THE THEORY of composting municipal solid waste other than just yard trimmings on a centralized basis is just as valid today as it was 50 years ago. The difference is that in the 1950s, the primary motivation to initiate projects was to mine the gold in the garbage. In these more "modern times" of MSW composting - more specifically the past 15 to 20 years - the motivation has come from finding a viable alternative to disposal or incineration. Because the need for alternative management scenarios has dwindled over the past ten years, rationalizing the need for composting MSW is more challenging. Projects on somewhat shaky ground technologically, politically, economically and/or waste flow wise - have found it more difficult to continue operating. On the other hand, those with the waste flow, cash flow, good process and odor management, viable end users, a well-defined mission and purpose and political support are doing well.
Two cliches come to mind when looking at the results of BioCycle's 2000 solid waste composting survey. The first is, "If the shoe fits, wear it." A number of the operating MSW composting projects are in locations where maximum recycling and composting are the best, if not the only, option for handling MSW. These include places with high volumes of tourists - thus generating waste streams with large amounts of recyclables and organics, but difficulty in getting consistent separation, e.g. Sumter County, Florida and Sevierville, Tennessee; islands with very high disposal costs, e.g. Nantucket, Massachusetts and Mackinac Island, Michigan; and situations where the economics actually can work in favor of composting (Marlborough, Massachusetts).
The second cliche is, "Survival of the fittest." What has become more than evident this year is that facilities with waste flow, a secure financial footing, a proven technology and well-trained operators are doing well in 2000, and prospects look good for the longer term. There have been plenty of lessons learned in this industry, and those projects doing well have applied them to their facility design, financing, contracts, composting technology and processes.
Perhaps one of the more surprising trends in 2000 is a renewed interest in residential separation and collection of organics other than yard trimmings. San Francisco's Fantastic 3 program is now servicing close to 15,000 households (see "San Francisco Takes Residential Organics Collection Full-Scale," February, 2000), and the city of San Jose, California is in negotiations with a hauler/composter team to initiate a similar program.
Fantastic 3 uses a cart-based collection system, where residents sort MSW into three fractions - commingled recyclables, trash and organics (primarily yard trimmings, food residuals and soiled and/or nonrecyclable paper). Trash and recyclables are cocollected in the same truck; a separate truck services the route to collect organics. In the San Francisco Bay area, two regional waste management companies (the one servicing San Francisco and another company) have invested in a composting infrastructure for commercial organics and now are pursuing separated residential organics (in addition to yard trimmings) to boost waste flows. In addition, local governments - under pressure to meet California's 50 percent recycling mandate by the end of 2000 - are more receptive to considering and investing in increased diversion from the residential sector. In Vermont, the Chittenden Solid Waste District has been running a residential organics collection and composting pilot.
THE 2000 NUMBERS
The 2000 BioCycle municipal solid waste composting survey identified 16 operating facilities and seven projects in various stages of planning or development. In 1999, there were 19 operating plants and six in planning or development. Table 1 provides a summary of this year's projects.
Of the 16 operating plants, five opened their doors ten years ago or more. Another five started in 1990 or 1991, and the remaining six started within the past five years. Six of the 16 are using the Bedminster rotating drum technology in the first stage of their operations; another is using a refurbished drum. Each of these operations go into an aerated windrow, aerated static pile or windrow process for remainder of the composting phase. The drum serves to open garbage bags, separate organics from inorganics, do some size reduction and begin initial composting. The nine other projects use the following composting methods: Windrow - 5; aerated static pile - 1; enclosed aerated static pile (Ag-Bag) - 1; aerated windrow - 1; in-vessel (OTVD) - 1.
Four projects closed their doors in the past year; however, in each case, the project managers note that the shut down may be temporary. Composting stopped at the beginning of the year in O'Neill, Nebraska because it was taking too long, says Kevin Seger, facility manager. A drop in income due to less material brought by the hauler was another reason. Seger hopes composting resumes in the future using windrows within an enclosed facility.
In Crisp County, Georgia, a mixed waste processing plant designed to handle 800 tons/day (tpd) had a sizable composting area to handle organics from the separation line. Composting of MSW stopped in January and there are no plans to resume in the near future. Inability to remove inerts from the waste stream led to the program's demise. "As we were running material through the plant, mechanical sorting would do what it could, but in trying to obtain a certain level of throughput, there was too much burden on the manual sorting belts to get inorganic material pulled out," explains Mike Guest, quality control manager for the Crisp County Solid Waste Management Authority. Crisp County is processing some paper products that come directly from the county's recycling programs, as well as wet and dry tobacco by-products and ground wood chips.
