October 1990

Two recyclers from Southern California crossed the Atlantic to visit recycling facilities in Switzerland and Italy. What they found may foreshadow developments in our own backyards.

By Richard Anthony and James Mang

On the '90s, the necessity of choosing from a mix of collection, processing, and disposal technologies adaptable to changing demands complicates meeting the challenge of integrated waste management demands, including the need to conserve energy and natural resources in an increasingly urbanized world. In the United States, the rapid proliferation of source separation of municipal refuse helps to simplify solid waste systems. Recent trends move toward the concept of integrated waste management involving source reduction, recycling, transformation and disposal as a means to provide sound system control and environmental protection. With more personalized and convenience-oriented commodities, conversion of waste to industrial feedstocks presents one way to reduce disposal masses as well as provide for societal-material needs.

The economic and political concept of supply and demand leads to a social and technical transition toward integrated waste management systems. With acute shortages in land and raw materials, Europeans, out of necessity, developed considerable experience in mechanical recovery systems. Municipalities and private waste management companies want to know if this experience in operating municipal refuse recovery plants applies to American systems of source separation and separate collection. We visited European plants with different mechanical processing systems and end-products and also reviewed the accompanying solid waste systems to help answer that question.

We traveled to the recovery systems built by Triga in Neuchatel, Switzerland (processing for materials separation and incineration); Daneco in Tolmezzo and Udine, Italy (processing for materials separation and composting); and Sorrain in Perugia, Italy (processing for materials separation and composting). At each of the plants, the companies modified the present day operating systems over the mature-plant operating life to meet the standard of changing market needs and increasingly-strict environmental statutes.
In all cases, the operations
made adjustments in the
collection systems to
accommodate source
separation and prepared
end-market materials.

Augers move the organic materials collected in Perugia, Italy to a discharge belt over a 28-day cycle.

Many similarities in the three waste management systems existed. In all cases, they made adjustments in the collection systems to accommodate source separation, predominantly glass and newspaper, and prepared end-product materials for local market demand. Several communities shared the management of the systems in shared partnerships. And in each case, operating permits and environmental regulations necessitated development of alternative separation systems.
The overall goal of each plant was to reduce the amount of residual material landfilled and to minimize costs within environmental limits.
Local markets determined the waste stream and subsequent recovery technology, however different. Neuchatel built its waste-to-energy system prior to initiating materials separation. It added the processing technology to reduce costs and provide a cleaner and more consistent fuel. The system in Tolmezzo served as a prototype for Udine and by design provides soils amendment for surrounding agricultural operations. Volume reduction at the landfill and production of a quality agricultural product drive the separation system. In Perugia the operation of the collection and disposal system demonstrates technically improved mechanical equipment to provide better quality resources, as well as extend the life of the existing landfill. In all cases they view source separation as a technically desirable method to enhance materials-market quality and improve environmental compliance.
Southwest of Zurich, west of Bern and just east of France lies Lake Neuchatel. Along the shore of Lake Neuchatel live 120,000 people in 48 townships. The town of Neuchatel is clean and well kept. The convenient location of litter collection container mitigates some of the impacts of tourism economy. Igloos accepted color-sorted glass and we saw evidence of scheduled separate collection for newsprint throughout the community. Rear-loading trucks handled collection efficiently and separate routes allowed for the capture of commercial waste separately from mixed residential waste.
FIBER-RICH. In 1968, 48 communities joined to form a limited Swiss operation named SALOD Co. The company financed, constructed and continues to operated a waste-to-energy incinerator with a front-end separation system. The plant began operation in 1971 and continuously updated its facility to comply with environmental requirements. In 1989 it added front-end processing to contend with increasing waste flows and to decrease environmental emissions. This resulted in improved quality and an increased variety of marketable resources. The processing phase of the overall management system captures the fiber-rich commercial waste stream by means of facilities designed by Triga.
A blade conveyor transports commercial waste to a trommel for separation of fiber and wood from organic, metal and glass. Magnets remove any ferrous material. Workers hand sort the resulting non-fiber fractions from other metals.
The also hand sort the fiber fraction line, primarily to recover corrugated cardboard. The facility bales the resulting fiber fractions for uses as a high energy fuel additive in the incinerator.
The operation transport the metal to the town of Lausanne for sale as scrap. Residual from the non-fiber fraction travels 20 miles for landfilling. Residential non-source separated materials move directly to the incinerator for generating steam and electricity as products of volume reduction. Ash remains on-site.
Elected shareholders (elected officials from member communities) operate the plant and currently plan to expand material sorting and to improve air emissions controls. These plans aid in developing recovery programs for aluminum, other metals, and miscellaneous materials such as batteries and florescent lights. Workers dump and aggregate drop-off bins containing separated clear and colored glass at the plant for rail haul to markets. The facility also processes newspaper and cardboard. Landfill cost increases as well as the limited capacity of the incinerator helped to increase interest in mechanical separation quality and source separation systems.
Source separation in the Neuchatel system improved the quality of the refuse derived fuel used by the mass burn system and by increased supplies of recycled materials.
The interchangeability of the combustible/fiber supply provides the community with a more reliable heat source in the cold, winter months. The facility saves some mixed paper separated in the summer for use as auxiliary fuel in peak winter demand periods.
Udine, Italy lies in the Venetian are region (within an hour's drive from Austria and twenty minutes from Yugoslavia) where agriculture and light manufacturing make up the main industries. Near Udine is the small town of Tolmezzo nestled in the mountainous Carnia Region. Operated under contract with the Comunita Montardella Carnin and 48 communities in neighboring areas totaling 85,000 inhabitants, the Tolmezzo processing facility uses magnets and a trommel/cyclone combination to clean rural-collected solid waste for compost and RDF production.
A trommel set at a 6 percent angle separates the plastic from shredded paper at the Perugia Italy facility. The plastic, which appears to consist of approximately 90 percent film, then goes to a washer, dryer, extruder, die cut and pellitizer line currently under construction.

