Nickolas J. Themelis and Scott M. Kaufman
BioCycle April 2004, Vol. 45, No. 4, p. 22
In January 2003, BioCycle published a comparison of waste generation in California and New York by the Earth Engineering Center (EEC) of Columbia University. Surprisingly, the rate of generation of municipal solid waste (MSW) in these states was double the national rate of MSW generation reported in the 2001 study by Franklin Associates for U.S.EPA (0.81 tons /capita). The rate was much closer to BioCycle’s 13th State of Garbage in America (SOG) survey (December 2001) for the year 2000 that had estimated a national rate of 1.47 tons per capita. An explanation for the discrepancy that was advanced by some at that time was that the Franklin survey did not include construction and demolition (C&D) and some industrial wastes, while EEC and BioCycle may have done so.
As a result of the publication of the EEC article in BioCycle, the journal invited Columbia University to collaborate in the 2003 BioCycle survey. As described in the 14th SOG report (see “State of Garbage In America,” January 2004), the survey questionnaire asked participants in the solid waste management departments of the 50 states to differentiate between MSW and C&D/industrial wastes. A total of 47 states participated in this survey. The three that did not – Alabama, Alaska and Montana – have a population of six million, thus representing about two percent of the U.S. population.
The total MSW generation for the 47 reporting states was 369 million tons, corresponding to 376 million tons for the U.S. as a whole. This number is 35 million tons lower than that reported in the 13th SOG, presumably because in the 2003 survey, states were asked to distinguish between industrial and MSW waste tonnages.
SOG, FRANKLIN-EPA AND BECK-CHARTWELL SURVEYS
It is interesting to compare the BioCycle/EEC survey (reporting 2002 data unless noted by states) and the Franklin/EPA 2001 MSW “Facts and Figures” with a third survey, carried out in 1999 by R.W. Beck and Chartwell Information. (R.W. Beck and Chartwell Information Publishers, “Size of the U.S. Solid Waste Industry”, April 2001; study sponsored by Environmental Research and Education Foundation.) Beck/Chartwell surveyed 1,856 companies and 825 municipalities engaged in the collection and processing of MSW (carting, transfer stations, waste-to-energy (WTE), landfills). Therefore, it presents a different viewpoint than the BioCycle/EEC survey. Table 1 suggests that the Franklin/EPA study seriously underestimated the tonnages of MSW generated and landfilled in the U.S. (Franklin Associates Ltd. uses a “materials flow method” to estimate MSW generation and management. The methodology is based on production data by weight for the materials and products in the waste stream.)
Unlike the 14th SOG survey, the Beck/ Chartwell studies did not report the breakdown of solid waste to the traditional categories of MSW, C&D and industrial wastes. As we found in the course of the SOG survey, however, in many cases it is a difficult task to make this distinction, both for public and private waste management organizations; e.g., the solid waste of a small company may be carted away by a municipal authority, etc. We found that some states counted “C&D recycling” as “MSW recycling,” while others did not. These semantic differences complicate comparisons between different states and communities.
Beck/Chartwell reported 55 million more tons of solid waste generated than BioCycle/EEC. This difference is quite likely explained by the fact that states’ data may not capture all the “commercial” wastes handled by private carters. Also, the Beck/Chartwell survey reported landfilling of 346 million tons that includes all materials discarded in MSW-designated landfills, not only MSW. In their study, they reported another 22 million tons discarded in C&D-designated landfills. The only numbers that are consistent among the three studies are MSW tonnage to waste-to-energy plants. This reflects the fact that there are 98 WTEs in the U.S., all of which are highly controlled industrial plants.
Interestingly, on the basis of the Beck/Chartwell survey, the national recycling rate, including C&D and metal scrap from automobiles, was 146 million tons of materials, i.e., 26.7 percent of all reported solid waste. Coincidentally, this figure is nearly the same as the 14th SOG MSW recycling rate.
ESTIMATION OF PER CAPITA GENERATION
The 14th SOG survey calculated per capita MSW generation rates based on states’ reported tonnages of MSW recycled, combusted and landfilled. Of the 47 states providing data for the BioCycle/EEC State of Garbage In America survey, only California, Georgia and Texas did not provide tonnage of MSW generated. Therefore, the national per capita MSW generation rate – 1.31 tons – was calculated based on 44 states’ data. This average generation rate, in combination with the reported tonnages of MSW combusted and landfilled, was used to calculate the tonnages of MSW recycled in Georgia and Texas.
However, due to the size of the population and its impressive attention to waste reduction and recycling, we decided to try to more accurately gauge California’s data (rather than using the average 1.31 tons per capita). The only tonnages reported by the state were the MSW tons to “WTE” and “landfilling.” Recycling tonnages were not reported directly – only in the form of a 48 percent “diversion rate.” Because of this lack of data, we assigned California the same generation rate as that of the neighboring state of Nevada (1.55 tons per capita). This resulted in a 40 percent recycling rate for California.
It is interesting to note that in 1989, California state law mandated that 50 percent of waste statewide be diverted from landfills by 2000. The California Integrated Waste Management Board website reports that 37.6 million tons, i.e. 1.07 tons per capita, were landfilled in 2002. The corresponding figure for 1989 was 1.49 tons per capita. Therefore, in one decade, California succeeded in reducing landfilling by 30 percent. On the other hand, the reported rate of MSW generation increased from a low of 1.5 tons per capita, in 1992, to 2 tons per capita in 2002 (Figure 1).
