Worming Their Way To No More Waste

Worming their way to no more waste

An innovative manure treatment experiment may offer solutions to handling nutrients in a neighbor and environmentally friendly way

By Eleanor Jacobs

There’s no doubt about it. Dairy producers will have to find different ways to handle manure’s vital nutrients, while impressing upon their neighbors and regulatory agencies that their practices meet high environmental standards.
Government agencies have concluded that animal agriculture can lead to excess nitrates in groundwater, pathogens in drinking water, and excess nutrients and sediment in surface water. That is if it’s not handled properly.
Society may consider environmental issues when it raises concerns about manure handling. But for the most part, your neighbors focus on odors.

Eliminating Waste
    To answer these concerns, Fessenden Dairy, King Ferry, N.Y., is experimenting with a manure-handling system that, as Tim Fessenden says, will “handle all the waste so there is no waste.”
    Agricultural Consulting Services, Rochester, N.Y., is drawing up the 550-cow dairy’s CAFO plan. And it has more than adequate crop acres, at 1,100, to handle nutrients for its herd size.
    Still, that’s not enough, says Fessenden, who operates the farm in partnership with his brother John. “I haven’t been happy with how we handle manure, even at 120 cows,” he says. “As the farm has grown, manure concerns are greater on my mind.”
    Nutrient loading and balance have been missing from manure-handling approaches, Fessenden says. “Approaches such as irrigation didn’t address the volume of manure. It’s still there.”
    The Fessendens were ready to try a new manure-handling technology, one that was untested in the real world of farming, when Tim met Richard McClimans, a professor at Syracuse University.
    McClimans, who had done 10 years of laboratory work on manure, was searching for someone willing to do a field trial with his technology. Fessenden Dairy was ready, willing and able.

    The process, which Fessenden emphasizes is purely experimental at this point, has three steps. The experiment is sized for 100 cows.
    1. Manure is pumped from freestall barns to one of two 19-by-40-foot reception pits that are 8.5 feet deep. The pits are in a 60-by-148-foot pole barn. The 14-feet-tall barn has two overhead doors to access the pits if solids settle.
    The manure is pumped from the pit through two FAN separators. “The reason for two separators is to get as much of the solids out of the liquid as possible,” Fessenden says. Raw manure is 10% solids; one separation lowers it to 5% solids. The second separation yields manure that’s less than 3% solids. The reason for low solids becomes clearer in the final step.

Worm castings, says Tim Fessenden, turn composted cow manure into high-end compost.

    2. A conveyor moves the solids into compost windrows laid out in the separation barn. Air is forced through air channels in the floor to aerate these static compost piles and create mature compost in 10 days.
    Because the Fessendens want to market the compost and not use it on the dairy, they implement another process at this point.
    “Each day, we pick up the finished compost and apply it to worm beds in the old heifer barn,” Fessenden says. Through the worms’ actions and dropping of castings (worm manure), the compost is converted to vermiculture.
    “It’s high-end compost,” Fessenden says. “Cow manure is low-end compost in the marketplace.”
    Fessenden takes worms very seriously. Like cows, they need the right environment and feed to survive.

    3. Liquids go into a third pit where Fessenden monitors the ammonia and pH levels. He installed an aeration system that creates what Fessenden jokes is a Jacuzzi effect when the pit bubbles. The purpose is serious, however. It lowers the ammonia level, which is critical for the next, and most experimental, phase of this manure handling system.
    The liquid is irrigated at a rate of 1 inch a day through overhead sprayers onto tall fescue grass growing in two 30-by-90-foot greenhouses. Each greenhouse should be able to handle liquid from 50 cows.
    “We created a controlled environment to use the liquids,” Fessenden says. “The purpose is to use the liquids where they won’t be an environmental concern.”

