|
2000 BIOCYCLE NATIONAL SURVEY SOLID WASTE COMPOSTING TRENDS IN THE U.S. Projects with waste and cash flow, good process and odor management, viable end users, a well-defined mission and purpose and political support are doing well in this age of abundant disposal capacity. Dave Block and Nora Goldstein 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 BioCycles 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 Franciscos 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 Californias 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 years 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 ONeill, 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 programs 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 countys 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 years 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. Theres 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 countys cost to $2 million and need for borrowing to $1 million. Marthas 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 companys responsibility for compost marketing. Marthas 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. Were going to partner with the wastewater plant because we dont want to land apply anymore. Its 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 countys fiscal officer. The longer its 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. Its 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 Heres 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 plants overtime problem and allowed it to go from six to five days/week of operation. When the digester cant keep up with volume, we send some sludge to the dehydrator, says Phil Hayes, facility supervisor. Were 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 Sumter County, Florida Cobb County, Georgia 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 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 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 plants excess capacity during off-peak 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. Were 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; its a question of how you do it economically. Theres 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 theres an economic interest in separating. Mackinac Island, Michigan Fillmore County, Minnesota Lake of the Woods County, Minnesota Pennington County, Minnesota 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 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 Columbia County, Wisconsin www.jgpress.com |