It is generally agreed that there are two main sources of national data on how solid waste is managed in the United States. The first is BioCycle’s “State of Garbage in America” survey, started in 1989 and done annually since then, with the exception of 2002. The other is an annual survey that Franklin Associates conducts for the U.S. Environmental Protection Agency, known as “Municipal Solid Waste In The U.S.: Facts and Figures.” State of Garbage In America has always collected tonnage data on municipal solid waste (MSW) generation, and asked states to estimate – by percent – the amounts recycled and composted, combusted, and landfilled. Conversely, Franklin Associates has always used economic and population data to estimate MSW generation on a per capita basis, and then extrapolated data to estimate tonnages recycled and composted, combusted and landfilled.
An article by Professor Nickolas Themelis of Columbia University’s Earth Engineering Center in the January 2003 issue of BioCycle, “Analyzing Data In State of Garbage In America, EPA Reports,” shed light on the differences in the data from these two approaches to tracking solid waste management in the U.S. Themelis used findings from BioCycle’s 2001 “State of Garbage In America” report (based on 2000 data and published in the December 2001 issue) and EPA’s “Municipal Solid Waste in the United States: 2000 Facts and Figures” (also based on 2000 data) to do his comparison. The analysis highlighted where the significant differences lie. For example, BioCycle reported 409 million tons of MSW generated in 2000, while Franklin data reported 232 million tons. Similarly, BioCycle reported 131 million tons of MSW recycled while Franklin reported close to 70 million tons.
After some thought and discussion, it was decided that the best way to identify the reasons for the data differences – and to test data gathering alternatives – was to have BioCycle and the Earth Engineering Center collaborate on the 2003 State of Garbage In America report. The information in this article is the culmination of that collaboration, which was conducted by the authors of this report. The contributions of the state solid waste and recycling officials who provided the data for this survey (see sidebar) are most appreciated.
The fundamental approach to the 2003 State of Garbage In America survey was to request all data in actual tonnages. In previous surveys, BioCycle asked states to provide the annual tons of MSW generated and a percent breakdown of tons recycled, composted, combusted, and landfilled. The 2001 State of Garbage In America survey questionnaire did ask states to provide the actual tonnages used to generate the percentages, but few states supplied that data. The tonnages of MSW recycled, combusted and landfilled were calculated using the percentage breakdowns and MSW generation tons for each state. Those tonnages (based on weighted averages) were used to calculate the national rates for recycling, combustion and landfilling (see years 1988-2000 in Table 1 on page 33).
The old approach worked for several reasons: a) It was used every year, so the year-to-year data could be compared to show trends; b) The incineration and landfill data provided by the states (and used to tally generation and percents incinerated and landfilled) typically included fairly accurate tonnages because of permit requirements for landfills and combustion plants. Therefore, the balance they calculated and attributed to recycling was fairly consistent from year to year (about one-third to half the states also provided specific recycling tonnages, similar to those shown in this year’s Table 10); and c) The tonnage-based approach – combined with information from the states on what categories of waste and recycled materials were included – allowed for some state-to-state comparisons.
The primary disadvantage of the “old” approach is that even though we re
|Ano da Publicação:||2004|
|Fonte:||BioCycle January 2004, Vol. 45, No. 1, p. 31|
|Email do Autor:||email@example.com|