Marketing difficulties were among the problems that led to last year's closing of the MSW plant in Hot Springs, South Dakota. At least for now, the equipment remains in case the city wants to bring the operation on line again. Lexington, Nebraska stopped composting after a fire unrelated to composting ravaged its facility. Although it achieved a 47 percent diversion rate, the operation was never more than a break-even proposition, according to Dave Sterner, manager of the Lexington Area Solid Waste Agency in Nebraska. "In the future, we will use it to do a small amount of material," he says. "We have a meat processing plant in town, for example, that produces solids from its preparation of animal hides."
The composting plant in Mora, Minnesota never really got off the ground, and there are no immediate plans to open it. The East Central Solid Waste Commission had proposed a solid waste fee to generate money for the facility, but one of its five member counties opposed it. The site may be used for yard trimmings composting.
PLANNED START-UPS
A number of facilities are in development. The five members of the Mariposa County (California) Board of Supervisors are leaning toward approval of an MSW composting facility using Herhof technology, says Tom Starling of the county Department of Public Works. For a county of less than 16,000 residents, the $5 million price tag is steep. However, $1.8 million in federal funding has been approved due to the fact that Mariposa handles garbage from adjacent Yosemite National Park, bringing the total daily waste flow to 100 tpd. "That material is very high in organics," says Starling, "and we have minimal C&D debris. There's so much food waste coming to the landfill that would be ideal for composting, as well as lots of paper." Rural community grants may generate another $1.2 million, bringing the county's cost to $2 million and need for borrowing to $1 million.
Martha's Vineyard in Massachusetts has to ship all of its garbage to the mainland. The island has accepted a bid from Waste Options, based in Newport, Rhode Island, to develop an MSW composting facility that would process an estimated 25,000 tons/year of material. In the last weeks of October, it was in negotiations with Waste Options, which would finance and own the plant under a long-term contract. The operation would be similar to the Bedminster system used in Nantucket, as would the company's responsibility for compost marketing. "Martha's Vineyard has some agriculture, but landscaping is the primary outlet on both islands, particularly because they have sandy soils and a lot of vacationers with large lawns," says Nelson Widdell, part owner of Waste Options. "Right now, all soil products are imported from the mainland."
In Rapid City, South Dakota, a facility is being designed to cocompost 200 tpd of MSW with 15,000 gallons/day of treated municipal biosolids at 90 to 92 percent moisture. Bids for construction will be sought next May. "We should be on-line in 2002," says Jerry Wright, solid waste superintendent. "We're going to partner with the wastewater plant because we don't want to land apply anymore. It's cheaper to cocompost than purchase land and go through the cost of land application. Another reason is that MSW is high in carbon and the sludge will add moisture. The sludge is a perfect partner." Windrows were considered initially, but an enclosed system is the most likely option. "We want to keep the operator out of the turning process due to concerns about the environment and worker safety," says Wright. "This will be more expensive to build, but cheaper to run."
Although Agranom, Inc. has been awarded a contract to build a facility to process 60 to 70 tpd of source separated organics for Harvey County, Kansas, the project has been put on hold. "The expense is the major reason," says Charlie Summers, the county's fiscal officer. "The longer it's been investigated, the more labor it appears to require for producing the product we want." If approved, the operation would process residential and commercial materials.
The planned $16 million-plus MSW composting facility slated for Delaware County, New York still needs authorization from the Board of Supervisors. "It's a money issue," says Sue MacIntyre, solid waste coordinator. The plant would use Conporec technology to cocompost up to 100 tpd of MSW with 25 tpd of biosolids.
Wright County, Minnesota closed its MSW composting plant in February, 1997 because of low feedstock volume and high operating costs. There is a good chance that it may reopen, according to Ginny Black of the Minnesota Office of Environmental Assistance. "It was one of our best facilities," she says. A lawsuit filed by a landfill has kept the facility from reopening, but is expected to be resolved soon.
OPERATING FACILITIES
Here's a look at some of the operating MSW composting facilities in the U.S. Details on the composting methodology and throughput are in Table 1:
Pinetop-Lakeside, Arizona: A dehydrator was brought on line in January as a secondary biosolids handling system because the operation outgrew its existing capacity. The dehydrator has solved the plant's overtime problem and allowed it to go from six to five days/week of operation. "When the digester can't keep up with volume, we send some sludge to the dehydrator," says Phil Hayes, facility supervisor. "We're trying to blend the dry material with compost and come up with a new product, although we make very little dried sludge." Compost is sold for $14.02/ton to a soil blender who mixes it with topsoil and markets to golf courses.
