Recycling Behavior during a Pilot Food-scrap Recycling Program in the Central Terminal of Seattle- Tacoma International Airport

Transcription

1 Recycling Behavior during a Pilot Food-scrap Recycling Program in the Central Terminal of Seattle- Tacoma International Airport Mark Vande Kamp Aviation Planning Executive Summary A combination of unobtrusive observation and interview methods was used to assess the effectiveness of a pilot program to encourage food-scrap recycling at Sea-Tac Airport. Results showed that: 1. Travelers who sorted their waste (i.e., the 25% who deposited waste in more than one bin) were willing to deposit food-scraps and compostable waste in the food-scrap bin (21% of all sorted deposits). 2. There was substantial opportunity to increase diversion of recoverable materials. At least 11 percent of travelers dumped waste that clearly included recyclable materials into the trash, and recyclable materials may have been present in all the waste deposited by the other travelers (64%) who dumped their waste in a single bin. 3. There was substantial opportunity to decrease contamination of recyclable materials. At least 15 percent of observed travelers incorrectly dumped all their waste in the recycling or food-scrap bin and an additional 11 percent of observed travelers sorted at least one item into an incorrect bin. 4. Problems with communication were likely responsible for much of the contamination of recyclable materials. In particular, the complexity of recycling guidelines and the need to keep signs simple left many travelers confused. As a result, those who sorted waste into the recycling bin were nearly as likely to deposit incorrect materials (11% of all deposits) as correct materials (12% of all deposits). The primary implication of the results is that the pilot program could increase its effectiveness by making it easier for travelers to correctly divert recyclable materials.

2 Food-scrap recycling at STIA -2- Background In 2010, Sea-Tac recycled about 23 percent of its waste (trash). By reducing the amount of trash going to landfills, the airport saved about $180,000. The latest goal is to increase the airport recycling rate to 50 percent. One way to move toward that goal is for travelers who purchase food to sort their waste into separate bins for, a) Paper/Plastic/Aluminum (recycling), b) compostable food waste, and c) trash. To test the effectiveness of such a program, five stations with sets of three such bins were placed in the Central Terminal food court. As part of this pilot program, a recycling behavior study collected information concerning travelers use of the recycling stations. Method Overview Two study components were used to describe the behavior and characteristics of travelers disposing of refuse in the Central Terminal. These components consisted of: 1. Unobtrusive observation of waste sorting and disposal into the recycle, food, and trash bins 2. A brief interview to collect demographics and information about recycling knowledge from some of the observed travelers Target population The study assessed the recycling behavior and characteristics of persons who disposed of waste after consuming food or drinks in the southern portion of the Central Terminal food court between October 3 and November 21, Observational study The survey crew consisted of a team of three. Two workers were stationed above the Central Terminal eating area at the railing of the Flight Deck employee dining area. From that area they could unobtrusively observe two of the five recycling stations at one time. When they observed a party finishing their food and preparing to depart, they selected one individual in the party who was carrying refuse and recorded: A. Was there a recycling information sign on the table? (Y/N) B. What was the primary concession/source of the refuse? (Palino, Q doba, etc.) C. Did the party pre-sort refuse before leaving the table? (Y/N/indeterminate) D. Direction of final approach to the recycling station? (back, front, side) When the individual reached the bins, the observer recorded: E. Did the individual pause in front of the bin before disposing of waste (Y/N)

