HBI-94-009-02
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 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 an oil extraction and soap manufacturing facility. The objective of the assessment was to identify actions that would:
Overall, the assessment identified two pollution prevention opportunities that could provide annual savings of at least $6,000 for a one time investment of $23,000. If implemented, these changes could reduce energy and water use per unit output, reduce contaminated waste water, and improve product quality.
This facility refines olive oil and soybean oil for consumption. The facility also makes soap from high acid oils and other fat sources. The plant operates three eight-hour shifts, employing 37 permanent workers and 20 seasonal workers.
The plant has two main unit operations: oil refining and soap making, as shown in Figure 1 [provided in source document].
The refinery process removes phospholipids, neutralizes the oil's acidity, and decolorizes and deodorizes the oil. Phosphoric acid is added to the heated crude oil to eliminate the phospholipids. An 18-20 percent solution of sodium hydroxide is mixed with the oil and then centrifuged to separate the oil and soap waste. The oil is mixed with water for washing in a second centrifuge. The effluent is waste water.
EP3 is sponsored by the U.S. Agency for International Development.
The oil is decolorized by mixing bentonite clay with the oil at 80-100 degrees C for 10-15 minutes, then filter pressing. Deodorization is accomplished through the use of superheated steam in a vessel installed in 1933. This refined oil is sold for consumption.
Oil of insufficient quality for refining (as well as the soap stock from the neutralizing step in refining) is 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 soap that floats on top of the tank. The waste water from the bottom is diverted to another tank where it again mixes with sodium hydroxide and salt to make more soap stock. Subsequent steps include salt washing and multiple rinsing.
The wet soap feeds by gravity to a small holding reservoir. From there it is filtered, steam heated, and vacuum dried. The soap, now with a lower moisture content, passes through a high-shear mixing machine to where it is cooled and molded into a continuous rectangular solid. The continuous soap bar is cut, inspected, and placed onto the dryer. The finished soap bars are boxed for shipment.
At the time of the assessment, there were a number of pollution problems at the facility, including:
The assessment identified two pollution prevention opportunities. One could save the facility $6,000 per year for an investment of $4,000, while the other could save the facility an undetermined amount for an investment of $19,000. If implemented, these pollution prevention changes can reduce the loss of high value oil to lower value soap stock, reduce the generation of waste water, and improve productivity and product quality. Table 1 presents the assessment's findings in order of unit operation processes.
| Unit Operation | Pollution Prevention Action and Environmental/Product Quality Benefit | Cost | Financial Benefit | Payback Period |
|---|---|---|---|---|
| Refining Oil: Neutralization Pre-Treatment, First Centrifuge | Purchase oil, acid, and caustic flow controllers and flow meters - reduces oil losses to water stream. | $19,000 | Measurable once equipment is installed and used | Measurable once equipment is installed and used |
| Refining Oil: Neutralization Wash Water, Second Centrifuge | Reduce water flow to no more than 10 percent of oil flow rate and use mixer; purchase flow meter and flow controller for wash water - reduces waste water. | $4,000 | $6,000 per year | 8 months |
| TOTALS: | $23,000 | $6,000 per year plus 1 unquantified opportunity | ||
The recommendations also could help the facility produce superior oil and soap by:
These recommendations will improve the facility's competitiveness in a market that is likely to become more competitive in the future.
If implemented, these pollution prevention improvements will reduce the volume of waste water and its BOD and COD levels, and the amount of solids in the waste water.
EP3 is developing a methodology for measuring and tracking pollution prevention performance. The approach uses simple but critical ratios to compare data among facilities in the same industrial sector.
This assessment identified two critical ratios, as shown in Table 2:
| Ratio | BIP: Current Ratio at Facility |
|---|---|
| Cubic meters of refinery water per ton of crude oil processed | 2: 8 |
| Kilograms of caustic soda per ton of crude oil processed | 10: 20 |
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 apenderg@habaco.com.