(160p) Technical and Economic Feasibility of Phosphorus Recovery As a Coproduct in Soybean Processing Facility

Phosphorus (P) in water bodies is a constant threat to the interconnected food, energy, and water (FEW) systems. Processing of grains produces nutrient rich wastewater that have adverse effects on water quantity and quality downstreams. Overenriched water leads to eutrophication, which can cause hypoxial or anoxial zones, threatening the aquatic life in water bodies, for example, hypoxial zone in Gulf of Mexico, and phosphorus control is a critical factor in abating this issue [1, 2]. Soybean and corn are the two major crops grown in the mid-west, and the processing of these grains produces a significant amount of P as waste that ends up in water bodies. The shift of food processing industries from meat-based to plant-based protein has helped mitigating the nitrogen run-off as well as greenhouse gas emissions. Soybean is a popular choice for the replacement of meat protein due to its high total protein yield and protein quality [3]. This has led to increase in beans processing, which produces wastewater high in phosphorus that enters the wastewater treatment plants. Investments in bean processing are constantly increasing and markets for bean products are estimated to grow in near future in North America to meet the demand of new fast food chains and restaurants offering plant-based meat analogs. These new plants will significantly change the load of nutrient in waste and groundwater. Common methods to remove P from wastewater is aerobic oxidation in the treatment facilities, which is expensive and results in captured P that are not usable for agriculture or other applications that could reduce recovery costs. The objective of this study is to use a chemical method developed previously to recover phosphorus from soybean processing facility [4, 5]. The second part of the study focusses on evaluating the technical and economic feasibility of phosphorus recovery from soybean processing facility on a commercial scale using process simulation. Phosphorus content in every stream in a biodiesel production facility was analyzed using ICP analysis. Soapstock and lecithin streams in the facility were observed to have highest concentration of phosphorus (21395 ppm and 2706 ppm, respectively), and were used to recover phosphorus chemically. The hypothesis of the study is that recovering phosphorus upstream would lessen the load of phosphorus in the wastewater from the plant, and the recovered phosphorus would be applicable as fertilizer on agricultural lands. 1526 MT/day soybean processing facility was simulated in SuperPro Designer, and phosphorus flow in streams was included. In the next part of the study, a separate P recovery unit will be modeled, with experimental data generated. The model simulations would provide the experimentally quantified P that is recovered, the fixed and operating cost of the P recovery unit, energy use, and overall revenues generated due to the addition of a co-product, in comparison to the existing soybean plant. Sensitivity analysis will be performed by varying the P recovery conditions that would identify an optimum cost of recovery based on input requirements.

References

1. Rabotyagov, S.S., et al., The economics of dead zones: Causes, impacts, policy challenges, and a model of the Gulf of Mexico hypoxic zone. Review of Environmental Economics and Policy, 2014. 8(1): p. 58-79.
2. Carpenter, S.R., Phosphorus control is critical to mitigating eutrophication. Proceedings of the National Academy of Sciences, 2008. 105(32): p. 11039-11040.
3. Stice, C., et al., De-risking Protein Strategies Using a Systems Approach: Novel Analytical Framework. 2015.
4. Juneja, A., et al., Techno‐economic Feasibility of Phosphorus Recovery as a Coproduct from Corn Wet Milling Plants. Cereal Chemistry, 2019.
5. Juneja, A., R. Cusick, and V. Singh, Recovering phosphorus as a coproduct from corn dry grind plants: A techno‐economic evaluation. Cereal Chemistry, 2020. 97(2): p. 449-458.