3 Food-scrap recycling at STIA -3- F. What was their disposal behavior (by placing check marks in the appropriate boxes of this matrix) BIN Refuse Class Recycle Food Trash Recycle Food Trash Indeterminate This matrix recorded information about what waste they had and what they did with it. Depending on the cell checked, each deposit could be correct, incorrect, or indeterminate. Interview survey The third survey worker acted as the interviewer. He was clearly identifiable wearing a blue survey apron -- but stayed away from the recycling stations. After a traveler s disposal behavior was observed and recorded, one of the observers used a hand-held radio to tell the interviewer which traveler to approach for the survey. Travelers were approached after they had walked away from the recycling stations. On approach, the interviewer asked the traveler to participate in an airport survey taking less than 2 minutes. If the traveler hesitated, the interviewer offered to ask questions while walking with them. Interview responses were recorded using an ipad tablet computer running software from isurvey ( Questions included: 1. Is this your first time visiting Sea-Tac? 2. Is the main purpose of this trip business or leisure? 3. Did you know that Sea-Tac Airport has food-scrap recycling? 4. Do you have food-scrap recycling at your home or work? 5. Did you notice the signs on the waste bins explaining how to sort food waste, recyclables, and trash? a. (If noticed) Are the instructions on the signs confusing or clear? 6. What are the primary reasons that you think people might not recycle food scraps at Sea-Tac? 7. What year were you born? 8. What is your home zip code? (Country if outside US) 9. Where did you start your travels today? 10. Where will you be ending your trip?

4 Food-scrap recycling at STIA -4- Results Sample size Observations of disposal behavior could be (and were) made while the interviewer was busy conducting an interview. Thus, the total number of observations was much larger than the number of interview contacts (see Figure 1). Of travelers contacted for interviews, 78 percent agreed to participate. Observation and interview data were collected independently and 92 percent of interviews were matched to observation data based on the times Figure 1. Sample sizes. recorded in each data set. Accordingly, analyses involving both observed behavior and interview responses used only those travelers for whom data were matched. Disposal behavior Analyses of disposal behavior were organized hierarchically into several levels. The first distinguished between travelers who dumped all their waste in a single bin and those who sorted (i.e., placed waste in more than one of the three bins). Figure 2 shows that one-quarter of observed travelers sorted their waste. Figure 2. Travelers sorting waste.

5 Food-scrap recycling at STIA -5- Dumped deposits. Further analysis of each group tells us much more about diversion of recyclable materials and contamination of the recyclable waste streams during the pilot program. Figure 3 shows the percentage of all dumped deposits that fell into five different categories: Figure 3. 1) Uncertain content dumped in the trash bin. Most trash deposits were uncertain because many travelers put all their refuse in its original sack before disposal and observers were instructed (erroneously, in retrospect) to code such deposits as trash rather than indeterminate deposits. 2) Deposits in the trash bin containing some divertable material. Observers recorded recyclable material or food scraps in these deposits. 3) Incorrect/Contamination in the recycle or food-scrap bins. Observers recorded food scraps dumped in the recycle bin, recyclable material dumped in the foodscrap bin, or trash dumped in either bin. 4) Correct diversions. Deposits consisting of recycling or food scraps that were dumped in the correct bin. Deposits in the recycle or food-scrap bins that included indeterminate refuse but were otherwise correct were also included in this category. 5) Uncertain content dumped in the recycle or food-scrap bins. These deposits contained only indeterminate refuse. Sorting effectiveness. Travelers who sorted their waste into multiple bins were grouped into six categories. Figure 4 shows the different categories in order of

6 Food-scrap recycling at STIA -6- desirability for diversion of recyclable material. Almost 40 percent of travelers observed sorting sorted all items correctly, and (collapsing across categories) more than 40 percent (11% of all travelers) sorted at least one item incorrectly. For later analyses comparing the effectiveness of sorting, 1 to 6 points were assigned to each observed traveler who sorted waste, with 6 points for all deposits in correct bins. Figure 4.

