What is in this article?:
Single-stream versus dual stream recycling management: Do the benefits justify the means?
Disclaimer: This study was conducted using municipal solid waste data from between 1996 and 2009 (the most recent data available at the time of the study). All facts and figures are correct in relation to the data used.
Florida wants to increase its recycling rate to 75 percent by the year 2020 and single-stream recycling may be one way to help reach that goal. Although there are many supporters and detractors for single-stream recycling, a closer look at how it has affected Florida since its inception in 2005 may help gauge the true results. By performing a quantitative analysis on the benefits of single stream and its effect on recycling rates and contamination rates in Florida, and by comparing those rates to counties that still maintain dual-stream recycling systems and contamination rates of the host counties of the end user mills, a better understanding of the true effects of single stream can be realized.
The research analyzed whether single-stream recycling in the state of Florida was more beneficial, environmentally and economically, than dual stream recycling. It attempted to determine whether single-stream recycling encouraged residents to increase their recycling participation and, if so, if the size of the bin, the freedom from sorting or the ability to include more materials were responsible for the potential increase. In addition, the contamination level of recyclables entering single-stream processing facilities and end-user mills was compared to that entering dual-stream processing facilities to determine if more or less contamination was being sent to processing facilities or end-user mills as a result of the conversion to single stream.
A quantitative research approach was used that compared several years of Department of Environmental Protection data related to municipal solid waste handling in the state of Florida, specifically data from 1996 to 2009. Comparisons of the data between counties that had converted to single stream and counties that still operated dual-stream were carried out to identify possible trends in recycling rates and contamination rates. The specific counties that converted to single stream were Brevard, Broward, Charlotte, Collier, Escambia, Martin, Miami-Dade and Okaloosa. Dual-stream counties were Duval, Hillsborough, Marion, Orange, Pasco, Pinellas, St. Lucie and Sarasota. Figure 1 illustrates the unadjusted recycle rate trend for the eight single-stream counties while Figure 2 shows the unadjusted recycle rate trend for the eight dual-stream counties.
The trends for counties that still use dual-stream recycling methods closely resemble their single-stream counterparts. Samplings of eight dual-stream counties that have similar populations and collect similar amounts of municipal solid waste (MSW) show that they are trending between 30 and 40 percent (Figure 2) while single-stream counties are trending between 13 and 39 percent (Figure 1). There also seems to be very little fluctuation of the rates from year to year. The difference, however, is that the highest recyclable collection rate for a county that uses single-stream recycling is Martin County at 39 percent while the highest recyclable collection rate for a county that uses dual-stream recycling is Duval County at 45 percent.
In addition, Hillsborough, Pasco, St. Lucie, and Sarasota counties all have recycling rates above 38 percent. This seems to challenge the conventional thinking that single-stream recycling brings in more material since the three counties with the highest percentages of recyclable material all operate under a dual-stream system and use 14-gallon bins.
A look at the rates to determine if the size of the bin had any influence on the recycling increases or decreases is inconclusive as Broward, Charlotte, Collier, and Escambia counties all use the 64-gallon bins and experienced increases while Miami-Dade County, which also uses the 64-gallon bins, experienced a decrease. In addition, Brevard and Martin counties experienced increases with smaller bins while Okaloosa County experienced a decrease. The two counties experiencing the greatest increase, Collier with an eight-point swing and Martin with five, use different sized bins, 64 gallon and 28 gallon, respectively. A larger sample size taken over at least five more years may be necessary in order to quantify a correlation between increased recycling rates and bin sizes.
To determine if single-stream recycling significantly reduced the amount of material going to the landfill, comparisons between counties that converted to single stream were made by looking at the recycling and contamination trends before and after the counties converted to single stream.
Although a decrease in the amount of material going to the landfill should be positive, the landfill rate trend for eight single-stream counties indicates that the only county that managed to significantly reduce its landfill percentage was Martin County; Brevard, Broward, Charlotte, Collier, Escambia and Miami-Dade counties all saw reductions in their landfill percentage by at least two percentage points but still remain basically flat, while Okaloosa County managed to gain two percentage points. A closer look at the trend from 1996 to 2009 shows that six out of the eight counties are landfilling more material in 2009 than they did in 1996.