Shannon Leavitt says he can’t produce enough compost to satisfy all of the customers who ask for it.
For 18 years, Leavitt has owned the Natural Fertilizer Co. in Wildorado, TX, which he says was started by Fletcher Sims, “the father of mass-production composting,” in the late 1960s.
Annually, the Natural Fertilizer Co. produces an average of 40,000 tons of compost from feedlot manure in the Texas Panhandle. Leavitt says he hasn’t had to actively market the product for more than a decade.
In South Carolina, Charleston County Environmental Management (CCEM) is one of the most effective municipal solid waste composting operations in North America-the largest compost producer in the state and one of the largest on the East Coast.
The county-run program takes in yardwaste from local municipalities as well as pre- and post-consumer foodwaste for feedstock for its compost operation.
The operation has gone from producing 20,000 tons per year of nutrient-rich compost in 1993 to 59,000 tons from a facility that covers 36 acres and processes 100% of the yardwaste generated.
In Killeen, TX, creating beneficial-use compost from materials previously considered a disposal challenge was the focus of a regional composting facility opened in August 2011 by the Bell County Water Control and Improvement District No. 1 (WCID No.1).
Composting is here to stay, but it takes the right system to make it work.
The US Composting Council’s Conference & Trade Show in Austin, TX, gives municipal solid waste management operators an opportunity to “kick the tires” of the variety of technologies that are available, see demonstrations, and obtain input from composting experts, leading to more educated decisions, points out Rod Tyler, vice president of the US Composting Council’s board of directors and CEO of Filtrexx.
At the US Composting Council’s Conference & Trade Show, Morbark will be showing equipment from its Wood Hog line of horizontal grinders.
The Wood Hog is an industrial-grade grinder designed to process brush, yardwaste, debris-including storm debris, C&D waste, other mixed woody feedstocks, and asphalt shingles-into saleable products. “All Wood Hogs come standard with the Morbark Integrated Control System to maximize production and engine efficiency, a laser-cut, factory-balanced rotor for unsurpassed durability, and an aggressive feed wheel with an internal Poclain drive that has no chains or sprockets for more torque and reduced maintenance,” says Chris Edmonds, industrial sales manager for Morbark’s western region.
The breakaway torque limiter driveline protection system protects against catastrophic damage from contaminants, says Edmonds.
An optional Morbark Quick Switch grinder-to-chipper conversion kit enables operators to produce high-quality biomass fuel chips or sawdust, he adds.
Komptech Americas will be introducing its new direct drive Crambo. “This machine will have all of the functionality of the hydraulic Crambo like reversing shafts and programmable reversing ability, but will have increased performance with decreased fuel consumption,” notes Todd Dunderdale, vice president of marketing.
Komptech’s machine is designed specifically for the composting market, says Dunderdale. “We also produce high-speed grinders for the forestry market where biomass is produced. However, for composting you want a dual-shaft, low-speed shredder,” he points out. “This is because this machine is designed to blend and mix the material prior to windrowing.”
The machine also is designed to be resistant to the contaminants that often find their way into greenwaste, such as axe heads and other steel, Dunderdale adds. “A big concern nowadays is plastic contamination,” he says. “A low-speed shredder keeps the plastic pieces bigger, allowing for easier removal during screening, whereas high-speed machines tend to grind the plastic into many small pieces that can get into the finished product.”
Vermeer has a number of tier projects being engineered. Its latest introduction into the marketplace is the TR620 trommel screen, which was launched in early 2014.
Vermeer’s composting equipment is designed to address the needs of waste management and provide products for applications such as top-dressing for yards and golf courses; compost socks, which consist of mesh tubes filled with compost that will slow and filter water on a construction site capturing soil and reducing erosion; and erosion control on disturbed areas such as construction sites, development (and planting) projects and exposed stream banks, and organic fertilizer or soil conditioners.
Compost turners are designed to efficiently produce large volumes of compost by introducing oxygen into the compost pile to help speed the decomposition process.
There are two types of compost turners: drum and elevating face. Vermeer compost equipment is designed to process up to 4,000 cubic yards of compost per hour, depending on the turner’s type and size.
Amadas Industries offers a trommel screen system for the final screening of material before sale of the compost. The company also offers manual bagging machinery for bagging the finished compost for retail sale. Amadas Industries may be introducing a municipal compost or mulch loader during the conference and trade show, says Tiny Andrews, industrial sales manager.
MSW operations that are not putting foodwaste into the landfill need a way to process it onsite. ALLU Group Inc. offers solutions.
The company’s machinery is designed to screen, mix, aerate, and downsize foodwaste in a one-step process, says Jesse Allen, marketing manager.
