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Nutrient Recovery: Ultrafiltration and Reverse Osmosis

alternative practice names:

UF; RO; Membrane Separation

Ultrafiltration (UF) and Reverse Osmosis (RO) are advanced membrane-based technologies designed to efficiently treat dairy manure wastewater. These processes enable the separation and recovery of valuable nutrients and clean water from the waste stream, providing an environmentally sustainable solution for manure management.


UF employs membranes with openings typically 0.1 microns or smaller to remove virtually all suspended solids from the wastewater. Its outputs include UF concentrate, a nutrient-rich slurry that contains a high concentration of phosphorus (approximately 25-30% of the original waste volume), and UF permeate ("tea water"), a clarified liquid, free of most suspended solids, that is directed to the RO system for further treatment. Since phosphorus binds to solid particles, UF captures over 90% of the manure's phosphorus content in the UF concentrate.


RO uses finer membranes to remove a significant portion of dissolved solids, including ammonia and most remaining nitrogen, from the UF permeate. Its outputs include an RO concentrate with high levels of nitrogen and other dissolved nutrients (approximately 25-30% of the original waste volume) and clean water (approximately 30-50% of the original waste volume) that can be safely discharged or reused on the farm for irrigation or other purposes.


Before using either UF or RO technologies, coarse and fine solids need to be removed from the manure using other separation technologies. Some dairy operations may only need to utilize UF technologies to meet goals and objectives; others may also need to include RO to take manure separation to clean water. Systems utilizing only UF are generally less expensive than those requiring additional RO for advanced water purification from manure. 

When used, in what regions in the U.S. is the practice found: 

Northwest, West, Upper Midwest, Northeast

FARM SIZE 

When used, typically found on farms of the following sizes:

Over 5000 cows

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Practice Benefits 

Regulatory compliance: Many dairy regions face stringent environmental regulations aimed at reducing nutrient pollution. Nutrient recovery technologies help farms meet these regulations by efficiently managing the nutrient outputs, thereby reducing the risk of non-compliance penalties.


Targeted nutrient partitioning: Nutrient recovery systems allow for the partitioning of nutrients such as nitrogen and phosphorus from manure into more concentrated and manageable forms. The different output streams allow farms to customize the nutrient delivery for crops.


Reduced manure transport costs: Nutrient recovery technologies process and concentrate manure into more nutrient-rich, less voluminous products. This reduces volume costs associated with land application, such as fuel, labor, and vehicle wear and tear.


Diversified income: With the number of manure separation streams and nutrient partitioning, markets can be created to sell the nitrogen and phosphorus-rich manure streams. Some carbon credit markets are emerging that will pay for manure separation technologies.


Odor control: The nutrient recovery system significantly reduces odors by breaking down volatile organic compounds in manure, resulting in less odor during land application of the outputs. 

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Implementation Insights

Site-specific or Farm-specific requirements 

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  • Manure handling: This technology is only applicable to farms that handle manure as a liquid or slurry. 

  • Optimizing nutrient management in high livestock density areas: This technology is specifically developed for farms that face a surplus of nutrients and lack adequate land for spreading manure in compliance with local regulations. It offers a targeted solution for managing excess nutrients efficiently and sustainably, addressing the challenges posed by high livestock density.

Required Capital Expenditures (CapEx)

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  • Coarse- and fine-solid separation: The systems must include compatible coarse- and fine-solid separation processes that meet the efficiency requirements necessary for the membrane technologies to operate effectively.

  • Processing facility: UF and RO systems should be housed within dedicated structures to protect them from environmental conditions.

  • Storage facilities: More complex systems with multiple separation processes require several manure storage solutions to manage different outputs, including temporary tanks to balance flow and discharge rates.

Required Operational Expenditures (OpEx)

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  • Labor: Extra training may be required to operate the UF and RO units, in addition to daily, weekly, and monthly inspections. 

  • Chemicals: Some UF and RO systems utilize coagulants, flocculants, and/or other chemicals to assist in the manure separation process. Other products may also be used to clean and back flush the units.

  • Maintenance: Over time, the membranes will wear out and require replacement. Components from other manure separation technologies will also require maintenance to keep the entire system operating smoothly.

  • Energy consumption: RO systems, in particular, are energy-intensive due to the high pressures needed to overcome osmotic barriers and filter finer particles, influencing ongoing operational costs.

Implementation Considerations

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  • Manure pretreatment to remove solids: Sand, coarse solids, and fine solids should be removed from the animal manure stream before entering the ultrafiltration and reverse osmosis treatment system. The more coarse and fine solids removed prior to UF and RO, the more efficiently the system will function, and fewer membrane cleaning operations will be required. The dairy should determine how much waste separation is required for the operation. When installed systems fail to deliver the promised performance or cost savings, the root cause is often ineffective pretreatment for solids. This inadequacy leads to frequent and costly fouling of the membranes, which in turn increases electrical demand due to the added pressure on the membranes.

