Removing and recovering nitrogen and phosphorus from animal manure

Authors: Vanotti, Matias; GARCIA-GONZALEZ, MARIA - Instituto Tecnológico Agrario De Castilla Y León (ITACYL); Szogi, Ariel; HARRISON, J. - Washington State University; SMITH, W. - Tarleton State University; MORAL, RAUL - Miguel Hernandez University

Submitted to: American Society of Agronomy Monograph Series
Publication Type: Book / Chapter
Publication Acceptance Date: 3/13/2019
Publication Date: 1/9/2020
Citation: Vanotti, M.B., Garcia-Gonzalez, M.C., Szogi, A.A., Harrison, J.H., Smith, W.B., Moral, R. 2020. Removing and recovering nitrogen and phosphorus from animal manure. In: Waldrip, H.M., Pagliari, P.H., He, Z., editors. Animal Manure: Production, Characteristics, Environmental Concerns, and Management. p. 275-321.American Society of Agronomy Special Publication. https://doi.org/10.2134/asaspecpub67.c22.
DOI: https://doi.org/10.2134/asaspecpub67.c22

Interpretive Summary: Animal production in the USA has increasingly moved to very large-scale operations. Since the 1950s, the animal production has more than doubled while the number of operations has decreased by 80%. Because of this intensification, expansion and agglomeration, there is a net import of nutrients as feed in some areas and limited nutrient absorption capacity of the nearby land. Therefore, many areas produce more manure nutrients than available cropland can assimilate. Among all nutrients in manure, nitrogen (N) and phosphorus (P) cause the greatest environmental concern. More sustainable techniques using P recovery for both solid and liquid waste are important to close the P cycle in modern human society and address future scarcity. Treatment technologies can play an important role in the management of animal manures by providing a more flexible approach to land application and acreage limitations and by solving specific problems associated with excess nutrients such as surface and groundwater pollution, ammonia emissions, and P contamination of soils. In addition, fertilizer prices have escalated in recent years, thus there is renewed interest on developing technologies to recover and recycle nutrients from manure. An overview is provided on existing alternative technologies for removing and recovering nitrogen and phosphorus from animal manure. The chapter is organized as follows: Section I.A provides a flow diagram on alternative approaches to traditional land application of manures; Section I.B shows desirable characteristics of the products; Section II shows solids separation and dewatering methods to concentrate nutrients; Section III reviews technologies for separation of phosphate concentrates; Section IV shows technologies for recovery of the nitrogen; Section V describes biological N and P removal processes; and Section VI describes the agronomic utilization of the recovered nutrients.

Technical Abstract: Many areas in the United States produce more manure nutrients than available cropland can assimilate. Among all nutrients in manure, nitrogen (N) and phosphorus (P) cause the greatest environmental concern. Treatment technologies can play an important role in the management of animal manures by providing a more flexible approach to land application and acreage limitations. Development of technologies for nutrient-reuse was identified as one of the five main challenges in waste management within a circular economy. Manure treatment can be accomplished with the use of biological, chemical, and physical methodologies as part of treatment systems that are integrated with the needs of the land and create additional value through nutrient concentration and recycling, water quality credits, energy production, greenhouse gas reductions, and other beneficial by-products. This chapter reviews the alternative approaches for removing and recovering N and P from animal manure using both on-farm and off-farm management. Major components include diet manipulation, solid-liquid separation, and anaerobic digestion. The resulting materials are subsequently treated using a variety of technologies developed for solid or liquid fractions that include: composting, thermochemical processes, extraction of phosphate concentrates, recovery of the ammonia, biological nutrient removal processes, and vegetative or algal nutrient removal systems. Desirable properties of the recovered products and agronomic utilization are also discussed.