ALLU Group offers two different types of buckets to do so: a screener/crusher to process material from five-eighths of an inch to a 5-inch size, and a fine screener to screen out smaller fragments, such as rocks and other debris.
The recession became a driving factor in finding ways to compost efficiently, Allen says. “When you can find ways to process this material without having to take numerous steps to do so, you’ll be able to save money,” he says.
While the learning curve in operating the equipment is relatively easy, Allen says, the company does train onsite. “It’s not a piece of equipment with challenges,” he says. “It’s a piece of equipment that you can overcome challenges with.”
Resource Recovery Systems International manufactures straddle-type windrow turners with a variety of options.
The company customizes the windrow turners to the owner’s specifications. “They have a range in sizes and engine horsepower, four different drum styles, several tire sizes, tracks, and four-wheel drives,” says Les Kuhlman, company president.
In determining what grinding equipment is best suited for composting, “you need to consider what size feedstock you will be running, such as stumps, greenwaste, or limbs, and how much throughput you want from the machine,” says Michael Spreadbury, marketing manager for Peterson Pacific.
“Grinding is all about horsepower,” adds Spreadbury. “A more powerful machine will reduce material a lot faster than a smaller machine. You don’t want to waste time and fuel with a smaller horsepower machine when a large one can get the job done much faster.”
At the 2015 US Composting Council Show, Peterson Pacific will introduce its latest grinder, the Peterson 6700D, which is the company’s largest horizontal grinder. “It is designed for operations that need the most durable, highest output machine,” notes Spreadbury.
Peterson specializes in developing delivery and processing equipment that turns low-grade organic materials into high-value products, he adds.
The 6700D is powered by an 1,125-horsepower, Tier II Caterpillar C32 engine or an optional Tier IVi Caterpillar C32 engine. “With a feed opening of 66 inches by 50 inches, the 6700D can even process large stumps that used to be reserved for tub grinders,” notes Spreadbury. “With the R+package, the 6700D can be configured as a mid-speed grinder to handle heavily contaminated piles or a high-speed grinder for typical land clearing operations.”
Peterson’s three-stage grinding process, with an up-turning rotor and large grate area, enables the 6700D to produce materials to exact specifications. “Our quick-change multiple-grate system makes it easy to customize grate configurations to produce a wide variety of finished materials,” says Spreadbury. “Grates are removed through an enlarged access door on the side wall of the 6700D.”
The 6700D features Peterson’s Adaptive Control System, which controls all components of the feed system to optimize output. “This system monitors the grinding load and varies the speed of the feed system to keep the engine working at the top of its power curve,” says Spreadbury. “It automatically accelerates the feed system when the engine load is light, slows when the load is high, and reverses if the engine speed drops. It even monitors the engine temperature and varies the cooling fan speed to minimize power usage and reduce fuel consumption.”
Peterson grinders feature a latching impact release system, which minimizes damage from contaminants in the feed material. “The anvil and first grate open on a severe impact, -allowing the contaminant to be ejected, and then re-latch to permit continuous grinding,” says Spreadbury.
Peterson horizontal grinders are operated by remote control, which is kept in the cab of the wheel loader or excavator feeding the machine, notes Spreadbury. “As the machine operates, the loader can make the necessary adjustments to the machine without leaving the safety and comfort of the cab,” he says. “Daily maintenance is crucial to a long machine life.”
The machine should be cleaned and inspected for damage at the end of each shift, Spreadbury says. “Depending on the material being reduced, the bits will need to be rotated or replaced as they wear, but are easily serviced with the onboard air compressor and simple pneumatic tools,” he adds.
Diamond Z offers tub grinders, hori zontal grinders, enclosed grinders, and solid waste grinders from 440 horsepower to 2,400 horsepower.
Diamond Z equipment is used by composting facilities in such places as San Diego and Los Angeles. “They have machines running up to 1,200 horsepower doing nothing but composting,” says Jens Jensen, sales and service manager. “There are companies in Washington that are mixing food waste into it and are now having huge successes with our larger machines that are mixing soils and food waste and wood waste and anything else they can.”
The most used machine in composting operations is the DZH4000. The machine features a C18 Caterpillar engine combined with a down-cut mill to deliver production rates up to 120 tons per hour. MSW operations like it because “it’s a really productive machine, using less fuel, and it’s lighter in weight and maneuverable on tracks,” says Jensen.
Diamond Z endeavors to design machines that are uncomplicated, Jensen says, adding that the company provides startup training.
“It’s easy to maintain,” he adds. “That’s what’s most important out in the field, is that you’re putting product on the ground. People don’t want to work on machines; they want to grind.”
