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Manure Treatment: Vermifiltration

alternative practice names:

Worm Bed; Filter Bed; Biofiltro

Vermifiltration is an innovative biological system that treats wastewater from livestock operations by using microorganisms and earthworms to process the waste aerobically. This emerging technology effectively filters and reduces the nutrient load in wastewater, serving as a tertiary or polishing treatment. In a vermifiltration system, earthworms and microbes break down the organic material in the incoming waste stream, leading to the production of nutrient-rich castings containing nitrogen and phosphorus. The tunneling activity of earthworms enhances porosity, aids in nutrient retention, and facilitates aeration, further improving the efficiency of nutrient removal from the effluent.


The vermifiltration system consists of three layers: a bottom layer, made of coarse drainage material to facilitate efficient water flow; a middle layer, comprised of crushed stone or river gravel, providing additional filtration and structural support; and a top layer that measures roughly three feet in depth and consists of wood chips populated with earthworms—typically red wriggler worms—which serve as the primary site for biological activity and waste decomposition. Aeration piping runs through all three layers to maintain aerobic conditions throughout the system, which is crucial for the effective breakdown of waste.


Vermifiltration systems require careful management to optimize their performance, including the following practices:


  • Wastewater application: The wastewater is evenly distributed across the bed using an irrigation system, such as a lateral move irrigation system. Along with wastewater, beneficial microbes are introduced to enhance the breakdown of organic material.

  • Surface management: The wood chip layer is periodically tilled to prevent surface crusting and maintain aeration, promoting optimal conditions for microbial and earthworm activity.

  • Layer refurbishment: Due to the natural decomposition of wood chips, the top layer requires periodic refurbishment, typically every 18 to 24 months, to ensure continued system performance.


As the wastewater passes through the vermifiltration beds, organic matter and nutrients are digested and transformed, leading to a significant reduction in nutrient content in the liquid. Effluent is removed from the beds through a drainage basin located at their base and stored in a holding pond until reuse. This process not only yields nutrient-reduced water suitable for efficient and sustainable irrigation but also produces high-quality worm-casting compost, providing circularity to the farm.

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

Northwest, West, Southwest

FARM SIZE 

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

Over 1000 cows

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Practice Benefits 

Substantial nutrient reduction: Vermifiltration systems demonstrate a high capacity for nutrient reduction. The system decreases organic carbon, Total Kjeldahl Nitrogen (TKN), ammonia-nitrogen, phosphorus, and calcium. 


Impact on water reuse: By reducing total nitrogen concentrations, the treated effluent becomes more suitable for reuse on the dairy farm, particularly for irrigation and flush water. Solids removal prevents clogging in sprinklers.


Diversified income: Vermicompost is a byproduct of this process and can be sold. Worms can also be harvested and sold through various markets. Some carbon markets may pay for manure treatment with this technology.


Lower odors: Separation of solids and use of the aerobic filter bed reduces odors and improves air quality.

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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. 

  • Climate: Depending on the climatic environment, a building structure may be required. Excess rainfall could flush nutrients through the bed. Cold temperatures may have a negative impact on the worm performance and longevity.

  • 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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  • Manure separation system: Farms implementing this practice will also need a separation system to remove sand, coarse solids, and fine solids from the wastewater stream before entering the vermifiltration bed treatment system. The more coarse and fine solids removed prior to vermifiltration, the more efficiently the system will function.

  • Vermifiltration bed: The system will need to be designed by a professional engineer or engineering firm to fit within the existing or proposed dairy operation. The open concrete bed is a major construction cost, but once installed it should last for many years. Obtaining each of the filter bed layers can also be a significant cost, and the purchase price for the number of worms required should also be included.

  • Sprinkler irrigation system: A sprinkler irrigation system is needed to apply wastewater to the beds in an efficient manner.

Required Operational Expenditures (OpEx)

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  • Labor: Staff should be trained in the operation and maintenance of the various waste separation technologies. Additional training may be required to operate the vermifiltration system. This may require daily, weekly, and monthly inspections. 

  • Bed media: The wood chips break down over time and have to be replaced every 18-24 months. Vermicompost and compost will be generated, and the worms should be harvested at this time as well. They can be reintroduced into the new wood chip bed or sold through various markets. 