Figure 2 shows the reported annual percent changes in California for waste generation and population from 1989-1999. In the first few years of enactment of the mandatory recycling law, there was a decrease in waste generation. However, since 1992 there has been a rapid increase in waste generation that cannot be explained by the corresponding population growth in the state (one would expect generation and population rate to increase by roughly the same percentage). The darker bar – the percent change in solid waste generation – shows a dramatic yearly increase from 1997 to 1999, the year before California communities were required to meet 50 percent diversion.
One interpretation of this dramatic jump is that a higher generation rate yields a higher diversion rate. More significant to a survey like State of Garbage In America, however, is how a reported 48 percent diversion rate in a state with the highest population in the country (35 million according to the 2002 Census) affects the national recycling rate. As an example, let’s assign California the per capita generation rate of 1.8 tons (roughly the highest per capita rate reported in the 14th State Of Garbage survey). Using the 2002 population, the corresponding solid waste generation would be 63.2 million tons and the recycling rate would be 30.7 million tons, i.e., 48 percent of the generated solid waste. The tonnage of MSW generated in all 50 states would increase from 376 million to 385 million tons and the national recycling rate would increase from 26.7 to 28.4 percent.
In assigning Nevada’s 1.55 generation rate to California, we attempted to compensate for the non-MSW tonnages that are clearly present in California’s reported generation of 2.0 tons per capita. Using 2.0 tons would have skewed the national picture. Changing California’s per capita generation rate from 1.55 to 1.8 tons (as above) demonstrates how great an effect this populous state has on national percentages. Estimates of percentage recycling can compromise the reliability of national data. This reality further reinforced the methodology developed for the 14th SOG survey to use actual tonnages wherever possible.
The effect of estimations/percentages versus tonnages can be viewed graphically in Figure 3, which plots the per capita rate of MSW generation across the nation, using the data from the 14th SOG survey. The second peak represents the influence of California at the assumed MSW generation rate of 1.55 tons per capita.
Conversely, the distribution of the landfilling rate with the U.S. population (Figure 4) follows a more normal distribution curve than Figure 3. On average, U.S. citizens generate 1.31 tons of MSW and landfill 0.86 tons per capita, i.e., 65.6 percent of the generated MSW. Because landfills are strictly required to record all incoming tonnages – while recycling facilities, for the most part, are not – analysis of landfilling provides a much more accurate picture of waste management practices, especially if all states were to report MSW landfilled separately from industrial and C&D wastes landfilled.
RECYCLING AND COMPOSTING
Figure 5 shows that there is a correlation between low landfilling rates and high recycling rates. The states with the seven lowest landfilling rates are plotted with their associated recycling rates. Five of these states have significantly higher recycling rates than the national average. Conversely, 19 states, accounting for about 20 percent of the U.S, population, reported landfilling rates higher than 80 percent.
Figure 6 shows that a large segment of the U.S. population recycles between 30 to 40 percent of their MSW. Also, on the basis of the 35 states that reported both recycling and composting tonnages, 28 percent of the recycling was due to the composting of natural organics and wood. By assuming that the same ratio applies across all states, we estimated that the 26.7 percent “recycling” rate consists of 19.7 percent materials recycling and 7.0 percent composting.
EFFECT OF WASTE-TO-ENERGY
The 14th SOG showed that, on the average, 7.7 percent of MSW is combusted in waste-to-energy plants (Figure 7). An estimated 70 percent of the U.S. population sends between one and 20 percent of its MSW to WTE facilities. Coincidentally, the national WTE rate is fairly close to that of composting (7 percent).
States with high WTE rates tend to have high recycling and low landfilling rates. All the states shown in Figure 8 have landfilling rates less than 50 percent. Maine and Minnesota have recycling rates approaching 50 percent and landfilling rates of only 17.2 percent and 29.3 percent, respectively. The landfilling rate in Connecticut is 36 percent.
Comparison of the results of the 14th State of Garbage In America Survey with earlier years shows that landfilling has remained the dominant mode of waste management in the U.S. As long as this remains true – and as long as recyclers are not required to report recovered tonnage – landfilled tonnages will remain the best indicator of progress made in the sustainable management of solid waste. The next important milestone will be for all states to track what portion of landfilled waste is actually “municipal solid waste,” i.e., excluding the C&D and industrial streams. (Tonnage data for waste-to-energy typically reflects the MSW stream, as industrial and C&D feedstocks rarely end up at WTE plants.)
More states are making impressive efforts to compile accurate waste management data. To truly reach a sustainable system of waste management, however, governments and businesses need to work together to encourage – or mandate – reporting of waste data by tonnages rather than percentage rates of materials recycled, composted, combusted, or landfilled. The overall goal is to increase materials and energy recovery, which means matching waste resources with societal needs. To do this most effectively, we need a clearer picture of the waste landscape.
Nickolas J. Themelis and Scott M. Kaufman are with the Earth Engineering Center at Columbia University. The authors gratefully acknowledge Ms. Nora Goldstein of BioCycle and Dr. Karsten Millrath of EEC for their collaboration in the 14th SOG and to Mr. James Thompson of Chartwell Information Publishers for providing the results of the Beck/Chartwell survey. The support of Integrated Waste Services Association to the Integrated Waste Management group of EEC is gratefully acknowledged.