  • Nutrient management plan: With nutrient partitioning from UF and RO, a nutrient management plan can be developed to better meet crop requirements. Supplemental crop nutrient needs from commercial fertilizers may also be reduced. The clean water generated from RO can be used for various purposes on the dairy or discharged if the water quality meets the requirements as outlined by the nutrient management plan. With the removal of coarse and fine solids and partitioning of nutrients, irrigation of liquid manure is more efficient and effective.

  • Field application of concentrate: The concentrate produced from nutrient recovery will need to be field applied as it carries with it the original bulk of input nutrients. Given that it is quite dilute, has non-ideal salt-to-N ratios, and may also contain pathogens, this concentrate is unlikely to be sold off-farm.

  • Clean water discharge: The water produced by reverse osmosis (RO) systems can be characterized by higher hardness or elevated temperatures, making it unsuitable for direct discharge without further treatment. The need for additional treatment often depends on local and state regulatory standards, which can vary significantly. It's essential to check specific regulations to determine the appropriate treatment requirements for discharged water in your area.

Financial Considerations and Revenue Streams

There are no federal cost-share programs or conservation funding for this practice.


PROFIT POTENTIAL

The profit potential of nutrient recovery lies in reducing waste management and transportation costs. However, profitability depends on factors such as scale and local regulatory frameworks.

Additional Resources

► See the Newtrient Solutions Catalog to learn more about Ultrafiltration, Reverse Osmosis, and related solution providers.



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Environmental Impacts

MAY REDUCE GREENHOUSE GAS EMISSIONS

When combined with anaerobic digesters, nutrient recovery systems offer minimal additional potential for reducing greenhouse gas (GHG) emissions related to manure storage. Since anaerobic digestion already mitigates the bulk of methane emissions from manure, the role of nutrient recovery in further decreasing storage-related emissions is limited. Most nutrient recovery systems handle manure digestate post-digestion, meaning that the majority of manure-associated GHG emissions have already been addressed.


However, nutrient recovery processes can significantly lower GHG emissions related to nutrient runoff and ammonia volatilization during field application. By concentrating nutrients into more manageable, transportable forms, these systems reduce the likelihood of over-application or local nutrient saturation. Furthermore, nutrient recovery systems also reduce the volume of material requiring transportation, thereby decreasing the farm’s dependency on fossil fuels and its overall carbon footprint.


It should be noted that the operation of nutrient recovery systems may increase energy consumption, which, depending on the energy source, could lead to higher GHG emissions. The overall GHG impact should account for the balance between energy use and the emissions reductions achieved through more efficient nutrient management and transport. Research quantifying the impact of on-farm GHG emissions on nutrient recovery systems is limited, and a detailed assessment through process-based modeling or a life cycle analysis (LCA) is necessary to accurately determine the specific effects on an individual farm.


IMPROVES WATER QUALITY

Nutrient recovery systems allow for the partitioning of nutrients such as nitrogen and phosphorus from manure into more concentrated and manageable forms. This enables farmers to apply these nutrients specifically where they are needed, reducing the risk of run-off and leaching. 

REFerences

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Alignment with FARM Program

This practice is not included in the FARM program.

Contents

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We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

We're always eager to update the website with the latest research, implementation insights, financial case studies, and emerging practices. Use the link above to share your insights. 

Contents

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Practice Overview

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Ultrafiltration (UF) and Reverse Osmosis (RO) are advanced membrane-based technologies designed to efficiently treat dairy manure wastewater. These processes enable the separation and recovery of valuable nutrients and clean water from the waste stream, providing an environmentally sustainable solution for manure management.


UF employs membranes with openings typically 0.1 microns or smaller to remove virtually all suspended solids from the wastewater. Its outputs include UF concentrate, a nutrient-rich slurry that contains a high concentration of phosphorus (approximately 25-30% of the original waste volume), and UF permeate ("tea water"), a clarified liquid, free of most suspended solids, that is directed to the RO system for further treatment. Since phosphorus binds to solid particles, UF captures over 90% of the manure's phosphorus content in the UF concentrate.


RO uses finer membranes to remove a significant portion of dissolved solids, including ammonia and most remaining nitrogen, from the UF permeate. Its outputs include an RO concentrate with high levels of nitrogen and other dissolved nutrients (approximately 25-30% of the original waste volume) and clean water (approximately 30-50% of the original waste volume) that can be safely discharged or reused on the farm for irrigation or other purposes.


Before using either UF or RO technologies, coarse and fine solids need to be removed from the manure using other separation technologies. Some dairy operations may only need to utilize UF technologies to meet goals and objectives; others may also need to include RO to take manure separation to clean water. Systems utilizing only UF are generally less expensive than those requiring additional RO for advanced water purification from manure. 

Practices and technologies

Nutrient Recovery: Ultrafiltration and Reverse Osmosis

alternative practice name:

UF; RO; Membrane Separation