The end product is being used for bulk composting for residential and commercial applications, says Jensen.
“It seems that everything is heading toward being able to better manage foodwaste, with companies all around the country figuring out ways to better deal with it without the odor issues and figuring out a way to get the right mix,” notes Jim Coyne, business development manager for Ecoverse Industries, the parent company of DoppstadtUS, N40, and EnvEco.
Ecoverse Industries’ Backhus line offers a line of turners for windrow widths from 9 feet to 25 feet, trapezoidal piles, agitated bay systems, and bridge turners. The company also recently acquired an interest in Harvest Quest International, which supplies microbial treatments for compost operations.
“The Harvest Quest inoculant, along with a modified static aerobic pile [MSAP] composting method speeds up the breakdown of foodwaste and biosolids while reducing odors. We have also seen our inoculant and method remediate petroleum hydrocarbons from fracking discharge material in -Colorado,” says Coyne.
The end product of the compost with fracking discharge has been approved in Colorado as a soil amendment, he adds.
An increasing number of states are calling for a ban on the landfilling of foodwaste. “People are starting to see how they can turn foodwaste with the composting process into an organic fertilizer that they can then sell and turn into a whole new revenue stream,” says Coyne. “We’re seeing huge operations that run the composting for an entire city or region to smaller operations that just have arrangements with the deals with area grocery stores.
“It’s all about the microbial activity,” he adds. “It’s all of this natural bacteria that comes with our inoculant we have with compost piles.”
Coyne explains that instead of traditional composting, which occurs from the inside out, this process starts from the outside and works its way in. “That’s the way the bugs spread over the pile,” he says. “It turns an area that used to have a high ammonia smell that you get in those compost windrows to more of an earthy smell. It’s allowed us to spend a little bit more time getting to know what the compost industry is like.”
The company also sells the Tiger HS640, which functions as a shredder, screener, and an unwrapper in one machine. It handles both solid and liquid fractions, processing the organic wastes as they are.
The machine opens packaged organic materials and separates their organic content material from the container to ensure contamination-free feedstock introduction. “It’s good for a lot of grocery chains, large distributors of packaged products or even municipalities that deal with a lot of food waste and the packaging that goes with it,” says Coyne. “By being able to manipulate the controls, you get material you can put straight into an anaerobic digestion system or the same for compost. If you want to make sure there’s no plastic or contaminants in your products, you can use this and come out with a leachate.”
Scarab International LLLP is currently working on several different technologies that are going to enhance the performance of its windrow turner machines, says Jim Greer, sales manager for Scarab. “The changes coming include but are not limited to operator controls, wiring, and drum turning,” he says.
The company’s equipment is easy to -operate, Greer says. “Two joysticks control the drive wheels or tracks on both sides,” he says. “A person can be trained in five minutes to run a Scarab.”
Jensen notes composting is getting more prevalent and will continue on a growth path, fueled by a push to become more eco-friendly. “As a whole, we continue to see the composting effort continue to evolve and grow,” says Jeff Bradley, product manager for recycling and forestry with Vermeer. “That can be anything from people doing it in their backyards by creating small compost bins to large commercial-scale composting. People are seeing the benefits of it from a green initiative standpoint, doing the right thing for the environment, and we continue to see that education and knowledge base, even in the younger crowd. Schools are doing a much better job in that education piece.”
Foodwaste is growing in popularity as a feedstock for compost, says Allen.
Greenwaste is the mainstay of composting, says Bradley. “It’s been there for a lot of years and will continue to grow,” he adds. “Foodwaste is one of those key areas where each state has its own set of regulations based on recycling rates. Quite a bit of the foodwaste is going into the compost industry as well as anaerobic digestion.”
Kuhlman points out that while anaerobic digestion takes away some of the waste that is only composted, composting is “easy and a fairly low-cost process in the hierarchy of alternatives.”
Tyler says he sees a bright future for composting “as most communities are trying to recover more and more of their organics to meet their recycling goals or for other reasons.”
The finished product is finding its way into an increasing number of diverse applications, a trend that will continue as people becoming more cognizant of the properties in compost that help fix damaged soil.
“The markets for use of compost have always been developing,” he points out. “What’s interesting is the markets for using locally produced compost for things like creating urban gardens are now becoming much more vogue than when I started in the business 25 years ago.”
Tyler says he doesn’t foresee urban gardens replacing conventional agricultural but that they do offer an advantage for addressing critical “food desert” locales or providing potential beneficial use for the thousands of urban lots that are vacant in such cities as Cleveland and Detroit.
