October 25, 2006 | General

Managing The Organic Fraction Of Municipal Solid Waste (European Union)

BioCycle October 2006, Vol. 47, No. 10, p. 50
Directives from the European Commission have had a major impact on how the organic fraction of the solid waste stream is managed in Member States.
L. F. Diaz, A. Chiumenti, G. M. Savage and L. L. Eggerth

OVER THE past few years, the European Commission (EC) has issued several directives, guidelines and strategies associated with biological wastes that are significantly altering the solid waste management landscape of some member countries in the European Union (EU). The Landfill Directive and the Biowaste Directive, as well as the Soil Protection Strategy, have had a substantial effect on the quantities and methods of managing organic residues.
Landfill Directive 99/31, which came into force in 1999, addresses the quantities of biowaste that can be disposed in landfills in Member States. It requires a substantial reduction in the future – 65 percent by 2016. The overall intent is to: 1) achieve a reduction of the production of landfill gas (primarily methane from landfill sites) and 2) improve the operation of landfills. Consequently, those countries that have relied and continue to rely on landfills as the major means for waste disposal are in the process of evaluating the best approach for complying with the directive.
The European Commission’s Directive on Biological Treatment of Biodegradable Waste had the following objectives: Promote recycling programs for biowaste such that composting would have a fair and even development throughout Europe; Stimulate a balanced approach in the methods by which biowaste is diverted from landfills; Set limits and conditions for the use and marketing of compost among EU member states; and Address the role that mechanical/biological treatment processes would play in the management of residual waste to both deal with integrated waste management and to set conditions for use of the stabilized material produced.
One of the key provisions of the 2nd Working Document of the Biowaste Directive (2001) was a mandate for Member States to establish programs for the collection of source separated biowaste. Despite the general agreement at the time by stakeholders and Member States on the content of the 2nd Working Document, the Document did not evolve into a consensus directive. Instead, in December 2003, within the framework of the EU Soil Strategy, the EC published a “Discussion Document” which, once again, ignited the discussions among Member States and stakeholders about the key principles of a Biowaste Directive. Unfortunately, up to the present time a Biowaste Directive has not been finalized.
During the last few years, soil quality has become an important issue in the EU. The EC has indicated that the substantial loss of organic matter in soil, especially in Mediterranean countries, is a pressing problem of great significance. Consequently, in 2002, the Commission issued a communiqué entitled “Towards a Thematic Strategy for Soil” in which the EC advanced its intention to deal with the matter of soil protection. In this document, the Commission described the possibility of replenishing organic matter and thus improving the fertility of European soils through the use of, in addition to other materials, “composted organic residues.” Quality of the compost applied to the soil and methods to monitor the quality are expected to be critical components of this strategy.
The implementation of the directives and guidelines in the EU has led to a substantial increase in the use of biological waste processing in Europe. With a few exceptions (Portugal, Ireland, Greece and large parts of Spain), all the western European countries have made substantial progress in implementing programs to collect source separated organic matter and to process the organic matter by mostly biological treatment methods.
In 2003, there were approximately 1,800 plants in Europe processing about 11 million tons of biowaste and 7 million tons of green waste annually. In addition, about 3.5 million tons of residential and commercial food residues were processed using anaerobic digestion. In 2003, the 15 member states generated about 50 million tons of organic wastes, consequently, the above facilities processed on the order of 42 percent of the organic waste generated. Since the landfill directive requires a diversion rate of up to 65 percent of the organic wastes away from landfills by 2016, it is expected that the number of facilities will continue to increase.
The collection systems established include: 1) Collection of biowaste once every two weeks in Northern and Central European countries; 2) “Fetch” (curbside collection) systems in 80 to 120 liter bio bins for kitchen and garden waste in Northern and Central Europe; and 3) Use of small biodegradable bags for inexpensive door-to-door collection of kitchen waste in hot Mediterranean climates (in some instances with daily collection); and 4) “Bring” (drop off) system for green waste at recycling centers. In general, the concentration of organic matter in the source-separated biowaste is greater than 95 percent. However, the proportion of organic materials found disposed in the grey bin (residual or rest waste) still is considerable. The concentration of biodegradable material has been found to vary from 20 to about 50 percent.
The Member States’ efforts associated with the collection and recycling of source-separated organic wastes in the EU can be divided into four general levels:
Level One: Countries that recycle about 80 percent of the source-separated materials. These countries include Austria, Belgium (Flanders region), Germany, Luxembourg, Netherlands Switzerland, Sweden, most regions of Italy, and a region of Spain (Cataluña). The preferred method of recycling in these countries is composting.
Level 2: Countries in the process of establishing the framework for setting up systems for the collection and processing of organic matter. Denmark and Great Britain are in Level 2.
Level 3: Countries already have developed the required strategies and are beginning to implement programs. The Czech Republic, Finland, France, and Hungary fall in Level 3.
Level 4: Countries that have not developed policies for the implementation of separate collection of the organic matter. These countries include Belgium (Wallonia), Greece, Ireland, Portugal, the major portion of Spain and several of the acceding countries from Eastern Europe.
Countries that have instituted some type of biological waste treatment system are implementing it as an integrated program. The integrated program normally includes: composting, anaerobic digestion, as well as mechanical-biological treatment (MBT). Furthermore, the programs are designed to take into consideration economical, social, environmental and political conditions of the area. Mechanical-biological treatment primarily is used to process the residual (rest) waste. The following is a brief overview of trends.
Composting: Due to current legislation dealing with animal by-products and odor problems, there seems to be general tendency in Europe towards the application of in-vessel systems. Composting of green waste in open windrows using mechanical turners is relatively common in all European countries. In addition, this is the preferred method of composting in Denmark, Finland, France, Ireland and in England.
AD: Anaerobic digestion is used to treat source-separated organic materials from residential, commercial and industrial generators. There are about 87 commercial facilities in EU countries with a capacity of approximately 3.5 million tons per year. Nearly 50 percent of the facilities are dry digestion systems, and the remainder are wet digestion systems.
Recently, there has been a notable increase of digestion capacity for residential and commercial food waste, especially in Germany and Austria. The growth is due to the subsidies offered for the production of renewable energy. Subsidies in these countries have also led to the construction of about 5,000 on-farm codigestion plants.
In other developments related to anaerobic processing, Spain is trying to produce a marketable product from the digestion of mixed municipal solid waste. Sweden only provides support for the production of fuels from biogas, and Denmark is planning to digest source-separated biowaste from residences in existing agricultural anaerobic digestion plants. The present trend in Europe is to build new digestion facilities with capacities greater than 50,000 tons per year.
The implementation of a quality assurance program at all of these facilities guarantees the production of high quality compost. The EU has a quality assurance program that monitors about 620 facilities with a total capacity on the order of 9 million tons for composting and 2 million tons for anaerobic digestion.
MBT: Mechanical-biological treatment systems use a series of mechanical sorting (wet and dry) and biological stabilization technologies with two goals in mind: Stabilize the organic fraction prior to landfilling; or Increase the calorific value of a fraction of the residual waste for use in thermal processes. In Central Europe, mechanical-biological pretreatment has been applied primarily to residual waste.
As of 2004, Austria had approximately 15 facilities with a capacity of approximately 0.5 million tons/year. Germany had about 60 facilities with a capacity of more than 5 million tons/year; Italy had more than 90 plants with a capacity of 7.5 million tons/year. Projects have been initiated in Belgium, Spain and in the UK. A listing of some of the largest MBT plants in the EU is presented in Table 1.
It is important to note that the marketability of compost is greatly affected by the concentration of contaminants such as heavy metals and organic compounds. Nevertheless, some facilities in Europe are processing mixed waste (composting and anaerobic digestion) with the intent of recovering a product suitable for landscaping and for use by the agricultural sector. The standards for applying compost to farmlands and marketing conditions make the use of mixed MSW compost very difficult. Furthermore, the EU Strategy for Soil Protection aims at trying to conserve current quality of soils and control pollution due to heavy metals and organic compounds. These contaminants are found in relatively high concentrations in mixed MSW, and in substantially lower concentrations in source-separated organic matter. Therefore, it is expected that in the EU, only limited and controlled applications of compost made from mixed MSW (such as in restricted nonfood farming activities, land reclamation activities or as landfill cover material) are likely to be allowed in the future.
Luis Diaz, George Savage and Linda Eggerth are with CalRecovery, Inc. in Concord, California. Alessandro Chiumenti is with the University of Udine, Italy

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