Operators in the control room of the Perugia, Italy complex oversee the functions of the 400 tons per-day facility

The regional government monitors the tests on the quality of the
compost and its effect on agricultural crops.
MODEL FACILITY. A Daneco-designed gasifier, designed to convert the RDF to gas to be used to generate electricity, is under construction in Tolmezzo. The plant serves as the model for a significantly larger facility designed by Daneco (an engineering design firm) and currently under construction in Udine. When completed, Udine expects the facility to serve its urban population of more than 100,000.
Daneco plans to refine its technology for application in the Udine facility. The compost from Tolmezzo is currently being tested at an agricultural research farm. The regional government monitors the tests on the quality of the compost and its effects on agricultural crops for crop quality and solid waste-related impacts. Concerns with lead and other trace metals in the compost provides impetus to include ferrous recovery in the mechanical processing. Other aesthetic concerns necessitated addressing glass and plastic removal techniques.
The Daneco system accepts mixed residual and commercial waste in a recovery pit. A crane delivers the waste to a hopper-conveyor system that includes a bag breaker and a magnet for ferrous removal. The material then enters a rotating cylinder for a half-day to allow microbial activity to begin. Conveyers next move the material to a trommel and cyclone processing system to remove other heavy and oversized materials. This achieves a high removal of nonferrous metal, inerts and glass. The system takes the remaining, predominantly organic material to a curing area for air injecting and conversion of the material into compost. A vibrating screen removes any large non-composted items and completes the final refining of the compost.
Public concern for groundwater protection from landfilling resulted in a Daneco contract with the city of Udine for an expanded and updated compost and RDF production system. Local efforts in Udine increased the feedstock cleanliness with drop-off collection containers to recover paper and sorted glass. Officials expect the upscale facility for Udine to cost about $18 million. It's location near the city's sewage treatment plant provides the potential currently under evaluation of adding treated sludge for compost process enhancement.
The Udine system's flexibility allows it to enjoy the benefits of source separation. The extraction of metal, glass, and plastic increase the quality of the organic materials, and city officials expect tot develop markets for the compost. RDF remains another market in a development stage. Gasifying the refuse derived fuel provides additional resource recovery potential through generating electricity. The residual material destined for a landfill consists of a stable mix of dirt, inerts, glass, mixed metals and small amounts of organics.
STRICT CONTROLS. The town of Perugia dates from ancient Rome and contains numerous secular and ecclesiastical structures from the Middle Ages. Today, in addition to being an industrial and commercial center, it serves as the capital of Umbria and boasts a thriving, international university. The facility in Perugia demonstrates the latest Sorrain waste processing technology and operates under strict environmental controls. Although no burning takes place in uses scrubbers to reduce air emissions. It treats and recycles all wastewater. The basically mechanical resource recovery system uses no hand sorting. Italian law forbids facilities to hand sort mixed wastes.
Sorrain renegotiated its contract with the town of Perugia in 1984 to provide collection , street sweeping, mechanical waste processing and disposal. The city and company work in a partnership where they share the profit (55 percent goes to the company and 45 percent to the community). The system handles 400 tons per day and charges the residents by land-size fees. The average home of about 80 to 100 square meters pays about t $100 per year for refuse management. Perugia initiated and then later discontinued a source separation collection program due to continually decreasing participation. The University of Perugia tests compost from the Sorrain plant for environmental parameters.