The current markets for composted material include land applications for agriculture, bagged sales, erosion control, landscaping companies, compost resellers, home gardens, farming, soil remediation, and municipal solid waste cover.
“Also, there are some homes in new areas required to use compost for water-saving aspects,” adds Kuhlman.
Municipal solid waste operations are challenged with looking at composting one of two ways, says Tyler. “Either they look at composting as a way to handle their wastestream with a process-oriented, get-rid-of-it mentality, or as organic recovery, an opportunity to use organic resources more sustainably locally,” he adds.
The latter view allows MSW operations to offer the product for use in urban gardening, stormwater or erosion control, steep-slope stabilization, or to promote general soil health, Tyler says.
“In doing that, the whole low-impact development [LID] envelope of products and applications is available to them,” he adds.
Without using compost, an LID option can be difficult to achieve, Tyler points out. “For example, Atlanta is one of the first cities to pass a law that any redevelopment has to use LID technologies. A lot of these municipalities, therefore, are challenged with the current footprint, any remaining build-out that they have, and all of the impervious surface that comes along with natural development,” he says. “The only thing that counterbalances that is LID designs, in which a lot of them use compost.”
For the municipal sector, an opportunity arises to consider organic residuals as a resource “so that the current pressure they have to face on infrastructure is reduced from water inflow and infiltration,” says Tyler.
The use of organics in those applications creates a market for products that the MSW operations are trying to banish, he adds.
Composting is a good way for municipalities to take most of the yardwaste out of the wastestream, which translates to more available space in the landfill, says Andrews.
As CCEM managers point out, -adding compost to soil increases the amount of organic matter, helping to increase nutrient levels and conserve water.
South Carolina soils typically have an organic matter content of less than 1%, insufficient for ideal water retention. Compost can hold up to 10 times its own weight in water.
Other benefits include reduced soil compaction and increased root growth, increased nutrients and beneficial soil microbes, reduced need for fertilizers, healthier plants, and more rapid growth rates.
Greer points out that composting eliminates foodwaste and yardwaste, returns oxygen and nitrogen to the earth, eliminates the need for such “unhealthy” chemicals as fertilizers and pesticides in soil, cleans up contaminated soil, prevents pollution, prevents erosion, enables manure from feedlots to be turned into compost, and promotes “green living.”
If done correctly, composting is a way to repurpose the traditional wastestream to a valuable end product, says Bradley. “Along those same lines, rather than sending that to the landfill, you’re actually creating an end product and reducing the greenhouse gasses while you’re extending that landfill life,” he adds. “Another thing you’re doing on the benefit side is that you’re creating a soil amendment, which actually has high levels of micronutrients and increases the water-holding capability of the soil that you put this in as you mix it in. Also, you’re supplying organic farmers with a fertilizer, because this definitely does have a decent NPK value as a fertilizer.”
There are, however, drawbacks to consider when producing compost. “It takes from 90 to 180 days to convert a mulch product into a compost product,” says Edmonds. “There’s additional equipment needed to turn the compost, to hydrate it, keep it moist and allow the compost to break down properly. There is also, in many areas, a shortened and seasonal sales cycle for compost as opposed to a year-round, constant demand for wood fuel products.”
Other potential drawbacks include the amount of land required, transportation costs, regulations, time investment and equipment costs, feedstock, managing waste, and economic feasibility, says Greer.
Finding qualified personnel to run the operation is another challenge, says Edmonds. “An operation getting into composting should research and know its potential competition: Who else is in the market, and what is the scale of their operations?” he says. “Also, a composting operation requires more permitting and has more regulations to follow than many other woodwaste operations. Since the material has to sit there for a longer time while it is turning into valuable compost, there are potential runoff issues that require additional site preparation and permitting.”
The biggest drawback of composting has been the increased regulation in the past years, Dunderdale adds. “All of the permits and regulation required have increased the costs to process material. If companies cannot make money composting, they won’t do it.”
Site layout and marketing the finished products are other challenges, Dunderdale points out.
One of the challenges inherent in working with foodwaste or biosolids is having the right mix for the process, Coyne says.
For instance, the ratio could be shifted by the presence of more biosolids than yardwaste. “A lot of operations are looking to grow big. Sometimes they just want to make the piles higher, but that will change the entire makeup of what they put into their composter,” he says.
There are concerns with respect to foodwaste composting of which those planning to engage in it should be aware, Bradley says.
Primary among them is odor control.
Operators can get into trouble in a hurry if they’re not educated about handling foodwaste, Bradley says. Getting foodwaste under control is worth the effort, he adds.
“That definitely is one of the biggest driving factors from an overall waste standpoint,” he says. “That contributes as much as greenwaste as far as the national tonnage goes. The opportunity is huge to be able to pull that out of the wastestream and do something beneficial with that material.”