  • Power: With the number of unit processes being incorporated, adequate energy is required to operate all of the technologies. Compared with other nutrient removal technologies, vermifiltration uses much less energy. 

Implementation Considerations

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  • Land use: Adequate space is needed to implement this practice. Land use for some of the cropland, feedlot, or other areas may need to be changed to account for the area utilized by the filter bed.

  • Coarse and fine solid separation: The more suspended solids removed before the worm bed, the more efficient and effective the system will perform. Excess solids may cause a seal to form on the surface of the vermifiltration bed reducing the ability for wastewater to infiltrate, which reduces performance. An aerobic environment must be maintained for the system to operate properly. 

  • Operational variability: Vermifiltration systems can experience operational inconsistencies, such as fluctuating flow rates and unplanned shutdowns. These disruptions may affect the system's overall efficiency and reliability. 

  • Uneven manure application: Uneven irrigation patterns across vermifiltration beds can lead to inconsistent nutrient uptake, while environmental factors such as temperature and humidity shifts can further impact performance. 

  • Inconsistent nitrogen removal efficiency: The nitrogen removal efficiency of vermifiltration systems can vary significantly, depending on external factors, particularly moisture conditions within the compost material. There is often a correlation between Total Kjeldahl Nitrogen (TKN) reduction and humidity, indicating that stable moisture conditions are crucial for effective nutrient uptake. 

  • Sodium concentration in wastewater treatment: Vermifiltration systems may experience increases in sodium concentration within the liquid manure as it progresses through the treatment process, potentially due to evaporation and the lack of biological sodium uptake. While some sodium retention might occur within the filter beds, high sodium concentrations can still appear in the treated effluent. 

  • Manure storage areas: Since coarse and fine solid separation is required prior to entering the filter bed, multiple waste streams are generated. Additional manure storage areas should be planned to accommodate all waste streams.

Financial Considerations and Revenue Streams

FEDERAL COST-SHARE PROGRAM

Funding is available for this practice through USDA's Natural Resources Conservation Service (NRCS) Environmental Quality Incentives Program (EQIP).

Notes:

  • Check with the local NRCS office on payment rates and practice requirements relevant to your location.

  • To quality for EQIP funds, the dairy is required to obtain a Comprehensive Nutrient Management Plan (CNMP) to guide practice implementation.


CARBON MARKETS

This practice is commonly credited in carbon markets. The practice can generate both offset and inset credits.

Notes: 

  • One Vermilfiltration project has an offset project registered leveraging methane avoidance opportunities. 

  • Certain systems may also be eligible under California's Compliance Offset Protocol.

  • As avoided emissions, this practice provides an annual opportunity for renewal but can only be started when the practice is first implemented. 

  • The volume of emissions reductions is calculated by comparing baseline practices, using default IPCC emissions factors, to the efficiency of methane control by implementing the vermicomposting system. In some cases direct methane monitoring may be required. 

  • Biofiltro, a technology firm employing vermicomposting systems for carbon crediting, claims to reduce up to 7 tons of methane emissions per head of dairy cattle within its systems (see BioFiltro White Paper).


FINANCIAL RESOURCES, TOOLS, AND CASE STUDIES

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Environmental Impacts

MAY REDUCE FARM GREENHOUSE FOOTPRINT

Although detailed research quantifying the impact of nutrient recovery on farm greenhouse gas (GHG) emissions is limited, models indicate that vermifiltration can reduce emissions associated with manure storage. Vermifiltration systems promote aerobic conditions, thus minimizing methane production. The controlled aerobic environment in vermifiltration systems also leads to lower nitrous oxide emissions. 


See research highlights below:

  • Milton et al. (2022) evaluated vermifiltration as a treatment method for liquid dairy manure, observing significant reductions in gas emissions. The vermifilter system achieved reductions of 84–100% for NH₃, 58–82% for CO₂, and 95–100% for CH₄. N₂O emissions were largely undetectable, as they fell below the sensitivity limits of the measurement instruments and were therefore not reported.


IMPROVES WATER QUALITY

Vermifiltration systems can help mitigate the environmental risks associated with manure management by lowering the nutrient load in liquid effluent and concentrating nutrients in a more stable, transportable form.

