This began to change with the birth of modern American environmentalism in the 1970s - somewhere along the line, people began to speak of 'reduce, reuse, recycle' and it became fashionable to 'divert' waste from landfills. Crude metrics such as recycling and diversion rates were instituted by federal and local government as a way of measuring the progress made. Missing from this picture, however, has been a coherent methodology for total accounting of the use and ultimate fate of resources.

As people began to equate recycling with environmental stewardship, the ideal overcame the reality. States would mandate recycling rates with little consideration of whether there were markets for a large fraction of the 'recycled' materials. Others would celebrate '50% diversion' without mentioning the corollary jump in waste generation. When media attention was devoted to issues of waste management, it took on sensationalist tones (the 'New York garbage barge') or vague notions of a prescribed national recycling rate. Lost in this discussion were matters of substance - 30% of how many tonnes, and what are the environmental impacts of dealing with the other 70%?

Though these kinds of questions usually went unanswered, it was important that waste came to be an issue of consequence - at least among some of the population. Once this happened, it seemed time to begin truer accounting of how the US was managing a previously neglected resource.

Measuring waste in the US

Data collection for the 2002 survey

In this way, we were able to correct for different methods of collecting data among states. For example, California includes construction and demolition (C&D) wastes in its MSW reports. As this is typically a waste stream with higher recycling rates, combining it with the MSW serves to increase the state's overall 'diversion rate', that is, solid waste that is not sent to landfill. Of the 50 states, 47 responded, representing 98% of the US population, and provided varying degrees of detail and accuracy. The differences can be partly attributed to the fact that not all state governments monitor waste disposal closely. In general, states that do track wastes closely fall into one or both of the following two categories:		Waste to be compacted for processing. PHOTOS: N. MITOS, THERMOELEKTRON
relatively densely populated states, usually in the Northeast, where traditionally easy solutions (landfilling) are becoming more problematic 'environmentally conscious' states like California, New York, Minnesota and Oregon, where there is generally greater public awareness and initiative to manage waste in sustainable ways

For the purposes of the 14th SOG study, MSW generation was defined as follows:

Results of the 2002 survey

The reported recycling rate was 26.7%, of which about one quarter was composted. The 26 million tonnes of MSW treated in WTE facilities represented 7.7% of the amount generated and not 13% as estimated earlier on the basis of the much lower rate of generation reported by USEPA.

ABOVE LEFT Cans, bottles and plastics waste are collected for recycling
in Harwich, Massachusetts ABOVE RIGHT A community collection point
of clothes and donations at Harwich, Massachusetts

As explained earlier, the 14th SOG survey was based on data recorded or estimated by the state agencies responsible for solid waste management. On the other hand, the USEPA data were based on a 'materials flow' method that compiles industrial production and consumption records. It then makes certain assumptions about the lifetimes of products and materials, and of discard patterns. According to previous SOG surveys (see Figure 1), the generation of solid waste increased by an average of about 11 million tonnes/year between 1990 and 2000. In contrast, the USEPA reported that the rate of growth of MSW generation over this period increased by an average of only 3 million tonnes/year, which corresponded to nearly 1% per year. Coincidentally, the US population during the same period increased by about 3 million people per year, i.e. also 1%.

FIGURE 1. Comparison of SOG surveys findings with those
from USEPA 2001 survey

Figure 1 also shows the results of the 14th SOG survey, which estimated MSW generation at 336 million tonnes. It is believed that the reported generation in earlier SOG surveys included some C&D waste and wastes from small industrial operations that end up in landfills. For example, the shredding of millions of discarded automobiles generates several million tonnes of automobile shredder residue (ASR). Despite the fact that ASR consists of over 60% combustible plastics, it is currently disposed of in landfills in the US. In another example, repulping of used paper generates 10%-15% of a mixed plastics and paper residue that is also landfilled. The approach EEC took in the 2002 survey was to make the data and methodology as transparent as possible. While it is certainly important to try to quantify waste reduction, this was outside the scope of the EEC study: the tonnes of waste recycled, combusted or landfilled must add up to the tonnes of waste generated.

Implications of the survey findings

• Large nationwide corporations own a substantial fraction of the contracts with municipalities to haul and dispose of waste, as well as the landfills to put it in.
• The relative abundance of 'open' land - especially in the West - results in very low tipping (gate) fees for landfills. The gate fees reported (by only a few states) in the 14th SOG survey ranged from $50 to $90 per tonne of MSW. However, in some states, the gate fees can be as low as $20 per tonne.
• The USEPA does publish a hierarchy of treatment methods listing landfilling as the last resort, but it has not moved towards legislative action such as the EU Landfill Directive, which requires near-term phasing out of the landfilling of biodegradable materials.