The benefits of composting far outweigh any drawbacks, Dunderdale notes. “There is an urgent need to replace valuable nutrients that have been removed from our soils,” he says. “Everything from reduced plant disease to increased water retention and better yields all can be obtained from using compost on the soil.”
The drawbacks are not insurmountable. Bradley encourages those wanting to get into composting or expand existing operations to educate themselves on the process. “The US Composting Council offers an operators training course as well as a number of other organizations across the US, such as North Carolina State University, Iowa State University, and Cornell University. A lot of different places offer some training to minimize those issues that show up, such as an odor issue.
“We’ve heard a lot of those lately in the news, a few big ones in the East,” he continues. “All of those things that go publicly wrong really affect the market and the public’s perception of the industry. Whatever we can do to help minimize that is definitely worth the time.”
There are a number of tools online and privately for purchase where compost operations can create their own “recipe” to minimize odor and runoff issues to deal with the leachate coming out of the compost pile because it may be too nitrogen-rich, Dunderdale notes.
What each MSW operation needs to start or augment a composting program is related to the size and scope of municipal generation, says Tyler. “The needs of one that generates 10,000 yards of compost a year versus 100,000 yards of compost a year are vastly different,” he points out. “The equipment that’s required for those operations is vastly different.”
To determine what equipment is needed for composting, customers have to determine from many different operational aspects what kind of composting operation they can handle, says Greer. “It is our belief that the fastest and best way to make quality compost is by windrow composting,” he says. “Site considerations such as location, size, layout, and space limitations, as well as incoming volume, and other equipment such as screeners, crushers, or loaders help determine the size of the windrow compost turner that is needed for the individual site.”
“You have to match your incoming volume allotment,” says Bradley. “How much physical space you have on the site can tell you whether you need to do a windrow compost turner or a continuous stack compost turner.”
Vermeer’s CT10TX has a conveyer system that offers a continuous stack so there are not spaces between every windrow. “You can fit almost twice as much compost on the site as you do with the traditional windrow turner,” says Bradley. “You almost have to lay it out from start to finish and understand your space and size. You also have to allow room for the receiving area, the curing pile, and loading and unloading areas. All of the space is a huge concern when you’re trying to define what equipment you’re going to need.”
The Backhus windrow turners work well in operations constrained by their surroundings, says Coyne. “In terms of being able to do toe-to-toe composting and make sure you’re getting the maximum amount of it turned and not missing the bottom layer, you’re making sure that every inch is covered,” he says.
“You’re also looking at the long run of fuel costs, man-hour operations, and training people to use equipment,” he adds. “Backhus is one of the only cabins in the market that has an ergonomic cabin in which a person can train another person in it. The jump seat gives the operator the ability to do a lot more than has ever been available in the past with windrow turners.”
The Backhus, used in conjunction with the Harvest Quest, which doesn’t require as much turning and cuts back on the amount of man-hours and fuel costs, presents a win-win when combined in operation, Coyne says.
Jensen concurs that throughput is one of the factors that composting operations should consider when adding equipment. “If you’re going to bring in a small amount of product, you’re going to look for a smaller machine,” he says. “You don’t want to overpurchase your machine and overburden yourself. You don’t want to kill your business out the gate, but you also want to give yourself enough room to improve.”
It’s best to buy a machine that offers at least 10% to 15% more than what is needed to accommodate growth needs, he adds. “Have some room to expand but not overwhelming,” says Jensen. “If you need 500 tons today, you don’t need to buy a machine to produce 15,000, because it’s just a little too much for you. There’s no sense having them sitting there unused most of the time.”
A number of other factors determine what an operation should consider when choosing the appropriate equipment for a composting operation, Edmonds points out.
“What feedstocks will they be processing? What is the size of the operation, and what volume of materials needs to be processed? These will help the company choose a machine and setup that will handle what they’ll throw at it,” he says.
Regulations on such factors as emissions are another consideration, be they local, state, or EPA. “This will help determine if they need a Tier IV engine or if they should consider electric-powered equipment,” Edmonds says. “We’ve worked with a number of companies and municipalities to help them work through these questions and to choose the machine that will work best for their specific circumstances.”
“You have to make sure all of your Is are dotted and your Ts are crossed and that you are not permitted for too small of an operation,” adds Andrews. “You can find yourself really throttled by the size that you thought you were going to be versus where you need to be. Acreage or tons per day incoming is how it is regulated.”