7 Food-scrap recycling at STIA -7- Sorted deposits. Further analysis of sorting classified each observed deposit of waste (see Figure 5). Of the 854 sorted deposits (2.4 per sorting traveler), over 65 percent were deposited in the correct bin and 22 percent in the incorrect bin (note that divertable material deposited in the trash was classified as incorrect). The proportion of incorrect deposits was highest in the recycle bin, intermediate in the food-scrap bin, and lowest in the trash bin ( 2 (2, 749) = 79.3; p <.001). Figure 5. Trash was much more likely to be put in the recycling or food-scrap bins (129 deposits) than divertable materials were to be put in the trash bin (37 deposits; ( 2 (1, 724) = 39.0; p <.001)). Further analysis of incorrect recycling. The ratio of correct to incorrect deposits in the recycle bin varied depending on the outlets where travelers bought food. Figure 6 shows the five outlets where 19 or more travelers (a number sufficient to support statistical analyses), a) bought food, b) sorted their waste into multiple bins, and c) made at least one deposit in the recycle bin. Based on 2 tests of independence, the proportion of travelers making incorrect deposits was not related to the outlet for Qdoba (Mexican) and Maki (Asian food), incorrect deposits were significantly higher for Wendy s (burgers; 2 (1, 171) = 6.8; p =.009) and Ivar s (fish and chips; 2 (1, 171) = 6.0; p =.015), and were significantly lower for Pallino (Italian; 2 (1, 171) = 7.3; p =.007).

8 Food-scrap recycling at STIA -8- Figure 6. Table-top signs As part of the pilot program, some of the tables in the observed area had a vinyl sign covering the table top that explained and promoted recycling. The signs were intended to motivate travelers to sort their waste before leaving the table but such pre-sorting was observed only 14 times, and was not reliably more common at tables with signs. Travelers seated at table-top signs were not reliably more likely to sort their waste or to sort waste effectively. Those who dumped waste in a single bin were more likely to dump it in the correct bin when their table top had a sign (82%) than when the table was plain (75%; 2 (1, 882) = 6.6; p =.01). Direction of approach Because the bins had openings only on one side, observers recorded whether travelers approached from the front, back, or sides of the recycling station. Direction of approach made no statistically reliable difference in whether travelers sorted. There were marginally significant relationships between the direction of approach and the effectiveness of sorting (F(2,338) = 5.22; p =.096; approaches from the side were worst) and whether travelers dumped waste in the correct bin (F(2,1034) = 2.60; p =.075; approaches from the back were worst).

9 Food-scrap recycling at STIA -9- Set of bins observed Three different recycling stations were observed during the study. There were no statistically reliable differences between the stations in whether travelers sorted, or in travelers sorting effectiveness. The proportion of travelers that dumped all their waste in the correct bin differed by location (A = 77%, B = 70%, C = 82%; 2 (1, 1002) = 20.2; p <.001). Pause before deposit Travelers who sorted waste were much more likely to pause in front of the bins (73%) than those who dumped waste in a single bin (22%; 2 = 288; p <.001). Dumped waste was marginally more likely to be deposited in the correct bin by travelers who paused (84%) than those who did not (79%; 2 = 3.3; p =.068). Pausing was not reliably related to sorting effectiveness. Analyses of interview data The ability of these statistical analysis to detect small effects was somewhat limited by the number of travelers who completed interviews. In particular, analyses of sorting effectiveness were based on a maximum of 91 interviewed travelers who sorted their waste. Nonetheless, sample sizes were adequate to detect most moderate to large effects. Individual differences. The interview included five questions measuring individual differences in travelers: First time at Sea-Tac Business or leisure trip Have food scrap recycling at home or work Age Distance of residence from Sea-Tac None of these variables were reliably related to sorting, sorting effectiveness, or whether travelers dumped waste in the correct bin. Knowledge of pilot program. Travelers who sorted their waste were more likely to say that they knew Sea-Tac had food-scrap recycling (88%) than those who dumped waste in a single bin (68%; 2 = 14.0; p <.001). Reported knowledge was not reliably related to sorting effectiveness or whether travelers dumped waste in the correct bin. Noticed signs on bins. Of all interviewed travelers, 89 percent said they noticed the signs on the bins that explained how to sort waste. Travelers who sorted their waste were more likely to say that they noticed the signs (98%) than those who dumped waste

