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2016 Annual Report
Objectives
1: Enable commercial processes for transforming animal protein into new marketable flocculants.
1a. Develop processing techniques for the solubilization of rendered protein with emphasis on intact proteins and high molar mass protein fragments.
1b. Evaluate technological alternatives for transforming raw chicken blood into a high potency flocculant at low processing cost.
2: Enable market growth for flocculants based on animal proteins by improving their performance and expanding their market applications.
2a. Apply a series of covalent modification strategies to improve blood and rendered protein flocculant performance.
2b. Identify particular application areas to which blood and rendered protein flocculants are well suited.
Approach
Both rendered protein and chicken blood have inherent flocculant properties, but these substances also have other properties which make them unsuitable for commercial flocculant applications in their ‘raw’ state. Poor solubility is a primary obstacle to commercial utilization of rendered protein as a flocculant. Instability, high water content, and dark red color are among the obstacles to blood utilization. The project will focus on developing processing techniques for surmounting these obstacles under Objective 1. With the current state-of-the-art, rendered protein or blood flocculants have significant performance limitations. Improving their performance through covalent modifications is the focus of Objective 2a. Finally, any class of flocculants is well suited to some particular application areas and not to other areas. In Objective 2b, the focus is on identifying particular application areas appropriate for rendered protein and blood flocculants.
Progress Report
Rendered protein meals, such as meat & bone meal (MBM), may be good sources for flocculant proteins, but MBM proteins have poor solubility. Past attempts at solubilizing this protein produced unsatisfactory results; either the proportion of the protein solubilized was too low or the protein was digested into fragments that were too small to be useful. Objective 1a seeks to develop new approached to this problem. During the period covered by this report, we adapted an obsolete method found in old protein structural analysis literature. The method uses dilute acid and carefully selected conditions to cut proteins at very specific sites; this allows the protein to be solubilized without having it digested into very small fragments. Although the method has not previously been used with substrates like MBM, our results show that it works well. Future work along these lines will attempt to further adapt this method for commercially practical processes; a formal agreement to do this research in collaboration with a Portuguese rendering firm is pending a final signature, and is not included in the International Collaboration section of this report.
Our work has shown that blood or blood components can function as very effective flocculants. Objective 1b is intended to examine how a blood-based flocculant could be commercially produced. Although past work has suggested that the economics of a blood-based flocculant product are favorable, we recently examined this in much greater detail by conducting a techno-economic analysis of a hypothetical commercial-scale facility processing blood into a flocculant product. The analysis included details beginning with collection and transport of raw blood to the packaging of the final product. The results suggest that such a facility could operate profitably and market a product that would be price competitive with the conventional flocculant known as PAM. A commercial collaborator has been awarded an SBIR grant to work with our group to test and develop blood processing; the associated CRADA is pending approval and is not included in the Technology Transfer section of this report.
Hemoglobin is a component of blood that is responsible for most of the flocculating activity of blood. Until now, it has not been clear whether the extra expense of isolating hemoglobin from blood is justified for the purposes of producing a flocculant product. Our recent research into this issue has shown that hemoglobin isolation provides only a small benefit of increasing the flocculant potency. Whole blood was expected to add more contaminants to water than isolated hemoglobin, but this was shown not to be the case when the flocculant is used at appropriate doses. The previously mentioned techno-economic assumed that hemoglobin isolation was required, so the finding that this is not required suggests the processing costs could be greatly reduced by omitting certain steps in the processing.
While hemoglobin is a very effective flocculant, it does suffer from certain limitations. Objective 2a seeks to overcome these limitations by applying chemical modifications to hemoglobin. One particular limitation is that its effectiveness diminishes when the acidity of the water to be treated is too low. To mitigate this limitation, a simple chemical reaction was used to modify hemoglobin; the modification was anticipated to improve the flocculant performance of hemoglobin under low acid conditions. Experiments compared normal and modified hemoglobin in terms how well they clarify water, and the dose required to achieve good clarification. The results show that the modification had the desired effect of improving performance in water that is near neutral pH. The modification also had the unexpected effect significantly improving overall flocculant performance; under some conditions, the modified hemoglobin could clarify water as well as regular hemoglobin with only one quarter the dose. This research has provided a simple, inexpensive way to improve the performance of a hemoglobin-based flocculant. Such an improvement will expand the opportunities for commercial application of the flocculant.
Finally, Objective 2b focuses on identifying particular application areas to which blood and rendered protein flocculants are well suited. During the reporting period, we investigated using blood-based flocculants to treat a waste stream from the bioethanol industry known as “thin stillage”. The stillage was treated with different concentrations of hemoglobin, animal blood, and a commercial cationic flocculant with and without centrifugation. The amount of precipitated material was measured after flocculant treatment over a range of times. Tests have been initiated to determine whether phosphate, protein, carbohydrate or lignin are selectively precipitated by flocculation.
Accomplishments
1. Commercial feasibility of a blood-based product demonstrated. It has been known that a product made from waste slaughterhouse blood can serve as a very effective bio-based substitute for certain water treatment chemicals. It was unclear, however, that this technology could be commercialized profitably. ARS researchers in Wyndmoor, Pennsylvania, in cooperation with researchers at Iowa State University, developed a comprehensive computer model of a facility for processing blood. The model included details beginning with collection and transport of raw blood to the packaging of the final product. The model demonstrates that such a facility could operate profitably; such results should facilitate commercial adoption of ARS-developed protein flocculant technology.
2. Modification of hemoglobin improves its water clarification properties. Hemoglobin can be used as a bio-based substitute for certain water treatment chemicals. The performance of hemoglobin in this application is very good, but the water to be treated must be slightly acidic. ARS researchers in Wyndmoor, Pennsylvania modified hemoglobin through a simple chemical reaction which attaches alcohol molecules to specific sites on hemoglobin. The modified hemoglobin was much more potent in water clarification and had significantly reduced need for acidity. The modified hemoglobin produced in this research should be substantially more attractive as a bio-based water treatment chemical, compared to the unmodified hemoglobin.
None.
Review Publications
Piazza, G.J., Lora, J., Garcia, R.A. 2015. Recovery of wheat straw soda lignin using flocculation by proteins, synthetic flocculants, and a metal coagulant. Journal of Biobased Materials and Bioenergy. 9(4):447-455. DOI: 10.1166/jbmb.2015.1542.
Kimball, B., Stelting, S., Mcauliffe, T., Stahl, R., Garcia, R.A., Pitt, W. 2016. Development of artificial bait for brown treesnake suppression. Biological Invasions. 18:359–369.