In making a choice for screening, one must first know how many yards of finished compost is being produced, says Andrews. “Secondly, you would need to know what sales are driving the requirements for the production: how much you are going to be able to sell and if you have the capacity to keep up with that. That is how you choose the size of the trommel, either by length or diameter of the drum. That typically depends on the production rates or sales requirements. Typically, our baggers will do 18 to 22 bags a minute. As fast as you can hang a bag, it will charge it.”
It’s critical to become educated on the process, Bradley says: “You need to understand what your finished material and use is going to be. What market are you targeting? You have to know where you want to go to figure out how you’re going to get there.”
An operator also needs to consider seasonal variations and the site surface, be it a hard surface or soil, Kuhlman says.
The size of the site in relation to the amount of incoming material is another consideration, he adds.
If a site is small but takes in material that would be more suitable for a larger site, “the tendency is to have a larger turner because you get more material out of a given area,” he says.
Traditional bulk compost for landscapers is going to require different equipment than supplying to an agricultural application or a golf course, Bradley points out. “That determines what machinery you need on the front side, how fine you grind your material, what you screen out your -material to,” he says. “You don’t have to screen it on the back side if you’re going to an -agriculture application.”
Material type is another factor, Bradley adds. “Are you going to be doing logs? Utilizing a mulch product? Foodwaste, grass clippings, leaves—what are those materials that are coming in, and how are you going to have to process it? That’s key to what grinder and what turner style you’re going to need.”
Leavitt points out that there must be a clear customer base for compost. “If you go to a lawn-and-garden place to buy compost, it can be defined as anything from a bag of leaves to a bag of raw manure and anything in-between,” he says.
Leavitt says he believes compost should be a “very specific, very finished product.”
“The biggest challenge to somebody making compost is to gain credibility with their customers so their customers know they’re going to produce a consistent and finished product,” he says. “Once those customers have that assurance, then at that point they can move forward in trying it to see how it compares to commercial fertilizer costs.”
The feedstock is a critical factor in composting. Operations considering composting should make certain they have plenty of available green yardwaste, says Harvey Gibson, compost superintendent for CCEM.
“A lot of places take too much foodwaste and don’t have enough of the green yardwaste to do it with the least odor problems,” says Gibson. “You just naturally have problems with that. You have to have a large amount of greenwaste to start to make sure you use it as a filter, a bedding, a mix. You have to have a lot more than you ever think you would. We’re fortunate that we do have that.”
“If you build it, they will come,” says Gibson, quoting the motion picture, Field of Dreams. “We started out small and tripled our size within five years. If you don’t think you have that much yardwaste or foodwaste to actually build it and get it up and running, everyone comes out of the woodwork and will bring it to you.”
On occasion, the Natural Fertilizer Co. receives “highly classified documents that are disintegrated from one of the weapons facilities in Amarillo,” says Leavitt.
“It’s paper trash, and we blend that with the manure as an added carbon source.”
Additionally, the feedlot effluent is used to make the compost. “It’s one of my favorite things,” notes Leavitt. “We don’t use good drinking water to make compost—we use the runoff water that’s also a waste material that needs to be gotten rid of.”
The compost product is sold mostly to large farming operations, with a small percentage of the product purchased by those wanting it for home gardening and yards. Some organic farmers in Santa Fe, NM, buy the compost for their farmers’ market.
The driving factor is the production the end users get from the compost, Leavitt says. “The cost of fertilizer versus the value of the nutrients in my compost is significant,” he says. “If you buy the nutrients that are in my compost—the nitrogen, phosphorus and potassium—in equal amounts as to what’s in my compost, it would be double what I charge for my compost.”
The biological activity is the most significant value of the compost, Leavitt says. The commercial farmers who buy the compost are getting optimal production with it, he adds.
Natural Fertilizer Co. workers begin the process by gathering the manure in the pen and stacking it in windrows with equipment that includes the 18-foot Scarab compost turner. Choices for the turner include width and height to match the required processing capacity; a standard drive system or pad saver model for toe-to-toe windrows; and -Caterpillar, Cummins, Detroit, and John Deere diesel engines from 190 horsepower to 530 horsepower.
The turner has a high-capacity radiator and a selection of track- or tire-drive systems to handle adverse pad conditions, drum styles, and size to match feedstock, operating and marketing goals, and a choice of hydraulic- or belt-driven drum. A digital load controller is standard.
The Scarab turner has an open design for easy access and lower maintenance costs, a cab designed to be spacious and ergonomic with a panoramic view and three rear-facing cameras, an intuitive joystick control, and a fully lined tunnel to control dust, prevent rust, and resist tunnel cleanup problems associated with steel tunnels.