10 Food-scrap recycling at STIA -10- in a single bin (85%; 2 = 14.0; p <.001). Noticing signs was not reliably related to sorting effectiveness or whether travelers dumped waste in the correct bin. Of the travelers who said they noticed the signs, 22 percent said that they did not know that Sea-Tac had food-scrap recycling. Apparently not all travelers who noticed the signs read them very closely. Ratings of sign clarity. Travelers who said they noticed the signs were then asked if those signs were confusing or clear. Most (72%) reported that the signs were clear or very clear. However, caution is merited when interpreting these ratings for two reasons. First, because travelers who said they did not know that Sea-Tac had foodscrap recycling were just as likely to say the signs were clear (71%) as travelers who said they knew about the pilot program (72%). Second, because ratings of clarity were not reliably related to sorting, sorting effectiveness, or whether travelers dumped waste in the correct bin. Reasons for not recycling food scraps. Travelers were asked for the primary reasons they thought people might not recycle foodscraps. Figure 7 shows the most common responses. When comparing travelers who sorted and those who dumped waste in a single bin, there were no reliable differences in the frequency of listing any of these reasons. Analyses also tested whether the effectiveness of sorting or likelihood of dumping waste in the Figure 7. correct bin was related to reasons travelers listed for not recycling. Only one relationship was statistically reliable dumped waste was more likely to be deposited in the correct bin by travelers who listed inconvenience as a reason for not recycling (93%) than those who did not (76%; 2 = 6.4; p =.011). In general, the reasons given for not recycling were very consistent for people who did and did not recycle. Discussion To be effective, the pilot program must achieve two objectives, a) it must motivate travelers to divert recyclable materials from the trash by depositing recycling and food

11 Food-scrap recycling at STIA -11- scraps in the appropriate bins, and b) it must minimize contamination of the recyclable waste streams caused by deposits of incorrect materials. The discussion section begins by focusing separately on each of these objectives, and then examines the effectiveness of communication before concluding with several implications for the pilot food-scrap recycling program. Diversion The pilot program clearly demonstrated that many travelers (the 25% who sorted and 3% who correctly placed all their waste in the recycling or food-scrap bins) will divert recyclable materials. Prior to the pilot program none of the compostable material deposited in the food-scrap bin (21% of all sorted deposits) would have been diverted. The primary opportunity to improve diversion in the pilot program is by increasing the proportion of travelers who sort waste. 1 Under the current program, 25 percent of travelers sorted, but many more travelers could divert recyclable materials. Observations of travelers who dumped waste in a single bin showed that 11 percent of travelers were observed dumping recyclable materials into the trash (see Figure 3; 15% of dumping = 11% of all travelers), and that recyclable materials may have been present in all the waste deposited by the other travelers (64%) who dumped their waste in a single bin. Analyses of sorted deposits (see Figure 5) show that there is relatively little opportunity to increase diversion in that group. In fact, travelers who sorted appeared to be trying too hard to divert waste. They were much more likely to put non-recyclable material in the recycling or food-scrap bins (15% of sorted deposits) than to put recoverable materials in the trash bin (4% of sorted deposits). Discussion of ways to increase sorting is included in the section below concerning the implications of the study results. Contamination The largest source of contamination occurs when travelers dump all their waste (consisting entirely or in part of incorrect material) in the recycling or food-scrap bins. Figure 3 shows that such deposits are made by 15 percent of all travelers (20% of dumped deposits). Several marginally significant findings suggest that careful placement of the bins could decrease this source of contamination. Travelers approaching the recycling stations from the back were somewhat more likely to dump 1 Diversion is rarely accomplished without sorting only 3 percent of travelers correctly dumped all their waste in the recycling or food-scrap bins (see Figure 3; 4% of dumping = 3% of all travelers), probably because most purchases produce a mix of waste.