Vacaville, California: The B&J Composting Facility, owned by Norcal Waste Systems, began as a yard trimmings composting site. The Ag-Bag enclosed aerated static pile technology was used from the beginning because of the windy nature of the site, and labor considerations. In 1998, B&J began taking commercial organics from a collection program in San Francisco. Then, when San Francisco launched its Fantastic Three residential program in early 2000 (see above), the organics fraction started being taken by the hauler (Sunset Scavenger, which also is owned by Norcal) to the B&J facility. A town closer to Vacaville also is taking source separated residential organics, including food residuals and yard trimmings, to B&J. The site's current capacity is 300 tpd (see "Flexible Processor Simplifies Commercial Organics Diversion," August, 2000).
Sumter County, Florida: Incoming volume has increased from 42 to 75 tpd due to a population increase spurred in part by the fastest growing retirement villages in the United States, says Terry Hurst, county solid waste superintendent. Volume is expected to increase another 12 to 15 tpd when the influx of visitors and seasonal residents hits this winter. Because the rotating drum's capacity is only 50 tpd with 25 tpd of biosolids, some material is being landfilled. A $3.5 million grant approved by the state legislature will fund another drum (to be supplied by A.C. Equipment Services) and create the Florida Organics Recycling Center for Excellence (FORCE), which will conduct research, technology evaluation and development, and operator training. FORCE, which will involve the University of Florida, the state Department of Environmental Protection and others, will be located at the composting plant.
Cobb County, Georgia: Recovering from setbacks caused by odors and two fires several years ago, the MSW plant ramped up to its full capacity of 300 tpd of MSW and 20 wet tpd of biosolids early this year. For the most part, the biofilter - comprised of wood chips and compost - has taken care of odors. An emergency generator has been added in the past year to run the fans, blowers, digesters and major equipment in the event of a power failure. A 7,000-square-foot addition to the facility holds spare parts. "We're proactive in terms of maintenance," says Joe Accortt, who heads up the solid waste program. "We change parts before they break, which has led to our success."
Compost customers include residents, developers and golf courses. Sales are modest at several thousand tons annually; there also is an active giveaway program. "Market penetration has been difficult," admits Accortt, "although anybody who uses it comes back for more. One thing we have not done is to aggressively address this as a marketing issue. A private corporation probably would hire a marketing director, while we wait for people to come to us. We need to get out there and beat the bushes."
With more money available in the new budget, plans for the upcoming year include putting a cover on the biofilter. "If you live in this region of the country, you get hellacious rainstorms and tropical storms," says Accortt. "If the biofilter is exposed, it overloads the drainage system and has a deleterious effect on the media, which leads to changing it often. That gets to be expensive." Marlborough, Massachusetts
After a waste broker was hired to obtain feedstocks, the plant is composting 120 tpd of MSW, with 60 tpd biosolids. Approximately 50 tpd of MSW is from residential curbside collection, with the other 70 tpd from commercial sources (about 90 percent organic content by weight). "The lowest tip fee of $60/ton goes to MSW with no more than ten percent noncompostable residue by weight," says Bob Spencer, who manages the project for Bedminster Marlborough LLC. "We have been able to attract such waste from haulers serving grocery stores, restaurants, office parks, college cafeterias, etc. We try one or two loads from new sources to determine which category applies, or work with the hauler, who works with the generators to clean up the loads if they want to continue using our facility at the lower rates. The highest rate is about $85/ton, which assumes over 40 percent inorganic residue."
Biosolids come from both the Marlborough wastewater treatment plants, as well as the town of Hudson, Massachusetts. The plant added a biosolids hopper to provide greater storage capacity. It now has additional capacity that it is being marketed at a rate of about $70/wet ton.
Odors are under control at the plant, which has received only a handful of complaints. The biofilter was recently tested and determined to be operating at 95 percent odor removal efficiency after one year of operation. In September, the compost received Type I classification from the Massachusetts Department of Environmental Protection. "Our next challenge is to market the compost, since much of it has been stockpiled at our off-site curing area 30 miles away, awaiting the Type I classification." Nantucket, Massachusetts
The island's composting plant takes in 50 tpd during most of the year and twice that much at the height of the tourist season in July and August. The composting operation is located adjacent to a materials recovery facility to process recyclables. Together, the processing capacity is 60,000 tons/year. Waste Options claims a recycling rate of over 80 percent between the two facilities. Widdell expects that level to increase if plans to implement widespread use of biodegradable bags for residential collection are fulfilled next year. Vinyl fabricated structures for the composting area and biofilter were supplied by Universal Fabric Structures. The plant's 10,000 to 12,000 tons/year of compost are all used on-site for landscaping and beautification. A survey of commercial users on the island indicated great interest in the product when it becomes available on the market.
A double-lined landfill cell will be opened around this time next year to store inorganic residue screened out of composting and mixed construction debris loads. Meanwhile, the MSW plant's excess capacity during offpeak months will be used to start mining an old landfill. "Our first step was to reshape the landfill from 45 to 22 acres," says Widdell. "We're in the process of closing it completely."