FYI
To learn more about manure systems, plan to attend the NRAES conference, Dairy Manure Systems: Equipment and Technology, on March 20-21, 2001, in Rochester, N.Y. For registration information, contact NRAES at (607) 255-7654. E-mail: NRAES@cornell.edu
Web site: www.NRAES.org

    The fescue, noted for its ability to take up nutrients, will be cut frequently to keep it in a vegetative state. Fessenden may feed it to replacements to recycle it back to the herd.
    In one greenhouse, the grass grows on compost laid over woodchips and municipal ash, which according to McClimas’ work retains its structure regardless of the amount of water applied.
    The other greenhouse has grass and compost over gravel. The ash/woodchips and gravel bases provide further treatment to the liquid as it percolates through the root zone.
    A liner and storage tanks are below this 30-inch root zone. “Theoretically, the liquid could be dischargeable,” Fessenden says.

If It Works
    “We’re excited about it,” Fessenden says of the experimental manure-handling system. “We take manure from one end and nothing comes out the other end.”
    As for the compost, Fessenden looks forward to taking the expense of handling manure and turning it into income. “We’d like to show it’s economically sound, that there’s a return. And we wanted something we could do year-round and not have to deal with weather.”
    Any manure-handling technology worth its salt costs something. Working with the local Soil and Water Conservation District, the Fessendens applied for cost-share funds through the New York State Environmental Bond Act and EPA moneys. The Northeast Dairy Producers Association (NEDPA) also supplied some funding.
    The bottom line: The investment in an experimental manure-handling project has so far totaled more than $700,000.

Manure handling systems offer promise

If you’re not ready for vermiculture and irrigated liquid on grasses grown in a greenhouse, other methods to handle manure are being tested and improved upon.
• Biodrying: Manure is biodried by recycling dry compost as the amendment to a composting mixture. The heat generated in the aerobic decomposition is used to dry the manure/compost mix with forced air.
Advantages:

Odor, pathogen, volume and weight reduction
Equipment for solids handling is available on most farms; liquid handling equipment would not be needed.
Storing solids is safer environmentally than storing liquid.
All manure may be marketed.

Disadvantages:

Possibly high labor and electric costs.
Time consuming to handle materials.
A possible need for additional compost amendment.
Cost control through marketing compost.
A need for building and blowers.

• Anaerobic Digestion: Digests manure to produce an odorless effluent that has reduced solids with nutrients. Recovered methane gas can be used to run an engine generator.
Advantages:

Odor reduction.
Production of electricity and/or heat.
Effluent, reduced in solids content, can be further reduced by mechanical solid separation for easy irrigation. It will have very little odor.
Marketing solids.
Settling may concentrate nutrients.
Pathogens are reduced but nutrients preserved.
May provide a positive return over the long term.

Disadvantages:

High capital costs.
Working with an electric utility may be difficult.
Diluted manure requires a large digester and more heating.

• Fixed Film Anaerobic Digestion: This process takes diluted or separated liquid manure at less than 4% solids and digests it within three to eight days, producing an odorless effluent. The digester can be much smaller and less costly than a conventional digester.
This system may help smaller farms use anaerobic digestion for odor control.
Advantages:

Odor reduction
Capital expense is less than for conventional anaerobic digester
Effluent, with lower odor, has reduced solids content for easy irrigation.
Solids can be marketed.
Nutrients are preserved.
No need to involve a utility.

Disadvantages:

Energy recovery is low.
Operating costs won’t be covered by energy sales.

• Lagoon Treatment or Bion System: Manure is diluted, usually by flushing housing, and solids removed mechanically or by allowing them to settle in large shallow pools. They eventually flow to a facultative lagoon to be recycled as flush water to dilute more manure.
Treatment occurs by building a biomass of organisms that decompose the manure either aerobically, anaerobically or faculatatively. The solids can then be harvested, dried, screened and sold as a soil amendment.
Advantages:

Odor reduction.
Separated solids can be marketed.
Works with a barn flush system.
Liquids can be irrigated or further treated in a terraced overland flow system.
Phosphorous removed
A flat site with low permeability soil lowers installation costs.

Disadvantages:

Solid harvesting can be difficult or expensive.
Large surface areas may result in extra water volumes.
Impermeable soils on moderately flat terrain are required to keep cost down.
Aeration is sometimes required.
Nutrients are removed, if you want them.
Solids need to be marketed to get any return.