12 Food-scrap recycling at STIA -12- incorrectly than those approaching from the front or side (75% vs. 80%), and the direction of approach to the three observed recycling stations differed dramatically (A = 3% front, B = 2% front, C = 53% front), with more travelers dumping their waste incorrectly at the station where the most travelers approached from the back (A = 21%, B = 28%, C = 15%). Anecdotally, observers reported that they commonly saw travelers who approached recycling stations from the back or the sides quickly dump all their waste in the closest bin and then react (too late) when they noticed the sign saying the bin was for recycling or food-scraps. 2 Incorrect sorting was a smaller, but still significant source of contamination. Figure 5 shows that 18 percent of sorted deposits were placed incorrectly in the recycling or food-scrap bins. The challenge of improving sorting accuracy is discussed further in the section Effectiveness of instruction below. General effectiveness of communication Three different types of results collected in the study together provided mixed evidence regarding the effectiveness of communication in the pilot program; a) direct evaluation, b) reasons for not recycling, and c) relationships with disposal behavior. Direct evaluation. When asked directly, most interviewed travelers (89%) noticed the signs on the bins and a majority of them (72%) said the signs were clear. However, the validity of these ratings was cast into doubt because they were unrelated to measures of recycling knowledge and disposal behavior (see Ratings of sign clarity in the Results Section above). Reasons for not recycling. Several of the reasons given when respondents were asked why travelers might not recycle food scraps suggest that signs were not entirely effective ignorance and confusion were the second and third most commonly mentioned reasons. Relationships with disposal behavior. There were relatively few statistically reliable relationships between the three primary measures of disposal behavior (sorting, correct dumping, and sorting effectiveness) and having a table-top sign, having knowledge of Sea-Tac food-scrap recycling, noticing the signs on the bins, or pausing in front of the recycling station (necessary to read the signs). 2 Using different bins, so deposits could be made from more than one direction might help with the problem of orientation, but could complicate the design of the signs because the information would have to be visible from multiple directions.

13 Food-scrap recycling at STIA -13- These mixed results might best be understood in light of the multiple functions required of the pilot program communication. Effectiveness in serving three functions of communication Ideally, the signs in the pilot program would, a) alert travelers of the recycling program, b) instruct them how to correctly dispose of waste, and c) persuade them all to act as instructed. Effectiveness in alerting travelers. The findings that, a) the majority of travelers (73%) said they were aware that Sea-Tac had food-scrap recycling, and b) that most travelers (85%) either sorted their waste or dumped it in a bin that did not contaminate recyclable materials suggests that the signs were effective in alerting most travelers. The findings that travelers were more likely to dump all their trash in the correct bin when their tables had signs and when they paused in front of the bins also suggest that the signs served an alerting function. In addition, these results suggest a basic level of instruction most travelers apparently understood which bins should be used for recyclables and which for trash or mixed waste, but more detailed instruction about the specifics of sorting waste appeared to be less effective. Effectiveness of instruction. Effective sorting required that travelers understand detailed instruction. However, many travelers who sorted (44%) deposited at least one item in an incorrect bin, and a substantial portion of sorted deposits (22%) went into incorrect bins. Further analyses failed to support the hypothesis that the pilot program communication reliably increased sorting effectiveness there were no reliable relationships between sorting effectiveness and having a table-top sign, having knowledge of Sea-Tac food-scrap recycling, noticing the signs on the bins, or pausing in front of the recycling station. Instruction was particularly ineffective for the travelers who sorted waste into the recycling bin. Figure 5 shows that almost as many deposits in that bin were incorrect (11%) as were correct (12%). One factor contributing to this result was that some common waste items, such as paper cups, cardboard food baskets, or plastic silverware might appear (incorrectly) to belong in a bin with other paper and plastic recyclables. Further analysis by purchase outlet (see Figure 6) support this hypothesis because the outlets with the highest rates of incorrectly sorted deposits (Wendy s and Ivar s) use more of these materials and fewer materials that could be correctly recycled. Effectiveness of persuasion. The study results provide only weak tests for the persuasiveness of the pilot program communication. Sorting was reliably related to, a) knowledge of Sea-Tac food-scrap recycling, b) whether travelers noticed the signs, and c) whether they paused in front of the station, but it is at least as likely that sorting

