months |
| Oil Extraction: Vapor Vent Condensing | Purchase a shell and tube condenser to maintain a negative pressure (vacuum) on the system - reduces hexane emissions. | $7,000 | $213,000 combined | 3 months |
| De-Solventizing Grignon: Steam Measuring | Purchase and install flow meters and pressure gauges - reduces hexane emissions. | $15,500 | $21,000 combined | 1.5 years combined |
| Miscella Distillation: Hexane Evaporation | Purchase and install heat exchanger to pre-heat the miscella with the hot oil exiting the stripper - reduces hexane air emissions; reduces by 95 percent the volume of hexane contaminated waste water (equivalent to 91,200 kg of hexane and 96,000 cubic meters of water per year). | $8,000 | $162,000 combined | About 1 year |
| Miscella Distillation: Water Cooling | Purchase and install an efficient cooling lower with a fan - same as above. | $58,000 | $162,000 combined | About 1 year |
| Miscella Distillation: Hexane Vent Recovery | Purchase and install a mineral oil absorber - same as above. | $58,000 | $162,000 combined | About 1 year |
| Refining Oil: Neutralization Wash Water Centrifuge | Purchase and install wash water flow controller and meter - reduces waste water volume. | $4,000 | $6,000 | 9 months |
| Decolorization | Purchase and install a shell and tube heat exchanger to cool oil before storage - reduces loading on decolorizing system and reduces waste volume. | $7,000 | $18,000 combined | Less than 5 years |
| Decolorization | Increase the holding time in the bleacher from 15 minutes to 30 minutes - reduces operating wastes and costs in decolorization. | None | $18,000 combined | Immediate |
| Deodorization | Purchase and install two shell and tube vacuum condensers - reduces fatty acids dumped into the sea. | $29,000 | $6,000 | 5 years |
| TOTALS: | $236,000 | $426,000 | ||
A number of the recommendations can help the facility produce superior oil for consumption, including:
If implemented, these pollution prevention improvements will reduce:
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 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 the market 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.
For further information on this assessment or other activities sponsored by EP3, call the EP3 Clearinghouse at (703) 351-4004, send a fax to (703) 351-6166, or on Internet apendergathabaco.com.