At the Neuchatel, Switzerland operation, refuse derived fuel helped provide steam for heat in the winter months.
Collection igloos serve as collection points as part of Udine, Italy's recycling program.

The plant in Perugia utilizes a mechanical system of classification and "cold-working" (non-combustion separation of paper from cans). Sorrain designed it to recover the following materials:

  • Organic, 45 percent;
  • Inerts (glass, etc.), 25 percent;
  • Paper, textiles, cardboard and wood, 20 percent;
  • Plastic, 7 percent; and
  • Ferrous, 3 percent

The system initiates processing with a pit and crane. A bag-breaker conveys the material to a trommel that consists of two cylinders rotating in opposite directions. Magnets remove the ferrous fraction and conveyors take the metal to a baler.

RDF PELLETS. Air blows the large materials into a cyclone to divide lights from heavies. The system directs the light material to a differential shredder which cuts paper but leaves plastic (polyethylene) intact. A trommel at a 6 percent angle separates the paper from the plastic. The equipment densifies the paper into RDF pellets for marketing as a fuel additive for cement plants. The plastic, which appears 90 percent clean film, goes to a newly constructed washer, drier, extruder, die cut, and pelletizer line.
The organic fraction moves to a composting plant where a trommel is separates out small non-organic heavies and metals. The organic material is spread evenly in a large pit where augers remove it over a 28-day cycle to a discharge belt. The cleaning and screening system uses two trommels, air classifiers and cyclones and effectively removes most non-organics. Residual material goes to a landfill at a facility located adjacent to the composting plant.
To visit these integrated systems in different countries with different currencies and languages we negotiated planes, trains, taxis, autos, buses and subways using common symbols with few spoken words as we only conversed in English. The medium of exchange for service remained universal: money. Because of universal symbols and technologies we booked rooms, attended soccer games, recycled certain commodities and disposed of waste properly with few problems. Udine and Neuchatel accomplished recycling easier, but each of the three cities operated efficient street cleaning and litter control systems. The universal desires for food, shelter, cleanliness, and material conveniences - basic human needs - know no international boundaries.
In the cities in Europe where we traveled, the legislative and educational approaches to waste reduction just began catching on. Europeans, however, generate less refuse than Americans. Citizen of Rome, as well as in most other European cities, generate about two pounds per person per day, significantly less than the American average of over six pounds. European refuse arriving at the processing facilities typically contains higher amounts of organic waste and tends to consist of significantly less convenience packaging materials than its American counterpart. The lack of garbage disposals in homes and the existence of a strong traditional scrap recovery industry accounts for some of these differences.
COMMON CONCERNS. The environmental results of source separation appeared clear in all visited programs. Each plant manager indicated that increased source separation improved capacity and product quality, reduced air, water and residual emissions, and provided additional revenue to the system. Although each area employed safeguards, they held common concerns about hazardous wastes and metal emissions. In the organic fraction, the visibility of small-sized hard plastics surfaced as a cosmetic problem.
In Europe the issue of provided public education for integrated waste involving waste reduction and source separation raised similar questions now being considered in the United States. As in the United States few trained professionals exist in the field. However in the three geographic areas we visited, many people understood the word "recycle" or recognized the international recycling symbol. It is apparent that waste management professionals in Europe recognize that waste reduction and recycling have ever-increasing public support.
American integrated waste management programs as introduced in Oregon, New Jersey, California, and Rhode Island represent an enhancement to the mechanical equipment developed and demonstrated in Europe.
Richard Anthony is the principal solid waste program manager for San Diego County, and James Mang is an environmental engineer.