Recycling in the US

States report as recycled all materials recovered either by separation at source or at material recovery facilities (MRFs). Non-recycled residues - either those from the MRF or the plants that process the recyclables - are included and can be substantial. For example, a 2001 study by EEC found that a large fraction of the plastics and glass reaching three New York City MRFs was finally landfilled due to a lack of markets.⁴ In addition, the residue from repulping of used mixed paper is also landfilled. It is therefore possible that some double counting of materials exists (as recycled and then as landfilled) in the data reported by the states. This would reduce the computed rates of recycling and MSW generation shown in Table 1.

Despite the obstacles, the US has come a long way over the years in advancing recycling to the present level. Almost 50% of the population has access to kerbside collection programmes - that's nearly 140 million people.

LEFT AND RIGHT Plastics and glass waste to be recycled. A 2001 study
found that a large fraction of the plastics and glass reaching three
New York City MRFs was finally landfilled due to a lack of markets.
PHOTOS: NICKOLAS THEMELIS

Waste-to-energy

The use of WTE does not appear to affect recycling rates. The states that sent the highest percentage of MSW to WTE facilities recycle at rates either slightly below, slightly above, or well above average for the US as a whole (see Figure 2).

FIGURE 2. WTE and recycling rates for six US states

WTE is used principally by more densely populated US states. In 2002, the 15 states with the highest population densities accounted for 85% of the total tonnage sent to WTE facilities. These states have a mean population density of 163 people/km2. The ten states with the lowest population densities had a total of just 0.4% of the WTE tonnage; the mean population density for these states is only 4 people/km².

FIGURE 3. Recycling and landfilling rates for US states with
the lowest population densities

Landfilling

Conclusions

Landfills and WTE facilities are required by law to keep careful records of input and output materials. They are therefore reliable witnesses of the fate of a large fraction of the solid waste generated. Recycling and composting facilities should also be required by states to maintain records of the materials received and of the residues that cannot be recycled or composted and therefore have to be combusted or landfilled.

Waste collection at the central truck-to-rail station at Cape Cod, Massachusetts. PHOTO: NICKOLAS THEMELIS		This study also showed that national and state agencies responsible for waste management should be concerned with both MSW and industrial and other residues sent to landfills instead of being recycled or used to recover energy. A kilogram of wood that is sent to a landfill instead of being recycled or combusted in an industrial boiler has the same environmental impact whether it originates in a home or following construction or demolition activity. In another example, solid waste that goes to a waste-to-energy facility is counted as MSW, but the resulting ash that is landfilled may not be. In all cases, society should provide incentives for minimizing all the materials that end up in landfills; landfilling has the highest environmental and land use impacts of all the principal means of waste treatment and disposal. As nations and communities move forward with analysis of different waste streams and selecting methods of treating them, it is important to remember that statements like 'a 50% rate of diversion' mean little if the computed rates of waste generation are also increasing inexplicably, as was shown to be the case for California by the 14th SOG survey.5 Manufacturers, waste haulers, waste processors, government officials and urban planners need more specific accounting of wastes - what is being recovered, in what quantities, and what are the inefficiencies leading to landfilling of non-used materials. This will enable society to better 'metabolize' these lost resources.
Although the US generates and landfills large amounts of solid wastes, it has succeeded in recycling an estimated 90 million tonnes of MSW, and combusts nearly as much as the EU. This is more than the total reported by all other Organization of Economic Co-operation and Development (OECD) countries combined.6 It is hoped that the methodology and results presented in this report will be of use to other nations facing similar problems.

References

1. Themelis, N. J. 'Analyzing data in State of Garbage in America, EPA reports'. In BioCycle, January 2003, Vol. 4, No. 1, pp. 22-25.
2. US Environmental Protection Agency (USEPA). Municipal solid waste in the United States: 2001 final report. Franklin Associates for the USEPA. July 2001. www.epa.gov/epaoswer/non-hw/muncpl/msw99.htm
3. Kaufman, S. M., Goldstein, N., Millrath, K. and Themelis, N. J. '14th annual nationwide survey of solid waste management in the United States: the State of Garbage in America'. In BioCycle, January 2004, Vol. 45, NO. 1, pp. 31-41.
4. Themelis, N. J. and Todd, C. A. 'Recycling in a megacity'. In Journal of Air and Waste Management Association, April 2004, Vol. 543, No. 4, pp. 389-395.
5. Themelis, N. J. and Kaufman, S. M. 'State of Garbage in America: data and methodology assessment'. In BioCycle, April 2004, Vol. 45, No. 4, pp. 22-26.

   Themelis, N. J. 'An overview of the global waste-to-energy industry'. In Waste Management World, July-August 2003, pp. 40-47.

References 1,3-5 are available at www.seas.columbia.edu/earth/wtert/wtertpublications.html