Vermifiltration systems reduce nitrogen and phosphorus concentrations in manure water. This reduction occurs as the wastewater passes through a filtration bed where earthworms and microorganisms help break down organic matter. The reduced nutrient concentrations in the "teawater" (the liquid effluent) result in a lower risk of nutrient runoff and leaching when responsibly applied to land, compared to raw manure. Vermicompost, the solid byproduct of vermifiltration, typically contains higher concentrations of stabilized nutrients like nitrogen, phosphorus, and potassium compared to the effluent. Because it is more nutrient-dense and easier to manage, vermicompost can be transported and applied to land in a more controlled and targeted manner, reducing environmental risks associated with over-application of raw manure.


See research highlights below:

  • Milton (2021) evaluated the use of vermifiltration to treat liquid dairy manure. The vermifilter achieved organic, nutrient, and solids reduction efficiencies of up to 90%. Results indicated that vermifiltration has a high potential to reduce organics, nutrients, and solids concentration in dairy wastewater.

  • Permana et al. (2024) reported that a vermifilter effectively removed 93% of Chemical Oxygen Demand (COD), 95% of Biological Oxygen Demand (BOD), and 93% of Total Suspended Solids (TSS) from dairy manure. Organic carbon, NH₃-N, and total macronutrients also showed significant reductions after treatment, with organic carbon dropping from 2.01% to 0.0001%, NH₃-N decreasing from 718 mg L⁻¹ to 3.75 mg L⁻¹, and total nutrients such as N, P₂O₅), and potassium (K₂O) also decreasing (0.2% to 0.02% for N, 0.19% to 0.04% for P₂O₅, and 0.57% to 0.18% for K₂O). Vermicompost produced in the filtration beds, where earthworms process the sewage solids, contains elevated levels of macronutrients—2.4% total N, 5.5% P₂O₅, and 0.75% K₂O—as well as 15.6% organic carbon, making it a valuable soil fertilizer. 

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Alignment with FARM Program

FARM Environmental Stewardship (ES) V2-V3 Alignment

FARM ES Version 3 will offer guidance on how users can account for a vermifiltration system by entering information within the custom solid-liquid separation portion of the evaluation.

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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Practical Insights.png
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Research Results.png
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Vermifiltration is an innovative biological system that treats wastewater from livestock operations by using microorganisms and earthworms to process the waste aerobically. This emerging technology effectively filters and reduces the nutrient load in wastewater, serving as a tertiary or polishing treatment. In a vermifiltration system, earthworms and microbes break down the organic material in the incoming waste stream, leading to the production of nutrient-rich castings containing nitrogen and phosphorus. The tunneling activity of earthworms enhances porosity, aids in nutrient retention, and facilitates aeration, further improving the efficiency of nutrient removal from the effluent.


The vermifiltration system consists of three layers: a bottom layer, made of coarse drainage material to facilitate efficient water flow; a middle layer, comprised of crushed stone or river gravel, providing additional filtration and structural support; and a top layer that measures roughly three feet in depth and consists of wood chips populated with earthworms—typically red wriggler worms—which serve as the primary site for biological activity and waste decomposition. Aeration piping runs through all three layers to maintain aerobic conditions throughout the system, which is crucial for the effective breakdown of waste.


Vermifiltration systems require careful management to optimize their performance, including the following practices:


  • Wastewater application: The wastewater is evenly distributed across the bed using an irrigation system, such as a lateral move irrigation system. Along with wastewater, beneficial microbes are introduced to enhance the breakdown of organic material.

  • Surface management: The wood chip layer is periodically tilled to prevent surface crusting and maintain aeration, promoting optimal conditions for microbial and earthworm activity.

  • Layer refurbishment: Due to the natural decomposition of wood chips, the top layer requires periodic refurbishment, typically every 18 to 24 months, to ensure continued system performance.


As the wastewater passes through the vermifiltration beds, organic matter and nutrients are digested and transformed, leading to a significant reduction in nutrient content in the liquid. Effluent is removed from the beds through a drainage basin located at their base and stored in a holding pond until reuse. This process not only yields nutrient-reduced water suitable for efficient and sustainable irrigation but also produces high-quality worm-casting compost, providing circularity to the farm.

Practices and technologies

Manure Treatment: Vermifiltration

alternative practice name:

Worm Bed; Filter Bed; Biofiltro