To create the compost, one must have carbon, nitrogen, oxygen, and water, says Leavitt. “The carbon and nitrogen come in the manure, the oxygen comes from the Scarab machine, and we get effluent water from the lagoon,” he says.
Charleston County’s original composting program was overhauled in 2009, when it banned yardwaste from the landfill, directing it to a compost facility. In 2010, the county introduced foodwaste composting. In 2011, the county instituted a yardwaste plastic bag ban; yardwaste must be placed in paper yardwaste bags to help keep plastic out of the finished compost product.
The operation starts with a Doppstadt AK 630 high-speed, high-volume grinder that processes the yardwaste brought in by municipal and commercial trucks. It is transferred to the active composting area and formed into windrows. The county’s site accommodates 70 windrows spaced 4 feet apart, with 12 feet between each pair of windrows, allowing access for loader and water truck.
The AK630 uses a flail hammermill chamber suited to processing wet materials and materials with high moisture content. The screen-to-hammer ratio is adjustable to match sizing needs, infeed material or wear characteristics, allowing for precise control over machine operation for consistent delivery of accurate material specifications.
The operation also has a Doppstadt DW 3060 low-speed shredder, featuring a high-torque, single-shaft design. A breakaway comb section is designed to ensure that unshreddable material is quickly passed without interrupting the machine and constant up time.
The fuel efficiency is designed to provide cost savings in per-yard or per-ton analysis of material processing. The windrows are monitored regularly for optimum temperature and moisture content. They are turned or watered as needed. Composted material is screened to remove oversized pieces with a trommel.
The nutrient-rich compost is produced within 90 to 120 days.
Although odor tends to be an issue with many composting operations, Gibson says his operation doesn’t have that problem, thanks to its abundance of yardwaste.
CCEM uses Harvest Quest International’s organic catalyst to accelerate and enhance the natural biological process of composting. The organic catalyst led to the MSAP composting method, a combination of static pile and windrow composting methods.
MSAP largely eliminates the need for mechanical turning while still maintaining aerobic conditions and optimal pathogen destruction.
The method is designed for less turning of the windrows, leading to a reduction in material moisture loss, odor production, particulate discharge, nitrogen losses through ammonia volatilization, overall composting time frame, and higher temperatures for longer time periods.
It also is designed to produce better-quality compost in less time with fewer costs. The final compost has been shown to increase numbers of beneficial bacteria in contrast to that produced with more traditional composting methods.
In the MSAP method, feedstocks are mixed using a bucket loader and placed to form windrows approximately 7 feet high by 16 feet wide.
Length is determined by material volumes using the predetermined height and width and can extend to more than 500 feet.
Basic principles of composting are followed with regards to moisture content and carbon to nitrogen ratios. Once a windrow has been constructed, a small amount of Harvest Quest’s catalyst is placed on the surface or mixed into the windrow at both ends to provide two areas of concentrated microbes.
The catalyst is not required to be mixed throughout the entire windrow.
The row is then covered with a layer of finished unscreened compost, ground wood, or greenwaste to provide initial odor control and maintain moisture and heat for increased bacterial activity.
Bacteria within the catalyst spread rapidly outward from the points of application, initially populating the windrow’s outer edges just beneath the capping layer. The initial temperatures on the pile’s surface generally exceed regulatory requirements.
The microbes then work their way toward the windrow’s center, breaking the pile down from the outside in. This action increases the windrow’s natural chimney effect, allowing sufficient airflow into the pile. The biological activity in the windrow’s outer layers provides an effective natural biofilter.
The temperature front moves from the windrow’s outer edges towards the center of the piles. Within several days, the temperature of the entire pile will far exceed 131ºF from just beneath the capping layer through to the core, and elevated temperatures will be maintained for several weeks.
The windrow remains undisturbed for an initial 30- to 45-day period. Following that, the windrow is turned for the first time to reduce compaction and redistribute moisture more evenly.
After 14 days of composting, the windrow is turned a second time, with moisture redistributed. The windrow enters the final composting phase, which can be completed in as little as 60 days.
In Charleston County, the end product is used internally, sold, or given at no cost to such programs as Farm to School. Branches of Charleston County government receive the compost. Compost also is sold at $2 for a 2-cubic-foot bag and $10 for a loose ton.
The county’s facility was the first in the state to be permitted by the Department of Health and Environmental Control to implement two major innovations: the use of compost as an alternative daily cover in the landfill and the initiation of a foodwaste composting pilot.
CCEM has garnered recognition for its efforts, having received the 2011 Outstanding Composting or Organics Recycling Program Award from the Carolina Recycling Association.
In January 2013, the program earned the United States Composting Council’s Seal of Testing Assurance, attesting that the finished compost consistently meets its high-quality standards.
