value-added products – Livestock and Poultry Environmental Learning Community

Purpose

A new approach for recovering nutrients and value-added products from waste is to search for a synergistic effect by combining two or more wastes. This work improved the recovery of phosphorus and proteins/amino acids abundant in swine manure by adding a second waste or product rich in sugars, such as molasses, fruit waste, or lactose waste. The second waste rich in sugars acted as a natural acid generator that replaced purchased acids and lowered the overall recovery cost.

What Did We Do?

A new approach was developed to separate and recover concentrated phosphorus and proteins from animal waste (Vanotti and Szogi, 2019). It was improved by adding a second waste or product containing sugars, such as molasses and fruit waste (Vanotti et al., 2020). They could be used as a natural acid precursor that replaces purchased acids and lowers the overall cost of phosphorus and protein recovery. In this study, the two model wastes were swine manure solids (source of extractable phosphorus and proteins) and peach waste (source of acid precursors).

What Have We Learned?

On a dry-weight basis, the swine manure solids contained high amounts of proteins (15.2%) and phosphorus (2.9%) available for extraction. It was shown that waste peaches, an abundant waste in the Southeastern USA with no cost except transportation, contain about 8% total sugars and can be used as an acid precursor to effectively extract phosphorus and proteins from swine manure (waste peaches were peaches that were too soft, had bad spots, or did otherwise not meet the grade at the Processing Plant for sale as fresh fruit). The waste peaches (Brix 7.7 deg) were added to the manure, and the combo received rapid fermentation (24-h) after adding an inoculum (Vanotti et al., 2020). Adding fruit waste to the manure and rapid fermentation produced abundant natural acids – lactic acid, citric acid, and malic acid – that effectively solubilized the phosphorus in the manure (Fig. 1). Further, the peach fermentation did not adversely affect the protein recovery from the manure. A pH of about five or less is a valuable target to optimize the phosphorus and protein recovery from manure. The target was successfully met using a variety of natural acid precursors (fructose, molasses, peaches, lactose). The phosphorus was precipitated with calcium or magnesium compounds, obtaining concentrated phosphate products with > 90% plant-available phosphorus. The proteins/amino acids in the manure were quantitatively recovered. Other fruits, vegetables, and food waste products also contain significant amounts of sugar, so this is not limited to only wasted peaches. It is contemplated that other sugar-containing agricultural by-products could be used in this process for the same purpose with minor adjustments for amounts depending on the sugar concentration and initial pH of the fruit or vegetable.

Fig. 1. Adding an acid precursor to the manure and rapid fermentation increased acidity and the phosphorus recovery from the manure, up to a plateau recovery (Vanotti et al., 2023).

Future Plans

Research will be presented showing consistent phosphorus extraction results obtained with swine manure and sugar beet molasses as the acid precursor, and with dairy manure and lactose waste as the acid precursor. USDA-ARS seeks a commercial partner to bring this technology to market. For more information on commercialization, contact: Mrs. Tanaga Boozer, Technology Transfer Coordinator, USDA-ARS, OTT Southeast Area, tanaga.boozer@usda.gov

Authors

Presenting & corresponding author

Matias Vanotti, USDA-ARS, Matias.vanotti@usda.gov

Additional authors

Vanotti, M.B, Szogi, A.A., and Brigman, P.W. USDA-ARS, Florence, SC

Moral, R. Miguel Hernandez University, Orihuela, Spain

Additional Information

Vanotti, M.B., Szogi, A.A. 2019. Extraction of amino acids and phosphorus from biological materials. US Patent 10,150,711. US Patent & Trademark Office.

Vanotti, M.B., Szogi, A.A., Moral, R. 2020. Extraction of amino acids and phosphorus from biological materials using sugars (acid precursors). US Patent 10,710,937. US Patent & Trademark Office.

Vanotti, M., Szogi, A., Moral, R., & Brigman, W. 2023 (November). Recovery of Value-Added Products from Swine Manure and Waste Peaches. In National Conference on Next-Generation Sustainable Technologies for Small-Scale Producers (NGST 2022) (pp. 38-42). Atlantis Press.

Acknowledgements

This research was part of USDA-ARS National Program 212, ARS Project 6082-12630-001-00D. Support by Mitsubishi Chemical Corporation, Japan, through ARS Project 58-6082-7-006-F, is also acknowledged. Mention of trade names or commercial products in this article is solely for the purpose of providing specific information and does not imply recommendation or endorsement by the U.S. Department of Agriculture.

The authors are solely responsible for the content of these proceedings. The technical information does not necessarily reflect the official position of the sponsoring agencies or institutions represented by planning committee members, and inclusion and distribution herein does not constitute an endorsement of views expressed by the same. Printed materials included herein are not refereed publications. Citations should appear as follows. EXAMPLE: Authors. 2025. Title of presentation. Waste to Worth. Boise, ID. April 7-11, 2025. URL of this page. Accessed on: today’s date.

*Purpose

The recovery of phosphorus and proteins from manure could be advantageous to both offset costs and to improve and lessen the environmental impacts of manure storage and treatment. Phosphorous in manure can contaminate rivers, lakes, and bays through runoff, if applied onto cropland at excessive rates. Thus, recovering phosphorous from manure can not only help reduce phosphorus loss in runoff, but also reduces the use of commercial fertilizer based upon phosphate rock. Phosphorus mines have limited reserves and viable alternatives for replacing rock phosphate as fertilizer do not exist. Protein is a natural resource used in a wide range of commercial applications from pharmaceuticals to dietary supplements, foods, feeds, and industrial applications.

What Did We Do?

A new method for simultaneous extraction of proteins and phosphorus from biological materials has been developed and is presented. The experiments used swine manure solids fraction after solids-liquid separation. From raw manure, wet solids are dissolved in acidic solution and then treated with a basic solution so phosphorus will precipitate and be reclaimed. The proteins in the washed solids can be extracted and concentrated with ultrafiltration and flocculation.

Test tubes filled with proteins from manure

What Have We Learned?

On a dry-weight basis, it was found that the separated manure solids contained 15.2-17.4% proteins and 3.0% phosphorus. Quantitative extraction of phosphorus and proteins from manures was possible with this new system. The phosphorus was first separated from the solids in a soluble extract, then the proteins were separated from the solids and solubilized with an alkali solvent. Both phosphorus and protein recovery were enhanced about 19 and 22%, respectively, with the inclusion of a rinse after the washing. The recovered phosphorus solids had 20.4% phosphates (P2O5). The protein extract was concentrated using ultrafiltration (UF) and lyophilization to obtain a protein solids concentrate. UF of 5 and 10 kDa captured all the proteins, but 30 kDa resulted in 22% loss. The protein solids were converted into amino-acids using acid hydrolysis. Further, the system was proved effective in extracting phosphorus and proteins from other biological materials, such as algae or crops. The recovered proteins could be used for production of amino acids and the recovered phosphorus could be used as a recycled material that replaces commercial phosphate fertilizers. This could be a potential new revenue stream from wastes.

Acknowledgements

This research is part of USDA-ARS Project 6082-12630-001-00D “Improvement of Soil Management Practices and Manure Treatment/Handling Systems of the Southern Coastal Plains.” We acknowledge the field and laboratory assistance of William Brigman and Chris Brown, USDA-ARS, Florence, SC. Support by The Kaiteki Institute, Mitsubishi Chemical Holdings Group through ARS Cooperative Agreement 58-6082-5-006-F is acknowledged.