Sumner Martinson of the Massachusetts Department of Environmental Protection believes that as with other types of composting, future success for MSW composting may depend on establishing supplies of clean feedstocks. "Without a good upfront screening program, residue costs are immense," he explains. "Plus you have wear and tear of the equipment. These operators would like to go source separated if they could; it's a question of how you do it economically. There's a possibility of giving the Marlborough facility a grant to do source separated collection to see how much organics are in the residential waste stream, and whether the product quality would be higher enough to make it worthwhile. We have to show people there's an economic interest in separating."
Mackinac Island, Michigan: Getting the bulk of its MSW during the summer tourist season, the Mackinac Island plant processes an average of 5 tpd of material. A little over 1,000 cubic yards (cy) of compost were sold last year, says Bruce Zimmerman, an increase of about 200 cy. The main customers are landscaping businesses and residential users. Some compost is reserved for landfill cover. A small amount of organics are diverted to a vermicomposting project. To head off future odor complaints, public works director Bruce Zimmerman will try out different masking agents for those hot days when the wind blows in the wrong direction.
Fillmore County, Minnesota: Nothing has changed with the operation over the past year, says John Martin, who runs the plant, but on the recycling side, the county may switch from commingled collection to a twosort system. Six tons/day are composted at the MSW composting facility, about half the amount of 1996. There are contracts to receive source separated material from four cities. "In terms of others coming on, I don't see it happening," says Martin. "They don't want to separate." Compost is sold for $1/cy to residents and landscapers. According to Ginny Black of the Minnesota Office of Environmental Assistance, Fillmore officials have been considering discontinuing MSW composting for the past year, partly because of an uncooperative hauler.
Lake of the Woods County, Minnesota: The MSW volume processed at the facility is gradually growing, hitting over 4 tpd. Two hundred feet of curing pad space will be added by the end of the year, notes Gary Lockner, county solid waste officer, bringing the total to 500 feet. "When we pour the floor, we're putting in collection pipes to heat the facility and keep the garbage from freezing," says Lockner. A Bivi-tech shaker screen will be another addition in the coming year. "The rotating screen has had trouble with moist material," Lockner explains. "With the shaker, you can fill it and walk away. You don't need to load it slowly and carefully; it's much more forgiving."
Pennington County, Minnesota: Composting volume has been downsized from 11 tpd to the 2,000 tons/year required for the county to keep the state grants received for the project. "We're losing money and nobody wants to buy the finished product," says Howard Person, who supervises the plant for the county. "People just don't want to buy compost made from municipal solid waste. We dispose of it on agricultural land and use it to reclaim gravel pits, but we don't get anything for it." The plant likely will shut down when the grant period ends in August, 2005.
The facility already has stopped producing MSW fuel pellets because of the poor market for them after an ethanol plant closed. Burdensome regulations and low costs for virgin fuel were factors in the decision to stop production, says Person. Market research was lacking when the compost and fuel pellet operations were planned, he adds.
Truman, Minnesota: About 55 tpd are processed at the plant, which produced 1,800 tons of compost in 1999. About half of the product is sold at roughly $3/ton to landscapers or as animal bedding for beef cattle, with the rest given away to farmers. "We have pretty good soils here," says Mark Bauman, director of the Prairieland Solid Waste Board. "The farmers don't want to spend much."
Medina, Ohio: The plant uses the equivalent of 1.5 staff persons to oversee composting of 80 to 120 tpd of material. Forty to 60 tpd of fines from mixed waste processing are added to yard trimmings and wood. A Komptech Mashmaster used for grinding and mixing includes a screw conveyor for dewatering. Compost is used for landfill cover.
Sevierville, Tennessee: Throughput has grown from 180 to 200 tpd over the past year, after the completion of system rehabilitation, says Tom Leonard, Sevier County solid waste manager. Compost is delivered for free in the immediate area, and for the cost of trucking when the distance reaches about 15 miles or further away. "In the past, we had to haul much of it up to 60 or 70 miles away," says Leonard. "We're delivering more of it locally now." About 13,000 tons were produced in 1999. The recent challenge for the facility operator, Professional Services Group, has been dealing with odor complaints. Much of them are coming from people who have recently moved into the area. "Even though we've been here for ten years, they don't like the smell," says Leonard. "We're working to improve it."
Columbia County, Wisconsin: After ten years of operation, the facility shut down for three months this spring to do repairs and preventative maintenance. Although the stoppage was scheduled, it took twice as long as anticipated. Burdensome regulations and the expense of a screen capable of removing small inerts has led the county to put aside thoughts of selling MSW compost to landscapers and nurseries. Instead, for the past year, it has been producing yard trimmings compost for those markets. The MSW compost is spread on farm fields. As time allows, a staff member is working on a machine to remove small glass particles.
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