Clemson University has deemed -Charleston County’s compost suitable for organic farming.
WCID No. 1 serves more than 275,000 people in the region that includes Fort Hood, the world’s largest U.S. Army base. More than 90 million gallons (340.7 ml) a day flows in and out of the water treatment plant.
Until that time, some 250 tons of Class B biosolid, or sludge, would be trucked from WCID No. 1’s three wastewater plants each week to permitted land specified for biosolid disposal at a cost of $75,000 per year.
The facility also met a need for brush and greenwaste disposal for the city of Killeen, which until that time had it hauled to a landfill near a transfer station.
Jerry Atkinson, general manager for WCID No. 1, explored alternatives to the land application in 2005. The district enlisted Lockwood, Andrews & Newnam Inc. (LAN), a Houston-based environmental engineering firm with experience in the design and build of various public works and energy facilities.
LAN conducted a feasibility study that included finding an appropriate site, which turned out to be the property where the city had been disposing of its brush. The city agreed to a long-term lease for 20 acres of land for the facility.
After district and LAN staff visited other compost operations for a year, it was determined that a site layout with the least amount of impact on nearby residents was an important factor.
Safety was another factor. The brush-grinding area was placed in the facility’s back corner away from traffic flows and employee work areas.
The newer windrows were located in the site’s lower area to stay clear of the wind and minimize odors.
Finishing windrows were placed closer to the front for final screening and easy pickup.
The district also developed a marketing plan to build a customer base for the compost, sending information on the facility to landscapers, nurseries, and Texas DOT contractors in a 50-mile radius. News releases were sent out. A grand opening in December 2011 drew more than 100 people from around the state.
The $3.3 million project was initiated when the district had enough money to do so without additional tax dollars or raising water and waste rates. The project also included landscaping, a sprinkler system, and a working windmill in the effort to make it more attractive. F.T. Woods Construction Co. of Georgetown, TX, was chosen to provide construction services.
To equip the facility, WCID No. 1 -purchased a Vermeer HG6000 grinder, a Wildcat CT718 compost turner, and a -Wildcat TR521 trommel.
The district uses a ratio of 1.5:1 brush to Class B biosolids. Each day, brush is brought to the facility and processed with the Vermeer HG6000 grinder into wood mulch. Biosolids delivered from the wastewater treatment plants are placed in a holding area in another part of the facility.
The windrows are created with a layer of wood mulch followed by a layer of biosolids and then a layer of brush. The ratio is 1.5 parts mulch to one part biosolids. The windrow is mixed together with the CT718.
It takes approximately four days for the windrow to reach the appropriate temperature from 115°F to 160°F. If the temperature doesn’t fall in that range, water is added to initiate the heat or else the pile is turned to reduce the heat. The windrow spends about 15 days in this “cooking” phase; then it will cure for 30 days. After 45 days, the compost is put through the trommel with a three-eighths-inch screen before it is considered finished and ready for sale.
Three types of compost in various grades are available. Contractors order compost by the trailer. Residents can help themselves to self-serve bins near the entrance. WCID No. 1’s product is labeled with the US Composting Council’s Seal of Testing Assurance Program as part of its certification process from the council.
Public buy-in is critical to the success of a composting program. “Public perception is very key,” says Bradley. “When creating a new site or expanding an existing site, the interaction with neighbors is critical to building a successful program. Go out and proactively engage with the neighbors, get their feedback and address their concerns upfront versus on the backside. Then you’re just trying to handle a bad situation, whereas if you build a relationship upfront, it’s very open communication and you can work it through much easier that way.”
Tyler notes that a trend is afoot among some entities to promote composting and recycling. Case in point: Ohio State University, whose Ohio Stadium is the largest stadium in the country to attempt zero waste by diverting 90% of materials—including foodwaste—from the landfill by recycling and composting.
That promotes the potential to establish positive habits in young adults, Tyler points out. “It’s going to take time for the habits to change,” he says. “There’s no problem with people taking care of their yard trimmings, because that’s separated already. It becomes an issue with commingled products.”
To that end, the US Composting Council has linked with the Biodegradable Products Institute (BPI) for a greater understanding about compostable and biodegradable products in the waste stream.
The US Composting Council’s training program, offered throughout the year at various locations, address some of the challenges, such as odor. “Part of that is training people to know how to manage and operate a compost facility with the understanding that if you operate it correctly, your chances to produce odors are minimized,” says Tyler.
“Each municipal situation is going to have different generation amounts of different organic feedstocks. It’s going to take somebody with the knowledge of composting to be able to help them decide what scale and size of facility will work best for them to generate what they want to generate without creating any issues.”
