BioCycle July 2004, Vol. 45, No. 7, p. 22
New York state community uses proven and innovative technologies to capture source separation benefits for its solid wastes.
Ralph J. Gall, Leonard Fiegl, Jeffrey Burroughs and Ian Miller
THE TOWN of Amherst – the largest suburb in Western New York with an approximate population of 117,000 – has taken significant steps to reduce solid waste volume going to landfills for disposal. The steps included a spectrum of proven and new technologies from recycling and yard trimmings composting to heat processing of biosolids. Treatment and processing options, coupled with community education to boost source separation, have led to significant cost savings. Amherst typically saves $2 to $2.5 million per year in avoided tipping fees.
Prior to 1988, homeowners contracted individually for collection services. Realizing that the town had greater bargaining power than individual homeowners, Amherst established a special district encompassing the entire township to collect tax revenues to pay for the solid waste program. The contract for town-wide garbage pickup was bid and awarded to a private firm. Disposal in the first year exceeded 55,000 tons and disposal costs were on the rise. Many landfills had closed and those remaining were ordered to comply with new environmental regulations. Local landfill disposal rates rose from $15 per ton to $60 per ton. Recognizing the impending solid waste crisis, New York State enacted the Solid Waste Management Act of 1989.
In Amherst, plans to comply with the Act were initiated with the appointment of a solid waste committee comprised of residents and town officials. The committee’s mission is to evaluate and re-evaluate the town’s solid waste program and serve in a consultative capacity to the town’s solid waste functions and the town’s governing body. In 1991, the committee recommended and instituted source-separated curbside collection program of both recyclables and yard waste.
Since 1991, all town residents and town facilities have participated in curbside pick up of recyclable materials and yard trimmings. The yard trimmings are collected from residences is delivered to the Amherst Compost Facility for processing into mulch and compost. Beginning in 1996, the Amherst Water Pollution Control Facility has used heat drying to convert sludge into fertilizer pellets that can be used on residential lawns and gardens.
To establish the recycling program, the town relied on the private sector to process and market collected material. Amherst ordered 40,000 recycling bins that were distributed to residents along with instructions on recycling and information on yard trimmings separation. At the time, the recycling menu included newspapers and magazines, glass containers, tin cans, corrugated cardboard, and plastics #1, #2 and #3. To finance the program, the town was charged $15.93 per ton of recyclables; however, even at that rate, the first year cost avoidance amounted to $1.2 million. The recyclables processing rate continued to decrease and since May 1995, the Town has received $10 per ton for recyclable materials.
The recycling program was expanded in 1994 to include wax-coated milk cartons, juice and drink containers, plastics #4, 5, 6 and 7, phone books, junk mail, and box board. Construction materials and debris placed curbside during a designated spring cleanup week are recycled through a local contractor. In addition, Amherst purchased a tire rim crusher, removing rims from the used tires collected. That year, the town recycled 85 tons of steel rims and received $6,750 for the scrap, while the tire recycling program cost the town $6,120.
Officials continuously review recycling opportunities as markets change and notify residents via mail and in local newspapers of any changes. Over the years, the recycling percentage has steadily increased from 40 percent in 1995 to 50 percent in 2002 due in part to activities designed to explore new cost-effective ways to reduce solid waste, and increase education programs.
AMHERST COMPOST FACILITY
In 1990, the Amherst Town Board approved a $1.8 million capital note and bond resolution to cover the design and construction of a yard trimmings composting facility. Construction began in the fall of 1990 and was completed in the fall/winter of 1990-1991. That season, the composting facility received the fall leaves, which totaled 14,000 cubic yards and composting began in April, 1991. By spring 1993, a majority of yard trimmings generated in the town was removed from the waste stream and processed at the composting facility. On average, the composting facility processes 72,000 cubic yards of yard waste annually.
The Amherst Compost Facility is situated on a 10 acre asphalt pad where the operations of grinding, windrow turning, screening and curing occur. The compost and mulch that is produced at the facility is made from leaves, grass, and ground mixed yard waste (brush and grass). Equipment used at the compost site include a Scarab compost turner, Diamond Z tub grinder, McCloskey Brothers trommel screen and John Deere front-end loaders. The price of compost is $12/cy. For commercial landscapers, the tip fee for mixed yard trimmings is $3.33/cy; for grass, the tip fee is $5/cy. Last year, the facility processed 110,000 cubic yards of yard trimmings into mulch and compost, generating $265,000 in revenue. Cost of operation was $458,342, while avoided landfill cost was $1,513,827.
WATER POLLUTION CONTROL FACILITY
The Amherst Water Pollution Control Facility is a 36 MGD tertiary pure oxygen activated sludge plant owned and operated by the town. The facility treats sewage from Amherst and neighboring municipalities. In late 1992, alternatives to sludge treatment were evaluated with the goal of reducing long-term costs of wastewater solids disposal. Many project options were considered including treatment at another facility, sludge drying, and sludge composting. At the time of the study, costs associated with disposal were on the rise. In 1994, landfill costs were $74.50 per ton with an annual cost of over one million dollars.
With financing available through the New York State Revolving Loan Fund, the town decided that the best way to manage the solids handling portion was to develop a facility that processes wastewater solids into an environmentally friendly material. The town focused on a biosolids drying process that produces a 1 mm “pellet”. The major components in the sludge drying process are: sludge thickening, anaerobic digestion, dewatering and drum drying.
The anaerobic digester system uses biological degradation to condition the thickened sludge prior to drying in the Andritz drum system. Digestion of organic material releases carbon dioxide, methane and water and uses up much of the available energy rendering the remaining solids stable. During digestion, 25 to 33 percent of the raw sludge is destroyed. Digested solids are dewatered using a centrifuge prior to processing of the solids through the pellet plant. Polymer is added to improve performance of the dewatering process.
From the centrifuge, the dewatered sludge (25 percent solids) is mixed with dry recycled material (94 percent solids) from the recycle material bin prior to being fed to the drum drying system. The drum dryer is a triple pass rotating drum that uses high speed hot air (700 °F) to dry the sludge until it is light enough to be pneumatically conveyed out of the dryer. The sludge is approximately 94 percent solids after it leaves the drum drying apparatus. The drying apparatus is designed to process approximately 1,800 pounds of pellets per hour and remove 5,000 pounds of water per hour. The production and sale of pellets saves the town over $500,000 per year in avoided landfill costs. The capital cost of pelletization equipment, associated plant upgrades and improvements was $8.2 million dollars. Digester gas is used to heat the digester and will also run the compressor that generate s oxygen for the activated sludge plant which is a pure oxygen system.
Looking to the future, the Amherst Solid Waste Committee had conducted preliminary studies of composting food residuals, recycling disposal diapers and nylon carpeting, as well as backyard composting incentives. Last year, Amherst received the New York State Governor’s Award for Excellence in Recycling.
Ralph J. Gall and Ian Miller are members of the Amherst, New York Solid Waste Committee; Leonard Fiegl is Senior Refuse Control Officer; and Jeffrey Burroughs is the town’s Assistant Municipal Engineer.
July 1, 2004 | General
SAVING MILLIONS IN LANDFILLING COSTS
BioCycle July 2004, Vol. 45, No. 7, p. 22