(521b) Economic and Environmental Evaluation of Olive Mill Wastewater Treatment Methods for a Self-Supplied American Olive Oil Mill

Olive oil is a highly versatile and popular consumer product, sold as food and used in other products such as cosmetics and pharmaceuticals. Consequently, there is a large global market for olive oil with a production estimate of 2.9 million metric tons in the 2016-17 season. Olive oil production in the United States (U.S.) occurs at a small scale, with about 5,000 metric tons produced annually, compared to 1.38 million metric tons by the largest producer Spain. Yet the U.S. is the largest non-European consumer of olive oil at about 10% of the world market. Thus, olive oil producers in the U.S. have recently started operating at larger scale.

With increased olive oil production comes increased production of olive mill wastewater (OMW). OMW has a very high organic load, with a COD greater than 220,000 ppm [Borja, et al. Grasa Y Aceites, 57.1, 34-46, 2006] and consequently it is phytotoxic and inhibits growth of soil and marine bacteria, posing a threat to ecosystems upon exposure. Polyphenols and phenol derivatives are the primary cause of OMW toxicity and the phenolic content of OMW can be extremely high, ranging from 500 mg/L to 24,000 mg/L [Borja et al., ibid]. Any wastewater treatment methods should be effective in removing these compounds. The permissible concentration of phenols for direct release to freshwater aquatic systems is 3.4 mg/L according to the EPA [Criteria and Standards Division EPA, Phenols: Ambient Water Quality Criteria, 1978]; OMW treatment methods must be able to remove large quantities of phenols.

The current literature details various proposed methods for OMW treatment but fails to consider their economic viability. Another result which is lacking is the overall environmental impact of the olive oil production process with treatment methods in place, taking into account the total usage of energy and water over the olive oil life cycle. We will present a model for a continuous olive oil production process that optimizes the operating revenue of a self-supplied American extra virgin olive oil mill. This model gives insight on the economics of wastewater treatment methods as well as detail the amount of wastewater to be treated. Alternative treatment methods will then be evaluated against the expected operating revenue and the environmental impact of the full process, assessed using a cradle-to-gate LCA.