14 Food-scrap recycling at STIA -14- caused the observed changes in the three measures regarding communication as it is likely that the measures of communication caused the sorting. Measures of recycling behavior provide a mixed picture of motivation. At least 11 percent of travelers (and likely many more) were not sufficiently motivated to sort recoverable materials when they dumped all their waste in the trash. However, the 25 percent of travelers who did sort waste seemed to be highly motivated. They were much more likely to put non-recyclable material in the recycling or food-scrap bins (15% of sorted deposits) than to put recoverable materials in the trash bin (4% of sorted deposits). Of course, it is unclear whether the pilot-program communication motivated them or they would have been highly motivated regardless. In either case, however, the data suggest that incorrect deposits by the travelers who sorted are more likely to occur because of misunderstanding than a lack of motivation. Summary of implications The primary implication of all the results is that the most effective way to increase the effectiveness of the pilot program would be to make it easier for travelers to correctly divert recyclable materials. During the study, the guidelines for what waste belonged in each bin were sufficiently complex and confusing that it took substantial training and practice before observers could correctly code traveler behavior. Accordingly, it seems likely that travelers reported that the signs were clear but also said that confusion keeps people from recycling because of a catch-22 type of situation a sign simple enough to be clear wasn t complex enough to fully instruct travelers in correct recycling. Anecdotal reports suggest that simplifying the diversion of recyclable materials would not only decrease contamination of the recyclable waste streams, but would also increase sorting. Observers reported that they commonly saw travelers approach the recycling station, pause briefly, and then dump all their waste in the trash with a shrug. Such travelers might sort their waste if it took minimal effort to understand how to do so correctly. There is some danger in the interpretation of null findings because the lack of a statistically reliable finding provides very weak evidence that the tested hypothesis is absent. Nonetheless, the study results showing no reliable differences in recycling behavior based on travelers demographic characteristics have positive implications for future recycling programs at Sea-Tac. It is simpler to design a single generic program than to design multiple programs targeted at multiple traveler groups with different recycling behavior. The only ways to make recycling guidelines simpler at Sea-Tac are for the food outlets to change their materials or for the recycling firms to change the materials they accept.

15 Food-scrap recycling at STIA -15- Such changes can be quite difficult. However, one relatively simple way to make recycling physically easier would be to change the placement of the bins at each recycling station. Figure 8 shows how the bins were most commonly placed, with considerable distance between each bin and often with imperfect alignment. Maintenance staff pushed the bins apart because the access door for emptying each receptacle was on the side of the bin. The study observers noted that this placement made it, a) more difficult for travelers to see all the signs at the same time and b) more difficult to sort waste correctly. Because this study did not manipulate the spacing of the bins we cannot quantify how many more travelers would have sorted their waste if the bins were placed together. Nonetheless, the bins used in any full scale program should be designed for placement next to each other because there is Figure 8. no reason why such placement should be a disadvantage and anecdotal evidence that wider spacing decreases recycling effectiveness. Finally, several additional results of the study support simplification of the recycling guidelines by illustrating difficulties inherent in the airport environment. Hurry and rush were the reasons most commonly mentioned when respondents were asked why travelers might not recycle food scraps, and over 20 percent of travelers refused to participate in our two-minute survey, even when the interviewer offered to walk along with them. Simplicity is crucial to the success of recycling programs in the airport environment because so many travelers are stressed and time-pressed, with little capacity to devote to recycling their waste. Although this paper has focused on ways to improve the pilot food-scrap recycling program, it is important to note that the program was very successful. Previously, all of the compostable material deposited in the food-scrap bins would have been sent to the landfill. Even with the challenges inherent in the Sea-Tac environment, many travelers sorted their waste, decreasing airport costs and placing a lighter burden on the environment.